wasa wastewater and potable water design requirements

Water And Sewerage Authority (WASA) Of Trinidad and Tobago

Water and Wastewater Design Guideline Manual

Revision 1 – October 2008

Water And Sewerage Authority (WASA) Water and Wastewater Design Guideline Manual Table of Contents

i October 2008R1

Major elements of revision no 1 – October 2008 :

In section 3.1, a minimum flood level requirement has been added.

In section 5.2.5.3, the minimum duration criteria for fire has been changed to one hour.

In section 5.6.2, the required specification for PVC pipe was changed.

In section 5.7.2, a new polyurethane coating section was added.

In section 6.6; 7.11; 12.16; 14.10, the height of fences have been reviewed to 2.1 m.

In a new section 6.2, requirements for impoundment reservoirs were added

In section 5.1 and 10.1, requirements for trenchless technologies were added

In a new section XX, criteria for As build and drawing standards were added.


ii October 2008R1

Table of Contents

Table of Contents

List of Abbreviations

Section 1 General Information .......................................................................... 1-1

Section 2 Design Approach & Approvals ......................................................... 2-1 2.1 Introduction ...................................................................................................................... 2-1

2.1.1 Multi barrier approach ........................................................................................................ 2-1 2.1.2 Sustainable development .................................................................................................... 2-1

2.2 Design Guidelines ............................................................................................................. 2-2 2.3 Review process of the guidelines ..................................................................................... 2-2 2.4 Approvals .......................................................................................................................... 2-2

Section 3 Design Standards ................................................................................ 3-1 3.1 Design requirements ......................................................................................................... 3-1 3.2 Acts, Codes and Standards ............................................................................................... 3-1 3.3 Other Design & Construction Standards .......................................................................... 3-2 3.4 Industry Standards ............................................................................................................ 3-2

Section 4 Process and Equipment Redundancy ............................................... 4-1 4.1 General .............................................................................................................................. 4-1 4.2 Minimum redundancy – Wastewater systems .................................................................. 4-1 4.3 Minimum redundancy – Drinking Water systems ............................................................ 4-1 4.4 Standby Power .................................................................................................................. 4-2 4.5 Standardization of Equipment .......................................................................................... 4-2

Section 5 Design of Water Distribution System ............................................... 5-2 5.2.1 Design Water Demand ........................................................................................................ 5-2 5.2.2 Average Water Demand (light industrial and commercial) ............................................... 5-3 5.2.3 Residential Per capita demand ............................................................................................ 5-4 5.2.4 Equivalent Population ......................................................................................................... 5-5 5.2.5 Fire Flow Requirements ...................................................................................................... 5-5 5.3.1 Pipe Design Flow ................................................................................................................ 5-6 5.3.2 Hazen Williams roughness coefficient ............................................................................... 5-6 5.3.3 Standard Pipe Sizes ............................................................................................................. 5-7 5.3.4 Minimum Pipe Sizes ........................................................................................................... 5-7 5.3.5 Pressure ............................................................................................................................... 5-7 5.4.1 Velocity ............................................................................................................................... 5-7 5.4.2 Pipe redundancy .................................................................................................................. 5-7 5.4.3 Pumping capacity ................................................................................................................ 5-8 5.5.1 Grid System ......................................................................................................................... 5-8 5.5.2 Location ............................................................................................................................... 5-8 5.5.3 Separation from Stormwater and Wastewater Mains ......................................................... 5-8 5.5.4 Pipe Depth ........................................................................................................................... 5-9 5.5.5 Valves .................................................................................................................................. 5-9 5.5.6 Hydrants .............................................................................................................................. 5-9


iii October 2008R1

5.5.7 Blow Off ............................................................................................................................ 5-10 5.6.1 Pipe Material ..................................................................................................................... 5-10 5.6.2 Pipe specification .............................................................................................................. 5-10 5.6.3 Structural Requirements.................................................................................................... 5-11 5.6.4 Tracer Wire ....................................................................................................................... 5-12 5.6.5 Water Service Connections ............................................................................................... 5-12 5.7.1 Polyethylene Encasement ................................................................................................. 5-13 5.7.2 Polyurethane coating ......................................................................................................... 5-13 5.7.3 Cathodic Protection ........................................................................................................... 5-13

Section 6 Drinking Water Reservoirs ............................................................... 6-1 6.1 General .............................................................................................................................. 6-1 6.2 Impoundment design ........................................................................................................ 6-1 6.3 Reservoir (tank) Design .................................................................................................... 6-1 6.4 Reservoir Capacity............................................................................................................ 6-2 6.5 Re-chlorination System Requirements ............................................................................. 6-2 6.6 Emergency Eye-wash ....................................................................................................... 6-2 6.7 Site Access Road and Security ......................................................................................... 6-2 6.8 Architectural ..................................................................................................................... 6-3 6.9 Structural .......................................................................................................................... 6-3 6.10 Mechanical ........................................................................................................................ 6-4 6.11 Ventilation ........................................................................................................................ 6-4 6.12 Instrumentation and Control ............................................................................................. 6-4 6.13 Alarms .............................................................................................................................. 6-5 6.14 Control System ................................................................................................................. 6-5 6.15 Equipment Redundancy .................................................................................................... 6-5

Section 7 Potable Water Pumping Stations ...................................................... 7-1 7.1 General .............................................................................................................................. 7-1 7.2 Pump design ..................................................................................................................... 7-1 7.3 Layout of Pumping Station ............................................................................................... 7-1 7.4 Equipment Redundancy .................................................................................................... 7-2 7.5 Pumping Station Requirements ........................................................................................ 7-2 7.6 Control System ................................................................................................................. 7-2 7.7 Instrumentation ................................................................................................................. 7-3 7.8 Alarms .............................................................................................................................. 7-3 7.9 Ventilation ........................................................................................................................ 7-4 7.10 Architectural ..................................................................................................................... 7-4 7.11 Site Access Road and Security ......................................................................................... 7-4

Section 8 Well Pumping Station Design ............................................................ 8-1 8.1 General .............................................................................................................................. 8-1 8.2 Well Construction ............................................................................................................. 8-1 8.3 Well Instrumentation & Control ....................................................................................... 8-2 8.4 Alarms .............................................................................................................................. 8-2 8.5 Preferred Layout ............................................................................................................... 8-3 8.6 SCADA System ................................................................................................................ 8-3 8.7 Equipment Redundancy .................................................................................................... 8-4


iv October 2008R1

Section 9 Water Treatment Plants .................................................................... 9-1 9.1 General .............................................................................................................................. 9-1 9.2 Drinking water standards .................................................................................................. 9-1

9.2.1 Microbiological ................................................................................................................... 9-2 9.2.2 Naturally occurring chemicals ............................................................................................ 9-2 9.2.3 Chemical contaminants ....................................................................................................... 9-3 9.2.4 Aesthetic guidelines ............................................................................................................ 9-6

9.3 Performance targets and treatment objectives .................................................................. 9-6 9.3.1 General ................................................................................................................................ 9-6 9.3.2 Minimum treatment objectives ........................................................................................... 9-7 9.3.3 Additional treatment objectives for Class I water supplies ................................................ 9-9

9.4 Calculations of the water treatment performance ........................................................... 9-10 9.4.1 General .............................................................................................................................. 9-10 9.4.2 Evaluation of the water treatment efficiency ................................................................... 9-11 9.4.3 Treatment based on physical removal of parasites and virus .......................................... 9-12 9.4.4 Treatment based on chemical inactivation of parasites and virus ................................... 9-14 9.4.5 Treatment based on physical inactivation of parasites and virus ..................................... 9-14

9.5 Treatment plant general design ....................................................................................... 9-15 9.5.1 Water intake ...................................................................................................................... 9-15 9.5.2 Monitoring ......................................................................................................................... 9-15 9.5.3 General design elements ................................................................................................... 9-15

9.6 Disinfection design guidelines ........................................................................................ 9-16 9.6.1 Chlorination System .......................................................................................................... 9-16 9.6.2 Ultraviolet Radiation (UV) ............................................................................................... 9-18

Section 10 Design of Wastewater Collection System ....................................... 10-1 10.2.1 Design Wastewater Flow .................................................................................................. 10-1 10.2.2 Average Dry Weather Flow .............................................................................................. 10-1 10.2.3 Peak Wastewater Flow Factor .......................................................................................... 10-3 10.2.4 Infiltration Allowance ....................................................................................................... 10-4 10.3.1 Manning’s Formula ........................................................................................................... 10-4 10.3.2 Coefficient of Roughness .................................................................................................. 10-4 10.3.3 Minimum Pipe Size ........................................................................................................... 10-4 10.7.1 Location of Wastewater Main .......................................................................................... 10-6 10.7.2 Pipe Depth ......................................................................................................................... 10-6 10.7.3 Grid Design ....................................................................................................................... 10-6 10.8.1 Concrete Pipe .................................................................................................................... 10-6 10.8.2 Polyvinyl Chloride Pipe .................................................................................................... 10-6 10.8.3 Polyethylene Pipe .............................................................................................................. 10-7 10.8.4 Glass Reinforced Plastics (GRP) Pipes and Fittings ........................................................ 10-7 10.8.5 Ductile iron ........................................................................................................................ 10-7 10.9.1 Maintenance Chamber Design .......................................................................................... 10-7 10.9.2 Manhole Hydraulics .......................................................................................................... 10-8 10.10.1 Street Line Connection ..................................................................................................... 10-8 10.10.2 Connection Size and Grade For Multi Family Sites ........................................................ 10-8 10.10.3 Pipe Material ..................................................................................................................... 10-9 10.11.1 System Design ................................................................................................................... 10-9 10.11.2 Pipe Size ............................................................................................................................ 10-9 10.11.3 Pipe Depth ....................................................................................................................... 10-10 10.11.4 Tracer Wire ..................................................................................................................... 10-10 10.11.5 Thrust restraint ................................................................................................................ 10-10


v October 2008R1

Section 11 Wastewater Treatment Plants ......................................................... 11-1 11.1 General ............................................................................................................................ 11-1 11.2 Wastewater Effluent treatment objectives ...................................................................... 11-2 11.3 Wastewater Loads ........................................................................................................... 11-2 11.4 Plant Layout .................................................................................................................... 11-2 11.5 Plant Design Capacity..................................................................................................... 11-3 11.6 Equalization tank ............................................................................................................ 11-3 11.7 Pre treatment – Inlet Works ............................................................................................ 11-3 11.8 Secondary and tertiary treatments .................................................................................. 11-4 11.9 Disinfection System ........................................................................................................ 11-4

11.9.1 Chlorination System .......................................................................................................... 11-5 11.9.2 Ultra-Violet (UV ) ............................................................................................................. 11-6 11.9.3 Sulphur Dioxide System ................................................................................................... 11-7

11.10 Sampling and monitoring ............................................................................................... 11-7 11.11 Odor Control ................................................................................................................... 11-7 11.12 Structural consideration .................................................................................................. 11-8 11.13 Water reuse for irrigation ................................................................................................ 11-8 11.14 Control System ............................................................................................................... 11-8 11.15 SCADA System .............................................................................................................. 11-9 11.16 Equipment Redundancy .................................................................................................. 11-9 11.17 Stormwater management ................................................................................................ 11-9

11.17.1 Combined Sewer System vs. Separate Sanitary Sewer .................................................... 11-9 11.17.2 Runoff impact .................................................................................................................... 11-9 11.17.3 Requirements ................................................................................................................... 11-10

Section 12 Wastewater Pumping Stations ........................................................ 12-1 12.1 General ............................................................................................................................ 12-1 12.2 Wastewater Pumping Station General Design ................................................................ 12-1 12.3 Wastewater Pumping Station Layout ............................................................................. 12-1 12.4 Configuration of Pumping System ................................................................................. 12-2 12.5 Wastewater Pumping Station Sizing Design .................................................................. 12-1 12.6 Wastewater Pumping Station (Inflow less than 20 l/s) ................................................... 12-1 12.7 Wastewater Pumping Station (20 l/s<Inflow < 200 l/s) ................................................. 12-1 12.8 Wastewater Pumping Station (Inflow > 200 l/s) ............................................................ 12-1 12.9 Pump Design ................................................................................................................... 12-2 12.10 Piping & Valve Design ................................................................................................... 12-2 12.11 Corrosion resistance........................................................................................................ 12-3 12.12 Pump Controls ................................................................................................................ 12-3 12.13 Odour Control ................................................................................................................. 12-4 12.14 Ventilation ...................................................................................................................... 12-4 12.15 Equipment and Material Specifications .......................................................................... 12-4 12.16 Site Access Road and Security ....................................................................................... 12-5 12.17 Instrumentation & Control Alarms ................................................................................. 12-5 12.18 SCADA System .............................................................................................................. 12-6 12.19 Equipment Redundancy .................................................................................................. 12-6

Section 13 Septage & Biosolids Management .................................................. 13-1 13.1 Septage Management – General ..................................................................................... 13-1

13.1.1 Stabilisation pond .............................................................................................................. 13-1 13.1.2 Wastewater Treatment Plant ............................................................................................. 13-1


vi October 2008R1

13.1.3 Alkali treatment ................................................................................................................ 13-2 13.2 Biosolids Management - General ................................................................................... 13-2 13.3 Sludge stabilization ......................................................................................................... 13-3

13.3.1 Aerobic digesters ............................................................................................................... 13-3 13.3.2 Anaerobic digesters ........................................................................................................... 13-3

13.4 Incineration and heat treatment ...................................................................................... 13-4 13.5 Dewatering ...................................................................................................................... 13-4

13.5.1 Sludge drying beds ............................................................................................................ 13-5 13.5.2 Vacuum filters, belt filters, belt filter presses, and other mechanical dewatering filters 13-5

Section 14 Architectural Standards .................................................................. 14-1 14.1 General ............................................................................................................................ 14-1 14.2 Laboratory control .......................................................................................................... 14-1 14.3 Roofing Design ............................................................................................................... 14-1 14.4 Windows ......................................................................................................................... 14-2 14.5 Doors .............................................................................................................................. 14-2 14.6 Ceiling ............................................................................................................................ 14-2 14.7 Wall Finishes .................................................................................................................. 14-2 14.8 Floor Finishes ................................................................................................................. 14-2 14.9 Light Fixtures ................................................................................................................. 14-3 14.10 Landscaping .................................................................................................................... 14-3

Section 15 Structural Standards ........................................................................ 15-1 15.1 General ............................................................................................................................ 15-1 15.2 Design of Water Retaining Structure .............................................................................. 15-1 15.3 Construction Requirements ............................................................................................ 15-1 15.4 Structural requirements ................................................................................................... 15-1

15.4.1 Concrete ............................................................................................................................ 15-1 15.4.2 Steel Reinforcement .......................................................................................................... 15-2 15.4.3 Precast Structural Concrete ............................................................................................... 15-2 15.4.4 Structural Steel .................................................................................................................. 15-3 15.4.5 Steel protection.................................................................................................................. 15-4 15.4.6 Concrete Block Masonry (C.B.M.) .................................................................................. 15-4

Section 16 Electrical Standards ......................................................................... 16-1 16.1 General ............................................................................................................................ 16-1 16.2 Equipment Identification Nameplates Requirements ..................................................... 16-1 16.3 Wiring Identification ...................................................................................................... 16-2 16.4 Panel Boards ................................................................................................................... 16-2 16.5 Seismic braces ................................................................................................................ 16-2 16.6 High Efficiency Electrical Motor ................................................................................... 16-2 16.7 Motor Control Centre ..................................................................................................... 16-2 16.8 Transformers ................................................................................................................... 16-3

16.8.1 High Efficiency Transformers .......................................................................................... 16-3 16.8.2 Distribution Transformers ................................................................................................. 16-3

16.9 Co-ordination Studies of Protective Devices .................................................................. 16-3 16.9.1 Co-ordination Studies of Protective Devices Report ....................................................... 16-3 16.9.2 Short Circuit and Protective Device Evaluation and Co-ordination Study ..................... 16-4 16.9.3 Protective Device Co-ordination Study ............................................................................ 16-4 16.9.4 Power System Study Report ............................................................................................. 16-5 16.9.5 Insulation Resistance Tests ............................................................................................... 16-5 16.9.6 Lamps ................................................................................................................................ 16-5


vii October 2008R1

Section 17 Instrumentation & Control ............................................................. 17-1 17.4.1 Design Criteria .................................................................................................................. 17-2 17.4.2 Interlocks ........................................................................................................................... 17-2 17.4.3 Field Instrument ................................................................................................................ 17-3 17.4.4 Indicators ........................................................................................................................... 17-4 17.4.5 Instrumentation Loops (Analogue) ................................................................................... 17-4 17.4.6 Control Circuits ................................................................................................................. 17-4 17.4.7 Automation of Treatment Process .................................................................................... 17-5 17.4.8 Variable Frequency Drive (VFD) Control ....................................................................... 17-6 17.4.9 Pump Control Systems for Wastewater Pumping Stations .............................................. 17-7 17.4.10 PLC/RPU Interface ........................................................................................................... 17-7 17.4.11 Services ............................................................................................................................. 17-7 17.4.12 Documentation .................................................................................................................. 17-7 17.4.13 Preventive Maintenance Program ..................................................................................... 17-8 17.4.14 Testing and Commissioning ............................................................................................. 17-9

Section 18 SCADA System ................................................................................. 18-1 18.2 SCADA Operating Characteristics ................................................................................. 18-1 18.3 SCADA System Requirements ....................................................................................... 18-2 18.4 SCADA System Control Levels ..................................................................................... 18-2

18.4.1 Field (Local) ...................................................................................................................... 18-2 18.4.2 Level 1 – Programmable Logic Controller (PLC) ........................................................... 18-3 18.4.3 Level 2 – PLANT .............................................................................................................. 18-3 18.8.1 Screen ................................................................................................................................ 18-7 18.8.2 Button Bars ........................................................................................................................ 18-7 18.8.3 Overview Screens ............................................................................................................. 18-8 18.8.4 Pop-Up Screen .................................................................................................................. 18-8 18.8.5 Control Pop-Ups Screens .................................................................................................. 18-8 18.8.6 Information Pop-Ups Screens ........................................................................................... 18-9 18.8.7 Setpoint Pop-Up Screens .................................................................................................. 18-9 18.10.1 Raw Water Monitoring Parameters (Water) .................................................................. 18-12 18.10.2 Treated Water Monitoring Program (Water) .................................................................. 18-13 18.10.3 Distribution System Monitoring Program (Water) ........................................................ 18-14 18.10.4 Raw Water Monitoring Program (Wastewater) ............................................................. 18-15 18.10.5 Treated Water Monitoring Program (Wastewater) ........................................................ 18-15 18.10.6 Process Parameters Monitoring Program (Wastewater) ................................................ 18-15 18.11.1 Trend Display Requirements .......................................................................................... 18-16 18.11.2 Water Treatment Plant Operating Statistics ................................................................... 18-16 18.11.3 Wastewater Treatment Plant Operating Statistics .......................................................... 18-19 18.13.1 Process Control Display .................................................................................................. 18-20 18.13.2 Standard Colour Convention – Process Stream ............................................................. 18-20 18.13.3 Standard Colour Convention – Pump/Motor/Valve ....................................................... 18-21

18.14 Symbols ........................................................................................................................ 18-21 18.17.1 General ............................................................................................................................ 18-22 18.17.2 SCADA System Operation Manual Requirements ........................................................ 18-23

18.18 System Architecture...................................................................................................... 18-26 18.24.1 PLC Program Structure ................................................................................................... 18-28 18.24.2 PLC Programming Protocol............................................................................................ 18-29

Section 19 Mechanical Standards ...................................................................... 19-1 19.1 General ............................................................................................................................ 19-1 19.2 Valves ............................................................................................................................. 19-1 19.3 Fittings ............................................................................................................................ 19-1


viii October 2008R1

19.4 Pumps ............................................................................................................................. 19-2 19.5 Piping & Equipment Identification ................................................................................. 19-3

19.5.1 General .............................................................................................................................. 19-3 19.5.2 Security equipment ........................................................................................................... 19-3 19.5.3 Piping Identification Labels .............................................................................................. 19-4 19.5.4 Colour Legend ................................................................................................................... 19-4 19.5.5 Method of Application ...................................................................................................... 19-6 19.5.6 Sizes of Characters ............................................................................................................ 19-7 19.5.7 Location of Labels ............................................................................................................ 19-7 19.5.8 Pumps & Valves Colour Schedule ................................................................................... 19-8 19.5.9 Nameplates ........................................................................................................................ 19-9 19.5.10 Equipment Name Tags .................................................................................................... 19-10

19.6 Equipment ..................................................................................................................... 19-10 19.6.1 Bearings ........................................................................................................................... 19-10 19.6.2 Pump Shaft Seals ............................................................................................................ 19-10 19.6.3 Couplings ........................................................................................................................ 19-10 19.6.4 Equipment Guard ............................................................................................................ 19-10 19.6.5 Gauge Taps and Test Plugs ............................................................................................. 19-10 19.6.6 Alignment ........................................................................................................................ 19-11

19.7 Equipment Maintenance Requirements ........................................................................ 19-11

Section 20 Ventilating & Air Conditioning Standards .................................... 20-1 20.1 General ............................................................................................................................ 20-1 20.2 VAC System ................................................................................................................... 20-1 20.3 Minimum Air standard ................................................................................................... 20-2 20.4 System Redundancy........................................................................................................ 20-2 20.5 VAC Control System ...................................................................................................... 20-2

20.5.1 VAC Master Control ......................................................................................................... 20-2 20.6 Verification of VAC System .......................................................................................... 20-2 20.7 Location of air intakes .................................................................................................... 20-2

Section 21 Diesel Generator Standard .............................................................. 21-1 21.1 General ............................................................................................................................ 21-1 21.2 Power Supply .................................................................................................................. 21-1 21.3 Approvals ........................................................................................................................ 21-1 21.4 Noise Attenuation ........................................................................................................... 21-1 21.5 Diesel Generator Power Requirements ........................................................................... 21-2

21.5.1 Water Supply System ........................................................................................................ 21-2 21.5.2 Wastewater Pumping Station ............................................................................................ 21-2 21.5.3 Ancillary Electrical and Mechanical Equipment ............................................................. 21-2

21.6 Diesel Generator System Operation ............................................................................... 21-2 21.7 Diesel Engine Requirements ........................................................................................... 21-3

21.7.1 General .............................................................................................................................. 21-3 21.7.2 Flame Detection System ................................................................................................... 21-3 21.7.3 Fuel System ....................................................................................................................... 21-3 21.7.4 Speed Governor ................................................................................................................. 21-3 21.7.5 Fuel Tank ........................................................................................................................... 21-4 21.7.6 Oil Lubricating System ..................................................................................................... 21-4 21.7.7 Intake and Exhaust System ............................................................................................... 21-4 21.7.8 Cooling System ................................................................................................................. 21-4 21.7.9 Ventilation System ............................................................................................................ 21-4 21.7.10 Gauges ............................................................................................................................... 21-5 21.7.11 Battery Start System ......................................................................................................... 21-5


ix October 2008R1

21.7.12 Failure Annunciator .......................................................................................................... 21-5 21.8 Generator Requirements ................................................................................................. 21-5

21.8.1 General .............................................................................................................................. 21-5 21.8.2 Voltage Regulator ............................................................................................................. 21-6

21.9 Control System ............................................................................................................... 21-6

Section 22 Treatment Plant Operation Manual ............................................... 22-1 22.1 General ............................................................................................................................ 22-1 22.2 Operation Manual Requirements .................................................................................... 22-1 22.3 Format of Operation Manual .......................................................................................... 22-1 22.4 Water Treatment Plant Operation Manual ...................................................................... 22-2 22.5 Wastewater Treatment Plant Operation Manual ............................................................. 22-4 22.6 Training on the Use of the Operation Manual ................................................................ 22-8 22.7 Training of WASA Staff ................................................................................................. 22-9

22.7.1 Training Provided by the Contractor ................................................................................ 22-9

I October 2008R1

List of Abbreviations

AI Analogue Input AO Analogue Output ANSI American National Standard Institute ARI Air-Conditioning and Refrigeration Institute ASHRAE American Society of Heating, Refrigerating and Air-conditioning

Engineers AWWA American Waterworks Association CAD Computer Aided Design CIBS The Chartered Institution of Building Services CPM Critical Path Method CV Curriculum vitae CVS Certified Value Specialist DI Digital Input DO Digital Output DTC Direct Torque Control EA Environnemental Analysis EIA Environmental Impact Assessment EPA Environmental Protection Act FAT Factory Acceptance Test FIDIC Federation Internationale Des Ingenieurs – Conseils

(International Federation of Consulting Engineers) HAZOP Hazard and Operability Study HFS Hydrofluosilicic Acid HLPS High Lift Pumping Station I&C Instrumentation and Control System (I&C) I/O Input / Output LOH Loss of Head MCC Motor Control Centre MoWT Ministry of Works and Transport MoALMR Ministry of Agriculture, Land and Marine Resources EMA Environmental Management Agency MoH Ministry of Health MoPD Ministry of Planning and Development

Water And Sewerage Authority (WASA) Project Design and Technical Specifications Manual List of Abbreviations

II October 2008R1

MoPUE Ministry of Public Utilities and the Environment NSF National Sanitation Foundation NTU Nephelometric Turbidity Units P&ID Proportional and Integral Derivative PDR Pre-Design Report PID Proportional Integral Derivative PLC Programmable Logic Controller QA Quality Assurance QC Quality Control RFP Request for Proposal RIC Regulated Industries Commission RPU Remote Processing Unit SAT Site Acceptance Test SCADA Supervisory, Control and Data Acquisition SMACNA Sheet Metal and Air Conditioning Contractors' National Association SPMDD Standard Proctor Maximum Dry Density THD Total Harmonic Distortion TKN Total Kjeldahl Nitrogen TTBS Trinidad & Tobago bureau of Standards UV Ultra Violet VAC Ventilation and Air Conditioning WASA Water And Sewerage Authority of Trinidad & Tobago WTP Water Treatment Plant WWTP Wastewater Treatment Plant WHO World Health Organisation

Water And Sewerage Authority (WASA) Water and Wastewater Design Guideline Manual General Information

1-1 October 2008R1

Section 1 General Information

As Trinidad & Tobago moves toward a 2020 vision of a modern and developed country, new and refurbished water and wastewater infrastructures are needed all around the islands. The Water And Sewerage Authority (WASA) of Trinidad and Tobago has put together this document in order to guide the engineering design and establish the recommended standards for all new water and wastewater infrastructure.

WASA has the responsibility for the provision of water supply and sewerage services in Trinidad and Tobago, under Water and Sewerage Act, chapter 54:40. Increasing the levels of service provided to the population has been a continuous concern for WASA. The present guidelines are adapted to Trinidad and Tobago’s context and are compatible with WASA’s long term operational policies. They present a comprehensive document for the construction and rehabilitation of new and existing water and wastewater infrastructures.

The 2020 vision requires capital works from the government of Trinidad & Tobago in order to meet the goals set. The implementation of water, wastewater and linear services projects requires the services of Consultants to provide the required engineering expertise in accordance with the requirements as specified herein. Consultants should therefore familiarize themselves with these guidelines and provide their services accordingly to meet WASA’s expectation.

These guidelines are primarily intended to outline acceptable levels of servicing and minimum criteria for future infrastructure in Trinidad & Tobago. They will assist consulting engineers, engineering staff and other designers in the preparation of water and wastewater system infrastructure design. Some of the design standards, detailed herein this manual, are not currently used by WASA in the implementation of water and wastewater projects. These include the Supervisory, Control and Data Acquisition system. However the information contained herein will serve as a preliminary basis for consideration by WASA and should be followed if no other directives have been stated.

This Water and Wastewater Design Criteria Manual is the property the Water And Sewerage Authority (WASA) of Trinidad and Tobago. The design guidelines as detailed herein are for the implementation of water and wastewater projects, including linear services and treatment plants.

The stipulated design guidelines must be complied with unless dispensation has been obtained in writing from WASA or specified in the Request for Proposal,

Other References

This manual shall be used in conjunction with:

1. All rules, laws and regulations of the Republic of Trinidad and Tobago

2. Project’s Tender documents

3. WASA requirements and standards

4. Policies and Guidelines from stakeholders

Water And Sewerage Authority (WASA) Water and Wastewater Design Guideline Manual Design Approach & Approvals

2-1 October 2008R1

Section 2 Design Approach & Approvals

2.1 Introduction These guidelines do not supersede nor replace any legislation governing the design of such treatment plants. Options and design optimisation are still to be conducted and investigated at the prefeasibility level. The Consultants must be fully familiar with Trinidad & Tobago legislations with respect to the design of water and wastewater infrastructure.

The guidelines and standards, as provided herein, were set by WASA in order to guide and frame the engineering and consultancy works and assure a standardised and adequate design level in the implementation of such systems. Approvals by WASA of infrastructures will require compliance to these guidelines in conformity with WASA’s Water and Wastewater Policies.

Since standards, technology and priorities evolve, this manual is aimed to be reviewed frequently and consultants are to assure that they are using the latest revision.

2.1.1 Multi barrier approach

In conformity with WASA’s policies, in order to ensure clean, safe and reliable drinking water, a multi barrier approach is to be implemented from the source all the way to the consumer's tap. This requires an understanding of the general characteristics of the water, the watershed or land surrounding the water source, as well as mapping all the potential threats to the water quality. The approach of the required design is to provide for barriers to either eliminate the threats or minimize their impact. It includes protecting the available source from contamination, using effective water treatment, and preventing water quality deterioration in the distribution system. Together the barriers work to provide greater assurance that the water will be safe to drink.

2.1.2 Sustainable development

An integrated water resources perspective ensures that social, economic, environmental and technical dimensions are taken into account in the management of water resources. WASA wishes to promote practices that encourage sustainable development so there won’t be any compromising of future generations’ ability to meet their needs.

As examples, protection of well’s head, installation of domestic water meters, and setting wastewater effluent standards are part of the sustainable approach provided in this manual. These are some of the good practices needed to assure long term sustainable and valuable water for Trinidad & Tobago.

The water treatment standards and guidelines are established to ensure production of safe drinking water. The amount and minimum scale of treatment processes are based on type and quality of raw water, including their variability.

Water And Sewerage Authority (WASA) water, wastewater and linear services projects Design Approach & Approvals

2-2 October 2008R1

2.2 Design Guidelines This manual provides details on the design of water and wastewater related infrastructure so that a standard of quality, reliability and uniformity will be achieved for WASA services to the population of Trinidad & Tobago. It covers a wide range of applicable standards and characteristics that need to be considered in order to assure the minimal quality requested. Items covered by this manual include the following:

1. Equipment redundancy

2. Architectural standard

3. Structural standard

4. Underground pipelines

5. Electrical standard

6. Mechanical standard

7. Instrumentation & control standard

8. Emergency standby diesel generator standard

9. Equipment coding system standard

10. Operation & maintenance manual standard

11. Water quality and treatment standard

12. Wastewater effluent and treatment standards

13. SCADA

2.3 Review process of the guidelines As technology, exigencies and standards evolve; these guidelines will have to be submitted for a regular review by WASA in order to reflect the latest findings and comments. It is recommended that this document be revised at minimum every five (5) years to comply with the best interest of the population of Trinidad & Tobago.

2.4 Approvals The Consultants shall comply with, and shall conduct all work with cognisance given to all relevant statutory regulations and requirements, and where required, shall apply for all relevant approvals or certificates.

In all cases, the Water and Sewerage Authority (WASA) should have granted approvals on the outline and details of all projects prior to the installation of any facility. The WASA’s administrative procedures are part of another document that must be consulted.

Water And Sewerage Authority (WASA) water, wastewater and linear services projects Design Approach & Approvals

2-3 October 2008R1

In addition, all projects must meet Environmental Management Authority (EMA) approvals by obtaining a Certificate of Environmental Clearance (CEC). Depending on the type of project, an Environmental Impact assessment (EIA) may be required as established by EMA.

The Consultants shall comply with other stakeholders’ Policies and Rules, or tender documents. They shall prepare all required documents for submission and review with WASA.

The Consultants must deliver to WASA a status report of all the applications for approvals required for the project. Where there are outstanding approvals, the Consultants shall indicate the time frame within which these approvals are expected to be in place.

Consultants are responsible for ensuring that plants designed by them comply with Acts, Codes, Standards and Guidelines. The Standards and Guidelines provided in this manual are intended to set the minimum acceptable standard and not to relieve them of their responsibilities to comply with their legal and contractual requirements and obligations.

For detailed information about WASA’s administrative procedures for review, including costs, type and number of copies of documents to submit for approval, consult WASA’s approval process documentations.

Water And Sewerage Authority (WASA) Water and Wastewater Design Guideline Manual Design Standards

3-1 October 2008R1

Section 3 Design Standards

3.1 Design requirements It is the Consultant’s responsibility to ensure that they have fully understood the requirements of the project as detailed in the Request for Proposal as they will be required to fulfil the specified scope of work.

The infrastructure work includes both water and wastewater projects. WASA retains the services of Consultants to provide the required engineering expertise to implement these projects in an integrated manner with all building, safety and quality requirements. WASA requires and expects that the Consultant will comply with the requirements as specified herein and therefore provide their services accordingly to meet this expectation.

All materials and equipment supplied shall be suitable for being delivered, store and operated under tropical conditions of high temperature, high humidity, heavy rainfall, mildew and fungus conductive environment.

All WASA buildings or structures shall be flood proof. The site for the new facility shall be appropriately selected or designed to be above the 20 years recurrence interval flood line.

When standards are provided, they are minimum requirements to be met by the system. When specified, these standards are mandatory unless otherwise specified in writing by WASA. Mandatory standards include drinking water quality standards and wastewater treatment plant effluent standards.

3.2 Acts, Codes and Standards The design of infrastructure shall comply with the following regulations, Acts, Codes, Standards, Guidelines for all projects undertaken by Consultants on behalf of WASA:

1. Environmental Management Authority (EMA) of T&T

2. Water And Sewerage Authority (WASA) of Trinidad and Tobago

3. Ministry of Public Utilities and Environment (MoPUE)

4. National Building Code

5. National Fire Code

6. OSHA

The standards specifications for materials should be consistent with the requirements of the following:

1. Trinidad and Tobago Standards (TTBS)

2. International Standards (ISO)

3. North American Standards (ANSI/AWWA)


3-2 October 2008R1

4. British Standards (BS)

3.3 Other Design & Construction Standards Consultants shall comply with all Trinidad & Tobago technical rules and regulations related to the design and construction of treatment plants as well as linear services.

Stakeholders if applicable should be included in the design. The T&T water and wastewater stakeholders include but are not limited to:

- Ministry of Public Utilities

- Town and Country Planning Division

- Environmental Management Authority (EMA)

- Ministry of Local Government

- Ministry of Works and Transport

- Ministry of Finance

- Ministry of Health

- Regulated Industries Commission

- Ministry of Agriculture, Land and Marine Resources

- Office of the Ombudsman (Ministry of Legal Affairs)

- Consumer Affairs Division (Ministry of Legal Affairs)

- Water Recourses Agency and Forestry Division

- Trinidad & Tobago Fire Services

3.4 Industry Standards All materials for potable water and sewers shall meet the ASTM, AWWA or other approved equivalent standards. The Standards also provide literature on Workmanship. The following standards are listed for guidance and are not final or exclusive to other standards.


3-3 October 2008R1

Storage Tanks

Welded Steel Tank Painting for Welded Steel Tanks Factory Coated Tanks Disinfection Concrete Structures for Retaining Liquids

ANSI/AWWA D100-84 ANSI/AWWA D102-78 ANSI/AWWA D103-80 ANSI/AWWA D652-86 AS 3735 1991

Pipelines

Polybutylene (PB) Polyethylene (PET) Poly Vinyl Chloride (PVC) Fabricated Steel Pipe and Fittings Steel Pipe Flanges Class D Coal tar protection coatings and linings for steel water pipelines Flanged Ductile Iron Pipelines Rubber Gasket Disinfection Pressure Test Grey Iron Casting GRP Elastometrix Joint Rings for pipework and pipelines Flanges and bolting for pipes valves and fittings metric series (copper alley and composite flanges) Metal Washers for General Engineering Purposes Metric Series Specifications for Poly Vinyl Chloride (PVC) Solvent Cement for use with unplasticized PVC Pipes and fittings for cold water applications Cast Iron Non-pressure pipes and pipe fittings metric units

AWWA C-902-78 AWWA C-901-78 AWWA C-900-75 AWWA C-208-83 AWWA C-207-86 AWWA C-203-86 AWWA C-115/A21 AWWA C-111/A21 AWWA C-651-86 AWWA C-600-82 BS 1452:1977 AWWA C 950 - ASTM D 3754

BS 2494:1986 BS 4504: Part 2 1974 BS 4320:1968 TTS 413-1992 AS 1631-1974


3-4 October 2008R1

Valves

Ball Valves Rubber Sealed Butterfly Valves Sluice Valves Predominantly key Operated Cast Iron Valves for Waterworks purposes Butterfly Valves Copper Alloy Gate Valve and Non-Return Valves for use in water supply and hot water services Float Operated Valves Specifications for Piston Type Float Operated valves (Copper Ally Body) (Excluding Floats) Specifications for Diaphragm type float operated valve (copper Alloy Body) (Excluding Floats) Specifications for Diaphragm type operated valves plastic bodies, for cold water services only excluding floats Draw off taps and stop valves for water services (screw down pattern)

AWWA C-507-85 ANSI/AWWA C-50 AWWA C-501-86 BS1 5163:1986 BS 5155:1984 AS 1628:1977 BS 1212 PT 1 1990 PT 2 1990 PT 3 1990 BS 1010 PT 2 1973

Safety Valves

Safety Valves Specification for safety valves for steam and hot water

BS 6759 PT 1 1984

Mixing Valves

Mixing Valves Non-Thermostatic, Non-Compensating mixing valves Specification for Thermostatic mixing valves

BS 1415 PT 1 1976 PT 2 1986


3-5 October 2008R1

Various standards

Glass Filament reinforced thermosetting plastics (GRP) Pipes Polyester Based-Water Supply. Sewerage and Drainage Applications Water Supply Metal Bodied Taps – Specified by performance Water Well Casing Specification for steel tubes for casing Specification for thermoplastics tubes for casing and slotted casing Stationary circulation pumps for heating and hot water service system Specification for Cold Water Storage and combined feed and expansion cisterns (polyolefin or olefin copolymer) up to 500L capacity used for domestic purposes Multi Standard Measurement of flow of cold potable water in closed conduits Safety and control Devices for use in hot water systems Code of Practice for test pumping of Water Well Storage Cisterns up to 500L Actual Capacity for water supply for domestic purposes Bitumen – based coatings for cold application, suitable for use in contact with potable water Bitumen based hot applied coating materials for protecting iron and steel including suitable primers were required Water Quality (Multi Standards) Physical, Chemical and Biochemical methods

AS 3571 1989 AS 3718 – 1990 BS 879 PT 1 – 1985 PT Z – 1988 BS 1394 BS 4213 – 1991 BS 5728 BS 6283 BS 6316 – 1992 BS 7181 – 1989 BS 3416 – 1980 BS1 4147 – 1980 BS 6008 PT 2


3-6 October 2008R1

Water Meters

Cold – Water Meters – Multi – Jet Type ANSI/AWWA C 708-82

Cold – Water Meters – Displacement Type Cold – Waters – Turbine type for customer service Filtering material Meters for cold potable water

ANSI/AWWA C 700-7 ANSI/AWWA C 701-78 ANSI/AWWA B 100 AS 3565 - 1988

Water Sampling

Water Quality – Sampling Pt 1 Guidance on Design of Sampling Programmes 13 p PT 2 Guidance on sampling technique PT 3 Guidance on the Preservation and handling of samples PT 6 Guidance on sampling of rivers and streams PT 8 Guidance on sampling of Wet depositions PT 9 Guidance on sampling from marine waters PT 10 Guidance on sampling of waste waters PT 11 Guidance on sampling of Ground waters

ISO 5667 – 1980 ISO 5667 – 1991 ISO 5667 – 1987 ISO 5667 – 1990 ISO 5667 – 1993 ISO 5667 – 1992 ISO 5667 – 1992 ISO 5667 – 1993

Water Testing of Pipes

Methods of test for unplasticized polyvinyl chloride (PVC) Pipes. PT4 - Effects of Sulphuric Acid – Requirements and Test method Method of test for unplasticized PVC pipes and fittings PT 3 - Determining the fracture toughness of UPVC Pipes Methods of test for unplasticized PVC pipes PT8 - Method for Hydrostatic pressure testing of UPVC short term test Methods of test for unplasticized PVC Pipes PT 9 - Methods of test for hydrostatic pressure testing of UPVC pipes long term test Methods of test for unplasticized polyvinyl chloride

TTS 16 80 30 PT 4 - 1991 TTS 16 80 30 PT3 - 1991 TTS 16 80 30 PT8 - 1991 TTS 16 80 30 PT9 - 1991 TTS 16 80 30 PT7 1991


3-7 October 2008R1

(PVC) Pipes PT 7 - resistance to external blows

Wastewater systems

Cement Aggregate Steel (Reinforcer) Structural Steel Manhole Bricks Precast Sections Manhole Frames Cones Reinforced Concrete Pipes Non reinforced Concrete Pipes Welded Steel Pipe Steel Fitting Couplings Gate Valves Sluice Valves Drain Pipes and Fittings Sewer Grey iron Ductile Iron Thermoplastic Pipe for Sewers Thermoplastics waste pipes and fittings Polypropylene Waste pipe and fittings (external Diameter 34.6 mm 41.0 mm 54.1mm) Unplasticized PVC (UPVC) Pipes and Fittings for storm and surface water applications Unplasticized PVC (UPVC) Pipes and Fittings for soil waste and vent (SWV) applications Design charts for water supply and sewerage Water supply – Mechanical backflow prevention devicesPlastics Waste Fittings Specifications for compact type float operated valves for WC Flushing Cisterns (including floats) Specification for Galvanized low Carbon Steel, Cisterns, lid tanks and Cylinders Specification for unplasticized PVC Drain, Waste and vent pipes Technical Drawing Installation, Graphical symbols for supply water and drainage systems

ASTM C-150 -60 ASTM C-33-59 ASTM A-15-58T ASA-ASA A57 1-1952 ASTM C-32-58 Grade MA ASTM C-478-61T usina Type II cement ASTM A48-60T ASTM C76-60T ASTM C14-59, l AWWA C 202-59 AWWA (Same as Water) ASA B16 10-1957 AWWA C 501-41T BS 4660 BS 4660, BS 5481 or Class B, BS 3505 BS 4622 BS 4772 ASTM D 2321, F-894 BS 5255 – 1989 BS 5254 – 1976 AS 1254 AS 1415 PT 1-4 AS 2200-1978 AS 2845-1986 AS 2887 – 1986 PT 4 -1991 BS 417 TTS 414-1992 TTS 31 85 006 PT 6 – 1998

Recommendations for the Design of buildings, plumbing and drainage systems

TTS 16 90 400 PT 4 - 1985

Water And Sewerage Authority (WASA) Water and Wastewater Design Guideline Manual Process and Equipment Redundancy

4-1 October 2008R1

Section 4 Process and Equipment Redundancy

4.1 General The provision for process and equipment redundancy depends on the process and/or the functionality of the associated process equipment. In the design of Water and Wastewater facilities, Consultants must ensure that the level of redundancy for process and/or equipment is provided such that the treated wastewater effluent or quality of the drinking water will be in compliance with the Design guidelines & Environmental Management Authority (EMA) Certificate of Environmental Clearance Rules or objectives at all times.

The current standard for provision of process and equipment redundancy level in water and wastewater treatment plants is minimal. As existing plants are upgraded or expanded in the future, key process equipments are to be provided with the redundancy level to safeguard the supply of potable water or the discharge of treated wastewater to the environment.

4.2 Minimum redundancy – Wastewater systems To ensure that the plant’s treated wastewater effluent will be in compliance with WASA’s criteria or objectives at all times, the following minimum level of redundancy for equipment and treatment processes shall be provided:

1. To ensure that the process train is available to meet the wastewater plant’s treatment capacity requirements, the minimum redundancy of unit processes such as aeration tankages, clarifiers, screens, etc. shall be equal to 50% of the total design capacity with the largest unit processes out of service.

2. Similarly, to ensure that the wastewater flow will be handled to meet the required hydraulic throughput, pumping stations shall be generally sized and installed with a 100% redundancy with the largest equipment unit out of service. See section 12 for more details.

3. Pipe lines and forced mains do not require redundancy.

4.3 Minimum redundancy – Drinking Water systems To ensure that the drinking water quality will be in compliance with WASA’s criteria or objectives at all times, the following minimum level of redundancy for equipment and treatment processes shall be provided:

1. To ensure that the process train is available to meet the drinking water treatment plant’s capacity requirements, the minimum redundancy of unit processes such as clarifiers, chemical dosers, filtration unit, etc. shall be equal to 100% of the total design capacity with the largest unit processes out of service.

2. Similarly, to ensure that the water flow will be handled to meet the required hydraulic throughput, pumping stations shall be sized and installed with a 100% redundancy with the largest equipment unit out of service. Other distribution equipment such as piping,


4-2 October 2008R1

valves, pressure reducing valves and water tanks do not require redundancy. See section 7 for more details.

3. Main water trunk systems should allow for some level of redundancy by aiming for smaller double parallel pipe layout with adequate valving rather than one large pipe diameter.

4.4 Standby Power Whenever feasible, power supply to WASA’s plants shall be provided with dual feed from the power supply grid network. Where this is not possible, standby power shall be provided in the following key process system:

1. Wastewater treatment plant

.1 SCADA System

.2 Plant VAC System

.3 Plant disinfection system

.4 All equipment required to enable effective treatment for plants discharging in environmentally sensitive areas.

2. Water intake pumps and equipment

3. Water Treatment Plant

.1 All equipment that is required to be operational to enable the water treatment plant to meet average day demand is to be provided with standby power or an alternate source of power.

3. Potable Water Pumping Station on main trunk systems. Other pumping stations shall be assessed to establish criticality based on network configuration, gravity feed reservoirs, type of supplied customers etc.

4. Wastewater Pumping Station

Power ratings for standby power are defined by ISO 8528-1 as the power available in the event of a main power network failure up to a maximum of 500 hours per year of which up to 300 hours may be run continuously. Load factor may be up to 100% of standby power. No overload is permitted.

4.5 Standardization of Equipment Consultants shall ensure that the selection of equipment for use in the plants shall be standardized as much as possible. In all cases, consultants must first refer to WASA’s available list of approved suppliers and manufacturers for each application. For each process, the variety of major equipment manufacturers should be limited to a maximum of three. The advantages of keeping the selection of equipment to a maximum of three are:


4-3 October 2008R1

1. Reduction of time required to review design information

2. Minimize the inventory of spare parts

3. Reduction of time for staff to become fully familiarized with new equipment and facility

In general, consideration shall be given for new equipment to be from the same manufacturer as those that are already installed in the same unit process train. This requirement will be reviewed at the detailed design stage and alternate equipment or technology will be considered at that time.

Approved and alternate equipment shall be specified in the tender document such that WASA has the right to accept or reject any equipment that the Contractor proposes to supply under the contract.

Water And Sewerage Authority (WASA) Water and Wastewater Design Guideline Manual Design of Water Distribution System

5-2 October 2008R1

Section 5 Design of Water Distribution System

5.1 General Requirement This section outlines the requirements for the design of water supply systems. However, the Consultants shall apply sound engineering judgement and approach to the design of such systems. All designs shall comply with Trinidad & Tobago National Plumbing Code, AWWA Standards of Practice and Specifications, relevant codes or design guidelines. The designs must as much as it’s applicable, include mechanism for water conservation, including but not limited to pressure control devices, low flush toilets, low volume faucets, etc.

Notwithstanding the above, the Consultants shall be familiar with the policy and standards related to fire protection services requirements in Trinidad & Tobago.

In all projects, assessment of trenchless construction techniques and rehabilitation methods for existing pipes shall be thoroughly prepared. The assessment shall as a minimum cover the geotechnical conditions, traffic disruptions, survey the existing utilities and sub surface structures, obtain right-of-way and property line information, take account of possible improvements to street or utilities, risk and safety, and include technology aspects on construction and costs etc. For all new communities, the Consultants shall establish the geodetic invert elevations and ties of all water service connections at the street line. All of this information shall be incorporated on the “As-built” plans. To avoid proliferation of booster stations and reservoirs within each development, each project should be assessed through modelling of regional network and optimum development scheme. WASA’s Master Plan for Trinidad & Tobago should be reviewed to grasp the bigger communities and regional planning priorities.

5.2 Water Demand In the past years, many studies have been undertaken to assess the water demand for the different types of consumers in Trinidad & Tobago. The available information is usually scarce and significant variations exist between the different studies. The following design criteria for water demands is based on different sources, notably the 1994 “Project Memoranda on Existing and Future Demands” by William Halcrow & Partners Ltd., the 2006 “Analysis and Estimation of Water Demand Forecasts” by Gordon Wyke, and various international figures including British and North American standards.

5.2.1 Design Water Demand

The system shall be designed to meet the greater of either of the following demands:

1. Maximum Daily Demand Plus Fire Flow

2. Maximum Hourly Demand


5-3 October 2008R1

Where applicable, individual studies shall be conducted for the following:

1. Special commercial establishments and major commercial areas

2. Special industries and major industrial areas

3. Institutional development

4. High density residential areas

5.2.2 Average Water Demand (light industrial and commercial)

If individual data is not available, the following typical numbers should be used in order to establish the daily average flow demand for light commercial and industrial facilities (sources : WASA, Metcalf & Eddy) :

Facilities - Consummation per usage [L/(capita·d) or L/(unit·d)]

Airport (per passenger) 15 Shopping malls

Per parking spot 8 Per employee 40

Vacation center

Vacation colony ; central bathroom (per person) 160 – 200 Workers

Work camp with bath facilities (per worker) 140 – 200 Theatre

Per seat 10 Outdoor (per car) 15

School (per student) With cafeteria 50 – 60 With cafeteria, shower and gymnasium 80 – 100 Boarding school or University Dormitory 285

Offices (per employee) 60 Health care facilities

General hospital (per bed) 1000 General hospital (per employee) 40 Other institution (per bed) 400

Hotels and hostels Hotel room (per client) 200 - 300 Room and pension (per person) 200 Motel with kitchen 400 – 600 Laundry self service (per customer) 190


5-4 October 2008R1

Conference center (per person) 30 Stores

Per customer 8 Per employee 40

Restaurants Medium size restaurant (per seat) 150 Medium size restaurant; open 24 h (per seat) 200 Bar (per place) 80

Gas station Per car served 30 Per employee 50

Industrial facility (small to medium size) Without cafeteria or shower (per employee) 70 With cafeteria and shower (per employee) 140

5.2.3 Residential Per capita demand

Residential Water demands have been historically high in Trinidad & Tobago. As water meters are installed throughout the country, it is expected that residential water consumption will linearly be lessened by 10% by 2020. When possible, per capita consumption and peaking factors should be determined from historical data for the area. The following design factors, based on the “Water Consumption & Demand Study” GENIVAR (2008), are to be used for the design of residential water distribution systems in the absence of actual flow data:

Water demand 2007 2020

Residential per capita demand

Trinidad

330 litres/cap.d

280 litres/cap.d

Residential per capita demand

Tobago

315 litres/cap.d

280 litres/cap.d

Note : The demand per capita does not include any unaccounted for water (UFW) which is historically very significant in Trinidad & Tobago. Depending on the region, the project and the state of the distribution system, a case by case analysis is required for each project to include the UFW and leakages of the system.

Maximum Daily and Maximum Hourly Demand Factors as noted in the table below:


5-5 October 2008R1

Peak Demands: Peak Day Peak Hour

Population 0 - 1,000 3 x Avg. Day 1.5 x Peak Day

Population 1,000 - 5,000 2.5 x Avg. Day 1.5 x Peak Day

Population 5,000 – 25 000 2.0 x Avg. Day 1.5 x Peak Day

Population > 25 000 1.5 x Avg. Day 1.5 x Peak Day

5.2.4 Equivalent Population

The design population is to be the ultimate for the area under consideration, the design life threshold or local recommendation. The following equivalent population densities shall be used to estimate the water service demand for the different types of developments in the design of water distribution systems.

The average daily demand shall take into account water distribution system leakages, water conservation as well as night time usage. The daily minimum flow is set as 35% of the average daily flow. 3. Recommended flows to be used are (area is development area excluding major public streets, freeways and railroad areas): Single Family Residential 13 litres/min/ha

Multi-Family Residential 20 litres/min/ha Walk-up Apartments 26 litres/min/ha Community Services 10 litres/min/ha Light Commercial 22 litres/min/ha Light Industrial 40 litres/min/ha

5.2.5 Fire Flow Requirements

5.2.5.1 Policy and Standards related to Fire Protection

The 2020 vision aims to provide an adequate water supply for fire fighting for every building. In general, fire flow requirements are established in close collaboration with insurance companies and must involve capacity assessment of the Trinidad and Tobago Fire Services (TTFS). Since insurance risk assessments or fire protection technical guidelines are yet to be established, the following guidelines are to be used, derived from different sources including Fire Underwriters Survey (FUS) and NFPA.

5.2.5.2 Reservoir Storage Capacity Requirements

Total reservoir storage capacity requirements shall be designed to be equal to the sum of the fire storage requirements, 18 hours of average daily demand, plus emergency storage, which is 25% of the sum of fire storage capacity and annual average daily demand. See section 6 for more details.


5-6 October 2008R1

The required fire storage capacity may be equal to:

Vrc = Vfs + 0,75 Vad + 0.25(Vfs +Vad)

Where Vrc = Total reservoir water storage capacity requirement

Vfs = Fire storage capacity required

Vad = Annual average daily demand

Pressure zones with reservoirs should allow local pressure zone area of 40 to 80 psi (28 m to 56 m). In all cases, the pressure shall not be over 100 psi (70 m) and below 20 psi (14 m) for all sectors supplied by the reservoir as recommended by the Regulated Industries Commission.

5.2.5.3 Fire Flow

For residential areas, the minimum acceptable fire flow shall be as stated in the following table for a duration of minimum 1 hour with a residual pressure of 140 kPa (20 psi). For other types of consumers, the fire flow shall be calculated on a case-by-case basis, but shall always exceed the minimum residential fire flow requirements. Unless specified, major industrial sites are not to be protected by the public water network. The required fire flow demand shall be supplied from at least two fire hydrants.

Development Type Fire Demand (usgpm) Fire Demand (lpm)

Residential 1 000 3 800

5.3 Hydraulic Design

5.3.1 Pipe Design Flow

The Consultants may use the following Hazen Williams equation or the Darcy-Weisbach equation in the design of watermains:

f = 0.2083 (100/c)1.852 q1.852 / dh

4.8655

where

f = friction head loss in feet of water per 100 feet of pipe (fth20/100 ft pipe)

c = Hazen-Williams roughness constant

q = volume flow (gal/min)

dh = inside hydraulic diameter (inches)

5.3.2 Hazen Williams roughness coefficient

The Hazen-William’s coefficients for water pipelines equal to or less than 300 mm diameter shall be set at 120 with no regard to pipe material. For pipe larger than 300 mm, use the following table :


5-7 October 2008R1

Pipe Material Hazen William’s “c” Coefficients

Ductile Iron 130

HDPE 140

PVC or FRP 140

Steel 130

5.3.3 Standard Pipe Sizes

The Consultants shall use the following standard pipe sizes for the design of water distribution systems:

150, 200, 300, 400, 450, 500, 600, 750, 900, 1050, 1200 mm diameter. No larger or other diameter pipes shall be used prior to a written approval by WASA. In all cases, Consultants must first refer to the WASA approved supplier and manufacturer list for approved supplier and available diameters.

5.3.4 Minimum Pipe Sizes

The minimum pipe size for residential areas shall be 150 mm diameter. The velocity of water flow should be between 0.9 and 1.55 m/s.

For dead end mains and mains exceeding minimum size, proper analysis shall be carried out to ensure that the required pipe size is adequate to deliver the required water demand.

5.3.5 Pressure

The maximum working pressure at the point of connection shall not be more than 550 kPa (80 psi) and the minimum shall not be less than 140 kPa (20 psi) under fire flow conditions or not less than 275 kPa (40psi) under normal operating conditions.

Any localized area which has a working pressure in excess of 550 kPa (80 psi), shall be provided with a pressure-reducing valve on the distribution main or on individual services as required.

5.4 Trunk systems Transmission pipelines are defined as larger diameter pipelines (typically 400 mm and higher) which serves to transport large flows of water in the Trinidad & Tobago national grid system.

5.4.1 Velocity

The trunk system must be designed so the velocity shall not exceed 2.4 m/s in the peak hour flow condition.

5.4.2 Pipe redundancy

Main water trunk systems should allow for some level of redundancy by aiming for smaller double parallel pipe layouts with adequate valving rather than one hefty pipe diameter.


5-8 October 2008R1

5.4.3 Pumping capacity

Booster stations on the Trunk system must be designed in order to allow bidirectional (up flow or down stream) pumping capacity so as to offer redundancy to the national grid system. The valving configuration shall allow pumping in both directions and be controlled by the SCADA systems to accommodate emergency situations.

5.5 System Layout

5.5.1 Grid System

Grid systems shall be designed to ensure flexibility of operation and to minimize the area of the community required to be shutdown for the repair of the water distribution network. Wherever possible, the Consultants shall consider the following in the design of the water distribution system grid:

1. Dead ends shall be minimized by looping all watermains.

2. The use of easements to loop watermains shall be minimized.

3. At the dead end of all watermains, provide a fire hydrant or purge system for washout.

4. Maximum allowable pipe joint deflection shall be 70% of the manufacturer’s specifications. Pipe barrel bending/deflection will not be permitted.

5. System should facilitate regular flushing of the network.

6. No flushing device is permitted to be directly connected to any stormwater, non potable water or wastewater main.

5.5.2 Location

In general, the location of watermains shall be off-set 1.5 m from edge of the Right-of-Way boundary.

5.5.3 Separation from Stormwater and Wastewater Mains

Lateral separation of watermains from stormwater and wastewater mains shall be a minimum of 2.5 m.

Under normal conditions, watermains shall cross above the stormwater and wastewater mains with a minimum vertical separation of 450 mm to allow for proper bedding and structural support of the watermain, stormwater and/or wastewater mains. As an alternative, the watermain may be located under the stormwater and/or wastewater mains with the required minimum vertical separation.

Where the watermain is located under the stormwater or wastewater main, the required vertical clearance between the stormwater or wastewater main and the watermain shall be a minimum of 0.6 m. The watermain pipe shall be centred over the crossing so that the joints of the pipe are equidistant from the stormwater or wastewater main.


5-9 October 2008R1

Where the specified vertical separation cannot be achieved, the stormwater and/or wastewater main shall be constructed of material and with joints that will comply with watermain construction standards and shall be pressure tested to assure water tightness.

5.5.4 Pipe Depth

Consultants shall allow a minimum of 0.9 m of cover for the watermain.

On open ditch or unimproved roads, a minimum cover shall be provided to allow for future road improvements or lowering of the road profile. In areas where minimum cover cannot be achieved, special provision shall be considered to protect pipe from live loading.

5.5.5 Valves

On distribution mains, gate valves shall be provided at every watermain junction but not greater than 500 m apart and shall be arranged and placed so that no more than 75 units (residential or commercial/institutional) and 2 hydrants are shut off at any time. On transmission mains over 250 mm diameter, location of the valves should be determined by the Consultants in conjunction with WASA, but shall not be greater than 1000m. Under normal circumstances on distribution mains, 3 valves shall be provided on a tee intersection and 4 valves shall be provided on a cross intersection. Line valves shall be the same size as the watermain up to and including 600 mm diameter. On 750 mm diameter and larger watermains, one size smaller valve is permissible. Single line valves up to and including 300 mm shall be buried. Valves and washouts larger than 400 mm shall be installed in adequately designed shallow valve boxes..

Pressure reducing or pressure sustaining valves and chambers are permitted. However, special designs shall be incorporated to meet the requirements of the water system and of pressure zones.

Resilient seat gate valves are to conform to AWWA C509, up to 300 mm (12 inch) size, with a non-rising spindle, to be opened by turning in a counter-clockwise direction. All bolts and nuts shall be 304 or 316 stainless steel.

Butterfly valves could be provided on watermains larger than 300 mm diameter and valve selection must be done in consultation with senior design engineer and utility owner.

5.5.6 Hydrants

Hydrants for fire fighting shall be of a type familiar to and approved by the Trinidad and Tobago Fire Service (TTFS). The connections are to meet BS336 as 2 x 63.5 mm diameter nozzles and be installed as per fire service recommendation on all distribution watermains with the following maximum allowable spacing: Maximum Allowable Hydrant Spacing

Development Area Maximum Spacing

Residential 250 m

Commercial, Industrial, & High Density Residential 100 m


5-10 October 2008R1

All hydrants shall be conform with TTS 622:20XX (in process by TTFS) and AWWA practices. Laterals shall have a secondary valve, valve box and anchor tee. Spacing of hydrants on all distribution watermains shall be adjusted to allow for the installation of hydrants at high points along the watermains and at all dead ends. Hydrants shall be located outside of the ditch line.

Maximum horizontal distance between any point on the building perimeter facing the street and the hydrant shall be 90 m.

An isolating valve shall be provided on each hydrant lead. This valve shall exist completely in the sidewalk or entirely out of the sidewalk and conform to the grade of the surrounding area.

5.5.7 Blow Off

A blow-off is not permitted for permanent installations but may be used during the construction stage for flushing of new watermains. Dead ends on mains 150 mm in diameter or larger shall be provided with a standard fire hydrant or a two-inch blow-off at the terminal end.

5.6 Pipe Requirements

5.6.1 Pipe Material

All pipes shall have a minimum designed pressure rating of 10 bar and calculation of the strength and thickness of the pipe shall be made in accordance with AWWA practice or procedures.

Pipes shall be one of the following unless otherwise approved in writing by the Local Authorities:

Pipe material passing through structural walls should generally be steel.

5.6.2 Pipe specification

See table below for the preferred watermain design range, joint type, service connections and specifications. The proper selection of water pipe material shall take into consideration the following:

Working and Surge Pressure Rating; Internal and External Corrosion Resistance; Negative Pressure Capacity; Ease of Installation & Repair; Availability; Material Composition e.g. pipes and shall be lead free; Pipe Rigidity with regards to trench conditions; and

Preferred Design Range for Watermains

Material Main Size Joint Type Services Specification


5-11 October 2008R1

Material Main Size Joint Type Services Specification

Ductile Iron (cement lined) ≤ 1600 mm Tyton > 50 mm AWWA C151, EN 545 or ISO

2531

Polyvinyl Chloride (PVC) < 300 mm Gasketed Bell &

Spigot > 100 mm AWWA C900, AWWA C905,

EN 1452 parts 1 to 5 ISO 4422

Steel Pipe

> 750 mm

Or when pipe exposed above surface.

Gasketed Bell & Spigot or flanged AWWA C200, EN 10244 or

BS 534

Glass reinforced plastic

(GRP) 450 mm to 3000 mm

Gasketed Bell & Spigot

AWWA C 950 - ASTM D 3754

5.6.3 Structural Requirements

5.6.3.1 Thrust Restraints

All watermains and thrust restraints shall be designed to withstand the cycling operation of water mains in T&T in addition to the maximum operating pressure plus the transient pressure to which it will be subjected. The value of the transient pressure will not be less than the pressure surge that would be created by immediate stoppage of a water column moving at 0.6 m/s. The design pressure shall not be less than 10 bar in any case.

All plugs, caps, tees and bends will have approved mechanical thrust restraints based on applicable AWWA standards. Concrete thrust blocks shall be used with WASA’s approval.

Mechanical thrust restraint devices shall have third party testing certification for water systems.

5.6.3.2 Bedding and Backfill

All buried pipes and conduits entering or exiting a structure shall be fully supported in backfilled zones by means of a structural bridge or other suitable system to protect against settlement. Bedding requirements shall be determined by the depth of bury of the pipe, soil type and trench conditions. As a minimum requirement, watermain shall be laid on 100 mm of sand bedding conforming with AASHTO M-43 requirement.

5.6.3.3 Above surface Pipe Support

Pipes shall always be supported adequately in accordance with applicable ANSI B31.1, ANSI B31.9 or other building service pipe codes. If unsupported span is required (for a river crossing per example), Consultants should address the requirements based on manufacturers recommendations, considering bending stresses and deflection. Also, the design must address the presence of concentrated loads (valves, strainers, etc) and changes in direction.


5-12 October 2008R1

5.6.4 Tracer Wire

Tracer wire shall be installed on all new installations of PVC and Polyethylene watermain pipes for locating purposes. A solid 1.5 mm diameter TWU copper wire shall be installed along the top of the pipe and strapped to the pipe at 6 m intervals. All wires shall be jacketed with a minimum of 0.76 mm Polyethylene.

The wire shall be installed between each valve and/or at the end of the new PVC watermain. Joints in the wire between valves are not permitted. At each valve, a loop of wire is to be brought up inside the valve box to the top of the box.

5.6.5 Water Service Connections

In designing service connections, the Consultants shall comply with the following requirements:

1. All underground water service connections up to and including two-inch sizes shall be extra Polyethlene PE pipe conforming to ANSI/AWWA C901-96. Connections shall be secure, durable and watertight.

2. All water services shall be installed at right angles to the watermain.

3. All underground services larger than 50 mm in size shall be ductile iron pipe or PVC pipe.

4. No electrical grounding shall be connected to the water service.

5. Water service connections to any transmission main shall be provided only if no distribution main is available. A pressure reducing valve shall be installed on the connection if required.

6. All water services shall be provided with a main stop, curb stop and service box at the property line. Valve box stem extension rods are to be used on water services up to and including 32 mm.

7. Double service connection is not permitted.

8. The size of water service connections shall be provided as follows: Minimum Service Connection Size

Type of Development Service Connection Size

Single Family 19 mm diameter

Commercial and Industrial 25 mm diameter or higher

9. Every water service shall be metered in compliance with WASA policies. Design calculations shall be done in accordance with AWWA M22. No soldered joints or fittings shall be allowed before the meter or on the bypass valve. The volume of water delivered to consumers must be measured by meters installed on all direct service connections. Meters must conform to WASA’s specification and must be installed, operated, calibrated, and maintained following generally accepted industry standards and information from the manufacturer. The meter setting shall be as close as possible to the property line at the point of entrance of the water service connection.


5-13 October 2008R1

10. Major water services 100 mm and larger shall be valved at the main. If the service crosses the road, it shall be valved at the main and at the property line.

11. Pipe manufacturer’s recommendations shall be followed on the use of saddles when tapping services to mains.

12. Services longer than 30 m to the meter in a single family dwelling shall be 25 mm in diameter. No service shall be longer than 60 m without WASA’s approval.

13. On high rise buildings or high buildings, where a booster pump is required, an approved check valve must be incorporated before the pump.

14. Fire lines connected to any private fire system using chemicals are to be equipped with an approved check valve and back flow fixture.

15. Minimum depth for water service line is 450 mm.

5.7 Corrosion Prevention The Consultants shall ensure that all metallic components in the water distribution system are protected from corrosion with appropriate protection measures. Soil condition reports and geotechnical recommendations should be applied where applicable.

5.7.1 Polyethylene Encasement

Polyethylene encasement can be used on metallic watermain pipes, fittings, restrainers and hydrants to top of lower barrel, and shall be manufactured of virgin polyethylene material conforming to the requirements of ANSI/ASTM Standard Specification D1248. The specified minimum nominal thickness is 200 microns. Material and installation methods shall be in accordance with the requirements of AWWA C105.

5.7.15.7.2 Polyurethane coating

Where soil corrosiveness is significant, 100% solid polyurethane coating shall be used on ductile iron pipe, fittings and specials. Coating should meet ASTM D4541, G14 and 2240 for their performance and material be conform to the latest AWWA standard or ASTM D-16.

5.7.25.7.3 Cathodic Protection

5.7.2.15.7.3.1 New Pipes

For new pipes, comply with the following requirements unless otherwise recommended by a geotechnical survey:

1. All sacrificial anodes shall be made of high grade electrolytic zinc, 99.99% pure conforming to ASTM standards.

2. All metallic watermains, fittings, hydrants and restrainers must be coated and catholically protected to have one zinc anode per length of pipe in sizes according to the table below.

3. Anode installation is not required within valve chambers, drain chambers or air release chambers.

Formatted: Bullets and Numbering



5-14 October 2008R1

4. All weld connections are to be coated.

5. For all anodes connected to new pipes, fittings, hydrants, restrainers or to existing metallic watermains, a Cadwelder and CA-15 or equivalent cartridge shall be used. Anode installation shall be performed in accordance with the manufacturer’s instructions and ASTM requirements.

6. Where new pipe is to be connected to existing ductile iron or cast iron pipe, a 14.5 kg magnesium anode is to be connected to the first length of existing pipe.

Anode Requirement for Pipes and Fittings

Pipe / Fitting Size (mm) Zinc Anode Size (kg)

150 and 100 2.7

200 5.5

250 5.5

300 11

400 11

450 11

Hydrant 11

5.7.2.25.7.3.2 Existing Pipe

For existing cast iron or ductile iron watermains, the Consultants shall consider cathodic protection requirements as follows:

1. Anodes may be used to cathodically protect existing cast iron or ductile iron watermains if the number of breaks is less than 5 break/km/yr for non-critical residential mains and 1 break/km/year for more critical mains. For watermains with a higher break frequency (based on structural failures), the watermain is to be replaced.

2. Soils investigation shall be undertaken to identify the aggressiveness of the existing soil conditions, including resistivity, pH value and chloride ion concentration. Based on the results of the soil investigation, the appropriate cathodic protection measure will be determined.

3. Anodes used for protecting existing pipe shall be packaged 14.5 kg magnesium anodes at a spacing to be specified by the Consultants.

4. All metallic pipe extension and services should be electrically isolated from the metallic main.

5.8 Pipe commissioning Once pipes are completely installed, leakage test shall be driven and be conform to AWWA standards C600 and C605. All new, cleaned or repaired water mains, tanks and equipment, which



5-15 October 2008R1

convey potable water or stored potable water, shall be flushed, and disinfected in accordance with the latest AWWA Standard C651, and a satisfactory bacteriological report obtained.

Water And Sewerage Authority (WASA) Water and Wastewater Design Guideline Manual Drinking Water Reservoirs

6-1 October 2008R1

Section 6 Drinking Water Reservoirs

6.1 General The design guidelines as provided herein are for the design of new or rehabilitation of existing drinking water distribution reservoirs and shall be read in conjunction with the guidelines and codes applicable to Trinidad & Tobago including those mentioned in section 3 Design Standards. Where the higher standards have been specified or required, comply with such requirements.

6.2 Impoundment design For new impoundment reservoirs, a complete assessment of the project including as a minimum siting, hydrology, nutrient loading, stratification, water quality, sediment accumulation, operation and maintenance should be established and reviewed by WASA. A separate report covering the safety, security and failure impact of a dam must be done by competent dam specialists. A source water protection plan enacted for continued protection of the watershed from potential sources of contamination shall be also provided.

New reservoirs site should be prepared by removing bushes and trees to the high level elevation. Several intakes with different elevations should be provided to assure good water quality down to the lowest level of the reservoir.

6.26.3 Reservoir (tank) Design Where land and topography allows, it is considered advantageous to provide gravity storage for potable water distribution. This will account for daily fluctuations in demand and will balance the network.

Finished-water storage facilities should have sufficient capacity to control the operation of pumps, balance the fluctuation in domestic demands, and provide emergency and fire protection reserves. This storage should be reliably available, preferably by gravity. If site conditions preclude elevated storage, pumping from ground level storage may be considered, in which case auxiliary power should be provided. The pressure zones are to be defined according to prevailing topographic conditions.

The reservoir shall be designed to meet the following criteria:

1. Locate inlet and outlet pipe separately to promote circulation of fresh water and minimize dead spots. To promote water circulation, interior walls (baffles) should be used.

2. Ensure that the full depth of the reservoir is available for operation. Preferred pressure zones are between 275 kpa (40 psi) and 550 kpa (80 psi). As a primary goal, reservoirs shall be sited at elevations which will ensure these pressures are maintained.

3. The reservoir should be divided in a minimum of two cells for maintenance and access. Each compartment should have human access and adequate ventilation. Provide isolation valve(s) and piping to permit the isolation of reservoir cell(s) for maintenance or construction work without having to shut the entire reservoir down.



6-2 October 2008R1

4. Prevent entry by birds, animals, insects, excessive dust, and other potential sources of external contamination

5. The design shall include provisions for a lockable weathertight roof, a screened roof vent, an overflow pipe with atmospheric discharge and sample collection capability.

6. Allow for future expansion of reservoir capacity to its ultimate capacity in an orderly manner.

7. Reservoirs floors should have adequate slope and finish to allow draining and cleaning.

8. Connection for pumps and washdown pump shall be made to the reservoir’s fill line.

Overflow from the reservoir is not generally permitted at any time unless emergency conditions arise. A separate instrumentation and control system shall be provided exclusively to prevent overflow. When the water level reaches the high high level (HHL) condition, the instrumentation and control system shall initiate the valve to shut off to prevent further water supply into the reservoir and at the same time activate the reservoir high high level (HHL) overflow alarm condition to the operator through the SCADA system.

Design reservoir to drain by gravity to the adjacent property drainage area. In the absence of municipal storm drain, consider controlled discharge such as pumps and holding ponds. In all cases, include adequate measures to control erosion of earthen channels or scouring of paved sections.

6.36.4 Reservoir Capacity The capacity of the required reservoir will be dictated by the water supply system need study. Operational, standby, and fire suppression storage volumes must be considered, as applicable, for all pressure zones to meet both normal as well as abnormal demands of the system. Refer to section 5.2.4.2 for calculation of recommended minimum storage.

6.46.5 Re-chlorination System Requirements Where specified, design and provide the required chlorination system at the reservoir with respect to Section 9.6 on chlorination systems. The re-chlorination system shall be sized to provide an increase to the total chlorine residual at the maximum inflow of water.

6.56.6 Emergency Eye-wash Provide an emergency eye-wash station in the vicinity of the chlorination system and also close to the analyzer location.

6.66.7 Site Access Road and Security Unless otherwise specified by WASA, or local approval agencies, the reservoir or tank access road shall be fenced off with 2100 mm high galvanized steel chain link fence and razor wire.

Access gate(s) to the property shall be 7000 mm wide and 2100 mm high. The location of the gate(s) may be required to comply with the requirements of the approval agencies and or area municipality.






6-3 October 2008R1

Design reservoir exterior exposed surfaces such as access hatches, doors etc are to be vandal resistant. Ensure that all ventilation louvers to the reservoir are properly secured to prevent entry of foreign material. All hatches are to be lockable and keyed to WASA’s master lock system.

The exterior of reservoir shall be provided with high pressure sodium vapour light fixtures (vandal and tamper resistant) with high power factor ballast and lamps suitable for horizontal, base up or base down operation. The need for surveillance camera and alarms shall be assessed for each site.

All exterior access such as the valve house doors and reservoir roof access shall be provided with locking devices.

6.76.8 Architectural Comply with Section 14 – Architectural Standards.

Design reservoir with valve chamber in front with access door and retaining walls.

The reservoir shall be architecturally designed to ensure that the exterior complements with its surrounding environment. The exterior material and or finishes shall be designed to be completely maintenance-free wherever possible. It shall be provided with two entrances and to be without any windows. All openings in the exterior walls shall be equipped with insect screens and vandal-proof louvers.

All roof drains shall have a dome protection. Drains inside the valve house shall have easily accessible traps.

Roof access hatches shall be fabricated of aluminium frame with insulated cover and watertight. It shall be provided with a snap lock with a removable handle for topside hardware, and recess padlock complete with cover.

Floor layout shall allow for an easy access to all equipment inside the Valve House. Floor areas shall be sealed with a waterproofing membrane and shall have a slip resistant finish. Interior finish shall require minimum maintenance. Walls shall be treated with a waterproofing membrane. Unless it is absolutely necessary, do not paint interior surface of Valve House.

All electrical equipment including control panel shall be located on the main floor. Interior lighting shall be wall mounted fluorescent light fixtures, and readily accessible for replacement/ maintenance purposes (but protected against vandalism).

Landscaping within the property limits shall comply with the regional authority Site Plan Approval requirements. It shall complement with the surrounding environment and require minimum maintenance or watering. Select plant species that are native to Trinidad & Tobago.

6.86.9 Structural Comply with Section 15 – Structural Standards.

For new reservoirs, glass lined steel tanks should be prioritised. Reservoirs should have a minimum of two (2) cells with isolation valves between the cells.

Reservoirs shall be designed to withstand all force imposed on them and be watertight.




6-4 October 2008R1

Interior of the tank shall be protected from corrosion by glass lining or other approved protection. Stainless steel will not be acceptable because of chlorine attack.

For expansion of existing reservoirs, design new cell(s) capable of being isolated from existing cell(s) for repair and or cleaning or to float independently on the water supply distribution system.

Reservoir to be designed with the structure half in and half out of the ground with the roof cover sloped to promote drainage, including granular zone at base of cover material.

Provide reservoir with an overflow piping capable of discharging the designed maximum inflow of water to the reservoir. Design overflow capacity from each cell to meet maximum pumped input and combine discharge with reservoir drain. Design drain to permit discharge of water in a controlled manner to the site drainage system. Provide perimeter drainage system and prevent erosion.

Provide access and ventilation shafts, two for each cell.

6.96.10 Mechanical Comply with Section 19 – Mechanical Standards.

Provide valve box as required to allow easy operation. Valve box shall be cast in place concrete with a lockable stainless steel cover. Ensure that the stainless steel cover is designed to prevent water from entering into the reservoir from the valve box.

Altitude valves with closing speed control are the preferred mode of control for inflow in the reservoirs.

The overflow pipe shall be secured with a non-corrodible mesh screen (size 25 mm) installed within the pipe at a location least susceptible to damage by vandalism.

Hardware inside the reservoir, ladders, handrails, safety chains and rails, equipment hatches, gratings etc., shall be corrosion and chlorine resistant.

Internal manway from valve chamber to the reservoir, if provided, shall be chlorine resistant material or Fibreglass.

6.106.11 Ventilation Comply with Section 20 – Ventilation and Air Conditioning Standards.

Provide dehumidification equipment in Valve House to reduce humidity below dew point.

6.116.12 Instrumentation and Control Provide one ultrasonic level sensor in each reservoir cell. Control of the inlet valve and monitoring of the reservoir water level should be made possible through ultrasonic level sensor.

Provide a backup float system which will detect the reservoir water level. At the overflow water level condition, system must initiate the valve to shut off further water supply into the reservoir





6-5 October 2008R1

and at the same time activate the reservoir high high level (HHL) overflow alarm condition at the Water Treatment Plant SCADA Control Room.

Reservoir PLC operation:

1. Reservoir Cell duty selection

2. Reservoir High Level

3. Reservoir High High Level

4. Reservoir Fire Zone Level

5. Reservoir Low Level

6. Chlorine metering pumps duty selection, manual or automatic mode (where required)

7. Chlorine residual set point, manually set by operator

8. Reservoir inlet/outlet control valve

6.126.13 Alarms The following alarm points shall be monitored at the reservoir by the SCADA System:

1. Fire Alarms

2. Levels sensor indications in each cell

3. Chemical metering pumps uncommanded stop

4. Chemical metering pumps uncommanded start

5. High/low chlorine residual level

6. Low chemical liquid level in the tank

7. Low reservoir level, normally set at the fire zone

8. High, High water level

9. Chlorine gas alarm

6.136.14 Control System For additional information on I&C and SCADA systems requirements, refer to Section 17 – Instrumentation & Control and Section 18 – SCADA System for control system requirements.

6.146.15 Equipment Redundancy Comply with Section 4 – Process and Equipment Redundancy.




Water And Sewerage Authority (WASA) Water and Wastewater Design Guideline Manual Potable Water Pumping Stations

7-1 October 2008R1

Section 7 Potable Water Pumping Stations

7.1 General The design guidelines as provided herein are for the design of new or rehabilitation of existing potable water pumping stations and shall be read in conjunction with the guidelines and codes noted in section 3.0 Design Standards. Where the higher standards have been specified or required, comply with such requirements.

7.2 Pump design For any particular project there is likely to be more than one acceptable booster pump station design concept. Pumps should be selected in order to have high efficiency under normal operating conditions. Firm pumping capacity for a water pumping station is based on the total pumping capacity with the largest pump out of service. Design should always consider the hydraulics in order to avoid cavitation, excessive vibration and noise. The pump’s parts and components should be chlorine resistant, weather proof and rated for continuous operation in tropical countries.

In addition to the selection of the appropriate pump type and size, there is also a need to select the suitable resistant material or coatings, which can guarantee an extended lifetime. Usually, where clean water is pumped, pump material to be employed is cast steel (with surface protection), with the impeller usually made from chromium steel. If there are solids suspended or dissolved in the water, the speed of the pump should be limited to avoid abrasion.

Booster stations on the Trunk system must be designed in order to allow bidirectional (up flow or down stream) pumping capacity so as to offer redundancy to the national grid system. The valving configuration shall allow pumping in both directions and be controlled by the SCADA systems to accommodate emergency situations.

7.3 Layout of Pumping Station Below are recommended requirements for the expansion or upgrading of pumping station:

1. Provide adequate space (min 1.0 m) to allow removal of pump, valve etc. between existing and new equipment for operation and maintenance requirements.

2. As much as possible, maintain similar types of existing equipment.

3. Provide flexibility for incorporating modification to facility to meet more stringent water quality requirements.

4. Ensure that the facility is designed to allow for future expansion works.

5. Lifting devices shall be provided for removing pumps or motors.


7-2 October 2008R1

7.4 Equipment Redundancy See Section 4 – Process and Equipment Redundancy. As per common practice the maximum number of pumps shall be limited to 5 or less in order to keep the complexity and lifetime costs at reasonable levels.

7.5 Pumping Station Requirements Usually there are two types of pumping stations. Low lift pumping stations are generally used to bring water from the intake to the treatment plant. High lift pumping stations are generally used for water distribution. Design the pumping station in accordance with the following guidelines. Where there is a more stringent design standard, comply with the higher standard.

Equipment Comment

1 Design Standard Hydraulic Institute Standards

2 Number of Pumps Minimum – 2

3 Capacity of Pumps Maximum Daily Demand

4 Preferred Type Horizontal Split Case Centrifugal Pump & Vertical turbine pumps in canisters (canned)

5 Pump’s Standard EN 733 DIN 24255

6 Variable Frequency Drive To be considered but not a standard requirement, and not to be provided for Standby Pump

7 Number of Standby Pump Minimum – 1

8 Capacity of Standby Pump

Equal to capacity of largest pump

9 Drive Unit Starter Solid State Reduced Voltage Starter or Variable Frequency Drive

10 Equipment Monitoring Requirement

1. RTD connections for windings, minimum one per phase 2. RTD for motor inboard and outboard bearings 3. RTD connections for pump inboard and outboard bearings. 4. Drive speed

11 Instrumentation & Control Programmable Logic Controller c/w all required field instrumentation hardware.

12 Emergency Standby Diesel Generator

Generator output shall be sized to meet pumps power demand for average day water supply demand as well as for SCADA and ventilation systems.

,

7.6 Control System The need for installing a Variable Frequency Drive (VFD) pump must be assessed with considerations to economical, operational and maintenance aspects of such equipment.

Pumps should be adequately valved to permit satisfactory operation, maintenance and repair of the equipment. For pipe diameter over 450 mm, isolating butterfly valves should be preferred. Check valves and surge valves (if applicable) on the discharge side of each booster pump are to be provided.


7-3 October 2008R1

Control systems shall include automatic and manual Start/stop control for each system.

7.7 Instrumentation Provision shall be made for the visual indication of the suction and discharge pressure at each pump and the common discharge line pressure. Provision shall also be made for the measurement of flow using a flow meter or other reputable flow measuring device at each pump station.

Pressure switches shall be installed at the suction line of each pump at water pump stations. A common discharge pressure switch shall be installed at water pump stations. The pressure switches shall be set as to trip pumps at low suction and high discharge pressures and to start pumps at the required pressure.

All pump stations shall be designed with due consideration for the effects of water hammer. Adequate protection for adverse effects should be included in the design.

Instrumentation should include ammeters and voltmeter for each station and include motor protection fixtures like thermal overloads and phase imbalance or loss protection. Disposition should be taken to control moisture and condensation. Permanent pressure and flow monitoring and recorder should be provided.

For additional information on I&C and SCADA systems requirements, refer to Section 17 – Instrumentation & Control and Section 18 – SCADA System for control system requirements.

7.8 Alarms The following equipment or logic-defined alarms shall be generated for the following:

1. Building .1 Access Security Authorized and unauthorized entry .2 Building – Smoke Smoke in building .3 Building – Flood Flooding

2. Pump(s) .1 Overload trip .2 Thermistor trip .3 Bearing temperature .4 Fail to start .5 Fail to stop .6 High pressure .7 Low pressure .8 Uncommanded stop .9 Phase unbalance


7-4 October 2008R1

7.9 Ventilation Comply with Section 20 – Ventilation and Air Conditioning Standards.

Provide dehumidification equipment in pumping rooms to reduce humidity below dew point.

7.10 Architectural Comply with Section 14 – Architectural Standards.

The building shall be architecturally designed to ensure that the exterior complements with its surrounding environment. The exterior material and or finishes shall be designed to be completely maintenance-free wherever possible. It shall be provided with two entrances and to be without any windows. All openings in the exterior walls shall be equipped with insect screens and vandal-proof louvers.

All roof drains shall have a dome protection. Drains inside the valve house shall have easily accessible traps.

Floor layout shall allow for an easy access to all equipment inside the pumping station. Floor areas shall be sealed with a waterproofing membrane and shall have a slip resistant finish. Interior finish shall require minimum maintenance. Walls shall be treated with a waterproofing membrane.

All electrical equipment including control panels shall be located on the main floor. Interior lighting shall be wall mounted fluorescent light fixtures, and readily accessible for replacement/ maintenance purposes (but protected against vandalism).

Landscaping within the property limits shall comply with the regional authority Site Plan Approval requirements. It shall complement with the surrounding environment and require minimum maintenance or watering. Select plant species that are native to Trinidad & Tobago.

7.11 Site Access Road and Security Unless otherwise specified by WASA, or local approval agencies, the building access road shall be fenced off with 2100 mm high galvanized steel chain link fence and razor wire.


Design building exterior exposed surfaces such as access hatches, doors etc are to be vandal resistant. Ensure that all ventilation louvers to the reservoir are properly secured to prevent entry of foreign material. All hatches to be lockable and keyed to WASA’s master lock system.

The exterior of the building shall be provided with high pressure sodium vapour light fixtures (vandal and tamper resistant) with high power factor ballast and lamps suitable for horizontal, base up or base down operation. The need for surveillance camera and alarms shall be assessed for each site.

Water And Sewerage Authority (WASA) Water and Wastewater Design Guideline Manual Well Pumping Station Design

8-1 October 2008R1

Section 8 Well Pumping Station Design

8.1 General The design guidelines as provided herein are for the design of new or rehabilitation of existing wells and shall be read in conjunction with AWWA Standard for Water Wells. Drilling and construction of wells shall be supervised by a hydro-geological specialist and be tested for yield and drawdown. A report of at least a 24-hour pumping test to determine yield shall be submitted. Wells shall be located so that the drawdown of any well will not interfere with the required yield of another well. The immediate 30 m radius surrounding of a well shall be protected from any source of contamination (minimum well head protection).

It is important that wells and underground water supplies be always assessed through a Source Water Protection program with regional coverage to assure sustainability and health protection for users. The issue of redundancy must be captured in the number of wells within the area so to allow operation on a rotational basis.

Water quality must be defined prior to the construction of the well. The water quality shall respect WASA water quality standard as defined in Section and if required, adequate treatments are to be provided to comply with the water quality standards. Treatment for all secondary aesthetic standards should be included after confirmation by WASA. All chemicals, substances, and materials added to or brought in contact with water in a public water system well shall have either standard ANSI/NSF 60 or 61 certification.

8.2 Well Construction Consultants shall make sure to protect the aquifer by avoiding the introduction of any contamination. All underground material shall be made of new material.

The well casing shall neither terminate below ground nor in a pit. Well casing shall be made of steel conform to ASTM A53/A53M-01 or ASTM A589-96 or plastic conform to ASTM F480-00. Tubing must be equipped with a drive shoe when driven. All casing and screen must be supplied with threaded flush joints or threaded couplers, PVC casing and screen must not have glue joints. The well casing should extend 0.9 meter above the ground surface when the well is completed and always above flood line. Screen shall be installed such that corrosion caused by contact with dissimilar steel casing is minimized. Thermoplastic screen may be attached to steel casing with the use of an appropriate coupler. The screen shall provide sufficient column and collapse strength to withstand installation and borehole pressures. Screen joints between screen sections and blank casing shall be welded, or threaded and coupled

The upper terminal of the well casing shall be equipped with a well cap and be watertight with the exception of a vent pipe or vent tube having a downward-directed, screened opening.

All underground connections with the casing shall be sealed and waterproof. Measures shall be taken to avoid infiltration on the side of casing. Adequate provisions for washout must be included.


8-2 October 2008R1

Every water supply well shall have a continuous bond concrete slab or well house concrete floor extending at least 1 meter horizontally around the outside of the well casing. Minimum thickness for the concrete slab or floor shall be 100 mm. For line shafts pumps, a pedestal shall be provided to support the pumps and the shaft.

The annular space remaining above the seal must be grouted. The grout mixture should be composed of Portland cement and powdered bentonite. The well must not be disturbed for at least 48 hours after grouting to allow the grout time to set up.

Plumbing and alignment shall be in accordance with the pump manufacturer’ requirements. Demonstration of well alignment shall be made by passing a 12 m long dummy through the inner casing.

All pipes will have to be anchored to prevent movement and damages. The discharge pipe must have a check valve and if applicable, an air release vacuum valve.

A water supply well shall be secured against unauthorized access (see section 14.10). All new wells, and wells that have been repaired or reconditioned shall be cleaned of foreign substances such as soil, grease, and oil, and then shall be disinfected.

8.3 Well Instrumentation & Control The well pumping station shall be equipped with the following equipments:

1. Turbidity meter

2. A totalizing meter shall be installed in the piping system from each well.

3. Pressure monitoring gages

4. Automatic chlorination equipment

5. Chlorine residual analyser

6. Level sensors inside the well

7. Mechanical Flow or pressure control device

8. Emergency standby diesel generator (if dual feed not available)

9. Chlorine gas detector

10. A sampling point

Comply with Section 16 – Electrical Standards for electrical protection requirements for the wells.

8.4 Alarms The following alarm points shall be monitored (if applicable) at the reservoir by the SCADA System:

1. Level sensor low level alarm

2. Chemical metering pumps uncommanded stop


8-3 October 2008R1

3. Chemical metering pumps uncommanded start

4. High/low chlorine residual level

5. Low chemical liquid level in the tank

6. Chlorine gas detector alarm

8.5 Preferred Layout Buildings must comply with Section 14 – Architectural Standards, Section 15 – Structural Standards and Section 20 – Ventilation and Air Conditioning Standards.

A preliminary assessment of type of well pump must be done for review to WASA.

If a building is required, install a skylight immediately over the centre of the pump to facilitate removal of pumping unit.

All electrical control panels and MCC panels shall be located in a separate room.

All chemical systems shall be located in a separate room.

All equipment shall be accessible for repair and or replacement and shall have a minimum clearance of one meter from the nearest obstruction.

Design of the well pumping station must allow for the removal of all equipment at all times when the work has been constructed. Adequate provision for wash out must be included.

Provide an emergency eye-wash station in the vicinity of the chlorination system and close to the analyzer location.

Hardware for the wells and inside the building shall be corrosion and chlorine resistant.

Landscape must be designed to allow drainage and aquifer protection.

8.6 SCADA System Tie the pumping station PLC/RPU to the SCADA system.

Provide all field instrumentation for local and remote control and monitoring of all equipment in the pumping station.

Provide fully automated chemical feed system with the capability of plant manual control through the SCADA HMI software.

Provide a remote processing unit RPU for local and remote control and monitoring of all equipment through the SCADA MMI software.

Comply with Section 17 – Instrumentation & Control and Section 18 – SCADA System design standard requirements.


8-4 October 2008R1

8.7 Equipment Redundancy No redundancy in process or equipment is required.

Water And Sewerage Authority (WASA) Water and Wastewater Design Guideline Manual Water Treatment Plants

9-1 October 2008R1

Section 9 Water Treatment Plants

9.1 General The following sections are the design standards and guidelines for water treatment plants, should any new plants be constructed or existent plants be expanded or upgraded in the future to current water treatment process standards.

The drinking water quality standards are a public health issue and have to be carefully set. The following standards are based on the 2006 World Health Organisation (WHO) addendum 1 to volume 3 maximum allowable concentration. Treatment systems or devices shall be piloted and designed to ensure finished water quality conforms to the latest World Health Organization (WHO) water quality standards

The water supply strategy shall adopt the multi barrier approach which will ensure safe drinking water based on four barriers:

• Source water protection • Water treatment • Distribution system integrity • Public information and legislation Protection of well’s recharge area (Source Water Protection) allied with concerted public involvement and watershed management are recommendations that should be implemented as part of a sustainable approach for drinking water. The aim is to frame the good practices needed for assuring acceptable raw water quality at the intake of treatment plants. These recommendations are specifically designed to ensure an adequate design, construction, sampling, maintenance, and operation practices; and a provision of safe and high quality drinking water in a reliable manner and in a quantity suitable for intended use.

All materials in substantial contact with potable water supplies shall conform to the ANSI/NSF Standard 60 or 61. Examples of water system components that would be considered to be in "substantial contact" with drinking water are filter media, storage tank interiors or liners, distribution piping, membranes, exchange or adsorption media, or other similar components that would have high potential for contacting the water. Materials associated with components such as valves, pipe fittings, debris screens, gaskets, or similar appurtenances would not be considered to be in substantial contact.

9.2 Drinking water standards The WHO has established guideline values for 94 parameters divided in three (3) different groups: microbiological contaminants, natural and chemical contaminants. These guidelines are to be used as the WASA`s Water Quality Standards and are presented in the following tables.


9-2 October 2008R1

Notes on standards : P=provisional guideline value as there is evidence of a hazard, but the available information on health effects is limited; T=provisional guideline value because calculated guideline value is below the level that can be achieved through practical treatment methods, source protection, etc; A= provisional guideline value because calculated guideline value is below the practical quantification level; C=concentrations of the substance at or below the health-based guideline value may affect the appearance, taste or odor of the water, resulting in consumer complaints. D=provisional guideline value because disinfection is likely to result in the guideline value being exceeded;

9.2.1 Microbiological

Values for verification of microbial quality Organisms value All water directly intended for drinking E. coli or thermotolerant coliform bacteria Must not be detectable in any 100-ml sample Treated water entering the distribution system E.coli or thermotolerant coliform bacteria Must not be detectable in any 100-ml sample Treated water in the distribution system E.coli or thermotolerant coliform bacteria Must not be detectable in any 100-ml sample Treated water in the distribution system Total coliform bacteria Must not be detectable in any 100-ml sample

9.2.2 Naturally occurring chemicals

Values for naturally occurring chemicals that are of health significance in drinking-water value Chemical (mg/litre) Remarks Arsenic 0.01 (P) Barium 0.7 Boron 0.5 (T) Chromium 0.05 (P) For total chromium Fluoride 1.5 Volume of water consumed and intake from other sources should be considered when setting national standards. Manganese 0.4 (C) Molybdenum 0.07 Selenium 0.01 Uranium 0.015 (P,T) Only chemical aspects of uranium addressed


9-3 October 2008R1

9.2.3 Chemical contaminants

Values for chemicals from industrial sources and human dwellings that are of health significance in drinking-water. Inorganics value (mg/litre) Remarks Cadmium 0.003 Cyanide 0.07 Mercury 0.006 For inorganic mercury Organics value (µg/litre) Remarks Benzene 10 Carbon tetrachloride 4 Di(2-ethylhexyl)phthalate 8 Dichlorobenzene, 1, 2- 1000 (C) Dichlorobenzene, 1, 4- 300 (C) Dichloroethane, 1, 2- 30 Dichloroethane, 1, 2- 50 Dichloromethane 20 Dioxane, 1, 4- 50 Edetic acid (EDTA) 600 Applies to the free acid Ethylbenzene 300 (C) Hexachlorobutadiene 0.6 Nitrilotriacetic acid (NTA) 200 Pentachlorophenol 9 (P) Styrene 20 (C) Tetrachloroethene 40 Toluene 700 (C) Trichloroethene 20 (P) Xylenes 500 (C)


9-4 October 2008R1

Values for chemicals from agricultural activities that are of health significance in drinking water.

Non-pesticides value (mg/litre) Remarks Nitrate (as NO3

-) 50 Short-term exposure Nitrate (as NO2

-) 3 Short-term exposure 0.2 (P) Long-term exposure Pesticides used in agriculture value (µg/litre) Remarks Alachlor 20 Aldicarb 10 Applies to aldicarb Sulfoxide and aldicarb Sulfone. Aldrin and dieldrin 0.03 For combined aldrin plus dieldrin Atrazine 2 Carbofuran 7 Chlordane 0.2 Chlorotoluron 30 Cyanazine 0.6 2,4-D (2,4-dichlorophenoxyacetic acid) 30 Applies to free acid 2,4-DB 90 1,2-Dibromo-3-chloropropane 1 1,2-Dibromoethane 0.4 (P) 1,2-Dichloropropane (1,2-DCP) 40 (P) 1,3-Dichloropropene 20 Dichlorprop 100 Dimethoate 6 Endrin 0.6 Fenoprop 9 Isoproturon 9 Lindane 2 MCPA 2 Mecoprop 10 Methoxychlor 20 Metolachlor 10 Molinate 6 Pendimethalin 20 Simazine 2 2,4,5-T 9 Terbuthylazine 7 Trifluralin 20


9-5 October 2008R1

Values for chemicals used in water treatment or materials in contact with drinking water that are of health significance in drinking-water. Disinfectants value (mg/litre) Remarks Monochloramine 3 Disinfection by-products value (µg/litre) Remarks Bromate 10 (A,T) Bromodichloromethane 60 Bromoform 100 Chlorate 700 (D) Chlorite 700 (D) Chloroform 300 Cyanogen chloride 70 For cyanide as total cyanogenic compounds Dibromoacetonitrile 70 Dibromochloromethane 100 Dichloroacetate 50 (T,D) Dichloroacetonitrile 20 (P) Monochloroacetate 20 Trichloroacetate 200 Trichlorophenol, 2,4,6- 200 (C) Trihalomethanes The sum of the ratio of the concentration of each to its respective guideline value should not exceed 1 Contaminants from Value (µg/litre) Remarks Treatment Chemicals Acrylamide 0.5 Epichlorohydrin 0.4 (P) Contaminants from pipes And fittings Values (µg/litre) Remarks Antimony 20 Benzo [a]pyrene 0.7 Copper 2000 staining of laundry and sanitary ware may occur below guideline value Lead 10 Nickel 70 Vinyl chloride 0.3


9-6 October 2008R1

Values for pesticides used in water for public health purposes that are of health significance in drinking-water. Value (µg/litre) Pyriproxyfen 300 Values for cyanotoxins that are of health significance in drinking-water Value (µg/litre) Remarks Microcystin –LR 1 (P) For total microcystin-LR (free plus cell-bound)

9.2.4 Aesthetic guidelines

The following guidelines called secondary drinking water guidelines are adopted by WASA. Some parameters are considered aesthetic objectives and others are considered operational objectives.

Acceptability aspects Parameter Aesthetic objective

(mg/litre) Operational

objective (mg/litre) Aluminium 0,2 Chloride 250 Colour 15 TCU Hardness 150 Iron 0,3 Manganese 0,05 Silver 0,10 pH 6,5-8,5 Sodium 200 Sulfate 250 Sulfide 0,05 Total Dissolved Solids 500 Turbidity < 5 NTU <1 NTU Zinc 5

9.3 Performance targets and treatment objectives

9.3.1 General

In order to evaluate disinfection performance at a water treatment facility, three (3) different pathogens micro-organisms be targeted: enteric virus, Giardia cysts and Cryptosporidium oocysts. The selection of those organisms is founded on the following facts: • The targeted organisms are frequently detected in surface water supplies of lakes, rivers and

occasionally in groundwater sources.


9-7 October 2008R1

• The targeted organisms have been known to have caused epidemics, some causing illness to thousand of people;

• The targeted organisms are resistant to disinfection. Thus, by eliminating the targeted organisms, it is very probable that other less resisting organisms will also be eliminated.

Giardia cysts and Cryptosporidium oocysts are considered among the most common intestinal parasites found in the world. The removal and inactivation of viruses, Giardia and Cryptosporidium to evaluate the disinfection effectiveness of a water treatment facility is the preferred approach in most jurisdictions having drinking water legislation. Water is disinfected but never completely sterilized in the water treatment process. This disinfection is a two (2) part process that includes: 1. Removal of particulate matter by filtration. A rule of thumb is that high

turbidity in the effluent is a potential health risk, because viruses and bacteria can hide within the rough texture of particulates. Therefore, removal of the particulates reduces the chance of pathogenic microorganisms in the effluent.

2. Inactivation of pathogenic microorganisms by chlorine, chlorine dioxide, ozone or UV radiation.

9.3.2 Minimum treatment objectives

Water sources are to be classified and the minimum treatment objectives for the removal of the targeted objectives be as per the ones included in Table 1.0. Log decimal is usually used as the method to evaluate organism elimination in a process train. One log decimal corresponds to a 90% reduction of the original concentration, 2 log decimal corresponds to 99% reduction and 3 log decimal corresponds to 99,9% reduction and so on. The log removal for the reduction of the virus and parasites can be obtained either by a combination of: • Physical removal such as coagulation/flocculation/sedimentation and filtration and/or

membranes; • Chemical inactivation such as chlorination or physical inactivation such as ultra-violet

radiation. For a specific water treatment facility, the sum of the total log removal obtained by physical removal and the total log removal obtained by inactivation must be greater than the treatment objectives established in Table 1.0. Table 1.0 – Minimum treatment objectives for various raw water supplies


9-8 October 2008R1

Class Raw water source Mandatory minimum treatment objectives

Cryptosporidium

Giardia

Virus

I

Surface water

2 log (99%)

3 log

(99,9%)

4 log

(99,99%)

II

Groundwater under the direct influence of surface water

2 log (99%)

3 log

(99,9%)

4 log

(99,99%)

III

Groundwater not under the direct influence of surface water

0

0

2log

(99%)

Class I water: Class I water means surface water bodies (lakes, wetlands, ponds - including dug-outs), water courses (rivers, streams, water-filled drainage ditches), infiltration trenches, and areas of seasonal wetlands. The minimum treatment objectives for raw water of Class I must necessarily be obtained with a filtration system (conventional filtration, direct filtration, slow sand filtration or membrane filtration). At least 0,5 log removal or inactivation of Giardia cysts and 2 log removal or inactivation of viruses must be provided through the disinfection portion of the overall water treatment process. Note: Systems that rely on Sea water and brackish sources are considered surface water and must also conform to these minimum requirements. Class II water: Ground water under the direct influence of surface water means ground water having incomplete or undependable subsurface filtration. The following drinking-water systems are deemed to be drinking-water systems that obtain water from a raw water supply that is ground water under the direct influence of surface water: • A drinking-water system that obtains water from a well that is not a drilled well or that does

not have a watertight casing that extends to a depth of at least 6 meters below ground level. • A drinking-water system that obtains water from an infiltration gallery. • A drinking-water system that obtains water from an overburden well, any part of which is

within 100 meters of surface water.


9-9 October 2008R1

• A drinking-water system that obtains water from a bedrock well, any part of which is within 500 meters of surface water.

• A drinking-water system that exhibits evidence of contamination by surface water. • A drinking-water system in respect of which a written report has been prepared by a

professional engineer or professional hydro-geologist that concludes that the system’s raw water supply is ground water under the direct influence of surface water and that includes a statement of his or her reasons for reaching that conclusion.

For drinking-water systems that rely on a raw water supply which is considered ground water under the direct influence of surface water, filtration should always be incorporated prior to disinfection. The filtration requirement could be waived if it can be demonstrated that raw water average monthly turbidity is always below 1 NTU. In that case, the filtration could be replaced by a double disinfection system consisting of UV radiation and chemical disinfection. Class III water: This class is for raw water which is considered groundwater meaning water located in subsurface aquifer(s) protected by overlay aquitards which act as an effective filter to removes micro-organisms and other particles by straining and antagonistic effect, to a level where the water supply may already be potable. In all cases water turbidity must be below 5 NTU. Disinfection is required as an additional heath risk barrier.

9.3.3 Additional treatment objectives for Class I water supplies

For surface water supplies, treatment objectives shall be adjusted to take into account the level of pollution in the source. The minimum water treatment objectives are for raw water supplies of good quality. For polluted sources, the level of treatment must be adjusted to the values included in Table 2.0. Table 2.0 – Treatment objectives for Giardia, Cryptosporidium and virus versus fecal coliforms contamination in the raw water supply Fecal coliforms concentration in the raw water (UFC/100 ml)

Treatment objective for Giardia

Treatment objective for Cryptosporidium

Treatment objective for virus

< 20 3 log 2 log 4 log 20 - 200 4 log 2 log 5 log

200 – 2 000 5 log 2 log 6 log 2 000 – 20 000 6 log 2 log 7 log

> 20 000 Must consider a change in the raw water supply The fecal coliforms values shown in the Table are annual arithmetic average values for fecal coliforms measured at the raw water source.


9-10 October 2008R1

9.4 Calculations of the water treatment performance

9.4.1 General

Once the treatment objectives have been determined, consultants must verify that the process train selected or in place will provide sufficient treatment to attain the treatment objectives. The treatment objectives must be achieved at all times including the critical seasons. Table 3.0 presents a series of water treatment technologies which are generally known to achieve log removal for virus and parasites. Water treatment technologies can be combined to achieve the total log removal requires. Table 3.0 – Water treatment processes and capabilities for the removal of Giardia, Cryptosporidium and virus Process

Targeted micro-organisms

Virus

Giardia

Cryptosporidium

Physical removal

Conventional treatment (1)

Yes Yes Yes

Direct filtration (2) Yes Yes Yes Slow sand filtration Yes Yes Yes Microfiltration (3) No Yes Yes Ultra and nanofiltration and reverse osmosis

Yes Yes Yes

Chemical inactivation

Chlorination Yes Yes No Ozonation Yes Yes No Chlorine dioxide Yes Yes No Chloramines (4) No No No Physical inactivation

UV radiation Yes Yes Yes (1) Includes coagulation, flocculation, settling and filtration (2) Includes a coagulation with or without flocculation (3) Excludes a coagulation (4) If use as secondary disinfection


9-11 October 2008R1

9.4.2 Evaluation of the water treatment efficiency

The evaluation of the water treatment process efficiency is done based on the physical removal of the targeted micro-organisms and on the chemical and physical inactivation of the targeted micro-organisms. For a particular process train, the log removal of each process must be added to obtain the total log removal for the water treatment facility. Log removal = Sum of the log removal obtained from physical removal + sum of the log removal obtained from chemical inactivation + sum of the log removal obtained from physical inactivation


9-12 October 2008R1

9.4.3 Treatment based on physical removal of parasites and virus

Performance credits for log removal can be allowed to various water treatment processes and for various targeted micro-organisms. Table 4.0 presents the log removal that can be obtained from various water filtration processes. Table 4.0 – Log removal credits for targeted micro-organisms for water filtration processes

Treatment technology

Log removal credit

Giardia

Cryptosporidium

Virus

Direct filtration

2,0 2,0 1,0

Conventional filtration

2,5 2,0 2,0

Slow sand filtration

2,0 2,0 2,0

Membrane filtration

3,0 + 2,0 (4) 0 to 2,0 +

Conventional filtration In order to be considered conventional filtration and meet the 2,5 log removal credit for Giardia cyst, the 2,0 log removal credit for Cryptosporidium oocyst and the 2,0 log removal credit for virus, the filtration process must meet the following criteria: • Use a chemical coagulant at all times when the treatment plant is in operation; • Monitor and adjust chemical dosages in response to variations in raw water quality; • Maintain effective backwash procedures, including filter-to-waste or an equivalent procedure

during filter ripening to ensure that the effluent turbidity requirements are met at all times; • Continuously monitor filtrate turbidity from each filter; and, • Meet the performance criterion for filtered water turbidity of less than or equal to 0,30 NTU

in 95% of the measurements each month.


9-13 October 2008R1

Direct filtration In order to meet the 2,0 log removal credit for Giardia cyst, the 2,0 log removal credit for Cryptosporidium and the 1,0 log removal credit for virus, the direct filtration process must meet the conventional filtration criteria above. Slow sand filtration In order to meet the 2,0 log removal credit for Giardia cyst, the 2,0 log removal credit for Cryptosporidium oocyst and the 2,0 log removal credit for virus, the slow sand filtration process must meet the following criteria: • Maintain an active biological layer; • Regularly carry out effective filter cleaning procedures; • Use filter-to-waste or an equivalent procedure during filter ripening periods; • Continuously monitor filtrate turbidity from each filter or take a daily grab sample; and, • Meet the performance criterion for filtered water turbidity of less than or equal to 1,0 NTU in

95% of the measurements each month. Because of the selective mechanisms of slow sand filtration, filtrate turbidity levels exceeding 1,0 NTU can occur as a result of passage of inorganic particles through the filter without influencing the effective removal of harmful organisms. Temporary filtrate turbidity levels of over 1,0 NTU therefore should not be interpreted as indicating an adverse water condition in the absence of additional supporting evidence. Membrane filtration In order to meet the 3,0 + log removal credit for Giardia, the 2,0 + log removal credit for Cryptosporidium oocyst and the 0 to 2,0 + log removal credit for virus, the membrane filtration process must meet the following criteria: • Maintain effective backwash procedures, including filter-to-waste or an equivalent

procedure, to ensure that the effluent turbidity requirements are met at all times; • Monitor integrity of the membrane by continuously particle counting or equivalently

effective means (e.g., intermittent pressure decay measurements); • Continuously monitor filtrate turbidity; and, • Meet the performance criterion for filtered water turbidity of less or equal to 0,1 NTU in 99%

of the measurements each month.


9-14 October 2008R1

9.4.4 Treatment based on chemical inactivation of parasites and virus

The efficiency of chemical inactivation or disinfection is founded on the CT concept. The CT disinfection concept uses the combination of a disinfectant residual concentration (in mg/L) and the effective disinfectant contact time (in minutes), to quantify the capability of a chemical disinfection system to provide effective pathogen inactivation to the required level. The use of this concept involves determining the CT values required at the actual, often variable, operating conditions (flow, temperature and pH) and ensuring that the employed disinfection process achieves these values at all times. Chemical disinfection CT values are calculated by multiplying the disinfectant residual concentration (in mg/L) by the disinfectant contact time (in minutes). CT = Concentration (mg/L) x Time (minutes) Varying degrees of disinfection can be attained by altering the type and concentration of disinfectant, as well as the time water is in contact with the disinfectant. The decision to use one type of disinfectant versus another will set the precedence for the remainder of the values needed to attain the proper disinfection. The log of inactivation obtained for a particular treatment step using chemical disinfection can be determines as follows: Log of inactivation = CT available = C residual x T10 CT required CT required where T10 must be calculated for the maximum flow exiting the water treatment facility. Refer to EPA’s “Technical Guidances for Implementation of the Microbial and Disinfection Byproducts Rules” for details.

9.4.5 Treatment based on physical inactivation of parasites and virus

Water treatment based on physical inactivation of parasites and virus is achieved by ultra-violets (UV) radiation. UV disinfection technology is developing rapidly across the world. Contrary to most of the other disinfectants, UV radiation does not inactive parasites and virus by chemical action. Ultraviolet (UV) disinfection systems are used in many water treatment facilities to control pathogens micro-organisms. UV units can be effective water treatment tools, but it is important to recognize what UV can do, what its limitations are, and what maintenance is required. Table 8.0 presents the required doses to inactive targeted micro-organisms.


9-15 October 2008R1

Table 8.0 – Design doses for UV radiation disinfection

Supply source

Dose (mJ/cm2) Parasites: 3 log

Virus: 2 log Parasites: 3 log

Virus: 4 log Surface water (1) (2)

40

80

Groundwater (3)

Not required

40

(1) Surface water with chemically assisted filtration, direct filtration, slow sand filtration or

membrane filtration (2) Surface water sources also include groundwater under the direct influence of surface water (3) For groundwater sources non under the direct influence of surface water

Refer to EPA’s “Technical Guidances for Implementation of the Microbial and Disinfection Byproducts Rules” for details.

9.5 Treatment plant general design

9.5.1 Water intake

The location of the intake should be set at such a depth that the quantity of suspended solids, colloidal matter, and plankton is as low as possible throughout the year. The river intakes are to be located in a reasonably accessible and stable reach of the channel, where erosion or deposition will not endanger the intake. The intake shall be buried and graded to prevent accumulation of grasses. Speed in the intake should be calculated with future peak demand and be low enough to limit impact on fish and sediments.

Screening of the water may be done with a coarse bar screen followed by a medium bar screen. Finer screening and grit removal may be necessary when the water has to be conveyed through a long pipeline or when it has to be pumped. Grit removal necessity is to be analysed in each project to eliminate gravel, sand or mineral particles larger than 200 microns from the water. All screening must be provided with automatic and reliable cleaning systems to avoid maintenance and operation works.

9.5.2 Monitoring

Water monitoring should be facilitated to allow monitoring of treatment efficiency at each unit process.

9.6.29.5.3 General design elements

It is not the intent of this manual to replace professional expertise and innovation from the hand of water treatment design engineers. It is therefore mandatory that a complete preliminary report be provided for review to WASA giving the rationale for the recommended processes and their



9-16 October 2008R1

design elements. This document must assess all the requirements of this manual and the following :

- Water need and design flows

- Characterisation of water

- Supply and treatment options

- Treatment processes

- Disinfection processes and by-products

- Taste and odour treatment

- Corrosion and stabilisation methods

- Sludge management

- Instrumentation and system control

9.6 Disinfection design guidelines All design must comply with WASA "Chlorine Policy and Procedures General Guidelines".

As a general rule WHO recommends that there should be a residual concentration of free chlorine of >0.5 mg/litre after at least 30min contact time at pH <8.0. Refer to section 9.4.4 for more details on method for proving effective disinfection. Free residual chlorination may be achieved through the use of chlorine gas, sodium hypochlorite, calcium hypochlorite or free chlorine producing electrochemical process.

9.6.1 Chlorination System

Chlorination pre and/or post-chlorination must be provided with gas-type chlorinator or electrically operated, positive displacement hypochlorite solution chlorinator. If necessary, alternative technologies such as ozone, UV etc. should be considered in accordance with associated design guidelines.

For distribution system, the system shall maintain a detectable residual disinfectant concentration measured as free chlorine, of at least 0.5 mg/L at all times (for 95% of the samples taken each calendar month).

In a reservoir, the re-chlorination system shall be sized to provide an increase to the total chlorine residual at the maximum inflow of water.

9.6.1.1 Gas Chlorination System

Depending on the plant process treatment capacity requirements, one chlorinator shall be provided for each chlorine application point. A minimum of two (2) standby chlorinators, sized to meet maximum day demand shall be provided. The chlorine piping and controls shall allow the use of the standby chlorinators for all possible application points.


9-17 October 2008R1

1. For gas chlorination system, provide one chlorinator for each chlorine application point. A minimum of one (1) standby chlorinator, sized to meet maximum day demand shall be provided. The chlorine piping and controls shall be configured to allow the use of the standby chlorinator.

2. Two (2) chlorinators shall be provided for Post-Chlorination

Where plants have SCADA system, the chlorinators shall have the capability of being controlled:

1. Locally at the equipment

2. At the PLC/Manual

3. At the PLANT/Manual through the SCADA Human Machine Interface (HMI) using the Graphics User Interface (GUI) main screen

The chlorinators shall be provided with the required switches to enable control of the feed rate through the SCADA system.

Chlorination room:

If gas chlorination is used, the following safety steps must be taken:

1. Consult WASA "Chlorine Policy and Procedures General Guidelines" for the requirements of the room and the preferred layout in the standard drawings.

1.2.The room dimension must allow for working staff to be able to work properly with no risk or hazard to their safety. Allow for at least 1.5 m free corridor for passage and operation around equipments.

2.3.The chlorinator and chlorine supply must be located in a separate, special room. The sealed chlorine dioxide tank(s) shall be vented to the exterior of the building, with door opening to out-of-doors and sign on door.

3.4.The ventilation start switch must be remote or door activated. The room must be properly vented with minimum one air change per minute. The exhaust shall be near floor and the fresh air intake near ceiling.

4.5.Scales must be provided with automatic switchover.

5.6.An observation window must be provided.

6.7.A gas mask must be provided and stored outside the chlorination room.

7.8.Chlorine gas detector shall be installed at each critical location.

The gas chlorination equipment room shall be provided with ventilation system that meets the requirement set by regulatory standards.

9.6.1.2 Hypochlorite Chlorination System

The raw water quality and chlorine demand should always be assessed prior of using sodium or calcium hypochlorite systems and results should evaluate impact on disinfection by-products’ impact. Unless specified, the following guidelines apply both to sodium or calcium hypochlorite disinfection systems.



9-18 October 2008R1

The hypochlorite chlorination system shall be positive displacement metering pumps with capacity located in the Hypochlorite Storage Room. In general, the application points for the hypochlorite chlorination system shall be located similarly to the gas chlorination system but the system should be reviewed to ensure the needs of the treatment process has been complied.

• Sodium and calcium hypochlorite facilities should include a cool, dark, dry, clean, above ground and vented area for the storage and use of the hypochlorite disinfectant. For hypochlorite facilities include covered make-up and feed solution tanks.

• Where hypochlorite is used, provide a minimum of two metering pumps sized for maximum day demand.

• When calcium hypochlorite is used for disinfection, the tablets or granules shall be completely dissolved in water prior to injection.

• The liquid hypochlorite shall be injected into the common inlet/outlet pipe by a metering pump and shall be controlled by the chlorine residual analyser or magnetic flowmeter. Isolation valves shall be provided so that the analyser can sample water from the reservoir inlet pipe only. The chlorination system shall only operate when the water is flowing into the reservoir and the reservoir inlet valve is in the open position. Provide strainer on the chlorine output to dosing pumps.

• Isolate hypochlorite tank(s) in a separate containment area. Volume of containment area to be equal to110% of volume of hypochlorite tank(s).

• The level of the hypochlorite in tank shall be monitored by the field instrumentation, which shall be connected to the SCADA System for the monitoring and alarm.

• Provide air vent to chlorine reservoirs and assure sufficient ventilation of room to avoid corrosion.

• Hypochlorite solution in tank should not be diluted unless dilution water treated for hardness.

9.6.2 Ultraviolet Radiation (UV)

UV water treatment devices must comply with Class A criteria under ANSI/NSF Standard 55 - Ultraviolet Microbiological Water Treatment Systems. UV water treatment device shall meet the following standards:

• Raw water quality shall be evaluated and pre-treatment equipment shall be designed to handle water quality changes and performance specs.

• The UV device shall be fitted with a light sensor to safely verify that UV light is being delivered into the reactor.

• The UV unit should be installed on a designated electrical circuit and equipped with a solenoid operated automatic emergency water shut-off valve that will shut off the water supply to the UV unit in the event of a loss of power supply to the UV unit or a drop in dosage below the minimum required level of 40 mJ/cm2. When power is not being supplied to the UV unit, the valve should be in a closed (fail-safe) position.


9-19 October 2008R1

• UV units installed vertically should have the water outlet located at the top to allow the chamber to completely fill with water and maximize water exposure to the UV lamp. Similarly, UV units installed horizontally should have the water outlet directed upward.

• The UV assemblies shall be accessible for visual observation, cleaning and replacement of the lamp, lamp jackets and sensor window/lens.

• A sufficient number (required number plus one) of parallel UV treatment systems shall be provided to assure a continuous water supply when one unit is out of service.

• Provide and have available on site at least one replacement lamp per unit and a 5 micron replacement filter where applicable.

• Provide with a mean of recording the water quality test data, dates of lamp replacement and cleaning, a record of when the device was shutdown and the reason for shutdown, and the dates of pre-filter replacement.

Water And Sewerage Authority (WASA) Water and Wastewater Design Guideline Manual Design of Wastewater Collection System

10-1 October 2008R1

Section 10 Design of Wastewater Collection System

10.1 General Requirements This section outlines the minimum requirements for the design of wastewater collection systems. However, the Consultants shall apply sound engineering judgement and approach in the design of such systems.

All wastewater mains and appurtenances shall be designed in compliance with all relevant codes, design guidelines or standards as well as in accordance with current Trinidad & Tobago National Plumbing Code,

For new communities, the Consultants shall establish the geodetic invert elevations and ties of all wastewater lateral connections at street line. The information shall be incorporated on the “As-built” drawings. To avoid proliferation of lift stations and package treatment plants within developments, each project should be assessed through modelling of regional network and optimum development scheme. WASA’s Master plan for Trinidad & Tobago should be reviewed to grasp the bigger communities and regional planning priorities.

In all projects, assessment of trenchless construction techniques and rehabilitation methods for existing pipes shall be thoroughly prepared. The assessment shall as a minimum cover the geotechnical conditions, traffic disruptions, survey the existing utilities and sub surface structures, obtain right-of-way and property line information, take account of possible improvements to street or utilities, risk and safety, and include technology aspects on construction and costs etc.

10.2 Design Flow

10.2.1 Design Wastewater Flow

All wastewater flow should be calculated to convey the maximum flow, including inflow & infiltration in wet weather flow. The following formula shall be used unless a more rigorous analysis is carried out:

Fd = Fadw x Kap + Ia Where Fd = Design flow Fadw = Average Dry Weather Flow Kap = Average Peak Wastewater Flow factor Ia = Infiltration Allowance

10.2.2 Average Dry Weather Flow

The average dry weather flow (ADWF) includes all flow components from residential, commercial, institutional and industrial usages. Detailed flow monitoring done in the Greater Port of Spain Region (Reid Crowther, nov 1998) & in the Eastwest corridor (Safege, april 2005) have established local reliable ADWF. Since 1998, a 10% increase of the residential flow is


10-2 October 2008R1

expected in order to contain the grey water inclusion in new developments. It is assumed that because of the planned metering of all supplied water, the domestic consummation should gradually linearly lessen by 10% for 2020.

The Consultants shall perform the wastewater design flow calculations based on the following tables. Individual studies are to be made for special commercial establishments, major commercial areas, special industrial areas, and major industrial areas.

General per capita flows for all types of development

2005 2020

Total ADWF without infiltration 280 (litres/ capita/ day) 252 (litres/ capita/ day)

Occupancy rate per unit house * 3.7 (person/unit)

3.5 (person/unit)

* From T&T Central Statistical Office census 2000 Residential Dry Weather Flow

Type of Development Equivalent PopulationDensity (persons/hectare)

Unit Wastewater Flow

lpcd l/ha/s

Single Family (new) 55 280 0.178

Single Family (existing) 45 280 0.146

High density single family 85 280 0.276

Semi-detached, duplex and 4-plex 100 280 0.324

Townhouse, Maisonette (6 storey apt. or less)

135 280 0.438

Notes: i) lpcd = litres per capita per day

ii) l/ha/s = litres per hectare per second

Commercial, Industrial, and Community Dry Weather Flow

Type of Development Equivalent PopulationDensity (persons/hectare)

Unit Wastewater Flow

m3/ha/day l/ha/s

Light Commercial Areas 90 25.2 0.156

Community Services 40 11.2 0.123

Light Industrial Areas 150 42 0.462

Notes: i) l/ha/s = litres per hectare per second ii) m3/ha/day = metres3 per hectare per day


10-3 October 2008R1

10.2.3 Peak Wastewater Flow Factor

Detailed assessment of peak flows, based on existing data and local conditions are required for each project. Design flows are to be set with consideration for daily average and hourly peak flows, inflow and infiltration, illegal connections, and rainy season wet weather peak flow.

10.2.3.1 Residential and Community Services Land Use

For residential and community services land use, the peak wastewater flow shall be derived by assessing existing available data based on local catchment basins. If these are not available, apply the ratio established by the Harmon Formula to the average wastewater flow for residential and community services areas as follow:

P++=

4141Kap

where, Kap = ratio of peak flow to average flow P = tributary population in thousands

Note: For small populations, do not use a peak factor higher than 4. 10.2.3.2 Commercial and Industrial Land Uses

For commercial and industrial land uses, the peaking factor shall be determined from a modified Harmon Formula as follow:

)4

141(80.0KapeP+

+⋅=

where, Kap = ratio of peak flow to average flow Pe = equivalent tributary population in thousands 10.2.3.3 Combined Land Use

When a tributary area consists of residential, industrial and commercial land uses, the peaking factor for the combined land use shall be calculated using the modified Harmon Formula as follow:

)4

141( Kape

av PPK

+++⋅=

where, CIR

CIRav AAA

AAAK

+++⋅+

=)(80.0

and AR = residential area AI = industrial area AC = commercial area


10-4 October 2008R1

10.2.4 Infiltration Allowance

Except under individual assessment or suspected poor condition collection system, infiltration allowance shall be determined at 5 000 l/ha/day for all types of land use. The Infiltration rate should be substantially higher in old existing areas of Trinidad & Tobago and/or with high water tables and care should be taken to include wet weather inflow problems. In those areas, infiltration rate up to 15 000 l/ha/day could be required with justification data to support.

Any manholes located in depressions are subject to an additional 0.4 l/s per manhole. Minimum flow is estimated between 0.3 to 0.5 the average daily flow. The value 0.4 should be used as general for Trinidad & Tobago.

10.3 Gravity Pipe Size

10.3.1 Manning’s Formula

To determine the pipe size and its capacity, the Manning’s Formula may be used. Manning’s Formula is expressed as:

ASRn

Q ⋅⋅= 2/13/21

where, Q = design flow (m3/sec) n = coefficient of roughness (dimensionless) R = hydraulic radius (m) S = slope (m/m) A = section area of flow (m2)

10.3.2 Coefficient of Roughness

For all pipe materials, the coefficient of roughness should be set as 0.013.

10.3.3 Minimum Pipe Size

For residential areas, the minimum pipe shall be 200 mm diameter.

For commercial and industrial areas, the minimum pipe size shall be 250 mm diameter.

10.4 Flow Velocities The flow velocity shall be determined from the following:

AQV =


10-5 October 2008R1

where, V = flow velocity (m/sec) Q = design flow (m3/sec) A = cross section area of flow (m2)

The maximum velocity shall not be greater than 3.0 m/sec with the pipe flowing full and the minimum velocity shall not be less than 0.60 m/sec with actual flow on a daily basis. The depth of flow should never exceed 75% of the internal diameter of the sewer.

10.5 Pipe Slopes & Manhole distances The minimum slopes shown are those required for “self-cleansing velocity set as 0.7 meter per second, The maximum length between manholes and the absolute minimum slopes for different sewer sizes shall conform the following:

Sewer size (mm)

Maximum length (m) between Man hole

Minimum slope (m/100m)

200 90 0.40 250 110 0.28 300 110 0.20 350 110 0.17 375 110 0.15 400 120 0.14 450 120 0.12 525 120 0.10 600 150 0.08 900 150 0.046 1200 assess 0.031 1800 assess 0.020

10.6 Structural Layout In determining the suitable pipe class to be used, live load, dead load, soil type and trench conditions shall be considered in the calculation. The pipe manufacturer’s recommendations shall be incorporated into the design. All pipes are to be provided with minimum 150 mm compacted granular bedding and backfill up to 300 mm above the pipe. In cases where geotechnical recommendations are not available, granular materials shall meet AASHTO M-43 requirement for the following pipe sizes:

Pipe size AASTHO M-43 size

Less than 375 mm 67, 7, or 8

375 mm to 750 mm 6 or 67

Greater Than 750 mm 57 or 67


10-6 October 2008R1

10.7 System Layout

10.7.1 Location of Wastewater Main

All new wastewater mains shall be located within the road allowance.

Location of replacement wastewater mains shall be determined specifically based on the location of existing utilities and other site conditions and will be dealt with as situation arises. Preferably, sewers are to be 1.5 m offset from roadway centreline. System arrangement shall include redundancy and overflows to propose alternate routes in case of blockage. Overflow shall be rerouted in the sewer system. Sewer easements are required if sewer located out of roadway.

Gas pipelines need a minimum separation of 0.9 m at crossings. See section 5.5.3 for distances from drinking water lines & pipes.

10.7.2 Pipe Depth

The depth for wastewater main pipe cover shall be determined in consideration of economic factor, the strength of the pipe and external loads due to trench backfill and wheel loads. Minimum cover shall be of 1.2 m for roadways and 0.9 m for open areas.

10.7.3 Grid Design

Wastewater mains changing in alignment shall have man holes at the point of the alignment change.

10.8 Pipe Material

10.8.1 Concrete Pipe

Reinforced concrete pipes may be used for pipe size greater than or equal to 300 mm in diameter. Portland Cement shall comply with ASTM C150.

All concrete pipes, fittings and joints shall conform to ASTM standards C-76 or EN 641. All concrete pipe to be manufactured to give Type V Sulfate Resisting Cement for all sub-structures. Sulphate resistant cement or concrete shall be used for on site concrete pouring.

For flat curves, straight pipe with joint deflections is permissible. Maximum joint deflection shall be 13 mm.

10.8.2 Polyvinyl Chloride Pipe

PVC pipe sizes from 150 mm to 375 mm in diameter are acceptable.

No curve radius or joint deflection shall be allowed on pipe layouts. Saddle type connections are not permitted. Tangent length of tee connections must be taken into considerations when calculating the minimum radius that can be achieved.

PVC pipes and gaskets shall conform to the requirements of ASTM D-3034-77 & ISO 4435.


10-7 October 2008R1

10.8.3 Polyethylene Pipe

High density polyethylene profile pipe sizes from 150 mm to 600 mm diameter shall conform to ASTM and ISO 4437 and fittings to ISO 8085. Joints shall be bell and spigot or butt fused. The pipe shall only be used with manufactured tees.

10.8.4 Glass Reinforced Plastics (GRP) Pipes and Fittings

Glass reinforced plastics (GRP) pipes and fittings for diameter over 200mm and shall comply with the relevant provisions of ASTM F1092-04, or BS 5480, and ISO 10639.

10.8.5 Ductile iron

Ductile iron pipe, fittings, accessories and their joints shall be conform to ISO 7186:1996 requirements and test methods applicable.

10.9 Maintenance Chamber (Manhole)

10.9.1 Maintenance Chamber Design

All maintenance chambers shall be designed based on the following criteria:

1. See section 10.5 for distances between manholes depending on pipe diameter.

2. At maintenance chambers where pipe sizes change from smaller pipe size to a larger downstream pipe size, match the pipes obvert elevations. It is not permissible to design downstream pipe size smaller than the upstream pipe size.

3. Drop maintenance chambers shall be provided where the difference in elevation is greater than 0.60 metres. The drop pipe shall be one size smaller than the wastewater main. The economic feasibility of providing deeper wastewater mains versus excessive invert drops, drop maintenance chambers, or excessively steep benching shall be ascertained prior to finalizing the design. Prefabricated drops internal to the maintenance chamber are not permitted on 1200 mm diameter maintenance chambers. Where the maintenance chamber depth exceeds 10 m, provide safety grating.

4. Watertight and locking covers shall be provided on maintenance chambers located on all easements and in areas where maintenance chambers are susceptible to flooding. Where significant sections of wastewater mains are provided with watertight covers, extended vents may be required which shall be determined by the Consultants on a case-by-case basis. Frames and covers to be a floating style (NF80 or 90) capable of withstanding H-20 loading.

5. Tee maintenance chambers may be used for wastewater mains 1200 mm or larger in diameter.

6. Sanitary sewer service connection to a maintenance chamber should be avoided. However, it may be permissible should the proposed sanitary sewer service falls within the same obvert elevation of the sanitary sewer entering the maintenance chamber.


10-8 October 2008R1

7. For commercial and industrial establishments, an inspection maintenance chamber must be placed at a location immediately behind the property line to service the lateral connection.

8. All enclosures and rails should be corrosion resistant.

10.9.2 Manhole Hydraulics

1. On runs with horizontal alignment changes from 0° to 15°, invert drops from 0.015 m to 0.030 m shall be provided.

2. Where the alignment change exceeds 15°, drops shall be provided in accordance with the following table.

Alignment Change and Required Drop

Alignment Change Required Drop

15o – 45o min. 0.030 m

45o – 90o min. 0.050 m

10.10 Connection from Main to Street Line

10.10.1 Street Line Connection

Single family and semi-detached dwellings in residential areas shall have a minimum of 150 mm diameter street line connection.

Dual connections or two separate lines in a common trench are acceptable in residential areas where the difference in basement elevation does not exceed 0.60 m. Two or more units serviced on a common line with wye branches are acceptable.

Where the diameter of the lateral connection is greater than or equal to half the diameter of the wastewater main, the connection shall be made with a tee-wye or wye connection.

The minimum and maximum cover at property line shall be 1.2 m and 1.8 m, respectively. A 2% minimum grade for lateral connections shall be maintained. Pipe size change must be made through similar quality eccentric pipe reducers.

10.10.2 Connection Size and Grade For Multi Family Sites

In multiple family blocks in residential areas, the lateral connections shall meet the following requirements:


10-9 October 2008R1

Connection Size and Grade

Diameter of Drain (mm)

Slope of Drain 2.0 % 4.0 %

Maximum No. of Fixture Units Per Connection

150 840 1000

200 1920 2300

250 3500 4200

300 5600 6700

375 10000 12000

10.10.3 Pipe Material

PVC pipe may be used for residential lateral connections. Service connections to the main line sewer shall be at a maximum of 45o from the horizontal.

10.11 Forcemains

10.11.1 System Design

All forcemains and thrust restraints shall be designed to withstand the maximum operating pressure plus the number and timing of the pump cycles to which they will be subjected. If the forcemains are subject to vaccum conditions, avoid plastic and HDPE pipes.

To allow pumping stations to be by-passed during emergencies or major modifications, all forcemains shall be equipped with suitable valve connections to permit connection of discharge piping from a portable pump.

Air release valves suitable for use with wastewater shall be positioned at all forcemain high points. The valve shall be set horizontally and an insulated coupling, ball valve, and pipe union shall be provided on each assembly to allow maintenance and removal of the air valve.

All plugs, tees and bends shall have approved design mechanical thrust restraints.

The bedding requirements for the forcemains will depend upon the type and the class of pipe used. As a minimum requirement, the forcemains shall be laid on 100 mm of sand bedding material conforming to AASHTO type 7 or as indicated by the geotechnical study.

The type of backfill material will usually be determined from the location of the forcemain within the right-of-way (ROW). Under the pavement, an approved granular backfill shall be used with conformity to road structural support and design.

10.11.2 Pipe Size

Forcemains shall be sized to have a flow velocity in the range of 0.7 to 3.0 m/s, with the lower limit being preferred for the initial phase. The minimum size of the forcemain shall be 100 mm in diameter.


10-10 October 2008R1

10.11.3 Pipe Depth

Consultants shall allow a minimum of 1.2 m of cover for forcemains.

10.11.4 Tracer Wire

Tracer wire shall be installed on all new installations of forcemain pipes for locating purposes.

Handwell spacing is not to be greater than 150 m apart. The wire shall be installed between each valve or handwell and/or the end of the new pipe. Joints in the wire between valves or handwells are not permitted. At each valve a loop of wire shall be brought up inside the valve box or handwell to the top of the box.

10.11.5 Thrust restraint

Mechanical thrust restraints shall be designed to withstand the maximum operating pressure plus the number and timing of the pump cycles to which they will be subjected. Concrete thrust blocks shall only be permitted for use in special circumstances subject to the approval of WASA.

Water And Sewerage Authority (WASA) Water and Wastewater Design Guideline Manual Wastewater Treatment Plants

11-1 October 2008R1

Section 11 Wastewater Treatment Plants

11.1 General These design criteria are minimum guidelines to be used for the comprehensive consideration of domestic sewage treatment, or disposal systems and to establish the minimum design criteria pursuant to existing state statutes pertaining to effluent quality necessary to meet state water quality standards. These criteria are intended to promote the design of facilities in accordance with good public health and water quality engineering practices.

This section deals with community collected sewage and does not cover the design of septic tanks and associated secondary treatment and disposal systems. The design requirements for that type of system can be found in TTS 16 80 400.

All inflow into the sewerage is assumed to meet the normal domestic water charges and quality. All collected users are required to meet WASA TES 101-2004 Trade Effluent Standards for Discharges into Sewers. These design standards supplements do not supersede the requirements of the EMA and or any legislation relating to the design and operation of wastewater treatment plants.

Whenever possible, existing data of flows and raw waste strength from the same plant or nearby plants with similar service areas should be used in design of treatment facilities. When using such data for design purposes, the variability of data should be considered and the design based on the highest flows and strengths encountered during normal operating periods taking into consideration possible infiltration/inflow. More information on wastewater design flows are found in section 10.

There shall be no water connection from any public drinking water supply system to a wastewater treatment plant facility unless made through an air gap or a backflow prevention device, in accordance with AWWA Standard C506 (latest revision) and AWWA Manual M14. All washdown hoses using potable water must be equipped with atmospheric vacuum breakers located above the overflow level of the washdown area.

The subject of effluent reuse should be assessed in the preliminary design stage since there is a considerable potential for the reuse of wastewater in irrigation of parks and gardens, agriculture and horticulture, aquaculture and some industrial processes.

Water And Sewerage Authority (WASA) Project Design and Technical Specifications Manual Wastewater Treatment Plants

11-2 October 2008R1

11.2 Wastewater Effluent treatment objectives The sets of standards for effluent quality are based on the T&T Water Pollution Rule 2004. Wastewater treatment plants shall be designed to consistently (95% average) meet the effluent concentration and loading requirements of the following criteria:

Discharge Point BOD mg/l

Suspended Solids mg/l

pH Fecal

Coliform MPN/100ml

Total Residual Chlorine

mg/l

Amm Nitrogen (NH3-H)

mg/l

Total Phosphorus

as P mg/l

Inland Surface Waters 20 * 20 * 6-9 400 1 10 5

Inshore Sea Waters 50 150 6-9 400 1 10 5

Offshore Sea Waters 100 200 6-9 400 2 10 5 Environmentally Sensitive Areas 10 15 6-9 100 0.2 0.1 0.1

* These criteria have been modified from the EMA 2006 objectives to impose a stricter environmental criteria and allow for design security,

11.3 Wastewater Loads There is limited data available in Trinidad & Tobago upon which to make an accurate estimate of the unit loading rate expected. Whenever possible, Consultants should assess the loadings in individual assessment reports, especially for areas with significant industrial development. Based on values measured in the Greater Port of Spain (Reid Crowther, Nov. 1998), the Eastwest Corridor (Safege, April 2005) and experience in the remainder of the world, loads contribution shall be based on the following table for T&T.: Maximum Dwelling Units Densities

Type of charges Unit Loads (g/c/d) BOD5 65

TSS 90

NTK 10

Total Phosphorus (Pt) 2

11.4 Plant Layout In designing the layout of wastewater treatment plants, consideration shall be given for future expansions of the plant to its ultimate site capacity in order to maximize the utilization of the available space of the property. Future expansion requirements are as a rule, identified in studies or in master servicing plan. The staging of each expansion phase is tied to the servicing of new development areas as well as growth in the existing urban designated areas.


11-3 October 2008R1

In this regard, consideration should be given at the design stage, to the requirements for future expansion as well as the economical and practical sizing of plant process requirements.

The Consultants should in all cases maximize the site’s ultimate capacity in planning the plant layout, which may be much higher than the capacity requirement. Designing of the expansion works should be carried out to permit the orderly construction of the facility economically with minimal disruption of the existing facility.

The piping within all plants shall be arranged so that when one unit is out of service for repairs, plant operation will continue and emergency treatment can be accomplished. Valves and piping shall be provided and sized to allow dewatering of any unit, in order for repairs of the unit to be completed in as short a period of time as possible. Removed wastes must be stored for retreatment or delivered to another treatment facility for processing. Consideration shall be given in design for means to clean piping, especially piping carrying raw wastewater, sludges, scum, and grit. H2S gas detectors shall be supplied with visual and audible alarms in order to protect staff working at wastewater treatment plants.

11.5 Plant Design Capacity

The design for various components of the wastewater collection system (collector sewers, interceptor sewers, pumping stations) will be based on peak hourly flow. Force mains from pumping stations will be sized to handle the pumping capacity of the station.

The design for various components of the treatment plant will be based upon either peak design flow or peak hourly flow. Generally, the organic loading of a wastewater treatment unit is based on the design average flow and the hydraulic loading of a unit is based on the peak design flow. Peak design flow is generally set between 2 to 2.5 times the average dry daily flow. Where recirculation is provided, the recirculation rate shall be added as required. The engineering report shall list the design influent flow, peak factors and concentration of BOD5, TSS, N, P, or other parameters.

11.6 Equalization tank The wastewater treatment facility, in general, shall consist of a minimum of two trains. Equalization units should be provided after screening and grit removal. Generally, an equalization facility requires a volume equivalent to 10% to 20% of the anticipated dry weather flow. Tankage should be divided into separate compartments to allow for operational flexibility, repair, and cleaning.

If a filter is present, backwash water is discharged into the two equalization tanks where it is then pumped to the clarifiers. Settled sludge from clarifiers is pumped to the thickeners. Normally, the sludge would flow from the clarifiers to the thickeners by gravity.

11.7 Pre treatment – Inlet Works Bar screens, screens, or shredders through which all wastewater will pass should be provided at all plants with the exception of plants in which septic tanks, Imhoff tanks, facultative, aerated, or partially mixed lagoons represent the initial treatment unit. In the event bar screens, screens, or


11-4 October 2008R1

shredders are located 1.2 meters or more below ground level, appropriate equipment shall be provided to lift the screenings to ground elevation. Where mechanically cleaned bar screens or shredders are utilized, a backup unit or manually cleaned bar screen shall be provided. A means of diverting flow to the backup screen shall be included in the design.

Inlet Works shall be sized to handle hourly peak flow into the facility. Peak flow is defined as the average dry weather flow multiplied by the peak flow factor plus the allowance for infiltration in the wastewater collection system (see section 10.2).

The Inlet Works shall be housed in a building and designed for ease of operation for the removal of grit bin(s), screen, and cleanup of the facility so as to promote a positive working environment for the Operators.

1. Provide screening compactor for the compaction of screening waste material.

2. Provide grit removal equipment sized to meet service requirements. Grit removal facilities should be considered for all wastewater treatment plants.

3. All screenings and grit shall be disposed of in an approved manner. All wastewater originating from the grit cyclone and classifier, automatic bar screen waste material bin, compactor and grit bins shall be piped for return to the plant process stream.

4. Design the Inlet Work’s ventilation system, including all necessary interlocks, for proper operation of the system. Control and instrumentation for the heating and ventilation system shall be explosion-proof for all electrical equipment and system.

5. Provide instrumentation for monitoring of the operation of the grit cyclone and classifier, automatic bar screens and compactor equipment in the Inlet Works. All monitoring and alarming methods shall be fail-safe.

6. Provide metering of wastewater entering the Inlet Works or Outlet, depending on the hydraulics of the headworks.

7. The ventilation systems shall be designed to maintain acceptable working and living environments for personnel and non- destructive conditions for equipment. H2S gas detectors shall be installed when such risks are present to working staff.

11.8 Secondary and tertiary treatments Secondary treatment is mandatory in all processes in order to attain the effluent objectives. Depending on type of environment or on the projects’ terms of reference, tertiary polishing treatments should be also assessed. Consultants shall assess the options for secondary and tertiary treatments as part of the prefeasiblity study and take into consideration all required information, including the site, economical and social constraints and treatment objectives.

11.9 Disinfection System Facilities for disinfection shall be provided in all cases to protect the public health and as an aid to plant operation. Adequate disinfection is to be provided for the Treatment Plant’s effluent in keeping with TT4417.1993 prior to its discharge into a receiving stream.


11-5 October 2008R1

Ultraviolet disinfection is the preferred mode of disinfection. Disinfection techniques not in widespread use, such as ozonation, bromine chloride, and chlorine dioxide, have to be submitted for approval on a case-by-case basis.

11.9.1 Chlorination System

Depending on the plant process treatment capacity requirements, one chlorinator shall be provided for each chlorine application point. Equipment shall be selected and installed which is capable of applying desired amounts of chlorine continuously to the effluent. Chlorination equipment may also be installed to control odors, remove nutrients and generally assist treatment. To accomplish these objectives, points of chlorine application may be established at the head of the plant for prechlorination, in the effluent chlorine contact chamber, or other suitable locations. Chlorination equipment shall have a capacity greater than the highest expected dosage to be applied. Chlorination systems shall be capable of operating under all design hydraulic conditions. Duplicate equipment with automatic switchover should be considered for standby service, so that continuous chlorination can be provided. A minimum of two (2) standby chlorinators, sized to meet maximum day demand shall be provided. The chlorine piping and controls shall allow the use of the standby chlorinators for all possible application points. 1. Two (2) chlorinators shall be provided for Post-Chlorination

2. One Standby Chlorinator shall be provided and sized for maximum day demand

3. A scale for determining the amount of chlorine used daily, as well as the amount of chlorine remaining in the container, shall be provided.

Where plants have SCADA systems, the chlorinators shall have the capability of being controlled:


2. At the PLC/Manual

3. At the PLANT/Manual through the SCADA Human Machine Interface (HMI) using the Graphics User Interface (GUI) main screen

The chlorinators shall be provided with the required switches to enable control of the feed rate through the SCADA system.

For each chlorinator, provide a GUI pop-up menu box to indicate the feed rate. In the CPU/Manual control mode, provide a GUI pop-up menu box for the respective chlorinator to permit changes of feed rate set point from zero to 100%.

For chlorination system, the feed rate will be based on a closed feedback loop.

Rapid initial mixing of the chlorine solution and wastewater is essential for effective disinfection. Contact chambers shall be designed to provide a minimum average hydraulic residence time (chamber volume divided by flow) of 20 minutes at the design peak hydraulic flow. Chemical disinfection is not normally required when the total residence time in the wastewater treatment system (based on design flow) is at least 21 days.


11-6 October 2008R1

11.9.2 Ultra-Violet (UV )

Ultraviolet disinfection systems are considered applicable to treated wastewaters with daily average BOD 5 and TSS concentrations consistently less than 20 mg/liter. Disinfection units will be designed in accordance with methodologies presented in the United States Environmental Protection Agency Design Manual, Municipal Disinfection, EPA/625/1-86/021. Turbulent flow is necessary due to non-uniform intensity fields in an ultraviolet reactor. Disinfection systems shall consist of a minimum of two ultraviolet banks in series and shall be capable of providing disinfection to the effluent fecal coliform requirements (See section 11.3) at the design daily average flow with the largest bank out of service. Ultra-Violet (UV) is the preferred choice for the disinfection system and design system as follows:

1. Provide a minimum of two banks of UV lamps with 100% redundancy. The two banks are to be operated in-series, each with a capacity to meet average day flow.

2. The ultraviolet unit shall be configured so that there is adequate space for the removal and maintenance of lamps. One person should be able to replace lamps without the aid of mechanical lifting devices, special tools, or equipment. Drains shall be provided to completely drain the ultraviolet reactor unless the equipment can be easily removed from the effluent channel, but lamps shall be replaceable without draining the unit. The materials used to construct the reactor shall be resistant to ultraviolet light. Ballasts and other electrical components shall be consistent with the ultraviolet lamp manufacturer's recommendations. Temporary screens shall be installed to protect the lamps and other fragile components from construction debris.

3. For wastewater treatment with tertiary treatment, provide low intensity UV lamps.

4. Where possible, the horizontal lamp arrangement is preferred over the vertical arrangements.

5. Provide a cleaning solution tank for the UV lamps adjacent to the UV channels and pump the spent cleaning fluid to the head of the plant.

6. Each individual ultraviolet lamp shall be provided with a remote operation indicator. Lamp failure alarms shall also be provided for a predetermined number of lamp failures. Techniques that result in nonirradiated flow pathways are prohibited. Each ultraviolet bank shall be equipped with at least one ultraviolet intensity meter or some means to monitor changes in ultraviolet dosage; however, intensity meters shall not be relied upon to automatically control system operation. A flow control device, such as an automatic level control, shall be provided to ensure that the lamps are submerged in the effluent at all times regardless of flow rate. The automatic level control shall be arranged so that it will allow suspended solids, which may settle, to be washed out of the area of UV disinfection. Proper ventilation is critical to the ultraviolet system operation. Cabinets containing ballasts and or transformers shall be provided with positive filtered air ventilation and automatic shutdown alarms at high temperatures. Provisions shall also be made to maintain the ultraviolet lamps at or near their optimum operating temperature and to filter ventilating air so as to limit ultraviolet light absorbance by dust accumulations. Elapsed operation time meters shall be provided for each bank of ultraviolet lamps.


11-7 October 2008R1

7. Provisions for routine cleaning such as mechanical wipers, high pressure sprayers, ultrasonic transducers, or chemical cleaning agents are required. Quartz sleeve ultraviolet systems shall have a chemical cleaning capability in addition to any ultrasonic and/or mechanical wiper systems. Operators shall be protected from exposure to ultraviolet light during normal operations.

11.9.3 Sulphur Dioxide System

Where the final effluent water must be dechlorinated as required by EMA or WASA, the dechlorination process shall be achieved by the use of sulphur dioxide or sodium metabisulphite.

Sulphur dioxide system shall be sized for maximum day demand and a minimum of two (2) sulphonators shall be provided.

Provide one additional standby sulphonator sized for maximum day demand.

All sulphonators shall have the capability of being controlled:


2. PLC/Manual

3. PLANT/Manual at the Plant through the SCADA HMI at the GUI main screen

The metering pump shall be provided with the required switches to enable control of the sulphonators through the SCADA system.

For each sulphonator, provide a GUI pop-up menu box to indicate the feed rate. In the CPU/Manual control mode, provide a GUI pop-up menu box for the respective sulphonator to permit changes of feed rate set point from zero to 100%.

11.10 Sampling and monitoring Monitoring stations shall be provided at influent, effluent and after each unit treatment during the process to allow for control and assessment of treatment.

Automatic sampling stations are required to perform discrete or composite, flow proportional and time proportional sampling at the inlet and the outlet of treatment plants. Sampling sequence is to begin with high pressure air purge of intake assembly to clear obstructions. Sampler enclosure is to be weatherproof, corrosion resistant, insulated and c/w forced air heater and thermostat, locking door and bolt down base. Provide with refrigerated sample compartment. Controller to be programmable with LCD display and include battery to maintain program settings and stored information in the event of power failure.

11.11 Odor Control Provide odour control with appropriate ventilation system designed to minimize the odour level in the Inlet Works working area. To protect working staff from gas inhalation risks, H2S gas detector shall be supplied with visual and audible alarms.


11-8 October 2008R1

Odour control may be achieved by isolation of the areas having odour problems and ventilating it separately or by providing direct ventilating capability at the source of odour. Alternatively, the air blower(s) air intake can be connected to the Inlet Works ventilation system for the removal of the odour and the air is used in a separate coarse air bubble aeration system in the aeration tank.

Where odour control is not feasible, provide odour treatment in the alternate with gas scrubbing system, which may be chemical or biological unit.

The need for odour control facilities shall be evaluated for each plant. Factors to be considered are the dissolved oxygen level of the incoming sewage and the type of treatment process proposed. When required, air supply must be sufficient to maintain 1.0 mg/litre of dissolved oxygen in the wastewater.

At the outlet of the odour treatment system, the concentration of pollutants must be lower than the following values:

Pollutant Concentration (mg/Nm3)

Hydrogen sulphide <0.1

Amines <0.07 (in methyl sulphur)

Ammonia <1

Mercaptans <0.7 (in methyl sulphur)

11.12 Structural consideration The structural design of treatment plants shall be sufficient to accommodate anticipated ground movement including any active geologic faults and allow for independent dewatering of all treatment units.

Basins having vertical walls terminating 1.2 meters or more above or below ground level shall provide a stairway to the walkway. Guard rails on walkways shall have adequate clearance space for maintenance operations. All enclosures and rails should be corrosion resistant.

Refer to Section 15 – Structural Standards.

11.13 Water reuse for irrigation If the wastewater treatment plants include a tertiary treatment, the design should allow for pumping and using some of the effluent flow for irrigation purposes of plants in the neighbourhood of the treatment plant.

11.14 Control System Where SCADA control is implemented at the facility, refer to Section 17 – Instrumentation & Control and Section 18 – SCADA System for control system requirements.


11-9 October 2008R1

A means for measuring effluent flow shall be provided at all plants. Consideration should be given to providing a means to monitor influent flow. Where average influent and effluent flows are significantly different, e.g., plants with large water surfaces located in areas of high rainfall or evaporation or plants using a portion of effluent for irrigation, both influent and effluent must be measured.

11.15 SCADA System Comply with SCADA design standards as noted in Section 18 – SCADA System.

11.16 Equipment Redundancy See Section 4 – Process and Equipment Redundancy

Auxiliary power facilities are required for all plants, unless dual power supply arrangements can be made or unless it can be demonstrated that the plant is located in an area where electric power reliability is such that power failure for a period to cause deterioration of effluent quality is unlikely. Acceptable alternatives to auxiliary power include the ability to store influent flow or partially treated wastewater during power outage. Auxiliary power is required for plants discharging near drinking water reservoirs, shellfish waters, areas used for contact recreation, and for plants discharging into environmentally sensitive areas.

Multiple units may be required based on the uses of the receiving waters and the significance of the treatment units to the treatment processes

11.17 Stormwater management

11.17.1 Combined Sewer System vs. Separate Sanitary Sewer

The philosophy for combined or separate sewer systems is assessed in the long term on its impact on the operation of the wastewater treatment plants capacity. The positive aspect of separate sewer systems will result in a reduced peaking factor at the plant. This has the advantage that the design capacity of the plant can be reduced to meet actual wastewater treatment capacity requirement only. Therefore the designed capacity of the plant can be reduced; size or capacity of process equipment can be reduced and it will also result in the reduction of chemicals and energy consumption. A combined sewer on the other hand has the opposite effects but it has the advantage that all wastewater is treated prior to the effluent being discharged into the environment.

The preferred design approach to be implemented in T&T is for separate sanitary and storm water sewer systems.

11.17.2 Runoff impact

Environmental impacts from stormwater runoff are not to be underestimated, particularly in areas with a high population density. A proactive approach should be implemented. Implementation of mitigation strategies on receiving environments are preferred rather than



restorative efforts, which are more expensive and time consuming before a positive effect is noticed on the benthic communities and the fish species. A stormwater program must be designed to:

• reduce pollution to the maximum extent practicable; • protect water quality; and • meet environmental effluent standard requirements (EMA 2004).

To achieve these goals one aspect of the management program is to prevent pollution and install measures to control runoff water quality. Experience in North America has shown that a key component to a proactive approach is a clear and consultative environmental planning procedure and the use of biological monitoring, particularly benthic community analysis. Possible strategies to be implemented are:

• Public education to prevent litter, pet wastes, and debris from street gutters and storm drains

• Provision of public disposal sites for used oil, antifreeze, paints, and other household chemicals

• Control of soil erosion on land, public parks and construction sites • Implementation of agricultural best practices to avoid nutrient and pesticide pollution • In new development areas, efforts should be made to attempt to maintain the volume of

runoff at predevelopment levels by using structural controls and pollution prevention strategies.

Treatment processes may be necessary to diminish pollution. Storm drains and catch basins could include some form of treatment technology to help minimize impact on local eco-systems. Urban surface runoff quality control installations (detention ponds etc.) are often very effective for suspended solids and oxygen-demanding matter controls.

11.17.3 Requirements

Unless otherwise directed by WASA, for all water and wastewater treatment facilities, Consultants are to provide for means of reducing development site runoff during and after construction. Minimizing these development impacts include simple techniques such as green areas, erosion controls, maximizing infiltration, rooftop gardens, vegetated swales, buffers, and preservation of trees.

Water And Sewerage Authority (WASA) Water and Wastewater Design Guideline Manual Wastewater Pumping Stations

12-1 October 2008R1

Section 12 Wastewater Pumping Stations

12.1 General Consultants shall design wastewater pumping stations in accordance with WASA’s requirements and all other codes, guidelines, design standards etc. to ensure compliance. Studies shall assess future growth so the facility design will provide sufficient space for future expansion work. These guidelines are intended to establish the basic design parameters to be used in the development of wastewater pumping stations. As each pumping station is inherently different, the specific design for each pump station will be unique and sound judgment and acceptable engineering practices are to be provided.

12.2 Wastewater Pumping Station General Design Different types of pumping stations are possible and should be based on the incoming flow of wastewater, the peak flow and the total head required. The space requirements of pumps, piping, and equipment, along with the storage volume required in the wet well, will be carefully determined so that the proper size, shape, and configuration of the pumping station can be selected. The size and shape of the station will often be dictated by equipment other than pumps, such as bar racks or screens.

Toilet/bath facilities are to be provided for wastewater pumping stations except for small submersible stations.

12.3 Wastewater Pumping Station Layout Design wastewater pumping station configuration based on most efficient layout of pumps and equipment for safe and cost effective operation and maintenance of the facility. Select specific pumps based on the optimal combination of pump efficiency, capital, operating and maintenance costs.

Influent pipe for in-ground pumping stations shall be designed with a minimum distance of two-volute diameter away from the pump centre line. Benching in the wet well shall be steep and close to the pump inlet to prevent sediment build-up on the wet well floor.

Access opening for the pump shall be located and sized for the efficient installation or removal of the pump. It must also be sized to permit the entry of Operators or Maintenance staff wearing retrieval equipment harness without having to disconnect the safety line. The minimum dimensions of the access hatch shall be 900 mm by 750 mm. The access hatch cover shall be fabricated with light non corrosive material and be hinged and lockable by a padlock.

Lock port shall be recessed and provided with drainage pipe. The cover shall be provided with the necessary hold open arm to keep the cover in the vertical position once it is opened. Vertical access ladder shall be a non-slip, non corrosive material. An overflow pipe will be required in all cases unless the location prohibits its installation. In such cases, standby power will be required. Overflow pipes (minimum 200 mm) shall be installed in the wet well as high as possible without

Water And Sewerage Authority (WASA) Project Design and Technical Specifications Manual Wastewater Pumping Stations

12-2 October 2008R1

causing a sewer backup or basement flooding, and shall be equipped with a dedicated overflow alarm. A pressure gauge shall be provided at each pump discharge pipe above the flood line.

All fixtures, enclosures and rails shall be made of certified corrosion resistant material.

Provide required equipment for the safe retrieval of personnel in confined space. Provide lifting devices for the removal and installation of equipment.

Provide a minimum of one (1) meter clear space around equipment for servicing.

12.4 Configuration of Pumping System Wet wells shall be designed to suit the pump capacity, which should in turn, be matched to the design flow for the station. The size of the wet well in relation to the suction pipe(s) shall be in accordance with the Hydraulic Institute to prevent hydraulic interference. The depth of the wet well shall be sufficient to ensure adequate control bands for each pump. Where the continuity of the pumping station operation is critical, consideration should be given to dividing the wet well into two sections, properly interconnected, to facilitate repairs and cleaning.

Coarse (50 mm and finer) screening systems must be provided upstream in the collection system to avoid damages to lifting pumps. The system must include a means of collecting and disposing of screen wastes. As a general rule, for each pumping station, the screening requirements must be analysed and assessed to define the need for type and size of screens.

In no case shall the wet well be designed which will result in the pump(s) cycling more than six (6) times per hour for a station with a motor of less than 30 kW. In no case shall this exceed that as recommended by the manufacturer but in all cases, the more stringent criteria shall apply.

All wet wells shall be provided with water service to enable flushing or cleaning of the wet well. Wet wells shall be designed to prevent deposition of solids. In all cases, provide piping from the pump discharge header to the bottom of the wet well for flushing when the pump starts for a short period of time. Duration of the flushing of the wet well shall be adjustable from the control panel or PLC. Water service shall be provided with backflow preventer, sized not smaller then 40 mm and shall be metered.

All electrical equipment in the wet well shall be explosion-proof in accordance with applicable codes and/or standards. Lights shall be explosion-proof and equipped with a switch located in the electrical utility box. All hardware inside the station shall be stainless steel.

Laser or Ultrasonic equipments are to be preferred in the pump control system, and their installations are to comply with the following:

1. Above the highest top water level, usually above the top of the overflow pipe.

2. Within easy reach of the operator for maintenance or repair purposes.

3. Away from all possible interference arising from the wastewater flowing into the wet well through the inlet pipe.

4. Away from all possible interference arising from water surface turbulence.

5. Provide floats controls as a backup to the ultrasonic pumps control system. Ensure that the floats are installed complete with anti-sway hardware.


12-1 October 2008R1

12.5 Wastewater Pumping Station Sizing Design

Station Size Building Type Number Of Pumps Standby Pump Requirement

Type of Drives

Gen Set

1 Inflow less than 20 L/s. Typically small in-ground prefabricated submersible pumping stations.

One (1) rated at peak flow.

Locate pumps in wet well.

One (1) rated at peak flow.

Direct Drive with float control

Provide for connection to mobile Generator

2 Inflow greater than 20 L/s but less than 200 L/s.

Submersible pumping station with wet well and superstructure for housing controls, MCC, standby generator etc.

Two (2) pump configuration, each rated at peak flow or

Three (3) equally sized pumps with two (2) in parallel at peak flow.

Locate pumps in wet well.

For three pumps configuration, one (1) standby pump rated at the same capacity of the largest.

Direct Drive with ultrasonic level control complete with backup float control

Provide Gen Set sized for peak flow.

3 Inflow greater than 200 l/s.

Pumping station with superstructure in a dry well configuration.

Pumps could be of submersible type.

Two (2) pump configuration, each rated at peak flow or

Multiple pump configuration. Design pumping system for most efficient configuration for peak flow.

Locate pumps in dry well.

For multiple pumps configuration, one (1) standby pump rated at the same capacity of the largest unit

Direct and VFD with ultrasonic level control.

(VFD with bypass for Direct Drive)

Provide Gen Set sized for peak flow.


12-1 October 2008R1

12.6 Wastewater Pumping Station (Inflow less than 20 l/s) Provide storage for a two-hour retention capacity on peak flow in the wet well. Provide a vandal-proof, lockable, electrical hardware connector and switch gear for hook-up on the exterior wall, designed to provide electrical power to the station by a portable electric generator under a local power supply grid network failure. Type and model of lock will be provided by WASA.

A visual and audible alarm system should be installed for reporting to WASA. The electrical utility box shall be compact and low profile to complement the aesthetics of the location. Cabinet shall be located so as to permit the removal of the pump without undue difficulties.

A positive forced air ventilator shall be provided with a switch in the electrical panel to permit operation of the ventilator on a required basis.

12.7 Wastewater Pumping Station (20 l/s<Inflow < 200 l/s) Design pumping station with two constant speed submersible pumps in a single wet well configuration; with each pump sized for peak flow. Additional on-site wet well storage capacity is not required. Control, MCC, generator and electrical equipment are to be situated in a dry well. Dry wells, including their superstructure, shall be completely separated from the wet well.

Design pump control system to alternate pumping sequence. Provide a separate union box for pump power supply and to enable the removal and installation of the pumps.

A bypass hook-up for the forcemain with the necessary isolation valves shall be located outside the wet well. The bypass, regardless of the forcemain size, shall be 200 mm in diameter, flanged and provided with a quick connector extending 450 mm above the finished grade. Bypass fittings, pipe and isolating gate valves shall be 200 mm in diameter.

Provide an emergency standby diesel generator to provide power supply to the largest pumping unit in the station and other essential electrical equipment such as louvers, fans, instrumentation, controls, etc.

12.8 Wastewater Pumping Station (Inflow > 200 l/s) Use pumps in a dry pit configuration. Common walls must be gas tight.

For a station with two fixed speed pump operating systems, size each pump to handle 50% of peak flow. Provide one standby pump sized for peak flow. Submersible pumps should be installed if there is a flooding risk.

For stations with a multiple-pump operating system, determine the most efficient pumping configuration for the station based on:

1. Equally sized pumps,

2. One small pump with several equally sized pumps,

3. Combination of the above, or

4. Combination of 3 with variable frequency speed pump(s)


12-2 October 2008R1

In all cases, provide at least one standby pump with equal capacity to the biggest operating pump.

Provide variable frequency drive pump(s) where there is a need for continual flow from one pumping station to the next pumping station or wastewater treatment plant. The final design decision shall be based on good engineering practices. In no case shall the minimum design discharge velocity be less than 0.8 m/s.

Where required, as dictated by the characteristics of the wastewater flowing into the pumping station, provide an automatic screen complete with compactor and grit bin and/or comminutor.

Provide an emergency standby diesel generator.

12.9 Pump Design Pumps shall be non-clog and able to pump a 3 inch diameter solid. Convert to a "Vortex" pump volute any time pumping liquid contains lots of solids. Provide a back up seal for each seal.

Provide pipe flushing connections to facilitate the cleaning of plugged lines or pumps.

Provide an air vent pipe from high point on pump volute continuously discharging to wet well above overflow level to facilitate priming after wet well pump down.

For a dry pit with wet well configuration, provide piping and valves to allow re-circulation of pumped wastewater into wet well to prevent solids built-up at bottom of wet well.

12.10 Piping & Valve Design In the design of wastewater pumping station piping, the Consultants shall comply with the following criteria:

1. Only ductile iron pipe shall be used for the forcemain. 2. Stainless steel piping is not permitted for use in the forcemain.

3. Butterfly valves shall not be used in the forcemain.

4. Depending on the size of the forcemain, isolation valves shall be resilient seated full port gate valve or knife gate. Knife gate valves shall only be allowed on the suction piping from the wet well to the pump when space is limited and the hydraulic head is less than 6 meters.

5. Sluice gates shall be fabricated from stainless steel. Operators shall be located at ground level. Sluice gates shall only be allowed for isolation of the trunk sewer from the wet well or to isolate two wet well compartments.

6. The piping from the pump to the forcemain shall be designed for horizontal connection and not vertical.

7. Design piping layout with “Y” configuration and not “T”.

8. All valves shall be located in the horizontal position. Valves are not permitted to be installed in the vertical position.


12-3 October 2008R1

9. Air relief, air-vacuum release, or combination air release and vacuum valves shall be of a type and brand manufactured for the specific purpose in sewage service, and shall be provided at critical locations in the pump station and force main.. For each air-valve assembly, the pipe-nipple connection to the manifold and all other piping in the assembly shall be copper. An insulated coupling, ball valve, and pipe union shall be provided on each assembly to allow maintenance and removal of the air valve.

10. Provide flushing connections to facilitate cleaning of the pipe.

11. Provide isolation valve on the discharge header prior to it leaving the pumping station.

12. Provide horizontally placed anti-slam check valves on all pump discharge headers.

13. Provide for surge protection by installing soft start/stop electrical control equipment or surge control on pumps main discharge header and recycle wastewater to the wet well above top water level (TWL).

14. Properly located and sized pipe supports shall be provided. No loads shall be transmitted to pump flanges. All pipe restraints shall be designed to resist maximum expected surge and earthquake forces. Pipe restraints shall be adequately anchored for vertical and lateral support.

12.11 Corrosion resistance The wet well interior and exterior concrete surfaces shall be corrosion resistant and receive as a minimum two coats of a coal tar epoxy coating to protect the concrete from the corrosion due to hydrogen sulfide in the influent sewage. HDPE lining is also an adequate means to ensure protection of concrete.

Type 316 stainless steel should be specified for guide rails, brackets, bolts, nuts, structural steel, supports, and stairs. Fiberglass grating and ladders are recommended. The exterior of ductile iron piping shall be epoxy coated. Corrosion resistant materials should also be specified for electrical components.

12.12 Pump Controls For each pump include the following indicator lights: pump electrical supply (white); pump running (green); pump off (red); and pump failure (flashing red), unless otherwise approved by WASA. All indicating lights shall be connected to a push-to-test button to test for proper functioning of the bulbs. Indicator lamps shall be either transformer or diode-type device. Provide an externally non-resettable elapsed time meter for each pump in service.

The configuration of the pumping system shall be set by level sensor or float devices and will generally be as follows:

1. Low Water Level (LWL) Pumps off

2. P1 Pump No.1 start

3. P2 Pump No.2 start

4. High Water Level (HWL) Standby pump starts


12-4 October 2008R1

Status reported by PLC to Central Control

5. High High Water Level Overflow condition

Status reported by PLC to Central Control

Where the operation of the pumps is controlled by ultrasonic level control tied to the station Programmable Logic Controller (PLC) or remote programmable unit (RPU), provide float switches hardwired to the pump motor starter for starting the pump(s) on High High Level in the event that the ultrasonic level control and/or PLC control fails.

The PLC/RPU for the pumping station shall be designed for integration with WASA’s Supervisory Control and Data Acquisition (SCADA) system for the operation of the wastewater collection systems and treatment plants.

12.13 Odour Control For pumping stations located in residential areas, provide odour control within 100 meters of residential dwellings.. The wet well air shall be treated by a replaceable activated carbon filter or an equivalent system.

12.14 Ventilation Stations with pumps in a dry well shall be designed with ventilation systems for the dry well to be a Class 1 Division 2 classification per NFPA 820. At a minimum, separate ventilation systems shall be provided for the wet well and dry well. Interconnections between the dry well and wet well ventilation systems are not allowed.

Ventilation of a wet well under normal operating conditions is not required.

For entry for maintenance and/or operation functions, provide intermittent positive ventilation in the well with 30 air changes per hour. The ventilation system in the well shall be started manually by a switch, which will also turn on the lights in the wet well.

If continuous positive ventilation is provided, then it shall have six (6) air changes per hour under normal operating conditions.

Ventilation ducts shall be maintenance free and shall preferably be fibreglass or plastic with an unpainted finished surface. All ventilation equipment such as dampers, fans or motors shall be readily accessible for maintenance and servicing.

Provide dehumidification equipment in dry wells to reduce humidity below dew point.

12.15 Equipment and Material Specifications The primary drive system for all new sanitary pump stations shall be electric motors. Motors shall be explosion proof, solid shaft squirrel-cage induction type. The enclosure shall be totally enclosed, fan cooled and the insulation shall conform to NEMA Class F, or H. Electric motors greater than 7.5 kW shall be of the high efficiency type and for motors greater than 90 kW, the efficiency shall be better than 94% when ever possible.

Bearings for all rotating equipment shall be rated for 100,000 hours as a minimum.


12-5 October 2008R1

If a residential area is nearby, noise reducing features should be provided to avoid noise level disturbances.

WASA’s list of preferred suppliers must be consulted in order to select the pump’s manufacturer.

12.16 Site Access Road and Security Unless otherwise specified by WASA, or local approval agencies, the building access road shall be fenced off with 2100 mm high galvanized steel chain link fence and razor wire.


Design building exterior exposed surfaces such as access hatches, doors etc to be vandal resistant. Ensure that all ventilation louvers to the reservoir are properly secured to prevent entry of foreign material. All hatches are to be lockable and keyed to WASA’s master lock system.

The exterior of the building shall be provided with high pressure sodium vapour light fixtures (vandal and tamper resistant) with high power factor ballast and lamps suitable for horizontal, base up or base down operation. The need for surveillance camera and alarms shall be assessed for each site.

12.17 Instrumentation & Control Alarms All new sanitary pump stations shall be equipped with a flow measurement device which will continuously measure the total flow being pumped by the station. Parshall flumes, Magnetic, Doppler, or ultrasonic meters are acceptable and the selection will depend on the anticipated grease and solid content of the wastewater. A pressure gauge shall be installed on the suction and discharge side of each pump that is installed in a dry well, and in the valve vault on the discharge side of each submersible pump.

The following equipment or logic defined alarms shall be generated by the PLC/RPU at the pumping station and transmitted to the SCADA system:

1. Building:

.1 Access Security – Authorized and unauthorized entry

.2 Building – Smoke in building

.3 Building – Flooding in basement

2. Wet Well / Dry Well :

.1 Pump(s)

.2 Overload trip

.3 Thermistor trip

.4 Fail to start

.5 Fail to stop


12-6 October 2008R1

.6 Uncommanded stop

.7 Low pressure

.8 Overflow

3. Diesel Generator:

.1 Fail to start

.2 Fail to stop

.3 Overload

12.18 SCADA System Comply with Section 17 – Instrumentation & Control and Section 18 – SCADA System design standard requirements.

12.19 Equipment Redundancy See Section 4 – Process and Equipment Redundancy.


13-1 October 2008R1

Section 13 Septage & Biosolids Management

13.1 Septage Management – General These design criteria deals with management of septage, which is classified as all matter (liquids and solids) that is pumped out of septic tanks and holding tanks. These guidelines aim to provide guidance for the treatment of septage if indicated by WASA for a particular project. Septage pumped from individual septic tanks is not adequately stabilized and should not to be applied directly on land so as to protect the public health and the environment. Once stabilized, septage solids are usually less metal contaminated than sewage solids, which allows them to be often used for land application.

13.1.1 Stabilisation pond

Stabilisation lagoons should be designed to treat septage solids based on organic and nutrient loading rates and also hydraulic loading rates. Solids retained in the lagoon are stabilized by anaerobic decomposition while the supernatant is treated in a second polishing lagoon or treated in a wastewater treatment plant. Solids must be periodically removed from the lagoon for use or disposal as indicated by WASA. Siting of the lagoon must be established with careful consideration to soil, hydrogeological characteristics, surrounding land uses, and protection of public health and water quality. Wind direction shall be assessed in order to prevent public nuisance. Multi celled basins with two parallel lagoons are the minimum configuration in order to allow capacity for maintenance of the lagoons. The lagoons should be capable of operating as a single or two-step unit. Retention time must be calculated based on end objective of disposal indicated by WASA. Slopes should be seeded and runoff prevented from entering the lagoons. The liner must be installed in order to protect from infiltration with monitoring wells included for control. Lime addition should be included if odor becomes be nuisance. Stabilisation ponds must be designed to allow easy access for loading and unloading septage. Site must be fenced and signage should indicate the hazard.

13.1.2 Wastewater Treatment Plant

If indicated by WASA, the design of the wastewater treatment plants should allow discharge and treatment of septage. The treatment plant must allow separation of solid and liquid streams. Design of treatment plants should be capable of treating these streams with careful knowledge of loadings in order to not adversely affect unit processes. The process usually involves screening, dewatering, and treatment of the separated liquid and of the solid fraction. The solid fraction should be stabilized (See section 13.3) based on end objective of disposal indicated by WASA. The facility must be designed in order to allow capacity and capability of treating the supernatant/liquid effluent with consideration to possible high BOD and grease contents. Assessment should be done on a case by case basis to properly design and keep the right mixture of septage to sewer water.


13-2 October 2008R1

13.1.3 Alkali treatment

If indicated by WASA, an alkali treatment site should allow for stabilization of septage. At the maximum design volume, the process must be able to maintain a pH of over 12 for at least 30 minutes, and shall include a minimum 150% over capacity for lime addition. Lime addition and replenishment should be mechanized with total control over rate of addition. Alkali facilities must be designed to allow easy access for loading and unloading septage and also screening of septage from hauled trucks. Screening should be mechanically compacted and disposed. The stabilization basin must allow for separation of liquid and stabilized solids. Sludge pumps must allow transfer of all the volume to a hauling truck for land application. If indicated by WASA, the facility should allow for dewatering (See section 13.5) of the stabilized solids and pumping of the liquid part into a sewer.

13.2 Biosolids Management - General These design criteria are minimum guidelines to be used for the comprehensive consideration of biosolid management and establish the bases of WASA’s requirements. Sludge processing and treatment shall be in agreement with the requirements of the ultimate form of disposal. The activated sludge can be thickened followed by disposal in the following manner:

1. The waste activated sludge can be used as an agricultural source of nutrient.

2. The waste activated sludge can be dewatered and the solids disposed off on land-filled site.

3. It can be dewatered and turned into pellets as a source of nutrient for farmers or gardener.

4. The dewatered cake can be dried and incinerated to provide energy at the plant.

The choice as to which method to proceed with depends on many factors. These alternatives should be reviewed at the pre-design stage to ensure that the most economic and viable option is selected for the plant handling of its bio-solids.

Provisions shall be made to insure that waste sludge will be discharged to the sludge digester in such a manner so as to minimize the volume of digester supernatant liquor. Provisions shall be made for the return of supernatant from sludge thickeners and digesters to the head of the treatment works or to the aeration system accounting for the impact on the treatment units.

All piping from clarifiers to thickeners, digesters, or other sludge processing facilities shall be arranged for ease of maintenance, with hose gates and cleanouts, and with sufficient hydraulic gradient to insure the flow of sludge. Maximum flow velocity is 1.8 m/s. Piping under stationary structures shall be arranged so that stoppages can be readily eliminated by rodding or with sewer cleaning devices. The sludge piping within the digester, including the sludge drain line, shall be a minimum of 150 mm in diameter. Appropriate facilities for transfer of supernatant liquor shall be provided. Piping shall include a means to observe the quality of the supernatant from each of the withdrawal outlets provided. All units shall be capable of being drained independently of one another.


13-3 October 2008R1

13.3 Sludge stabilization Sludge stabilization is recommended for all biological treatment processes with the exception of extended aeration processes (with a solids retention time of 20 days or more) in which case the sludge may be drawn directly to a sludge dewatering facility. Considerations should be given to sludge treatment at centralized facilities at key plants. Consult with WASA with regards to examination of social, financial and technical issues. Sizing requirements must be determined using the BOD5 and design flow of the raw sewage influent to the plant. Alternative stabilization techniques like composting, wet oxidation and other processes shall include the demonstrated level of stabilization achieved by the process to be employed.

13.3.1 Aerobic digesters

Aerobic digesters should be provided with sludge thickening capability. If a separate system of air compressors or blowers will supply air to the digester, then the compressor or blower system shall be designed so that the air requirements can be met with the largest single unit out of service. Adequate mixing of the sludge shall be provided to keep the solids in suspension and to bring the deoxygenated liquid continuously to the aeration device. The amount of mixing shall be based upon the sludge characteristics, the tank geometry, and type of aeration mixing device. A digester shall provide a minimum sludge retention time of 15 days. This volume should be provided in two cells capable of operating as a single or two-step unit. Provisions shall be made to include an effective means of removing solids from the digester.

13.3.2 Anaerobic digesters

The digester volume shall be designed with a minimum solid retention time (SRT) of 30 days for unheated digesters and a minimum SRT of 15 days for heated digesters. Heating of the digester means that adequate facilities shall be provided for heating and mixing the sludge and maintaining a year-round temperature of at least 35 degrees Celcius. Heating coils inside the digester is not recommended. All heated digesters shall include a thermometer with not less than a four-inch dial to indicate the temperature of digester contents.

The calculations for the required sludge digestion volume shall be based on the minimum percent solids in the sludge expected to be encountered.

Adequate mixing of digester contents is required for all first-stage and all single-stage digesters. Mixing may be performed by mechanical equipment, including external pumps, or by gas recirculation. The rate of mixing shall be such that the flow created in the digester is sufficient to completely mix the incoming sludge with the digester contents and prevent the formation of a scum layer. Anaerobic digesters are to be in a covered facility. Digester covers shall be equipped with an air vent which includes a flame trap, a vacuum breaker, and a pressure relief valve. The sludge and supernatant withdrawal piping for all single-stage and first-stage digesters with fixed covers shall


13-4 October 2008R1

be arranged in such a manner so as to minimize the possibility of air being drawn into the gas chamber above the liquid in the digester. All digester covers shall include a gas chamber adequate for the gas production anticipated. Digester covers shall be gas tight and the specifications shall require a test of every digester cover for gas leakage. The gas piping shall be adequate for the volume of gas to be handled and shall be pressure tested for leakage before the digester is placed into operation. The main gas line from the digester shall have a sediment trap equipped with a drip trap. Drip traps shall be provided at all other low points in gas piping. A natural or bottled gas source shall be utilized for the burner pilot. Flame traps with fusible shutoffs shall be included in all main gas lines. The gas line to the waste gas burner shall include a suitable pressure, vacuum, relief valve, flame checks or flame traps. The main gas line shall be provided with a manometer or other acceptable devices which measure the gas pressure in inches of water. Manometers may be used to measure the gas pressure in other gas lines. All manometers shall be vented to the atmosphere outside digester buildings. A gas meter to measure the rate of gas production is desirable. All rooms in digester buildings with floor level below grade shall be adequately ventilated. The discharge end of sludge inlet piping shall be separated from the overflow of the supernatant liquor withdrawal point by a minimum distance equal to the radius of the digester tank. Every digester shall be provided with an overflow. A means shall be provided by which the level can be varied from which supernatant liquor is withdrawn either automatically or by the operator. If this means is by withdrawal of pipes at different levels in the digester, at least three different levels of supernatant liquor withdrawal shall be provided. All supernatant liquor withdrawal systems shall be provided with sampling cocks or other means of inspecting and testing the supernatant liquor from each level. Piping for hot water heating systems may be of any size adequate for the flow. The fresh water supply to hot water heating systems shall be from a tank with an air gap between the top of the tank and the fresh water supply pipe to prevent a cross connection between the digester hot water system and the fresh water supply system. Supernatant liquor from anaerobic digesters may be treated by chemical means or other acceptable methods before being returned to the plant.

13.4 Incineration and heat treatment The equipment shall be housed in a fireproof building. Adequate facilities shall be provided for storage of sludge during the longest period that drying and or incineration units might normally be out of service for repairs or maintenance. Plans for control of odors, insects, fly ash, and for adequate facilities for the disposal of dried sludge or ash shall be provided.

13.5 Dewatering Sludge shall be dewatered sufficiently to meet the requirements of the ultimate form of disposal.

As part of the biosolids handling and disposal process, the dewatering facility will also require the construction of a cake receiving and transfer facility to enable the hauling of the cake to landfill site or to the incinerator.


13-5 October 2008R1

13.5.1 Sludge drying beds

The area of sludge drying beds to be provided will vary in accordance with the average rainfall, average humidity, and type of treatment process used. The required area for aerobic sludge dewatering shall be determined from using a waste load based on sewage strength and the daily average flow of the raw sewage. Because of the rainy season, provisions shall be made in the design of beds for covering the beds, means of accelerated dewatering, or extra storage capacity and alternate dewatering methods to effectively dewater the sludge during inclement weather.

At least two sludge drying beds shall be provided and they shall be constructed at elevations above groundwater level. Construction shall be such as to exclude surface water runoff from the beds and seepage from the beds into the ground. Channels shall be of sufficient grade and size to facilitate the flow of the sludge to the various beds. Runners should be provided to facilitate sludge handling. The filtrate (or drainage) from the sludge drying beds shall be returned to the head of the treatment works or to the aeration system. A splash block or slab shall be provided at the point where digested sludge is discharged onto each of the beds. Appropriate means shall be provided to facilitate the removal of the dried sludge from the beds for disposal without bed damage resulting. Every sludge drying bed should include a removal gate or stop planks on one end to provide access for machinery and trucks to remove and haul away the dried sludge. A minimum depth of 300 mm of filtering material, of which 100 to 150 mm is coarse sand, is required. To exclude surface water and eroded earth, the bed shall be protected by a permanent wall which shall extend at least 300 mm but not more than 600 mm above the finished surface of the beds.

13.5.2 Vacuum filters, belt filters, belt filter presses, and other mechanical dewatering filters

Where dewatering of sludge is proposed, the design engineer shall provide data to document sufficient capacity, alternate disposal means, or storage facilities capable of maintaining normal daily operations during breakdowns, upsets, etc. The filtrate from the filters shall be returned to the head of the treatment works or to the aeration system. Consideration shall be given to the impact of the returned filtrate on the treatment units and to provide odor and insect control facilities. If sludge is to be treated using portable mechanical dewatering units, provisions shall be made in the facility plan or preliminary engineering report for the location and connection of the portable dewatering unit(s) during facility operation.

Water And Sewerage Authority (WASA) Water and Wastewater Design Guideline Manual Architectural Standards

14-1 October 2008R1

Section 14 Architectural Standards

14.1 General These design criteria are minimum guidelines and establish the recommend WASA’s design standards. Architectural design criteria are to allow Water and Wastewater infrastructure facilities to be:

1. Energy efficient;

2. Have minimal maintenance requirements; and

3. To withstand vandalism

4. Is conforming to requirements specified in the Occupation Safety and Health Act (OSHA).

5. Allocate sufficient space for hygiene and safety, and provision for fire

6. Be able to withstand hurricane/earthquake for the region.

In all cases, designs must comply with the architectural code of practice and Trinidad & Tobago Small Building Code.

14.2 Laboratory control Laboratory capability for operational control and testing shall be provided. The laboratory should be located on ground level and easily accessible to the treatment plant and sampling points. The laboratory should be located away from vibrating machinery or equipment which could have an adverse effect on the performance of the operation of laboratory instruments. The extent of the equipment to be provided and the specific tests to be performed will vary according to the capacity and type of plant.

The needs of male and female employees, the handicapped, and visitors to the plant, should be considered in the design of sanitary facilities. Hand washing facilities should be provided for the protection of operating personnel.

Appropriate facilities should be provided for the storage of tools and spare parts, and a workshop should be provided to allow repairs and maintenance.

Upon completion of the treatment plant, the grounds should be properly graded for surface drainage. Asphalt, concrete, gravel, or shell walkways should be provided for access to all treatment units and to the final sampling point.

14.3 Roofing Design Roofs are to be designed to complement the surrounding environment.

Consultants shall design the roofing architectural treatment and where the choice of roofing material is clay roofing tiles, pre-painted aluminium or steel roofing tiles, these shall be included

Water And Sewerage Authority (WASA) Project Design and Technical Specifications Manual Architectural Standards

14-2 October 2008R1

as part of the conventional roofing construction works to be installed by experienced roofing contractors.

The installation of the engineered roofing system shall be performed by applicators approved by WASA and the Consultants and are to be specified in the tender Specifications.

14.4 Windows Where possible, design plants with a minimal number of windows on the ground floor level unless they are located on a secured site. For pumping stations or other such facilities, minimize the number of windows and where possible, avoid windows altogether. As much as possible, consider aluminium windows with anodic (clear or colored) or epoxy finishes.

14.5 Doors All exterior doors shall be insulated metal doors complete with touch-bar devices and concealed vertical rod devices.

The minimum width of all doors shall be equal to or greater than 900 mm and shall be provided with a minimum of four hinges.

All exterior doors shall be provided with extra heavy-duty closer mechanism.

All exterior doors shall be keyed to WASA’s master key lock system, where applicable.

14.6 Ceiling Where ceilings are specified, provide drop-in ceiling tiles having high sound-transmission resistance characteristics selected for the use intended.

Ceiling tiles shall be washable matte white finish with light reflectance of LR-1 (over 75%).

14.7 Wall Finishes Interior and exterior walls shall be provided with the following finishes:

1. All exterior exposed concrete walls shall be given a sack rub finish and comply with the required wall finish schedule.

2. All interior walls shall be architecturally co-ordinated to provide a level of finish for the use or service intended.

3. For bathrooms and washrooms, provide ceramic tile finishes on the wall not exceeding 1,800 mm in height.

14.8 Floor Finishes Floors are to be finished in accordance with the following usage criteria:

1. Office floor finishes shall be finished with industrial grade carpet material.

Water And Sewerage Authority (WASA) Project Design and Technical Specifications Manual Architectural Standards

14-3 October 2008R1

2. Laboratories, computer control rooms, lunchrooms and others for general use shall be provided with ceramic tile floor finishes.

3. Concrete floors that are subjected to a continuous flow of dirty water shall be given an epoxy finish with anti-slip additive. All other concrete floors shall be provided with non-coloured floor concrete hardener complete with floor sealer.

4. Exposed formed concrete walls shall be provided with a “sack rub”.

5. All other formed concrete finishes shall be at the discretion of the Consultants.

14.9 Light Fixtures Mercury vapour light fixtures shall not be specified unless the lighting requirement makes it absolutely necessary. In all lighting requirements, florescence light fixtures are preferable.

Locate ceiling light fixtures in readily accessible locations for maintenance, but of a model that sustains vandalism. Do not locate fixtures directly over tall equipment such as a chemical tank or in the middle of open tank’s ceiling such as a water filtration basin. Location shall be selected to provide (a) the required illumination intensity level in accordance with current legislation and (b) easy accessibility for changing of light fixtures. Fixtures may be located on walls to provide the required illumination intensity level and for maintenance accessibility.

For light fixtures that must be located in very high ceilings, provide access for servicing by crane or other practical alternate means of accessibility.

Provide with several sodium vapour dusk external lights to avoid vandalism.

14.10 Landscaping Design landscape requiring minimal maintenance work to meet the regional Site Plan Approval requirements. Specify only native plant or tree species in Trinidad & Tobago for landscaping design, which requires minimal watering.

Sod shall be provided only to areas, which are required immediately for the proper functioning of the plant. All other areas shall be seeded and mulched.

Landscaping shall be designed with minimum maintenance requirements such as watering or mowing of grass.

Exterior of building is to be fenced with 2.1 m high steel wire wall with razor wire. Double swing gates are to be installed with an adequate locking device.

Vehicular access to pump stations shall have a minimum five meter wide paved road at a 15 percent maximum slope, unless otherwise approved by WASA. Site layout of the pump station shall take into consideration vehicle access. Provisions shall be made for adequate turning radius and room for outriggers for WASA’s equipment, such as dump trucks, backhoes, and crane trucks required for the removal of equipment.The need for surveillance camera and alarms shall be assessed for each site.

Water And Sewerage Authority (WASA) Water and Wastewater Design Guideline Manual Structural Standards

15-1 October 2008R1

Section 15 Structural Standards

15.1 General Comply with applicable Acts, Codes or Design Guidelines as detailed in Section 3.0 – Design Standards.

For all non-water retaining structures, design structures in accordance with Ultimate Strength Design (USD). For water retaining structures, design structures in accordance with Working Stress Design.

Designs must assure that the structures are to sustain regional earthquakes and hurricane events.

15.2 Design of Water Retaining Structure Water retaining structure shall be designed with consideration for crack control design. A reference is ACI-350R-89, “Concrete Sanitary Engineering Structures”.

Design walls as propped cantilevers, permitting any combination of internal and external load (such as reservoir full, without backfill and vice-versa), thus transferring loading to roof slab and reducing wall thickness and the need for internal wall support struts. Design reservoir perimeter wall with reduced water depth.

Design an efficient structure to minimize the number of internal columns. For cast in place reservoir’s roof, design capital integral with column.

Ground storage reservoirs shall be designed with a minimum of two or more cells. Each cell must be capable of being isolated for inspection and maintenance purposes without affecting the operation of the other cell(s). Where possible, design entry into reservoir cells through submarine hatches. Each cell shall be provided with a minimum of two entry/exit points.

15.3 Construction Requirements Interior surfaces of new concrete structures shall be smooth and Consultants shall specify the application of the available formwork liner manufactured or available in Trinidad & Tobago.

Consultants shall specify wet curing period requirements for a minimum of 7 days.

The seismic design of civil structures will be based on an earthquake zone 3 as defined in UBC-1997. Should it be required by the Client, seismic calculations may be based on another earthquake zone.

15.4 Structural requirements

15.4.1 Concrete

Portland Cement shall comply with ASTM C150. The following types of Portland cement shall be used:

Burgas Regional Water Company – Project Implementation Unit Project Design and Technical Specifications Manual Structural Standards

15-2 October 2008R1

- Type I Ordinary Portland Cement for all superstructures (above grade works).

- Type V Sulfate Resisting Cement for all sub-structures (below grade works).

The minimum strength requirements, based on 28 days compressive strength as determined by tests on concrete cylinders according to ASTM, are as follows:

Minimum Strength Requirements for Concrete

Type of Construction Concrete Strength (N/mm2)

PSI

Unreinforced Concrete, Lean Concrete 10 1,450

Encasement, Duct Banks, Cast in Place Concrete Curbs 25 3,600

Superstructures 35 5,000

Sub-structures 35 5,000

Waterproofing shall be applied to all concrete surfaces in contact with soil or liquids.

For hot weather concreting, Consultants must ensure that specifications include provisions for procedures in conformance with American Concrete Institute (ACI) Recommended Practice 305, Hot-Weather Concreting.

Do not use brackish water or seawater in any connection with masonry construction.

15.4.2 Steel Reinforcement

Materials for structural steel shall comply with International Standards

a) Reinforcement bars shall be deformed, new steel bars complying with the “Specifications for Billet Steel Bars for Concrete Reinforcement”: ASTM A615 Grade 60 or approved equal, with a minimum yield strength of fy = 400 MPa (60ksi).

b) Sizes shall be as shown on the drawings. Bars shall be free of flaking rust, scale, grease or coatings of any character that would tend to reduce or destroy their bond with concrete.

c) Welded plain wire reinforcement shall comply with “Specifications for Steel Welded Wire Reinforcement, Plain, for Concrete” (ASTM A185) or approved equal with wire mesh sizes as shown on the drawings.

15.4.3 Precast Structural Concrete

1) Comply with the following codes, specifications and standards.


15-3 October 2008R1

1. American Concrete Institute (ACI) – 318 - Code requirements for reinforced concrete

ACI - 301 - Specifications for standard concrete for buildings

2. Precast/Prestressed Concrete Institute (PCI) MNL 120 – Design Handbook

PCI MNL 122 – Architectural Precast Concrete

3. ASTM Specifications

C33 – Concrete Aggregates

C150 – Portland Cement

A615 – Deformed and Plain Steel Bars for Reinforcement

2) Fabricate all precast units in a precasting plant designated by WASA and certified by the P.C.I.

3) Erect units without damage to shape or finish, level, plant and within design tolerances.

15.4.4 Structural Steel

The use of structural steel in a tropical environment requires painting exposed structural steel for interior uses. For exterior uses, consider high-strength, low-alloy steel with epoxy paint or elastomeric systems. As much as possible, avoid exterior bolted connections.

Where fasteners are exposed to the weather, specify galvanized or other corrosion resistant metals.

1) Structural Steel shall conform with international standards and with the following ASTM standards:

1. ASTM A369 A36M – Specifications for Structural Steel

2. ASTM – A193A & 193M – Specifications for Alloy-Steel and Stainless Steel for Bolting Material for High temperature Service

3. ASTM – A307, A325 & A490 – Specifications for Structural Steel Bolts and Bolted Joints.

2) Steel Structures shall be designed in accordance with ASTM A36 to resist forces, moments and shears.

3) Steel structures shall be fabricated in accordance with ASTM A36 and reviewed shop drawings. Welding must be done by a shop certified for both shop and field structural welding.

4) Quality control: - Inspection and testing of materials and workmanship will be carried out by a testing company designated by the WASA.


15-4 October 2008R1

15.4.5 Steel protection

All materials mentioned below shall be hot dip galvanized as follows:

a) Grating: Galvanized ASTM A569 or equivalent.

b) Checkered Plate: ASTM A36 or equivalent.

c) Handrail: ASTM A53 or equivalent.

d) Kick Plates: ASTM A36 or equivalent.

e) Stairs and Ladders: ASTM A36 or equivalent.

If surface is to be exposed to direct saline weather, reinforced steel shall be covered by a minimum of 75 mm of concrete.

Reinforcing steel may be epoxy coated for tropical construction to reduce corrosion damage in land based concrete construction.

15.4.6 Concrete Block Masonry (C.B.M.)

1) Block masonry shall conform with international standards and with the following standards:

1. ASTM – American Standard for Testing Materials

1. ASTM C90 – Specifications for Load Bearing Concrete Masonry Units

2. ASTM C129 – Specifications for Non-Load Bearing Concrete Masonry Units

3. ASTM C270 – Specifications for Mortar for Unit Masonry

4. ASTM C476 – Specifications for Grout for Masonry

2) Masonry construction shall conform to ASTM standards for load and non load bearing masonry units and for mortar and grout.

3) Reinforcing steel used in masonry construction should conform to the same specifications as for concrete work – (see 1.4.2). Use grout to ASTM C476 where reinforcing steel is grouted in the cavities in the block walls.

4) Quality control: - Inspection and testing of materials and workmanship shall be carried out by a testing company designated by WASA.

Water And Sewerage Authority (WASA) Water and Wastewater Design Guideline Manual Electrical Standards

16-1 October 2008R1

Section 16 Electrical Standards

16.1 General All designs must comply with the electrical code of practice TTS 171: Parts 1 & 2: 2002 of Trinidad & Tobago and the National Electrical Code of USA. Comply with applicable Acts, Codes or Design Guidelines as detailed in Section 3.0, Design Standards.

All materials and equipment supplied shall be suitable for being delivered, stored and operated under tropical conditions of high temperature, high humidity, heavy rainfall, mildew and fungus conductive environments.

16.2 Equipment Identification Nameplates Requirements Identify electrical equipment with lamicoid nameplates, 3 mm thick plastic engraving sheet, white face, black core, and mechanically attached to the equipment with self tapping screws. Self adhesive nameplates are not permitted. Use rivets and/or nut & bolts to fasten nameplates to the equipment where access is not available.

The general requirements and characteristics of nameplate shall be as follows:

1. Size of nameplate shall be as follows:

NAMEPLATE SIZES

Size 1 10 x 50 mm 1 line 3 mm high letters


Size 3 12 x 70 mm 2 lines 3 mm high letters





2. In general, the Consultants shall allow for an average of twenty-five (25) letters per

nameplate.

3. Nameplates for terminal cabinets and junction boxes are to indicate system and/or voltage characteristics.

4. Nameplates for disconnected switches, starters and contactors shall indicate the equipment being controlled and the operating voltage and shall be mounted externally on switch box cover. Typical identification – “Pump No. 1, 400 V, 3 phase”. Plates shall be installed and secured with self-tapping screws except on the inside of panel doors where gluing will be permitted.

5. Nameplates for terminal cabinets and pull boxes shall indicate system and operating voltage.

Water And Sewerage Authority (WASA) Project Design and Technical Specifications Manual Electrical Standards

16-2 October 2008R1

6. Nameplates for transformers shall indicate capacity, primary and secondary voltages, tap range and steps, % impedance and vector group.

16.3 Wiring Identification Identify all wiring with permanent indelible identifying markings, either numbered or coloured plastic tapes, on both ends of phase conductors of feeders and branch circuit wiring. Maintain phase sequenceing and colour coding throughout.

Control wiring to have identical tags at both ends.

16.4 Panel Boards For all new or replacement panel boards, all pertinent information including the voltage, amperage, and minimum system short circuit rating shall be specified on a one-line diagram. New panel boards shall contain minimum 20% spare circuit breakers. Provide 20% future branch circuit breaker bussed spaces and choose the standard size manufactured panel board. Main circuit breakers shall be provided for all panel boards which are not located in the same room as their feeder, disconnect or breaker. Adequate ventilation/cooling shall be provided for closets to avoid heat and corrosion. Avoid ferrous metal enclosures and boxes when exposed to salt-laden air.

16.5 Seismic braces Seismic braces shall be installed on all electric service cabinets and other freestanding equipment per Code requirements. Details of the seismic braces shall be included in the design drawings.

16.6 High Efficiency Electrical Motor All electric motors greater than 7.5 kW shall be high efficiency motors. For motors greater than 90 kW, the minimum efficiency shall not be less than 94% at the specified operating point. However, the final determination shall be made based on life cycle costing analysis

16.7 Motor Control Centre The Motor Control Centres (MCC) and all components shall be designed, manufactured and tested in accordance with the latest applicable standards of EN 60439 as well as applicable NEMA, NEC & UL Standards. The panels shall have individual lines and control leads brought to terminal boards suitably located in each starter. The complete panels shall have adequate ventilation to limit the internal temperature rise to 55°C. There shall be a continuous ground bus with accessible external connection for bonding to the station ground. All necessary control transformers, switches, indicating lights, wiring, fuses, interlocks, terminal boards, etc. shall be provided to suit the power and control requirements. All indicating light lamps shall be long life LED type. The MCC shall be complete with a neutral assembly to receive the grounded wye secondary conductor from the transformer. All compartmentalized vertical sections shall be provided with common power bus-bars. Each vertical section of the MCC to be designed to permit ready removal or addition of motor starters and control units as required. MCC shall be


16-3 October 2008R1

floor mounting, freestanding, dead front, completely enclosed control assembly and accommodating front mounting combination starters and circuit breakers.

All motor starters shall be equipped to provide under-voltage release and overload protection on all three phases. Motor starter coil and contacts shall be easily replaceable without removing the motor starter from its mounted position or without the removal of the phase conductors. Fuses shall be provided on the primary and secondary sides of the control power transformers and separate power control transformers for each motor starter.

It is recommended that all switchboards and motor control centers be installed in enclosed buildings.

16.8 Transformers Consultant to review the project load profile and select transformers to obtain peak loading between 60-80%. Adequate ventilation/cooling shall be provided for transformers enclosed in closets.

16.8.1 High Efficiency Transformers

High efficiency transformers shall be investigated; there is a potential benefit under the energy conservation programs. In order to qualify, each transformer bid must be evaluated based on the total life cycle cost.

16.8.2 Distribution Transformers

Distribution transformers for lighting and convenience loads shall be 3-phase, 115/230 V secondary. Distribution transformers shall be suitable for installation in the selected location.

16.9 Co-ordination Studies of Protective Devices

16.9.1 Co-ordination Studies of Protective Devices Report

The study report shall be presented in tables and on composite charts and shall include but not be limited to the following:

1. Maximum available short circuit current of systems.

2. Maximum available ground fault current of systems.

3. Feeder cables thermal short circuit damage curve.

4. Primary fuse to power the transformer.

5. Power transformer thermal short circuit damage curve, 3 phase, phase to ground.

6. Main secondary 400 volt system circuit breakers.

7. Largest 400 volt moulded case distribution breaker and characteristics.

8. Largest distribution transformer thermal short circuit damage curve. 9. Maximum available fault current, 3 phase and phase to ground for the 400 volt system.


16-4 October 2008R1

10. Main 230 volt breaker and characteristics.

11. Largest 230 volt distribution breaker and characteristics.

12. Maximum available fault currents, 3 phase and phase-to-ground for the 230 volt system.

13. Maximum available fault current RMS symmetrical at each panel.

14. Establish the required settings for all ground fault relays.

16.9.2 Short Circuit and Protective Device Evaluation and Co-ordination Study

In the short circuit study, provide:

1. Calculation methods and assumptions, the base per unit quantities selected, single line diagrams, source impedance data including power company system characteristics, typical calculations, tabulations of calculation quantities and results, conclusions, and recommendations.

2. Calculate short circuit interrupting and momentary (when applicable) duties for an assumed 3-phase bolted fault at each supply switchgear line up, unit substation primary and secondary terminals, low-voltage switchgear line up, switchboard, motor control centre, distribution panel board, pertinent branch circuit panel board, and other significant locations throughout the system.

3. Provide a ground fault current study for the same system areas, including the associated zero sequence impedance data. Include in tabulations fault impedance, X to R ratios, asymmetry factors, motor contribution, short circuit kVA, and symmetrical and asymmetrical fault currents.

4. The short circuit study shall be performed with the aid of a digital computer program and shall be in accordance with the latest applicable IEEE and ANSI standards.

16.9.3 Protective Device Co-ordination Study

In the protective device co-ordination study, provide:

1. Time-current curves graphically indicating the co-ordination proposed for the system, centred on conventional, full-size, log-log forms. Include with each curve sheet a complete title and one-line diagram with legend identifying the specific portion of the system covered by that particular curve sheet.

2. Include a detailed description of each protective device identifying its type, function, manufacturer, and time-current characteristics.

3. Tabulate recommended device tap, time dial, pickup, instantaneous, and time delay settings.

4. Include on the curve sheets power company relay and fuse characteristics, system medium voltage equipment relay and fuse characteristics, low voltage equipment circuit breaker trip device characteristics, pertinent transformer characteristics, pertinent motor and generator characteristics, and characteristics of other system load protective devices.

5. Include at least all devices down to largest branch circuit and largest feeder circuit breaker in each motor control centre, and main breaker in branch panel boards.


16-5 October 2008R1

6. Include all adjustable settings for ground fault protective devices.

7. Include manufacturing tolerance and damage bands in plotted fuse characteristics.

8. Separate medium voltage relay characteristic curves from curves for other devices by a least 0.4 second time margin.

9. When emergency generator is provided, include phase and ground co-ordination of the generator protective devices. Show the generator decrement curve and damage curve along with the operating characteristic of the protective devices. Obtain the information from the generator manufacturer and include the generator actual impedance value, time constants and current boost data in the study. Do not use typical values for the generator.

10. For motor control circuits, show the MCC full load current plus symmetrical and asymmetrical of the largest motor starting current and time to ensure protective devices will not trip during major or group start operation.

16.9.4 Power System Study Report

The results of the power system study shall be summarized in a final report and shall include the following sections:

1. Description, purpose, basis and scope of the study.

2. Tabulations of circuit breaker, fuse and other protective devices ratings versus calculated short circuit duties, and commentary, and commentary regarding same.

3. Tabulations of all protection and configuration settings for each microprocessor based protection relays including multifunction protection relays for branch feeders and motor protection relays.

4. Protective device time versus current co-ordination curves, tabulations of relay and circuit breaker trip settings, fuse selection, and commentary regarding same.

5. Fault current calculations including a definition of terms and guide for interpretation of computer printout.

16.9.5 Insulation Resistance Tests

Insulation resistance tests shall be performed for all wiring and equipment installed. Insulation resistance tests shall be performed with a 500V megger instrument for equipment up to 350V and with 1000V megger for 350-600V circuits and recorded in log book for reference. Lighting and power circuit feeders shall be meggered and the insulation resistance between live parts and ground shall not be less than that specified in the Trinidad & Tobago regulations.

16.9.6 Lamps

16.9.6.1 Fluorescent lamps

Fluorescent lamps shall be T-8 4100°K, 2900 (initial) lumens 75 CRI and unless otherwise specified, shall be rapid start and life rated at 20,000 hours (average).


16-6 October 2008R1

Lamps shall be provided with single or multi-lamp ballasts, approved for the type, voltage and rating of lamp, also for the operating and starting temperature of the ballasts. Unless otherwise indicated, ballasts shall be integrally mounted with the fixture housing and thus approved for the enclosure and ventilation. Ballasts separately mounted shall be accessible, spaced and located to enclosure proper temperature conditions. Ballasts capacitors shall not contain PCB’s.

Fluorescent ballasts shall be rapid start electronic energy conserving, high power factor, low harmonic distortion and shall be approved for use with T8 fluorescent lamps.

16.9.6.2 Emergency Lighting

Emergency lighting shall be battery operated units and heads.

Each battery unit shall be a sealed lead acid type, long life cells in plastic cases and ten (10) year design life. They shall be 24 volt with indicated capacity for one (1) hour (to 91% voltage) operation and shall be in a standard shelf mounted cabinet, and have integrally mounted 24 volt sealed beam or quality halogen lamps, as indicated on drawings.

Each battery unit shall have an integral charger which shall be fully automatic, solid state, high/low rate with indicating and pilot light, load transfer, meters, test switch, overload and low voltage protection and A.C. 230 volt line cord and plug. A D.C. fused block shall be provided for load circuits together with conduit entry.

Water And Sewerage Authority (WASA) Water and Wastewater Design Guideline Manual Instrumentation & Control

17-1 October 2008R1

Section 17 Instrumentation & Control

17.1 General Conform to the design standard as stipulated herein to ensure that the design of all instrumentation and control systems are uniform and consistent for seamless integration to existing system.

The main instrumentation and control components shall be interconnected to establish a complete control hierarchy.

All materials and equipment supplied shall be suitable for being delivered, stored and operated under tropical conditions of high temperature, high humidity, heavy rainfall, mildew and fungus conductive environment.

17.2 Local Control Switch All equipment shall be provided with a local control switch with LOCAL-REMOTE positions. The LOCAL position overrides all other control modes including PLANT. When in the LOCAL position, the equipment is activated based on START/STOP pushbuttons. When in the REMOTE position, the equipment is controlled in either MANUAL or AUTO mode from the PLANT level.

When in the AUTO mode - PLANT, the equipment is controlled by the programmable logic controller/remote processing unit (PLC/RPU) or is connected directly (hardwired) to the circuit of another piece of equipment. If controlled through the PLC/RPU, the equipment can be controlled in MANUAL mode through the Human Machine Interface (HMI), or it can be operated in AUTO mode using the control program in the PLC/RPU. As a general rule, the closer the control switch is to the equipment, the higher its precedence to control the equipment.

17.3 Instrumentation & Control General Information The main components of the Instrumentation & Control systems are listed below:

1. Local Control Panels (for equipment control and monitoring).

2. Junction boxes and interface cabinets as required.

3. All field instruments, and the installation, testing and commissioning of these instruments.

4. Fire Alarm System.

5. Security System.

6. Connection of common alarms and status signals from VAC and other process area to the Local Control Panel for connections into the PLC/RPU, and the SCADA system.

A detailed engineering specification of all major components, and all associated instrumentation for each process area shall be included as part of the engineering assignment.

Water And Sewerage Authority (WASA) Project Design and Technical Specifications Manual Instrumentation & Control

17-2 October 2008R1

The engineering will include detailed drawings showing connection of the instruments and equipment status signals into a Local Control Panel, which will also act as a termination cabinet for all input and output signals to and from the PLC/RPU dedicated to the process area. The signals will connect to the SCADA system through the PLC/RPU.

Control actions and the philosophy for control of the process will be defined by means of Process & Instrument Diagrams (P&IDs) and control narratives. These will be reviewed for conformity with the guidelines and will form as a part of the documentation package.

A review of the SCADA system and the software implementation of the process design requirements will be undertaken and include as a minimum, the following items:

1. Drawing/Specifications review

2. Factory or office simulation acceptance tests (FAT)

3. On-site functional acceptance tests (SAT)

17.4 Design of I&C System

17.4.1 Design Criteria

The PLC/RPU shall only control equipment associated with the local area of the process, but may provide limited status monitoring of other associated areas. This device will connect all field devices, i.e. pumps, valves, flow meters, switches, etc. to the SCADA system. It shall be provided with a display and keyboard, which provides all recorder, indicator, totalizer, annunciator, controller, and manual switches, required for full monitoring and controlling of the process area. The display may be an HMI workstation, depending on the system architecture design.

All automatic control shall be achieved by auto-programs in the PLC/RPU. The control hierarchy shall define how the field equipment, PLC/RPU and SCADA workstations are interrelated to provide a complete process control system. Process control systems shall include varying levels of hardwired and software interlocks to ensure safety of the personnel as well as the automatic control systems and its interlocks inputs into the PLC/RPU. Normal operation shall be in AUTO mode, and the PLC/RPU programming will ensure fail-safe conditions result, as defined during the design stage, in the event of equipment or instrumentation failure. In MANUAL modes of control, the same equipment and safety interlocks will still apply (when hardwired), but operator action will be required to initiate equipment control.

17.4.2 Interlocks

In LOCAL control from the Local Control Panel, the PLC/RPU software interlocks shall no longer be functional. Any personnel or equipment safety interlocks must be protected by means of hardwired interlocks, which will interrupt operation of the equipment until the condition is reset in the field. The following interlocks are possible hardwired protective interlocks and several of these are intrinsic to the design of motor control systems and each system must be evaluated on an individual basis. In several instances, software interlocks are sufficient to provide adequate protection.


17-3 October 2008R1

Hardwired protective interlocks shall be provided in accordance with the following table:

Interlock Application

Pressure Protection of piping, valves, pumps from high pressures (pipe blockages, closed valves, etc.); and

Low pressure protection for run out conditions

Temperature High temperature protection against overheating (motors, pumps, etc.).

Level Low level cutouts of pumps; and,

High level overflow protection (chemical tanks, reservoirs, etc.).

Flow No flow conditions - running pumps dry.

Vibration/Motion Damage to motor/pump/piping from excessive vibration.

Torque Valves - end of travel protection; and,

Pump shafts.

Current Motor overcurrent protection.

Voltage Motor over/undervoltage protection.

Prime/Seal Pump protection.

Limit Pump/valve operation in combination (pump discharge valves).

Gas Detection Personnel protection against hazardous and/or explosive gases and lack of oxygen.

17.4.3 Field Instrument

The PLC/RPU panel shall be located as required by the system architecture design, and the configuration of the facility.

Field instruments shall be standardized to a minimal acceptable number of different vendor’s equipment to minimize the stocking of different spare parts for water and wastewater treatment plants. During preliminary and detailed design, the PIU will review the tender documents of the specified instruments and models.

Field instrument enclosures shall be rated in accordance with the hazardous area classification assigned to the area.

All instruments mounted outdoors shall be in weather tight enclosures and should be suitable for operating temperatures from 0 to +50 deg. C.

All instruments mounted outdoors shall be provided with hoods formed by three sides and a sloping roof, to provide protection against sun, and rain. Those with viewing dials, or that require access for routine calibration, shall be provided with tip-up type hoods.

All instruments shall be provided with isolation devices.

Valves must be installed on all instrument lines to allow for its removal without disruption to the process. Electrical switches must be located near the equipment to allow for isolation while servicing or installing instruments.


17-4 October 2008R1

Local indicators shall be provided for all transmitters. Where manual operation of valves or other equipment is required, based on a transmitter signal value, the indicator shall be located adjacent to the valve or equipment local control panel.

17.4.4 Indicators

Indicators shall be provided with the following characteristics:

1. Local indicators shall read as follows: .1 Temperature – direct reading in °C .2 Level – 0-100 uniform as % of calibrated range .3 Flow – direct reading in m3/hr .4 Pressure – direct reading in bars or metres

2. Unless specified otherwise, or required due to process conditions, calibrated instrument ranges shall be selected such that the normal operating value will be between 50 and 75 percent of scale, taking into account both minimum and maximum values.

3. Dedicated or conventional analogue panel instruments such as chart recorders or indicators are not required unless specifically stipulated.

4. Nameplates carrying instrument/equipment numbers and services shall be provided for all equipment requiring manual operation (located locally at the equipment controls). Field mounted instruments generally require an identification number only.

17.4.5 Instrumentation Loops (Analogue)

All instrumentation loops shall be designed to conform to the following requirements:

1. All analogue instrumentation loops shall be 4-20 mA current loops (and 2 wire wherever possible). There shall be no dedicated or conventional analogue panel instruments such as chart recorders or indicators unless specifically stipulated. In cases where existing 0-10Vdc or other signals exist, incorporate these instruments into the PLC/RPU.

2. DC power supplies within the Local Control Panel shall be provided with power to the transmitters via fused terminal blocks or mini-circuit breakers.

3. The signal cables should be shielded twisted pairs and should run through metal conduit, which is not located in close proximity to high voltage power cables. The shields should be terminated and grounded to a dedicated instrument ground bar at the Local Control Panel end only.

4. Where field instruments such as analyzers require a 230V AC power supply, this must be run in separate conduit from the signal cables. The output of the transmitter should be 4-20 mA, and must be electrically isolated from the power supply.

17.4.6 Control Circuits

All control circuits shall be designed to conform to the following requirements:


17-5 October 2008R1

1. Control circuits shall use normally open push-buttons and avoid the use of switches to simplify the interface to the PLC/RPU. The PLC/RPU shall use momentary contacts instead of maintained ones in order to provide smooth bump less transfers without using tracking software.

2. Where maintained contacts must be used, provide tracking software in the PLC/RPU to allow bump less transfers from local to computer control. The use of mercury switches for such purposes, or for any other purposes, is not permissible in the water and wastewater treatment plants.

3. All equipment controlled by the PLC/RPU must be evaluated as to whether it is required to stop, or to continue running in the event of a PLC/RPU failure.

4. The PLC/RPU tracking software shall provide smooth transfers by ensuring that the output of the PLC/RPU reflects the condition of the field equipment status. Regardless of the mode of control, the PLC/RPU must be programmed to track all operator-initiated actions and adjust its output accordingly.

5. For PLC/RPU outputs that have electronic devices rather than mechanical relays, the output shall be in the “normally closed” status when the PLC/RPU is energised. Provide an interposing relay to maintain contact. These interposing relays shall be provided and installed in the Local Control Panel.

6. Status inputs from equipment, Local Control Panel LED’s and in general, all digital inputs to the PLC/RPU will be DC (nominal 24V DC) sourced from a power supply in the Local Control Panel or PLC/RPU cabinet.

7. Start, stop commands and in general, all digital output signals from the PLC/RPU will be 230V AC. This 230V AC shall be “sourced” from the equipment starter (MCC).

17.4.7 Automation of Treatment Process

In determining which process should be automated, the following factors should be taken into account. It is not necessary for all processes to be automated as this increases capital cost considerably without any real benefit.

1. Automation, when the process is under PLANT control, refers to the use of events, timing intervals or other trigger actions to affect control output to field devices in response to process changes.

2. Complete hardwired automatic control systems shall be implemented where it is deemed that the process is critical to the facility operation, and where the manual operation of such a process is not feasible for prolonged periods of time.

3. When LOCAL (at the equipment) control is required (maintenance, or operational mode changes due to equipment failure) automation in this context refers to provision of electrically powered actuators instead of hand wheels, push-button operation of multiple solenoid routing valves instead of numerous levers, etc.

4. Provide automatic control for equipment that is operated on a frequent basis. (Initial plant start-up and commissioning modes should be considered here.)


17-6 October 2008R1

5. Equipment used infrequently should not be automated but shall be provided with full manual control unless stipulated otherwise.

6. Where the increased downtime required by a manual changeover is not important, and the level of the manual operation required is not significant, do not implement automation.

7. For manually operated valves whose position is required to be known by the SCADA system, position indications via limit switches shall be provided.

8. Where motorized valves are installed, the valve position (limit switches) and its service status (local/remote) is required. For control of manual valves from the PLC/RPU in future automatic programs, provide control wiring from the manual valve to the Local Control Panel or PLC/RPU cabinet at the time of construction.

9. The PLC/RPU shall monitor the number of starts per hour and should the number of starts exceed the setting of the program an alarm shall be generated. Should the equipment fail to start after three consecutive attempts, the control system shall inhibit any further attempts to start the piece of equipment. An alarm shall be generated and indicated at the SCADA workstations.

10. The PLC/RPU shall monitor all equipment and should the equipment fail to stop, the control system shall generate an alarm immediately, which will be displayed through the SCADA system.

11. The PLC/RPU shall also monitor: .1 Equipment fails to open/start or fail to close/stop. .2 Power Supply loss of phase. .3 Process parameters and analytical instruments. .4 Uncommanded open/start or close/stop. .5 Equipment status, field alarm conditions, etc. .6 The control system shall generate an alarm immediately through the SCADA system.

17.4.8 Variable Frequency Drive (VFD) Control

All VFD’s shall be provided with a digital operator control module for control and indication of the following:

1. Start/Stop.

2. LOCAL-REMOTE.

3. Manual speed adjustment.

4. Speed indicator 0-100%.

5. Load indicator 0-100%.

6. Run indicator.

7. Power-on indicator.


17-7 October 2008R1

For a VFD/motor control system, in the event of a shutdown of the variable frequency drive due to a fault condition, the drive shall stay shut down until the fault is removed and the drive reset locally at the starter.

17.4.9 Pump Control Systems for Wastewater Pumping Stations

Standard pump control systems and alarm points connected to the PLC/RPU shall include the following:

1. Electronic level sensor used to monitor wet well level.

2. Automatic program capable of starting/stopping pumps based on wet well level, cycling pumps based on starts/runtime, duty control, and alarming.

3. Turn second duty pump on if first duty pump fails to start.

4. Hardwired float control to start/stop pump on PLC failure.

5. LOCAL-REMOTE switch and associated pushbuttons to allow for the pumps to operate in the event of float control failure and/or maintenance.

17.4.10 PLC/RPU Interface

Terminals, as an interface for all signals between the field equipment and the PLC/RPU, shall be supplied.

4-20 mA current loops from field transmitters shall be provided with 250 ohm termination resistors at or within the terminal blocks in the Local Control Panel or PLC/RPU cabinet.

17.4.11 Services

Electrical supplies for the PLC/RPU panel shall be provided. A minimum of three 230V AC, 15 A lighting panel supply, from the same phase, shall be allowed for, and conduit and wiring installed from the panel to the PLC/RPU cabinet location.

Additional dedicated conduit runs shall be provided from the PLC/RPU cabinet location to the designated building cable tray or cable access point, for the future installation of communication cables.

17.4.12 Documentation

Documentation and drawings are to be included as part of the complete Instrumentation & Control/SCADA package.

Process & Instrument Diagrams (P&ID’s) showing tag numbers of all inputs and outputs. ISA tag numbers shall be used for PI&D’s, loops to be from assigned blocks.

Loop drawings for analog devices showing clearly the relationship between primary and final elements, all terminals, wire tags, etc.

Provide process/control narratives in the English language.


17-8 October 2008R1

Provide all logic flow diagram of control functions and actions to control process including normal start-up, normal shut-down, emergency shut-down and alarm scenarios.

Interface wiring definition in tabular format, providing the following information with the following headings:

1. Instrument/signal identification number.

2. Process function or service.

3. Field contact status to achieve function (for DIs) or analog signal type (4-20 mA).

4. Instrument range and engineering units.

5. Calibrated range.

6. Setting (as required for function – alarm, safety, interlock).

7. DI, DO, AI or AO with respect to PLC/RPU.

8. Local control panel terminal block identification.

9. PLC/RPU cabinet termination point.

10. Software function required (alarm, monitor, control, interlock).

The tabular format shall be produced in a MS-Excel/MS-Access file format.

Local control panel(s) wiring diagrams, showing field and interface terminations.

Dimension layout drawings of local panel(s) with full legend plate and bill of material information for internal and panel mounted equipment.

Record drawings for all modifications within existing panels or cabinets, showing interface terminations between old and new equipment.

17.4.13 Preventive Maintenance Program

After the start-up and commissioning of equipment, WASA shall commence the implementation of a preventive maintenance program. In order to ensure that the preventative maintenance program is properly carried out, the Consultants shall provide the following information at start-up and commissioning. Submission of the information in both hard copy and CD-ROM is required.

1. Equipment and instrumentation list for the specific area.

2. Recommended routine maintenance, alternating and calibrating programs for the above items.

3. A paperwork system based on simple checklist procedure to monitor the ongoing maintenance.


17-9 October 2008R1

17.4.14 Testing and Commissioning

Testing and commissioning of all plants’ instrumentation and control circuits from the field instrument up to and including manual control from the Local Control Panel and appropriate status indication shall be provided.

Pre-delivery inspection and testing of instrumentation and controls for “package” equipment, or fabricated panels should be performed wherever possible, to minimize site work.

“Testing” includes wiring integrity and setting of field adjustable instruments according to specifications, and verification of equipment performance against manufacturer’s data sheets by shop calibration over a minimum of five points (0, 25, 50, 75, and 100%).

“Commissioning” includes operation of equipment using initially simulated interlock and alarm signals where necessary, to check functionality. It also requires completion of loop checks from field instruments by simulated or quantifiable process inputs to the terminals in the Local Control Panel, for interface with the PLC/RPU. These checks may require further calibration of field instruments.

Commissioning of the process area on LOCAL and PLANT-MANUAL control via the PLC/RPU, and on AUTO control via the PLC/RPU must be completed.

Water And Sewerage Authority (WASA) Water and Wastewater Design Guideline Manual SCADA System

18-1 October 2008R1

Section 18 SCADA System

18.1 General The use of the SCADA system technology in water and wastewater treatment plants in Trinidad & Tobago has not been systematic. However, consideration should be given for the inclusion of such a system in new plants or retrofitting to existing plants when they are expanded or upgraded in the future. The SCADA system offers the following advantages:

1. Reduces plant energy consumption from process equipment

2. Reduces plant consumption of chemical by monitoring and feedback to the chemical metering system

3. Monitors personnel safety

4. Monitors plant security

5. Monitors plant effluent and water quality

With confirmation from WASA, Consultants shall apply directives from the following documents in order of preference:

1- The WASA Masterplan SCADA Workplan SSP2 (Technology and Standards) and SSP3 (SCADA Project Delivery Procedures).

2- 2005 report by Ixanos Ltd., “WASA SCADA Consolidation Assessment and Design” 3- If specifically indicated as not applicable, the following recommendations (following

sections) shall be applied.

18.2 SCADA Operating Characteristics The Supervisory, Control and Data Acquisition systems (SCADA) shall be designed to have the following characteristics:

1. Real-time control and monitoring

2. Storage/retrieval of short and long term historical data

3. Easily expandable for future additions of new sites and interconnection of plants

4. Open architecture systems that will permit future applications or existing applications to migrate to this environment based on industry standards

The SCADA system has a Graphical User Interface (GUI) environment, which will provide a Human Machine Interface (HMI) to the operators for real-time control and monitoring of the facility or system.

Water And Sewerage Authority (WASA) Project Design and Technical Specifications Manual SCADA System

18-2 October 2008R1

18.3 SCADA System Requirements The system must be fully capable of real-time control and monitoring of all automated process operations within the water treatment plant and wastewater treatment plant, in the water distribution system and wastewater collection system on a continuous basis.

Unless specifically instructed in the Request for Proposal that automation in the facility is not required, all plant processes with analogue control capacities shall be fully automated through the SCADA system, including that of the water distribution system and wastewater collection system.

All automatic processes must also be configured to allow fully manual control of all process equipment from any workstation within the system.

Water distribution systems shall include all associated pumping stations, reservoirs, zone valve chambers, pressure reducing chambers and flow monitoring sites.

Wastewater collection systems shall include all pumping stations and flow monitoring sites.

All process standby equipment shall be configured such that it can be operated in a fully automatic control mode under the PLC/RPU or manually controlled and monitored from the SCADA workstation(s).

All automatic process control programs shall reside in the PLC/RPU.

The system shall be fully capable of archiving historical data and it must be capable of generating reports based on historical data as required.

The system architecture must be open and easily expandable to permit future additions as well as allowing future applications or existing applications to migrate to this environment.

All hardware and software (PLC/RPU programming and HMI application) must be standard off-the-shelf products requiring no customization of any kind.

18.4 SCADA System Control Levels The SCADA System, except for the FIELD level, has two distinct levels of control, which are as follows:

1. PLC

2. PLANT

18.4.1 Field (Local)

The FIELD layer is not identified as a control level, because this level will exist for all equipment, even those devices not connected to the SCADA system.

The field devices consist of the hardwired interlocks and the emergency stop pushbuttons. This layer also contains the Local/Remote switch that enables the equipment to be controlled locally at this level through pushbuttons or remotely in the subsequent levels. This also includes all field mounted instruments and equipment that directly or indirectly controls the process. They include


18-3 October 2008R1

devices/equipment such as air flow measurement instrument, D.O. level transmitters, blowers, modulating valves, chlorinators, limit switches, metering pumps and so forth.

The information gathered at this level may be transferred to Level 1, where PLCs/RPUs provide an interface between the field devices and the HMI of the SCADA system.

The Local Control Panel is intended to provide back-up control in the case of failure of the PLC/RPU at Level 1. From this location, it shall control and monitor selected equipment and parameters. There will be no automatic control available at this level unless, which is determined on a case-by-case basis, the process is critical to the operation of the facility, and would be difficult to operate under changing conditions (see instrumentation and control).

18.4.2 Level 1 – Programmable Logic Controller (PLC)

LEVEL 1 includes the PLC/RPU and all automatic programs shall be configured to reside there. The REMOTE mode selection is made through the SCADA workstations or an operator interface at LEVEL 2 (PLANT) of the hierarchy.

They also provide the interface between SCADA, field instruments and equipment.

Equipment supervision and alarm generation are tasks that are done at this level and reported to the SCADA level. All control, monitoring and alarming resides at this level.

Communication links at this level are generally at the plant level, but may involve remote site links via telephone lines, or other mediums dependent on the available systems at the sites involved. Communication between PLCs/RPUs will be selected on a site-by-site basis dependent upon the needs of the system.

18.4.3 Level 2 – PLANT

At the PLANT level, the Graphic User Interface (GUI) shall provide a Human Machine Interface (HMI) to the operator for total control of the plant through workstation(s) in PLANT mode of control. This level of control will have access to all monitored points and data in the plant. In PLANT mode, the operator will select, through a software switch, either PLT-MAN or PLT-AUTO modes of control. In the plant manual mode, the operator can start/stop equipment from the SCADA workstation or operator interface. The plant auto mode will transfer control to the automatic program residing in the PLC.

Through any workstation, given the correct security clearance, the operators shall be capable of controlling all equipment through the selection of control modes and setting of set points.

At the PLANT Level, through the HMI, it shall provide all the operating information such as historical trending, real-time trending and alarm prioritizing. At this level the system generates reports, logs data, and provides a link to other systems, where required.

18.5 Real-Time Control and Monitoring The configuration of the SCADA system architecture is to be based on the open distributed control concept.


18-4 October 2008R1

The SCADA system shall be provided with integrated support for a secondary server to take over data collection in the event of a failure of the primary server and must be capable of:

1. Automatic failover to secondary server.

2. Run-time point values, statuses and alarm are synchronised on both servers.

3. There must be no duplication in configuration.

4. Configuration provides for automatic update of secondary computer when the primary computer is updated.

5. Start/stop both systems from primary server.

6. Merge the two databases on recovery of a failure.

7. Global points are synchronized as are changes to alarm limits and the disabling of alarms.

8. Must automatically alarm when a communication error is detected and the graphic displays are changed to reflect error.

The Consultants shall provide a two level control hierarchy for all process related equipment. Regardless of the Terms of Reference, all process related control system shall be of the two levels of control.

Under LOCAL control, the equipment is controlled by local switches and pushbuttons at the equipment.

Under PLANT MANUAL control, the equipment is controlled manually through the HMI system located in the plant/system. All signals from the HMI are transferred to the PLC/RPU where the appropriate control actions are carried out.

In PLANT AUTO modes of control, the PLC/RPU will be controlling all of the associated process equipment based on setpoints and process feedback.

All automatic control programs shall be resident in the local PLC/RPU wherever practical for devices frequently operated.

18.6 Automatic Control Equipment that is normally frequently operated shall be automated and software interlocks will be provided in the automatic program to protect equipment and personnel.

Infrequently operated equipment shall be capable of manual operation through the SCADA System. Safety interlocks shall also be incorporated for all manual operation through the SCADA system.

For process that is critical to the facility operation and where manual operation of such processes is not feasible for prolong periods of time, local automatic control system shall be implemented. This includes both local and compound loop controllers.


18-5 October 2008R1

18.7 Minimum Equipment Control Requirements Pump discharge valves are a function of their respective pumps and do not require on screen independent control. However, the status of the valve must be shown. If the valve fails to open or close within the specified time, indicate the valve fail status in a pop up menu.

If the pump discharge valve is in an opened position, the software control logic in the PLC/RPU must inhibit starting of the motor.

Notwithstanding the above, the motor shall be hard-wired to permit manual start-up at the local control switch even with the discharged valve in the opened position.

For all equipment that uses a 4-20 ma control system, provide pop-up windows to indicate the setpoint in AUTO mode. In the MANUAL mode, provide a box on the menu such that a setpoint can be entered.

Maintain all software protection provided for any equipment in AUTO mode while they are operated in the MANUAL mode through the HMI. In the event of a transmitter failure, provide individual override buttons.

All setpoints must be accessible through the HMI.

For processes involving several pieces of equipment, such as a High Lift Pumping Station, provide a pop up menu to set-up the equipment duty setting.

Provide multiple start protection for all process equipment. Provide software reset for this protection. This protection shall be provided for all REMOTE modes of operation. In general, all equipment shall be inhibited from further starting after three (3) failed attempts by the PLC/RPU. Indicate failure status by a pop-up window.

Provide a separate fault reset button for process equipment’s software interlocks.

18.8 Control Process Narratives For each process, the following list details the standard required for the process narratives to be provided by Consultants:

1. Safety of Personnel

2. Security of the Process

3. Software Interlocks

4. Logic Flow Diagrams

5. Virtual Points generated by PLC/RPU and/or HMI

6. Options for Process Control

7. Setpoints for Each Process

8. Emergency Procedures (Shutdowns, etc.)

9. Troubleshooting


18-6 October 2008R1

10. Field Adjustable Timers (Equipment, Modes of Operation)

11. Tagging/Description

The format used to describe the required process operation and automatic control sequences to be implemented in the PLC/RPU shall be as follows.

1. GENERAL

2. BACKGROUND

Presents the terms of reference and purpose of the document.

3. PROCESS OVERVIEW

This Chapter introduces the entire process and briefly describes the major steps involved and their sequence. It is intended to outline the scope of the work and its general form.

4. CONTROL SYSTEM STANDARDS

This Chapter refers to the standard methods or guidelines that are being conformed to in the work. These standards and typically defined in other documents. A list of these documents should be included here.

Also include information that is common to all equipment but not described in other documents. This avoids repeatedly describing it in the more detailed information that follows. Any general deviation from the above standards should be elaborated upon in sub-sections. These could include control modes, I/O interface, alarm horns, alarm acknowledgement, etc.

5. SYSTEM

.1 Sub Process #1 Title

This title identifies the first portion of the process that uses one or more pieces of major equipment. This sub-process performs a distinct function that is the first major “building block” of the entire process.

This section briefly describes the major functions of this sub-process and its scope.

The extent of each of these building blocks is defined in terms of the material going in and out of each block.

.2 Equipment

A list of equipment including a brief description, equipment code, and location shall be presented here.

.3 Control Modes

The locations from where each component may be controlled are listed here. If there are any exceptions to the standards, these are noted here.

.4 List of I/O Points

All instrument signals for this equipment are listed here, grouped by device. For example, a large pump has 3 digital inputs (status, control mode, general alarm) and 2 digital outputs (start, stop).


18-7 October 2008R1

.5 Control Logic

Control logic shall be used for any equipment required to be operated in the AUTO mode. For AUTO logic which is hard wired, a description of this shall be provided. If the equipment is PLC/RPU controlled, then all PLC/RPU logic needed for this equipment shall be defined in detail. If standard methods are used, comply with the standards as referred to herein, along with any specific setpoints.

This includes definition of all input information required by this logic to operate correctly. When this information is unavailable, the default operation is defined.

The responses to all possible alarms or failure are listed (if this varies from a standard that has been referenced). Any time delays involved in these actions must also be specified.

.6 Sub Process # 2 Title

This is the next major “building block” of the process (if it exists). Sub process # 2 to be prepared as per Sub Process #1 above. Repeat as needed for all sub-processes.

18.8.1 Screen

Screen display shall be organized to provide various displays in predictable order. The following shall be the minimum screen display requirements for the SCADA system.

The options button on the Menu bar will provide miscellaneous information as follows and details will be decided on a per plant/process basis:

1. SCADA Node Status

2. Equipment Runtimes

3. Totalizers

4. Enable/Disable Alarm Horns

18.8.2 Button Bars

Button bar shall be provided at the top of every screen with the following buttons to enable the operator to navigate between screens:

1. Screens

2. Trends

3. Reports

4. Alarms

5. Map

6. Process

7. Options

8. Setpoints


18-8 October 2008R1

9. Process Narratives

18.8.3 Overview Screens

Provide the display hierarchy with the least detailed displays at the top, with increasingly detailed displays towards the bottom of the hierarchy. There may or may not be display screens at each level in the hierarchy. However, the structure should be maintained so that future graphics developments are similar. A flowchart illustrating the display hierarchy is noted below.

Three main divisions in the display hierarchy for overview screens include:

1. System Overview (if applicable)

2. Plant Overview

3. Process Overview

The process overview is further sub-divided into the following:

1. Detailed Views

2. Equipment Specific

The detailed view and the equipment specific screens form the contents of the pop-up screen. Alarms, trends, reports and event logs are each placed on a different screen. The button bar is displayed at the top of all screens which allows the operator to navigate from one display screen to another, view the alarm page summary, trends, reports, and enter setpoints.

18.8.4 Pop-Up Screen

Pop-Ups are generally accessed by clicking on the equipment icon from a process screen. Generally, three categories of programmable pop-ups exist:

1. Control

2. Information

3. Setpoints

Create appropriate pop-ups for both control and information control layouts that provide non-confusing layouts and language to the operator, which will allow the operator to interact quickly with the HMI. The pop-ups shall be accessible either by clicking on the Main Menu or by clicking at a particular device.

18.8.5 Control Pop-Ups Screens

Although there are several types of control pop-ups, they all permit the operator to interact with the equipment and its associated device specific setpoints and control outputs. The operator can operate the device, or change the operating mode from within a control pop-up.

Control pop-ups vary with each type of device or control element. A typical two-state (on/off or open/close) device pop-up allows an operator to:

1. Change the device’s operating mode from PLT-MAN to PLT-AUTO


18-9 October 2008R1

2. Change the mode of operation (depending on the operating philosophy)

3. Control the device (when in PLT-MAN mode)

A three-state device pop-up is similar to a two-state one. A typical three-state device pop-up allows an operator to:

1. Change the device’s operating mode from PLT-MAN to PLT-AUTO

2. Change the mode of operation (depending on the operating philosophy)

3. Control the device (when in PLT-MAN mode)

4. Manually set the speed (VFD) or a percentage open (modulating valve) in the PLT-MAN mode

5. Changing the mode or state of a device from the control screen is done by clicking on the button (Auto/Manual or Start/Stop). If the device is a VFD or a modulating valve, in manual mode, the operator can enter the desired setpoint by clicking on the user input box and using the electronic keypad to enter the setpoints.

18.8.6 Information Pop-Ups Screens

Information pop-ups provide information about equipment such as tag #, make, model #, etc. The information pop-ups do not allow the operator to control the equipment.

Information pop-ups are called by selecting the “Information” button which will reside on the control pop-up for a device. The information pop-up will include generic information as follows:

1. Tag Number

2. Make

3. Model Number

4. Plant Maintenance Information System Number

5. Location

18.8.7 Setpoint Pop-Up Screens

The setpoint pop-up allows the operator to enter values for parameters that are used to control the process. Setpoint pop-ups can be classified into 2 types:

1. Plant setpoints

2. Alarm setpoints

An operator will be able to enter plant setpoints by clicking on the “Setpoints” button on the main button bar. The Alarm setpoints can be accessed by clicking on the analog value display which will bring the transmitter (alarm setpoint) pop-up. The operators can then choose the process(s) or transmitter they want to view and change setpoints.

1. Plant setpoints will include the following where required:



.1 Equipment start/stop times

.2 Duty pump setting

.3 Process setpoints including start/stop flows, pressure, etc.

The alarm setpoint screen, as mentioned above, brings up the transmitter pop-up. This contains a description of the analog value being scanned, the units and the setpoints associated with the alarms for that date. The operator can disable or enable the alarms as well as the scan for the transmitter. The operator can also change the setpoints for the alarms associated with that transmitter provided he/she has the correct access level to do so.

18.9 Alarm An alarm is a device or a function that signals the existence of a critical or abnormal condition by means of an audible and/or visible indication, intended to attract operator attention to a specific condition. Alarms can be displayed by changing the colour or state of the equipment and/or by printing an alarm summary on an alarm summary display. The following is the standardized HMI alarming technique.

1. The alarm page will be accessible through the button bar located at the top of the screen.

2. The alarms will be categorized into critical alarms, non-critical alarms and advisory or warning alarms.

3. These can be visibly indicated by the usage of colour and/or animation of the associated device.

4. The critical alarm screen will pop-up regardless of the screen that is being currently being viewed.

5. The process area associated with an active alarm will flash to indicate the presence of an alarm.

6. Alarms will be acknowledged through an acknowledge button.

7. The alarm summary page will provide the following information, as a minimum, date and time of occurrence for each alarm, time it was acknowledged, the type of alarm (hihi, lo, etc.), the event (ack, alm, rtn), priority, comment, tag name, value and alarm state (unack_alm, ack_alm, etc.).

Any alarm generated by the SCADA system must be capable of being acknowledged on a global basis from any workstation.

All unacknowledged alarms shall be displayed in flashing red and acknowledged alarms be displayed in white.

This status shall be maintained even if the workstation crashes and has to be rebooted ie it must maintain its alarm status prior to the workstation crash.

Provide a system master reset switch for acknowledging all alarms. This normally occurs when the workstation handling alarms crashes and has to be rebooted. At that time, all acknowledged



alarms, if it is still in an alarm condition, will be shown to be in an alarm condition. The master reset switch will acknowledge all alarms activated at that time.

18.10 Trends/Reports Provide trends and reports to enable the evaluation of the performance of the system and make qualitative decisions about the processes. This also includes those that are required by the EMA and WASA. Configure software to provide required reporting, trending etc and integrate plant data with event, summary, configuration and production data.

The following pages include parameters for Water Treatment Plants and Wastewater Treatment Plants.



18.10.1 Raw Water Monitoring Parameters (Water)

Daily Weekly Quarterly

Flow Rate Total Coliform Alkalinity

pH Fecal Coliform Hardness

Colour pH Calcium

Turbidity Turbidity Sodium

Temperature Colour Iron

Conductivity Copper

Total Chlorine Residual Lead

Zinc

Arsenic

Aluminum

Manganese

Conductivity

Chloride

Sulphate

Ammonia and Ammonium (N)

Total Kjeldahl Nitrogen

Nitrite

Nitrate

Dissolved Organic Carbon

Phenols



18.10.2 Treated Water Monitoring Program (Water)

Daily Weekly Quarterly

Flow Rate Total Coliform Alkalinity

pH Fecal Coliform Hardness

Colour Standard Plate Count Calcium

Turbidity Turbidity Sodium

Temperature Colour Iron

Free Chlorine Residual pH Copper

Total Chlorine Residual Lead

Zinc

Arsenic

Aluminum

Manganese

Conductivity

Chloride

Sulphate



Nitrite

Nitrate


Total Trihalomethanes



18.10.3 Distribution System Monitoring Program (Water)

Weekly Quarterly

Total Coliform Alkalinity

Fecal Coliform Hardness

Standard Plate Count Calcium

Colour Sodium

Iron

Copper

Lead

Zinc

Arsenic

Aluminum

Manganese

Conductivity

Chloride

Sulphate



Nitrite

Nitrate


Total Trihalomethanes



18.10.4 Raw Water Monitoring Program (Wastewater)

Daily Weekly Monthly

Total Plant Flow Suspended Solids (Twice a week) Total Plant Flow

Plant By-Pass BOD5

Secondary By-Pass Total Phosphorus

Suspended Solids Ammonia

BOD5 TKN Nitrogen

Total Phosphorus

Ammonia

TKN Nitrogen

18.10.5 Treated Water Monitoring Program (Wastewater)


Chlorine Residual Suspended Solids (Twice a week)

BOD5 (Twice a week)

Total Phosphorus (Twice a week)

Ammonia (Twice a week)

TKN Nitrogen (Twice a week)

E-Coli

18.10.6 Process Parameters Monitoring Program (Wastewater)


Dissolved Oxygen Percentage Total Solid in Digester Sludge (Thrice a week)

Chlorine Used

Mixed Liquor Suspended Solids Percentage Volatile Solids in Digested Sludge (Thrice a week)

Other Chemicals Used

Sludge Volume Index Grit Removed

Waste Activated Sludge Screening Removed

Return Activated Sludge

Secondary Clarifier Sludge Blanket Level

Primary Clarifier Sludge Blanket Level

Chlorine Used

Other Chemicals Used

Primary Sludge to Digesters

Digester Sludge Removed

Digester Gas Total



Digester Gas Used

Digester Gas Wasted

18.11 Trend Display

18.11.1 Trend Display Requirements

Graphical trending display shall be provided for all processes, equipment run-time, water quality etc on the following basis:

1. Last 6 hours

2. Last 12 hours

3. Last 24 hours

4. Last 7 days

5. Last one month

6. Last six months

7. Last 12 months

18.11.2 Water Treatment Plant Operating Statistics

The following operating statistics for water treatment plant and water supply system shall be produced for each 8-hour shift. Each display page shall be configured for a 3-shift period with sub-total for each shift and the grand-total for each 24-hour period. At the end of each week, each calendar month and on an annual basis, provide a summary for the year for the following:

1. WATER QUALITY LIMITS

2. WATER QUALITY – DAILY REPORT

3. WATER QUALITY – GENERAL

4. WATER QUALITY – TURBIDITY

.1 Raw water turbidity and individual filter effluent turbidity.

5. PLANT FLOWS SUMMARY – RAW, FINISHED & WASH WATER

6. PLANT FLOW MONTHLY REPORT - RAW WATER FLOW

.1 Include Monthly average, high, low and total.

7. PLANT FLOW ANNUAL REPORT – RAW WATER FLOW

.1 Include Annual average, high, low and total.

8. PLANT FLOW MONTHLY SUMMARY

.1 Include daily average, minimum, maximum for raw and finished water. Include volume and percent of washwater and number of washes.



9. PLANT FLOWS - DAILY REPORT

.1 Include maximum and minimum rate for raw and finished water.

.2 Number of filter washes, volume and percent of wash water.

10. WATER QUALITY MONTHLY REPORT

.1 Individual filter water quality reporting average, high and low NTU.

11. FILTER STATUS

.1 Include service, status, flow, LOH, NTU, operating time, volume filtered, total number of washes and total filtration rate.

12. FILTER LIMITS

.1 Include filtration rate, headloss and turbidity.

13. FILTER MONTHLY REPORT

.1 Include operating time, volume filtered, number of washes, average wash volume and net production.

14. FILTER ANNUAL REPORT

.1 Include operating time, volume filtered, number of washes, average wash volume and net production.

15. CHEMICAL CONSUMPTION SUMMARY - DAILY REPORT

.1 Include average dose and total consumed.

16. CHEMICAL TREATMENT – DAILY REPORT

.1 Include current dose, daily average, set point, current residual, daily total consumed and status. Include total daily raw and finished water produced.

17. CHEMICAL TREATMENT – MONTHLY REPORT

.1 Include total consumed and average dosage rate.

18. CHEMICAL TREATMENT – ANNUAL REPORT

.1 See 9.4.2.17.

19. WATER QUALITY RAW WATER TURBIDITY – MONTHLY REPORT

.1 Daily report of the average, high and low raw water turbidity in NTU.

.2 Provide monthly average, monthly high and low.

20. WATER QUALITY RAW WATER pH – MONTHLY REPORT


.1 Include plant and water distribution system for current, range, high alarm and high advisory for raw and finished water turbidity, pH, temperature, pre and post chlorine residual, HFS residual.

22. DAILY RESERVOIR LEVEL SUMMARY



.1 For each hour.

23. DAILY WATER CONSUMPTION SUMMARY

.1 For each hour, for each zone and the total for each zone and the daily total.

24. DAILY PUMPING STATION PRODUCTION SUMMARY

.1 Include flow rate, pressure, reservoir level, operating pump(s) and Electrical power consumption for HLPS and the PS for each pressure zone.

25. ZONE CONSUMPTION ANNUAL REPORT

.1 Include average, maximum and minimum day and the date of occurrence, the total for each month. Include annual average day, maximum and minimum day, maximum and minimum hour for the year for each pressure zone.

26. TOTAL WATER CONSUMPTION ANNUAL REPORT

.1 For each month, provide average day, maximum and minimum day and the date of occurrence, the total for each month. Include annual average day, maximum and minimum day, maximum and minimum hour for the year for the entire water supply system.

27. TOTAL WATER CONSUMPTION SUMMARY ANNUAL REPORT

.1 For each zone, provide average day, maximum and minimum day and the date of occurrence, the total for each month. Include annual average day, maximum and minimum day, maximum and minimum hour for the year for the entire water supply system.

28. ANNUAL PUMPING STATION PRODUCTION SUMMARY

.1 For each month, provide the pumpage volume of finished for each zone. Provide the total for each month for each zone and the annual total.

29. ANNUAL SUMMARY OF PUMP RUNNING TIMES

.1 For each pumping station, show the total hours of running time for each pump.

30. MONTHLY SUMMARY OF PUMP RUNNING TIMES 31. MONTHLY PRODUCTION SUMMARY

.1 For each day, provide the pumpage volume for each zone pumping station. Provide also the daily total pumpage volume by day and zone.

32. RAW WATER CHLORINE RESIDUAL MONTHLY REPORT

.1 Include average, high and low residual level.

The above should be capable of being printed on the screen or on a laser printer. In addition, it should also be capable of being trended in accordance with 9.4.1 and printed on the screen and a laser printer.



18.11.3 Wastewater Treatment Plant Operating Statistics

The following operating statistics for wastewater treatment plant shall be produced for each 8-hour shift. Each display page shall be configured for a 3 shifts period with sub-total for each shift and the grand-total for each 24-hour period. At the end of each week, each calendar month and on an annual basis, provide a summary for the year for the following:


2. WATER QUALITY – DAILY REPORT 3. WATER QUALITY – GENERAL

4. PLANT FLOWS SUMMARY – RAW & TREATED

5. PLANT FLOW MONTHLY REPORT – RAW FLOW

.1 Include Monthly average, high, low and total.

6. PLANT FLOW ANNUAL REPORT – RAW FLOW

.1 Include Annual average, high, low and total.

7. PLANT FLOW MONTHLY SUMMARY

.1 Include daily average, minimum, maximum for raw and treated wastewater.

8. PLANT FLOWS – DAILY REPORT

.1 Include maximum and minimum rate for raw and treated wastewater.

9. CHEMICAL CONSUMPTION SUMMARY – DAILY REPORT

.1 Include average dose and total consumed.

10. CHEMICAL TREATMENT – DAILY REPORT

.1 Include current dose, daily average, set point, current residual, daily total consumed and status. Include total daily raw and treated wastewater processed.

11. CHEMICAL TREATMENT – MONTHLY REPORT

.1 Include total consumed and average dosage rate.

12. CHEMICAL TREATMENT – ANNUAL REPORT

13. WATER QUALITY RAW WATER TURBIDITY – MONTHLY REPORT

.1 Daily report of the average, high and low raw water turbidity in NTU.

.2 Provide monthly average, monthly high and low.

14. WATER QUALITY RAW WATER pH – MONTHLY REPORT

15. MONTHLY TREATMENT SUMMARY

.1 For each day, provide the collection volume for each drainage area. Provide also the daily total collection volume by day and area.



18.12 Archival of Historical Data Data collected at the PLC/RPU site shall be transferred to the SCADA workstation. At fixed periods, the data is transferred to the fileserver for long term storage. Short term access to the data shall be by reading the data from the remote workstation.

18.13 Process Control Graphic User Interface

18.13.1 Process Control Display

Process control display shall commence with the overall system followed by more detailed graphic display for each subsequent smaller process area. There shall also be screen display developed for specific purposes such as a screen display for all reservoirs or a screen display showing all the pumping stations, etc.

Each process screen shall be designed to appear as similar to the actual layout of the system as possible.

Two-dimensional graphical representations shall be used on all process display screens.

18.13.2 Standard Colour Convention – Process Stream

The following table lists the standard colour conventions for process Stream:

Element Colour Convention

Potable Water Light Blue

Raw Water Dark Blue

Influent Water from WWTP Light Green

Effluent Water from WWTP Dark Green

Chlorine (Liquid) Chemicals - Orange

Chlorine (Gas) Gas - Yellow

Aluminum Sulphate

Ammonia

Polymer

Sulphur Dioxide

Hydrofluosilicic Acid (Fluoride)

Ferric Chloride

Natural Gas

Digester Gas

WTP/WWTP Sludges Brown

WTP Backwash Wastewater

WWTP RAS/WAS

WTP Settled Backwash

WWTP Supernatant



Values appearing at various locations on the screen shall represent current value for flows, levels pressures, etc.

18.13.3 Standard Colour Convention – Pump/Motor/Valve

The colour convention for pump/motor/valve and miscellaneous details shall be as follow:

Device/Status Colour Convention

Pump/Motor

Running Red with Text

Off Green with Text

Alarm Flashing Magenta

Valve

Opened Red with Text

Transition Half red and half green

Closed Green with Text

Modulating Percentage open is displayed beside valve. Valve colour is green when less than 5% open and red when greater than 5% open.

Isolating Grey

Alarm Flashing Magenta

Miscellaneous

Hi or HiHi Alarm Flashing Magenta

Lo or LoLo Alarm Flashing Magenta

Background Process - White

Control - Black

Text Description - White on Pop-Up

- Black on Process Screen

18.14 Symbols Use standard symbols on a process overview screen. Comply with the following practices when developing graphics:

1. Symbols should reflect the P&ID drawings

2. It must be consistent, intuitive and user friendly

3. It should be developed for both dynamic and static equipment

4. Use ISA symbols (2-D)

18.15 Watchdog Program A watchdog program shall be provided where specified in the Request for Proposal.



The watchdog program, as defined herein, is a software program designed to track all changes made to the HMI and PLC/RPU logic software or database.

The watchdog program may be custom written software to be provided by the Consultants to meet the intent of this requirement.

The following is the information that must be tracked by the watchdog program:

1. Date

2. Time

3. Name of authorised personnel and security code

4. Name of authorising Supervisor and security code

5. Block of software or database changed

All such changes shall be saved in a file which cannot be erased unless authorised by the Supervisor.

18.16 System Security Security of workstations, plant networks and field controllers shall be installed to only permit access by authorised personnel with the required security clearance.

Security system shall be configured based on three levels of security. These are the workstation operating system (Window NT), the Network Access (for e-mail, corporate applications etc.) and the SCADA HMI (operator verification). Each of these will be one of two levels – administrator or user. The administrator (Supervisor and/or Manager) will assign the rights and privileges of the users on the network.

The SCADA system security shall be dependent on a logon system and the use of distinct logons for the MHI is required.

18.17 SCADA System Operation Manual

18.17.1 General

Provide Operation Manuals in accordance with the Project Guidelines. This includes operating procedure descriptions for both PLANT-MANUAL and PLANT-AUTO operation of the facility in the following sequence:

1. LOCAL Control

2. PLANT MANUAL

The sections covering PLC/RPU based operation will be developed from the English language process narrative and the logic flow diagrams produced. Allowance will be made in the Operational Manual for inclusion of this Chapter.



Hard copy, disk and CD-ROM to be provided for all custom ladder logic and SCADA system application software installed, as well as all original disks and CD-ROMs provided under the contract for the software packages.

18.17.2 SCADA System Operation Manual Requirements

As a minimum, the SCADA System Operation Manual shall include the following sections.

Section 1 INTRODUCTION 1.01 General Information 1.02 Control System Standards 1.03 System Configuration (See Note 1) 1.04 System Architecture Section 2 HARDWARE & SOFTWARE 2.01 System Overview 2.02 Hardware – Central Hardware 2.03 Hardware – RPU Hardware 2.04 Software – Central Software 2.05 Software – RPU Software 2.06 Hardware Configuration 2.07 Software Configuration 2.08 Replacement/Addition of Workstation Section 3 THE BASICS 3.01 The First Step 3.02 Disk Operating System 3.03 Microsoft Windows 3.04 Using Microsoft Windows 3.05 List of Running Programs 3.06 Windows Applications 3.07 Main Group 3.08 Accessories 3.09 PC Anywhere 3.10 Backup Basics 3.11 Spread Sheet and InTouch 3.12 The Second Step 3.13 HMI Software 3.14 Using the HMI Software 3.15 Plant/System Automation through the HMI 3.16 Troubleshooting 3.17 To Exit Windows Section 4 PROCESS DISPLAY 4.01 Process Displays (Process Displays shall include all displays configured in the HMI

and how to use them. It shall starts from the intake to the furthest



pressure zones; all plant processes; all chemical treatment processes; all pumping stations and reservoirs.)

Section 5 EQUIPMENT CONTROL 5.01 Device Control Mode 5.02 Equipment Control Displays & Popup Menus 5.03 Device Alarms 5.04 Transmitter 5.05 Process Area #1 (repeat for each major process area) 5.06 Facility Security Section 6 USING THE HMI BUTTONS 6.01 Top Row Buttons 6.02 Exit 6.03 Alarms 6.04 History 6.05 Map 6.06 Process 6.07 Systems 6.08 Reports (List and show all reports that will be generated) 6.09 Trends (List and show all reports that will be generated) 6.10 Options 6.11 Setpoints 6.12 Area 6.13 Previous 6.14 Next Section 7 PROCESS NARRATIVE 7.01 Provide all process narratives and for each process, include the

following minimum information: i. System Description ii. Equipment iii. Control Mode iv. I/O Points

Program Variables Virtual Points Field Points

v. Control Logic Normal Operation Fault Response Operation Hardwired Interlocks Associated Alarms

7.02 Include all Auto Control Programs Narratives Section 8 SYSTEM FAILURE 8.01 Communication Failure - Workstation



8.02 Communication Failure - Remote Workstations 8.03 Workstation Failure and Restart Procedure 8.04 System Crash and Restart Procedure 8.05 Power Failure and Backup Generator 8.06 Trouble Shooting SCADA System Section 9 SYSTEM SECURITY 9.01 SCADA Access Security 9.02 Passwords 9.03 Changing Password and Authorization 9.04 Watchdog Program 9.05 Function of Watchdog Program 9.06 Watchdog Historical Data 9.07 Erasure of Watchdog Data and Authorization Section 10 WASA AM/FM/GIS 10.01 Integration of WASA AM/FM/GIS System 10.02 Accessing into the SCADA System from WASA System 10.03 E-Mail Appendix A POINT LISTS Appendix B SCADA SYSTEM EQUIPMENT LISTING Appendix C SOFTWARE LISTING Appendix D REDUCED SET OF CONTRACT DRAWINGS In assembling the information for the SCADA system for the Operation Manual, the Consultants shall provide all the information of all workstation or view node software to be included under Section 2.06 - Hardware Replacement:

1. Hardware: .1 Monitor Manufacturer, Model and Resolution .2 Computer Manufacturer, Model, Hard Drive Specification, Input/Out put ports,

Video Card Specifications, Manuals .3 LAN Card Manufacturer, Model, Configuration Settings, Jumper Settings, LAN Card

Software, Installation and Operations Manuals .4 I/O Cards Manufacturer, Model, Configuration Settings, Jumper Settings, IRQ and

COM Port Addressing, Manuals .5 Modem(s) Manufacturer, Model, Configuration Setting, Setup Procedure for leased

Line Configuration, Specification for 2 or 4 wire, Manufacturer’s Manuals 2. Network LAN Hub Manufacturer, Model, User Manuals, Type of Cabling (e.g. 10

Base T)

The SCADA Software information shall be provided in the Operation Manual and the minimum requirements are as follow:

1. Software



.1 Operating System

.2 Office Applications

.3 All configuration settings for communications

.4 Port settings

.5 Device settings (video, mouse, etc.)

.6 Alarm Logger Configuration

.7 Alarm Printing

.8 Historical Logging Configuration

.9 Node configuration (communication, addressing, etc.)

2. PLC Software

.1 Node addressing for all PLC’s in the SCADA Network

.2 All port, jumper, etc. configuration settings

18.17.2.1 Replacement or Addition of Workstation

The procedure for the replacement and or addition of a workstation shall be provided as follows:

1. Step by step instructions on how to replace a work station which has failed. How a new computer would be configured to replace the existing workstation.

2. Step by step instructions on how to add a new work station to the system.

3. Step by step instructions explaining how to upgrade the SCADA system strategy (on all work stations) via a laptop computer. Note details which would be specific to each work station.

4. Detailed description of report writing macro and a step by step account of how to integrate a new workstation into the automatic report output.

18.18 System Architecture The system architecture is based on the following requirements:

1. The workstation operating system is to be Microsoft Windows

2. Database application software conforms to existing.

3. Networking at all levels is based on an Ethernet backbone.

4. The in-plant communications network is hard-wired to avoid delays and failures in communication (details to be developed during the pre-design phase).

5. Communication between the plants and the remote sites is to be optimal to avoid delays in data transmission.



18.19 SCADA Control Strategy The SCADA and control strategy shall be developed for each plant (the same application will apply to the remote stations linked to the plant) and must be capable of being updated from all view nodes through a single node. It must have the capability to monitor and control the plant and all the remote stations from any SCADA node within the plant’s LAN.

The SCADA system’s server must be provided with full redundancy backup, thereby insuring the ability to switch to a backup server if the main server fails. This will provide the continual ability to control the plant and sites from individual client nodes if the main server fails.

To ensure the security and integrity of the SCADA system, fire-walls and virus detection software shall be installed on all SCADA nodes.

The SCADA system shall be configured to provide the ability to use portable computers to dial into any LAN to view and control the processes.

18.20 Network Requirements Reliable and high speed communication network of the SCADA system for water and wastewater systems.

18.21 SCADA Software The standard requirements for HMI general configuration requirements for the system (server and client nodes) are as follows:

1. Single product HMI

2. A server-client configuration is required where there will be one server node and several client nodes

3. Each server will be a runtime node

4. The client node can be configured to be either a runtime node that allows control and monitoring features or a view only node

5. The server node will contain the application and all client (view) nodes will point to this directory on the server to run the application

6. The client nodes will maintain a copy of the application as well for redundancy

7. There will be one backup client node capable of operating as the server for redundancy

8. Visual Basic scripting will be used to notify and update the client nodes so that system development can be completed on one node and automatically copied to the client nodes

9. Use of a browser package that provides Internet visualization to view factory information anywhere and anytime



18.22 Database Software A real-time relational database that acquires and stores plant data will be implemented on the SCADA nodes. The database will have client applications that can be used to access this data for viewing, analysis, reporting, etc.

1. The database will be used as a real-time database for data storage and analysis; there will be one database server and several database clients

2. One server can be used for both the database and HMI software

3. The database server will be used to store all the data and the client nodes will be configured to provide the required analysis and summary/report generation

18.23 Communication Links Due to the high reliance of the SCADA network project on communication links, use high-speed communication to avoid delays which may be critical in various processes. For fast and reliable communication, the following strategy shall be implemented:

1. All in-plant communication to be hardwired (no modems)

2. ISDN (Two 64kb channels per connection) service to be used at all sites unless this service is not available

18.24 PLC/RPU Programming Standard

18.24.1 PLC Program Structure

The programming of PLCs shall be carried out in a uniformly structured manner, which shall be as follows:

1. Main Program

2. Start-Up Sequence

3. Output I/O Task

4. Input I/O Task

5. Input Conditioning

6. Data Communication

7. Alarm Handling Subroutine

8. Duty Selection

9. Automatic Control Logic

10. Equipment Control Logic Tasks

11. Device Driver Modules



18.24.2 PLC Programming Protocol

Consultants shall comply with IEC-61311 programming format. No program(s) will be accepted by WASA if it does not conform to this requirement. In addition, the Consultants shall also observe the following programming protocol when carrying out PLC or HMI programming. This may be verified through a third party retained to perform the peer review work.

1. Data addresses that are to be communicated to other controllers, operator interfaces, and/or SCADA workstations are to be grouped together.

2. The adoption of a predefined program structure that orders the common tasks to be used in PLC/RPU programs.

3. Use function blocks or subroutines to avoid repetitive blocks of identical logic. If these are not available, consider common flags/variables instead of repeated code.

4. Use the status of any field input only once in the I/O task to drive a logic relay/bit or register/word (point). This “translation” of all field inputs forms the first portion of the I/O task. One function of the “translation” is to ensure a ‘positive logic’ sequence in the development of the code. These logic points are then used by all other logic, rather than the field inputs. Debounce timers/ramps are required for all inputs and are included here.

5. Outputs are addressed as per inputs noted above, that is, all tasks except the I/O task address outputs through logic points. The I/O task then uses these logic points to drive the field outputs. The writing of all field outputs should be grouped together at the end of the I/O task. Any field output may be written at only one location in the code.

6. Place all checks for device response together in the I/O task, with a timer for each device.

7. Group all registers/words and relays/bits that are of interest to monitoring personnel in sequential blocks. This includes setpoints, timer limits, tuning constants, and status flags. This simplifies the transfer of this data to supervisory systems. Maintain the “translated” field inputs in separate block(s) from other data.

8. Use constants in the code only where it is unlikely they will ever be changed.

9. Layout I/O points having identical functions for successive devices in identical, consecutive blocks. For example, group the start/stop outputs for all low lift pumps in similar order and in adjacent terminals.

10. Avoid latches.

11. Avoid jumps.

12. Avoid drum sequencer.

13. Use an IBM compatible workstation to program the PLC and use the manufacturer’s programming software to fully document the code.

14. Label every register/word, relay/bit, and rung with a name or comment.

15. Do not sacrifice program clarity and simplicity to achieve higher execution speed and smaller code size.



16. Monitor and alarm all available diagnostic data such as task and I/O board errors.

17. Where PID loop control is required, disable the derivative factor.

18. Configure all alarm points in software to be TRUE when in alarm. (In general, field wiring of alarms is FALSE when in alarm.)

19. Include logic for simulation of normal field feedback. This is used in factory and site testing as well as training.

20. Include minimum times for equipment to be running and stopped, to prevent possible output ‘chattering’.

21. Include interlocks to prevent simultaneous starts of major equipment (in auto mode only).

Water And Sewerage Authority (WASA) Water and Wastewater Design Guideline Manual Mechanical Standards

19-1 October 2008R1

Section 19 Mechanical Standards

19.1 General Comply with applicable Acts, Codes or Design Guidelines as detailed in Section 3.0, Design Standards.

Mechanical systems shall be designed to provide ease of operation and maintenance. Choice of material and equipment shall be based on WASA standard and where such standard has not been provided, it shall be based on the track record of the material or equipment in a similar Trinidad & Tobago facility. All design shall comply with Trinidad & Tobago National Plumbing Code, AWWA Standards of Practice and Specifications, relevant codes or design guidelines. The design must as much as it’s applicable, include mechanism for water conservation, including but not limited to pressure control devices, low flush toilets, low volume faucets, etc.

19.2 Valves Valves shall comply with EN 593 and ISO 5996. All valves and actuators shall have at least 5 years of operating service in Trinidad & Tobago, and to be supplied by regional based vendors.

All valves used for potable water supply system shall be certified for potable water use.

Orient valves and valve operators to meet the following requirements:

1. Ease of operation

2. Limit interference with structures and with any other equipment or piping

3. Space allowance requirement for maintenance and disassembly

4. Valves mounted higher than 2 m shall be provided with chain for opening or closing

Specify valves operators, for both manual and electric valves, with indicator to clearly indicate whether the valve is in the opened, closed or partially opened/closed position. The indicator must be visible from 3 meters away, under normal plant operating conditions.

19.3 Fittings Flanges shall be Class 125, ANSI B16.1, for operating pressures up to 250 pounds per square inch. For operating pressures above 250 pounds per square inch, flanges shall be Class 250, ANSI B16.1.

Above-ground fittings shall be flanged, welded, or coupled. Nuts and bolts shall be hot dip galvanized steel or epoxy painted.

Below ground fittings shall be welded or coupled. Nuts and bolts shall be grade 316 stainless steel.

Gaskets shall be Butyl or EPDM.

Water And Sewerage Authority (WASA) Project Design and Technical Specifications Manual Mechanical Standards

19-2 October 2008R1

19.4 Pumps All materials and equipment supplied shall be suitable for being delivered, store and operated under tropical conditions of high temperature, high humidity, heavy rainfall, mildew and fungus conductive environment. All equipment and motors shall be supplied with corrosion resistant metal nameplates fitted securely in an location, which can be easily read, complete with stamped inscriptions of the following information where applicable:

1. Electric motors will meet the requirements of IEE 60034-1, 60034-5, 60034-6 and 60034-8.

2. For pumps, fans, valves, valve operators, instruments, etc.:

.1 Model Number

.2 Serial Number

.3 Head

.4 Capacity

.5 Impeller Diameter

.6 Efficiency

.7 Performance rating

.8 Other information required to uniquely identify the equipment

.9 Performance data in SI metric units

3. Bearings requirement:

.1 All rotating equipment shall be provided with bearings selected on the basis of life expectancy at rated conditions of service of at least 100,000 working hours.

.2 Bearings for electric motors shall be constructed so that no oil or grease can escape from them.

4. Alemite-type or buttonhead grease fittings shall be provided for bearing lubrication.

5. Equipment Operating Characteristics:

.1 Mechanical equipment furnished shall operate satisfactory without excessive wear, excessive lubrication or undue attention required by the operating staff. All rotating parts shall be in true dynamic balance and operate without vibration caused by mechanical defects, faulty design or misalignment of parts. In general, the limit of vibration velocity is 1mm/sec for equipment. A more stringent requirement may be specified in the detailed equipment specifications.

6. Equipment Guards:

.1 To be provided for all couplings, belts, chain drives and extended shafts.

.2 It shall be securely mounted, suitably reinforced and neatly formed of at least 12 gauge steel perforated sheet or expanded sheet metal.

.3 It shall be hot-dip galvanized after fabrication.

.4 It shall be painted yellow in colour.


19-3 October 2008R1

7. Base Plates:

.1 Equipment base plates shall be of heavy cast iron or of welded structural steel with a minimum thickness of 13 mm. For mounting equipment and driver base, the plates shall be at least 20 mm thick. Surfaces for mounting equipment and driver shall be machined to an arithmetical average roughness height of less than 125 micro-inches.

.2 For equipment where leakage or condensation may occur, provide base plates with a drip lip and drain connections to the exterior of the base. Piping shall be provided from the drain connections to the building drainage system. Bossed connection to drip lips shall be below the gutter invert and shall be at least 25 mm N.P.T.

.3 In general, equipment shall be installed directly on machined bases without shims. Where shims are required, provide stainless steel shims under driver mounting feet.

8. Equipment Noise Level:

.1 Equipment shall be designed for quiet operation with the overall sound pressure level at any equipment not exceeding 85 decibels when measured on the “A” weighting network (IEC 60034-9). A more stringent requirement may be specified in the equipment specifications.

19.5 Piping & Equipment Identification

19.5.1 General

All pipes inside the plant or valve house shall be colour coded in accordance with WASA requirements for pipe identification in water and wastewater treatment plants. These color requirements have been covered by the TTBS standard for pipe codes/colors. Provide arrows indicating the direction of flow.

All inlet, internal and outlet piping for pumping station shall be provided with isolation valve(s) to permit isolation/removal of pump(s) for maintenance work without impacting on the integrity or operational capability of the pumping station itself.

The labelling of all pipes shall conform to WASA.

All piping, fittings and valves, mechanical and electrical equipment including sleeves through floors, shall be painted.

Piping and equipment shall be properly identified as provided herein.

All existing equipment, piping etc shall be protected from paint splashes when new equipment or piping is painted.

19.5.2 Security equipment

All security guards and railings shall have a yellow colour to conform to WASA requirements.


19-4 October 2008R1

19.5.3 Piping Identification Labels

All piping shall be labelled to conform to WASA requirements as stated in applicable TTBS standard. If not covered, then the following standard based on ASME A13.1-2007 could be applied. Identify exposed piping and ductwork in locations as follows:

19.5.4 Colour Legend

19.5.4.1 Group #1

Piping System Label Band Background

Letter/ Colour

Max. Label Intervals

Max. Band Intervals

Flammable Materials Propane Gas Natural Gas Hydraulic Oil Fuel Oil Digester Gas

Yellow Black 3 m 3 m

19.5.4.2 Group #2

Piping System Label Band Background

Letter/ Colour


Max. Band Intervals

Fire Fighting (Protection) Standpipe System Sprinkler System Halon Fire Protection Carbon Dioxide Fire Protection

Red White 3 m 3 m


19-5 October 2008R1

19.5.4.3 Group #3

Piping System Piping Colour

Label Band Back-ground

Letter/ Colour


Max. Band Intervals

Dangerous Substances: Boiler Feed Boiler Blow Off Acid Drain Compressed Air > 670 kPa Ferric Chloride (High Temp Dom.) (Hot Water) LP Stream LP Condensate Hp Steam Lp Condensate

Purple White Black 3 m 3 m

19.5.4.4 Group #4

Piping System Piping Colour

Label Band Back-ground

Letter/ Colour


Max. Band Intervals

Other Chemical Substances:

Alum

Chlorine Solution

Polymer Solution

Lime Solution

Sodium or Calcium Hypochlorite Solution

Glycol Solution (Heating)

Diesel Exhaust

Orange White Black 3 m 3 m


19-6 October 2008R1

19.5.4.5 Group #5

Piping System Piping Colour Label

Band Back-ground

Letter/ Colour


Max. Band Intervals

Process Drainage

Raw Water

Clarified Water

Treated Water

Dom. Cold Water

Dom. Hot Water Sup.

Dom. Hot Water Ret.

Chilled Water

Condenser Water

Hot Water Heating

Storm Drain

Plumbing Vent

Effluent Water

Compressed Air

Instrument Air

Vacuum

Nitrogen

Sanitary Drain

Filtrate (San)

Return Sludge

Waste Sludge

Raw Sludge

Scum

Supernatant

Olive green

Aqua

Dark blue

Lt. green

Lt. green

Lt. green

Blue

Lt. Grey

Lt. Grey

Lt. Grey

Lt. Grey

Lt. Grey

Safety Blue

White

White

Orange

Dk. Grey

Dk. Grey

Mid-Brown

Mid Brown

Dk. Brown

Dk. Brown

Lt. Brown

Green

Green

Green

White

Red

Red

Green

Green

Red

Green

Green

Green

Green

Green

Green

Green

Green

Green

Green

Green

Green

Green

Green

White

White

White

White

White

White

White

White

White

White

White

White

White

White

White

White

White

White

White

White

White

White

White

6 m

6 m

6 m

6 m

6 m

6 m

6 m

6 m

6 m

6 m

6 m

6 m

6 m

6 m

6 m

6 m

6 m

6 m

6 m

6 m

6 m

6 m

6 m

Not

Required

19.5.5 Method of Application

On painted piping system (pipes up to and including 45 mm o.d.), labels shall be 2 mil vinyl/polyester of sufficient lengths to wrap completely around the pipe with a minimum of 8 mm overlap. Colours to meet WASA Standards. Label complete with permanent adhesive.

On painted piping system (Pipes over 45 mm o.d.), labels shall be 10 mil PVC sleeve complete with two-sided permanent tape and liquid weld. PVC to be 25/50 fire rated. Sleeve shall be of sufficient length to wrap completely around the pipe with a minimum 25 mm overlap. Colours to meet WASA Standards.


19-7 October 2008R1

On unpainted piping systems (pipe up to and including 45 mm o.d.), labels shall be vinyl/polyester of sufficient length to wrap completely around the pipe with a minimum 8 mm overlap. The label shall be 300 mm long complete with 100 mm colour banding at each end with colours to meet WASA Standards for colour banding. The labels shall be supplied as a one-piece unit and permanently self-adhesive.

On unpainted piping systems (pipe over 45 mm o.d.), labels shall be. 10 mil PVC sleeve complete with two-sided permanent tape and liquid weld. PVC to be 25/50 fire rated. Sleeve shall be of sufficient length to wrap completely around the pipe with a minimum 24 mm overlap. The label shall be 300 mm long complete with 100 mm colour banding at each end with colours to meet WASA Standards for colour banding. The labels shall be supplied as a one-piece unit.

Directional arrows are required with each of the above labels.

19.5.6 Sizes of Characters

Provide the following sizes of characters for labels:

Outside Pipe Diameter Letter Size

Pipe less than or equal to 25 mm 12 mm

Pipe greater than 25 mm but less than or equal to 50 mm 25 mm

Pipe greater than 50 mm but less than or equal to 300 mm 38 mm

Pipe Greater than 300 mm 50 mm

Ducts 50 mm

19.5.7 Location of Labels

Application of Labels shall conform to the following:

1. Apply identification label and directional arrows at or near the following locations:

.1 Both sides of valves

.2 All branch fittings and elbows

.3 Both sides where pipes and ducts pass through walls, floors and ceiling

.4 Straight runs at maximum distance, centre to centre, as indicated above

.5 Where circumstances make contents or direction of flow doubtful

2. Apply labels in positions that allow them to be easily read from normal operating positions.

3. All labels to be installed in a workmanlike manner.


19-8 October 2008R1

19.5.8 Pumps & Valves Colour Schedule

Pump Type Colour Schedule WASA Code

Sump Pump Light Grey

Sodium Hypochlorite Metering Pump Light Grey

Hydrofluosilicic Acid Metering Pump

Aluminium Sulphate Metering Pump

Chlorination Metering Pump Light Grey

Ferric Chloride Metering Pump

RAS Pump

Sludge Loading Pump

Wastewater Pump (Normally in Wastewater PS)

Washwater Pump Light Blue

High Lift Pumps Light Grey

Low Lift Pumps Light Grey

Valve Type Purpose Colour Schedule WASA Code

Manually operated butterfly valves Cell isolation Light blue

Electrically operated butterfly valves

Automatic reservoir level control Light blue

Check valves with lockable device Direction of flow control, lockable device to keep valve open for reverse flow application

Light blue

Gate valves Reservoir drainage Light grey

Valves Chemical solution Light grey

Valves Plumbing and drainage system Light grey

Equipment Colour

Emergency Standby Diesel Generator Light Grey

Equipment Guard Red

Air Blower Light Grey


19-9 October 2008R1

19.5.9 Nameplates

All equipment, except electrical, shall be provided with a nameplate with the following information stamped on it:

1. Pump

.1 Type

.2 Model

.3 Serial Number

.4 Rated Capacity (L/S)

.5 Rated Dynamic Head (TDH m)

.6 Number of Stages (Vertical Turbine Pump)

.7 Speed

.8 Diameter of Suction/Discharge

.9 Impeller Diameter

.10 Seals

.11 Bearing Details

.12 Weight

.13 Year of Manufacture

2. Drive Unit

.1 Size

.2 Type

.3 Serial Number

.4 Electrical Requirements

.5 Current Draw

.6 Frame Number

.7 Rated Temperature Rise

.8 Continuous Service Factor

.9 Bearing Details

.10 Weight

.11 Year of Manufacture

3. Submersible Pump

.1 Nameplate for submerged portion

.2 Nameplate for non-submerged portion



19.5.10 Equipment Name Tags

Special equipment name tags shall be provided to identify equipment. The equipment name tags shall be black embossed or engraved on polished rectangular aluminium tags 50 mm high, 1.5 mm thick and long enough to display adequately all the identification characters. The identification characters will be alpha numeric and 10 mm high and should be attached with at least two stainless steel self-tapping screws or black nylon ties where screws fasteners are not practical.

19.6 Equipment

19.6.1 Bearings

All equipment bearings shall have a minimum rating life of 100,000 hours, unless specified otherwise.

19.6.2 Pump Shaft Seals

1. Single, mechanical pump shaft seals, unless specified otherwise.

2. Non-destructive, cartridge type, self-aligning seals of the stationary design, which requires no wearing sleeve for the shaft.

3. Pump shaft shall have no reduction in size through the seal area.

4. For all contaminated water services, drill and tap for installation of seal water supply.

5. Stainless steel spring or Hastelloy C spring.

6. Buna-N or Viton O-rings for clean water applications. Specify Viton O-rings for sludge, wastewater, scum or grit applications.

7. Faces:

.1 Wastewater, Sludge – Sintered silicon (or tungsten) carbide on carbon

.2 Potable water – Tungsten carbide on carbon

19.6.3 Couplings

Provide flexible coupling for all equipment with drives over 0.4 kW and less than 120 kW and where the driver is directly connected to the driven unit.

19.6.4 Equipment Guard

Provide guard on moving parts fabricated of 1.5 mm sheet steel and galvanize after fabrication.

Equipment guard is to be removable to facilitate maintenance of moving parts. Make provision to extend lube fittings through guard. All guards shall be yellow painted.

19.6.5 Gauge Taps and Test Plugs

Provide gauge taps on the suction and discharge side of pumps, blowers and compressors and install gauges at each location.



19.6.6 Alignment

All rotating equipment is to be set and aligned in accordance with the more stringent requirements of either the equipment manufacturer or the following:

1. Level base, use machinists level on all machined surfaces.

2. Base is to be true and levelled.

3. Alignment of shafts, soft foot of motor and couplings shall be performed by reversed dial, rim to rim and face to face. Soft foot will be rim to rim vertical and horizontal mode. .1 Soft foot of motor shall be checked to be within a tolerance of 0.03 mm

.2 Shaft shall be aligned within a tolerance of ±0.025 mm to 0.070 mm

.3 Piping strains to pump shall be within a tolerance of ±0.025 mm to 0.070 mm

19.7 Equipment Maintenance Requirements Provide a minimum of one (1) meter of clear space around all equipment for maintenance work.

For equipment that requires replacing in the future, it shall be provided with electrical and mechanical isolation devices to permit removal without interfering with the operation of the process or facility. Isolation devices shall be as close to the equipment as possible and shall not require the use of a ladder for access. Isolation devices must be visible from the equipment to be removed.

In designing the layout of the equipment, the Consultants shall make provisions for its removal. No equipment shall be designed such that it cannot be removed and if it is to be designed in that manner, the intention must be identified by the Consultants and accepted by WASA. In addition, all required lifting devices for removal of equipment must be in place or can be put in place to facilitate its removal. All lifting device shall be engineered for the purpose intended.

Water And Sewerage Authority (WASA) Water and Wastewater Design Guideline Manual Ventilating & Air Conditioning Standards

20-1 October 2008R1

Section 20 Ventilating & Air Conditioning Standards

20.1 General Comply with applicable Acts, Codes or Design Guidelines as detailed in Section 3.0, Design Standards and also with The Trinidad & Tobago Building Code.

Installation shall meet and/or exceed the requirements of:

a) ASHRAE Guide and Data Book

b) SMACNA Sheet Metal and Duct Construction Standards (Low and High Velocity)

c) CIBS Building Services Code

d) CIBS Commissioning Codes

e) ARI Standards

f) Other relevant ASHRAE, SMACNA and ARI publications

g) Trinidad & Tobago ASHO Act

20.2 VAC System The ventilation systems shall be designed to maintain acceptable working and living environments for personnel and non-destructive conditions for equipment. H2S gas detectors shall be installed when such risks are present to working staff in wastewater treatment plants or pumping stations.

Provide the proper design, sizing and selection of equipment according to the purpose of each specific room or space. Humidity, temperature and rates of ventilation should be properly determined according to each specific environment to meet all codes and security standards. The design shall take into account both normal and emergency operation requirements.

Provide separate ventilation systems in laboratories.

Ventilation openings shall be screened with a sufficiently fine mesh to prevent entry by birds, rodents, snakes, and bugs.

Provide air conditioning or humidity control when electronic equipment (Control panel) is located in a room.

Power supply of equipment should be compatible with the new, future or existing site building.

Provide refrigeration piping, chill water piping and condensate drainage when required.

Engineering site supervision should be provided during construction.

Water And Sewerage Authority (WASA) Project Design and Technical Specifications Manual Ventilating & Air Conditioning Standards

20-2 October 2008R1

20.3 Minimum Air standard Ventilation networks shall be designed in order to avoid any hazard or discomfort by the working staff in the plants. The concentration of pollutants shall meet at minimum the following guidelines:

H2S : 4 mg/Nm3 or less

NH3 : 3 mg/ Nm3 or less

Methyl Mercaptan : 1 mg/ Nm3 or less

20.4 System Redundancy Where ventilation is designed to assure security of workers, per example to avoid intoxication by H2S emanations in wastewater treatment plants, the system must be of a higher quality and more robust. The robustness consists, but is not limited to, assuring 100% redundancy of ventilation systems, in order to avoid any hazard for the working staff in the plants.

20.5 VAC Control System Controls for the VAC system shall be digital with individual Application Specific Controllers (ASCs) for each zone. Avoid the use of pneumatic control systems.

Design the system to permit verification of cooling demand of the VAC system and provide all necessary field instrumentation.

20.5.1 VAC Master Control

The cooling requirements for each zone shall be achieved by a dedicated control unit linked to the master control system. However, the zone control unit must be capable of being over-ridden manually from the VAC master control system.

20.6 Verification of VAC System Consultants should request from the contractor that they provide all as-built drawings, Operation and Maintenance manuals for review and approval upon completion of project. They also have to emphasise shop drawing’s review for mechanical equipment and materials prior to purchase by contractors.

20.7 Location of air intakes The Consultants must consider the source and direction of the upwind to allow for adequate positioning of air intakes for the VAC system. As a general rule, the prevailing wind in Trinidad & Tobago is from the North East.

Water And Sewerage Authority (WASA) Water and Wastewater Design Guideline Manual Diesel Generator Standard

21-1 October 2008R1

Section 21 Diesel Generator Standard

21.1 General This section covers the requirements for the design and installation of diesel generators and all related ancillary equipment.

21.2 Power Supply Where possible, all plants shall be provided with two feeds from local utility power supply grid network. Where this requirement can be met, the provision of standby diesel generators may not be required.

Comply with Section 4.4 Standby Power, for the installation of diesel generator in the facility.

Where required by WASA, the Consultants shall specify the required synchronizing equipment to permit the generator to synchronize with local power supply grid for peak shaving.

Power ratings for standby power are defined by ISO 8528-1 as the power available in the event of a main power network failure up to a maximum of 500 hours per year of which up to 300 hours may be run continuously. Load factor may be up to 100% of standby power. No overload is permitted.

21.3 Approvals The Consultants are responsible for securing of all required approvals including the EMA and WASA and/or any other such regulations or Acts etc, that are in force at the time of award of the engineering assignment.

Determine the output capacity of the generator in accordance with the facility backup power requirements.

Prepare, submit and obtain approval for noise attenuation requirements for the proposed emergency diesel generator and emissions.

21.4 Noise Attenuation Arrange for a qualified Acoustics Engineer to prepare a noise attenuation report. Noise level shall be site specific and provide adequate protection to operators. Consult Trinidad & Tobago regulations such as the OSHA Act and Noise Pollution Control Rule.

Water And Sewerage Authority (WASA) Project Design and Technical Specifications Manual Diesel Generator Standard

21-2 October 2008R1

21.5 Diesel Generator Power Requirements

21.5.1 Water Supply System

For potable water supply pumping stations, where the water distribution system floats on a storage reservoir, the diesel generator shall be sized to meet the pump(s) electrical power requirement for the average day demand.

Ensure that the generator is capable of meeting the inrush power demand under all operating conditions. Specify reduced voltage starting for electric motors. Sequence pumps are to come on-line one at a time when power fails and power supply is from the generator.

In a closed loop system where system storage is not available, the standby power shall be sized to meet the pumping system power requirements for maximum hour plus fire flow demand.

21.5.2 Wastewater Pumping Station

For wastewater pumping stations, the standby power generator requirements are identical to the water supply system requirements and it shall be sized to meet the pumping system power demand under peak flow conditions.

21.5.3 Ancillary Electrical and Mechanical Equipment

In addition to the above, provide electrical power from the diesel generator to the following during power outages:

1. ventilation system

2. SCADA system

3. Chemical system (where applicable)

4. Blowers for aeration system (for wastewater treatment plant)

21.6 Diesel Generator System Operation The diesel generator is required to meet the power demand of the facility in the event of local power supply grid network power outages in order to maintain minimum operation services. The equipment that is to be maintained in service by the diesel generator will be reviewed and finalized at the Pre-Design stage.

An automatic transfer switch in compliance with UL 1008 standard, shall be included as part of the diesel generator power supply system. The automatic transfer switch senses power outage and:

• initiates start-up of the diesel generator;

• automatically transfers power supply to the emergency generator;

• on resumption of normal power supply, transfers load back to normal power supply;

• times the engine running without load and allows it to cool down and then shuts it off.


21-3 October 2008R1

21.7 Diesel Engine Requirements

21.7.1 General

1. The perspective of a bi-fuel engine must be assessed in the preliminary stage or as indicated by WASA.

1.2.The diesel engine net continuous power output at the engine flywheel, including de-rating and deductions, shall be equal to the generator net input power. The power rating should be rated for Standby power.

2.3.Diesel engine operating speed shall be 1800 revolution per minute, unless otherwise approved by WASA.

3.4.Engine shall be naturally aspirated or turbo charged, two or four stroke cycle with pressurized induction having a minimum of four cylinders and removable wet liner. It must be suitable for operation on commercial Grade No.2 diesel fuel oil.

4.5.Engine shall conform to EPA Tier 1-3 Emissions standards.

21.7.2 Flame Detection System

1. Dedicated infrared flame detector sensors shall be supplied and installed for each diesel generator and integrated into the fire alarm panel and monitored as individual alarm zones.

2. Infrared flame detector sensors shall also be monitored by the PLC and an alarm shall be sent to the plant Central Control Room.

21.7.3 Fuel System

1. Fuel system shall include injection equipment including fuel pump(s) and injectors with fuel rack or shutdown solenoid, energised to run (maximum fuel at start) and lift pump with the required minimum suction lift capability with check valves to maintain prime.

2. It shall be supplied with factory installed primary filter(s) and a secondary fuel filter/water separator. Fuel filter(s) shall be of the replaceable element type.

3. Fuel line piping shall be fully secured to the engine for the fuel supply, injector and bleed return. Provide flexible connectors, bronze corrugated type for the suction and return lines, located in a horizontal plane and secured at one end to the engine base.

4. Fuel line shall be provided with automatic shut-off system which may be initiated by the PLC following a signal.

21.7.4 Speed Governor

1. Diesel engine speed governors shall be mechanical or hydraulic type and shall be provided with micrometer screw type manual speed adjustment, shutdown lever and over speed stop.

2. Engine speed shall be maintained at plus or minus two (2) percent regulation, steady state, and at eight (8) percent speed regulation, transient peak no load to full load and full load to no load and at plus or minus one (1) percent stability at any constant load and free from further hunting or oscillation.



21-4 October 2008R1

3. The recovery time, from start of load to steady state condition, shall be better than three (3) seconds.

21.7.5 Fuel Tank

1. All diesel fuel tanks shall have a Vent to the exterior.

2. In addition to the integrated day tank, fuel tanks shall be provided and sized for 48 hours of continuous operation of the emergency standby diesel engine operating under full load.

3. Fuel tanks shall be of the double walled type and shall be floor mounted, with tapped connections for fill, vent, supply, return and drain. It shall be provided with a sight-glass for fuel level indication and condensate drain and cock.

4. Provide fuel level indicator(s) at the loading station. All required fuel line accessories shall be provided including manual shut-off valve and primary fuel filter, all with nipples required for connection.

21.7.6 Oil Lubricating System

Oil pumps must be engine driven gear type, with strainers and adjustable pressure relief valves, full pressure lubrication systems complete with oil filter(s) full flow element types and a sump drainpipe with gate valve and plug to extend 100 mm beyond bedplate.

21.7.7 Intake and Exhaust System

1. Air intake filter shall be of the dry replaceable element type located close to the inlet manifold.

2. Exhaust silencer shall be provided with condensate cock, plug and ASA flanges. Silencer capacity is to be sized so that the backpressure at the engine when loaded at 110% capacity, shall not exceed the manufacturer’s recommendation.

3. The noise emitted from the exhaust pipe shall not exceed the limits for the stationary engines, which requires that the noise at the property line shall not exceed 50 dbA in residential areas. This will dictate the type of silencer that will be required for the diesel engine.

21.7.8 Cooling System

1. Cooling of diesel engines by municipal water is not permitted under any circumstances and engines shall be cooled by a radiator complete with fan, shroud, fan guard and air duct adaptor flange.

21.7.9 Ventilation System

1. Ventilation systems shall be complete with fans; dampers etc to meet the required air volume for engine combustion and ventilation requirements.

2. Ventilation fans and dampers must be operating before the diesel engine is permitted to start.

3. Separate ventilation shall be provided for the room.


21-5 October 2008R1

21.7.10 Gauges

1. The following gauges shall be provided as a minimum:

.1 Lube oil pressure gauge

.2 Lube oil temperature gauge

.3 Coolant temperature gauge

.4 Electrical tachometer gauge, scaled in rpm to approximately 120 percent of rated speed

.5 Exhaust pyrometer(s)

21.7.11 Battery Start System

1. Diesel engines shall be started by an electrical cranking motor with power provided from storage batteries, which may either be 12 or 24 volts system.

2. Battery charger to be specified for 230 volts AC input. Locate charger outside the control panel.

21.7.12 Failure Annunciator

1. Annunciators shall be of individual visual type with long life lamp(s) removable from the panel front complete with manual alarm reset features and clearly labelled.

2. Relays shall be dry relay contacts with 230 V, 3 A minimum contacts. Relay shall be normally closed and to open under alarm conditions. Provide a common alarm relay for:

.1 Over-crank – nominal setting 20 seconds

.2 Overspeed – nominal setting 110 percent rated speed

.3 Low oil pressure – nominal delay 10 seconds

.4 High engine temperature

21.8 Generator Requirements

21.8.1 General

1. Generator shall be sized to meet the standby power loading requirements. Generator output supply shall be 400/230V, 3 phase 60 Hz, unless specified otherwise. It shall be horizontal synchronous type in protected enclosure with ground lug and readily accessible terminal box.

2. The generator revolving field shall be of amortisseur winding and have a brushless exciter connected directly to the generator shaft, with easily removal bolt-on diodes.

3. It shall be provided with Class H insulation or better.

4. It shall be provided with protective devices to sense generator overload condition and supply output contacts for SCADA and/or generator trip function.


21-6 October 2008R1

21.8.2 Voltage Regulator

1. Voltage regulator shall be an automatic, static type with ‘Fail-safe’ features, i.e. no excess voltage if the regulator fails when located on the engine control panel.

2. Control potentiometers arranged for clockwise rotation to increase the related function. Control rheostat or tapped choke, voltage range shall be plus or minus 2 percent of nominal volts.

3. It shall be capable of generator voltage build-up without batteries and protected against fault during under speed running.

21.9 Control System Refer to Section 17 – Instrumentation & Control and Section 18 – SCADA System for control system requirements.

Control panel shall have the following controls:

• manual Start/stop control switch

• Man-Auto-off Switch

• Battery condition monitor

• Current / voltage monitoring on all phases

• Frequency meter

• Rune time meter

• kWh meter

Alarms relays shall transmit the followings signals to the SCADA system:

• Start

• Stop

• Uncommanded stop

• Overload

• High temperature

• Overspeed

• Infrared flame detection

Water And Sewerage Authority (WASA) Water and Wastewater Design Guideline Manual Treatment Plant Operation Manual

22-1 October 2008R1

Section 22 Treatment Plant Operation Manual

22.1 General The Consultants shall prepare the structure and format of the Operation Manual for water and wastewater treatment plants as follows.

The Unit Operation Descriptor shall conform, as a minimum, to the included table of contents of the Manual. A Descriptor is a typical task to be performed for a Unit Operation. Depending on the Unit Operation, it may or may not require all of the Descriptor listed in a table of contents.

22.2 Operation Manual Requirements The Operation Manual shall be prepared in Microsoft WORD, version currently used by WASA, or as an online interactive document running under Microsoft Windows XP or VISTA. The Consultants shall ensure that the online text version, CD-ROM copy and the hard copy version must be identical. Date of issue of CD-ROM and hard copy must also be clearly identified.

22.3 Format of Operation Manual The Consultants are required to prepare and submit hard copies. In addition, submit two complete sets of CD-ROM of the Operation Manual when approved by the Project Manager.

The hard copy of the Operation Manual shall be bound in binders.

The spine of the binder shall be lettered with the full identification title of the project e.g.

[Name of Plant] WASTEWATER TREATMENT PLANT PROJECT No.

The front cover of the manual of the respective binders to be printed as follows:

POMORIE WASTEWATER TREATMENT PLANT PROJECT NO. OPERATION MANUAL VOLUME 1 CONSULTANT:

Water And Sewerage Authority (WASA) Project Design and Technical Specifications Manual Treatment Plant Operation Manual

22-2 October 2008R1

22.4 Water Treatment Plant Operation Manual The following is the Table of Contents for Water Treatment Plant Manual:

1. Table Of Contents 2. Introduction

2.1 Record of Revision 2.2 Title Page 2.3 Acknowledgement 2.4 Table of Contents

3. Operation Manual Overview

3.1 Technical Information 3.2 Operation Manual Organization

Section 1: Introduction Section 2: Operation Manual Overview Section 3: Plant Overview Section 4: Unit Operations Section 5: Design Parameters & Dimensions of Each Process Unit Section 6: Appendices

4. Plant Overview

4.1 General 4.2 Plant History 4.3 Utility Classification 4.4 Operator Classification 4.5 Distribution System Classification 4.6 Certificate of Approval and Design Brief 4.7 Water Quality 4.8 Public Relations 4.9 Plant Tours 4.10 Requests for Information/Literature 4.11 Complains 4.12 Vandalism/Theft 4.13 Spill/Pollution 4.14 Injuries

5. Detailed Unit Operations

5.1 SOURCE 10 Lake 20 River 30 Groundwater

5.2 RAW WATER HANDLING

10 Intake 20 Intake Pipe


22-3 October 2008R1

30 Screening 40 Low Lift Pumping 50 Pipeline

5.3 PARTICULATE REMOVAL

10 Microstraining 20 Flash Mixing 30 Flocculation 40 Clarification 50 Filtration including membrane ultra filtration or sand 60 Filter Backwash System 70 Sludge Handling

5.4 DISINFECTION

10 Pre-Chlorination 20 Post Chlorination

5.5 OTHER PROCESSES

10 Taste and Odour Control 20 pH Control 30 Fluoridation 40 Coagulation 50 Coagulation Aid 60 Dechlorination

5.6 STORAGE AND TRANSMISSION

10 Clearwell 20 Reservoir 30 High Lift Pumping 40 Elevated Tanks 50 Pumping Stations 60 Pressure Zones 70 Distribution System

5.7 COMMON UTILITIES

10 Heating, Ventilating, Air Conditioning 20 Plant Service Water 30 Plant Instrumentation/Air 40 Power Supply and Distribution 50 Emergency Standby Diesel Generator 60 Security/Alarm System 70 Communications 80 Supervisory Control and Data Acquisition 90 Laboratory


22-4 October 2008R1

6. Appendices 6.1 REFERENCE 6.2 CONVERSION TABLE 6.3 DIRECTORIES

Plant Personnel Treatment Plants Municipal Participants MOE Personnel Local Contractors Equipment Service Representatives Emergency Media

6.4 FORMS Index

6.5 GLOSSARY Acronyms and Abbreviations Water Treatment Chemicals General terms

7. List of Figures

8. Drawing Number/Section/Title

9. “As-Built” Contract Drawing Title

22.5 Wastewater Treatment Plant Operation Manual The following is the Table of Contents for Wastewater Treatment Plant Operation Manual:

1. Table Of Contents 2. Introduction

2.1 Record of Revision 2.2 Title Page 2.3 Acknowledgement 2.4 Table of Contents

3. Operation Manual Overview

3.1 Technical Information 3.2 Operation Manual Organization

Section 1: Introduction Section 2: Operation Manual Overview Section 3: Plant Overview Section 4: Unit Operations Section 5: Design Parameters & Dimensions of Each Process Unit Section 6: Appendices


22-5 October 2008R1

4. Plant Overview 4.1 General 4.2 Plant History 4.3 Utility Classification 4.4 Operator Classification 4.5 Wastewater Collection System 4.6 Certificate of Approval and Design Brief 4.7 Wastewater Effluent Quality 4.8 Public Relations 4.9 Plant Tours 4.10 Requests for Information/Literature 4.11 Complains 4.12 Vandalism/Theft 4.13 Spill/Pollution 4.14 Injuries

5. Detailed Unit Operations

5.1 WASTEWATER PUMPING STATIONS 10 Wastewater Pumping Stations 20 Odour Control

5.2 PRETREATMENT

10 Inlet 20 Fine Screening 30 Screenings Compactor 40 Grit Removal 50 Odour Control

5.3 PRIMARY CLARIFICATION

10 Primary Clarifier 20 Primary Sludge Pumping Facility 30 Primary Scum Pumping Facility 40 Odour Control

5.4 AERATION SYSTEM 10 Aeration Tank 20 Air Blower Equipment 30 Fine Bubble Diffuser System

40 Dissolved Oxygen Control 50 Odour Control

5.5 SECONDARY CLARIFICATION 10 Secondary Clarifier 20 Return Activated Sludge Pumping 30 Secondary Scum Pumping 40 Odour Control


22-6 October 2008R1

5.6 SLUDGE THICKENING/DEWATERING FACILITIES

10 Waste Activated Sludge 20 Digested Sludge 30 Thickening 40 Dewatering 50 Odour Control

5.7 INCINERATION 10 Preheating 20 Sludge Feed 30 Continuous Emissions Monitoring 40 Gas Scrubbing 50 Auxiliary Fuel System 60 Fluidized Bed (Air/Sand)

5.8 FLOW METERING FACILITIES 10 Metering Facilities

5.9 CHLORINATION FACILITIES

10 Chlorination Storage Facilities 20 Chlorine Contact Tank

5.10 CHEMICAL TREATMENT FACILITIES

10 Chemical Feed Systems 20 Chemical Storage Facilities

5.11 AEROBIC/ANAEROBIC DIGESTION FACILITIES 10 Aerobic/Anaerobic Digester 20 Sludge Handling Facilities 30 Odour Control

5.12 ULTRA-VIOLET DISINFECTION SYSTEM 10 Ultra-Violet Disinfection System 20 UV Lamp Cleaning System

5.13 VENTILATION & AC

10 Administration Facility 20 Pre-Treatment Facility 30 Wastewater Pumping Station 40 Blower Building 50 Sludge Dewatering Facility 60 Tertiary Treatment Facility 70 UV Disinfection Facility 80 Digester Gas Control Building


22-7 October 2008R1

5.14 SLUDGE LOADING/UNLOADING FACILITY 10 Digested Sludge Loading Facilities 20 Digested Sludge Pumping Facility 30 Digested Sludge Overflow Control & Cleanup

5.15 POWER SUPPLY AND DISTRIBUTION

10 Administration Facilities 20 Wastewater Pumping Station 30 Air Blower Building 40 Return Sludge Pumping Facility 50 Sludge Dewatering Facility 60 Emergency Standby Diesel Generator 70 UV Facilities

5.16 SAMPLING & MONITORING

10 Equipment 20 Raw/Activated Sludge Sampling 30 Digested Sludge Sampling 40 Flow Monitoring 50 Influent 60 Effluent 70 Dewatered/Thickened Sludge Sampling 80 Sludge blanket level monitoring 90 Dissolved Oxygen Monitoring

5.17 SAFETY & SECURITY

10 General 20 Sewers 30 Confined Spaces 40 Electrical Hazards 50 Mechanical Equipment Hazards 60 Explosion and Fire Hazards 70 Bacterial Infection Hazards 80 Chlorine Hazards 90 Ferrous/Ferric Chloride Hazards 100 UV Hazards 110 Safety Equipment 120 Process Chemical Handling & Storage 130 Facility Security 140 Emergency Response Program 150 References 160 WASA Compliance Manual

5.18 MAINTENANCE RECORDS

10 Process Operations and Daily Operating Reports 20 Monthly Reports


22-8 October 2008R1

30 Annual Reports

5.19 SUPERVISORY, CONTROL AND DATA ACQUISITION 10 Refer to SCADA Operation Manual

6. Appendices

6.1 REFERENCE 6.2 CONVERSION TABLE 6.3 DIRECTORIES

Plant Personnel Treatment Plants Municipal Participants WASA Personnel Local Contractors Equipment Service Representatives Emergency Media

6.4 FORMS Index

6.5 GLOSSARY Acronyms and Abbreviations Wastewater Treatment Chemicals General Terms

7. List Of Figures 8. Drawing Number/ Section/Title 9. “As-Built” Contract Drawing Title

22.6 Training on the Use of the Operation Manual The Consultants will be required to train the operators on the use of the Manual.

Prior to the project being closed out, the Consultants are required to:

1. Revise and bring the Manual completely up to date

2. Provide two copies of the Manual on a CD-ROM

3. Revise and bring the hard copies up to date


22-9 October 2008R1

22.7 Training of WASA Staff

22.7.1 Training Provided by the Contractor

Consultants shall integrate measures for providing training to WASA’s personnel/operators by skilled trainers retained by the General Contractor specifically for the purpose, in the proper operation and maintenance of the equipment and systems provided and installed under his contract.

The following information shall be submitted:

1. Lesson planned for each training session by the manufacturer’s representatives.

2. All training manuals, handouts, visual aids and other reference materials shall be provided to attendees.

3. Date, time, and subject of each training session and identity the qualifications of the individuals to be conducting the training.

4. Concurrent classes will not be allowed in training schedule.



Section 23 CARTOGRAPHIC CONCEPTS

CARTOGRAPHY Cartography is the art, science and technology of making maps, together with their study as scientific documents and works of art. It is also the process of designing compiling and producing maps.

Section 24 THE COMMUNICATION CHANNEL

As a Cartographer, CAD Designer or GIS Operator, you must be aware of the vital responsibility to communicate as clearly as possible, to produce a useful map.

The following channel of communication is noted: • From REALITY - (The Geographic Environment), a number of exercises can be done:

CENSUS; SURVEYS; REMOTE SENSING and COMPILATION. • Information received is recognized by the CARTOGRAPHER or GIS OPERATOR and a

series of steps follows that can be termed GENERALISATION. They are: SELECTION’ CLASSIFICATION; SIMPLIFICATION and SYMBOLIZATION.

• Producing a MAP that the MAP USER can do the following easily: READING; ANALYSIS and INTERPRETATION.

• Finally having THE MENTAL IMAGE OF REALITY by imagining what is supposed to be there.

24.1 OBJECTIVES & LIMITATIONS AFFECTING DESIGN

MAP CREATION (Objectives) • Convey geographic information. • Highlight important geographic relationships. • Illustrates analysis results. CARTOGRAPHIC DESIGN (Factors) • Objective: Determines the map’s final form. • Audience: Determines the map’s level of complexity. • Reality: Determines the authenticity of the portrayed facts. • Scale: Determines how much information can be placed on the map sheet. • Technical Limits: Determines the quality of what can really be produced using available

hardware and software. • Thematic Limits: Determines how far to reduce the number of thematic categories. • Locational



• Generalization: Determines, for the purpose of enhancing clarity, how far to move a feature from its original location, or how far to reduce the number of co-ordinates depicting a feature.

Section 25 SYMBOLOGY used in QUANTITATIVE and QUALITATIVE CARTOGRAPHY

a. Qualitative Symbology: Whatever symbols chosen should not show relative importance, unless its necessary to highlight one or more features, so that they stand out.

b. The SHAPE, COLOUR, TEXTURE and ORIENTATION / ARRANGEMENT of symbols are varied to show differences.

c. Quantitative Symbology: Data describing relative importance (e.g. more or less - and high verses low) and other numeric data showing numeric differences.

d. The SIZE, COLOUR, VALUE and INTENSITY of symbols are varied to show differences.

25.1 THE BASIC STEPS FOR MAP DESIGN

There are three basic steps in Map Design: 1. The initial Imagination / Visualization. 2. The Development of a Graphic Plan. 3. The Preparation of Specifications. Design HINTS to improve your maps. Remember: ... • Colours on the computer screen and on paper do not necessarily appear the same. • Not everyone has 20/20 vision. • Your taste may not represent that of the majority. • Consider the final production process. • Select useful symbol properties to suit the purpose. • The overall theme of the map must be known & seen at a glance.

25.1.1 GENERALIZATION Generalization is the process involving selection, classification, simplification, and finally symbolization. There are two types, like there are two (2) types of maps, THEMATIC and LOCATIONAL.

25.1.1.1 SYMBOLOGY - Classes of Symbols

There are four (4) basic symbol classes: 1. POINTS : To display point features at certain x,y locations. 2. LINES : To display linear features that are series of x,y locations. 3. AREAS : To display any two (2) dimensional areal extent bounded by a set of lines. 4. TEXT : To display descriptive information about features.



Section 26 THE GRAPHIC CHARACTERISTICS & INTERPRETATIONS

The graphic characteristics are as follows: • COLOUR : red, yellow, green, etc. • GRAYTONE/VALUE : how light or dark the colour is. • SIZE : how large or small the symbol is. • SHAPE : the symbol’s form (i.e. circular, triangular etc.) • TEXTURE : The spacing of the component marks within the symbol. • ORIENTATION : the direction of arrangement of elongated symbols or the direction of

components within the symbol. • PLACEMENT : the location of the map components within the visual field. 26.1.1.1 PERCEPTION OF GRAPHIC VISUALS

It is said that the human brain perceives a graphic image in a series of consecutive, organized steps. 1. The image or graphic visual is taken in. 2. The eye isolates more important visual elements. 3. Followed by the visual elements of lesser importance.

26.1.1.2 EYE LIMITATION

The human eye cannot distinguish between more than twelve (12) colours at one time. It cannot distinguish more than seven or eight different shades of the same colour in a single view.

26.1.1.3 TEXTURE VIBRATION

A symbol component that occupies 50% of a given space creates a visually unpleasant effect.

Section 27

Section 28 CARTOGRAPHIC DESIGN ISSUES

28.1 CLARITY & LEGIBILITY

ls used in cartography must be clear and legible. They must be precisely and correctly delineated. They must be large enough so that they can be easily read at the viewer’s distance from the map.

28.1.1.1 VISUAL CONTRAST

This is the most important element in Cartography Design. By this, it is possible to identify the different symbols used in a map.



28.1.1.2 PATTERNS

This is the systematic repetition of a mark within an area. VISUAL BALANCE Deals with laying out the map’s basic shapes in such a way, that the selected shapes appear to be in balance throughout the entire map.

VISUAL HIERARCHY This can be created by varying the graphic characteristics.

COLOUR Colour gives the Cartographer an additional, powerful, array of tools to work with in designing effective graphic images. It has become essential in many situations.

TEXT Like “Visual Contrast”, TEXT is a critical element in Cartographic Design. It conveys critical information to the map-reader. The following text characteristics must be adhered to:

• Typeface and font. • Size and scale. • Spacing. • Colour. • Contrast to background.

Section 29 PLANNING A MAP’S DESIGN & LAYOUT

In planning a design and layout the following topics must be kept in mind: • The Graphic Outline : This is the ‘key’ initial step. • The Geographic Features : This comprise features from coverage (multiple or portions of)

from your database. This is referred to as “Map Body”.

• Other Map Objects : These are objects that assist in interpreting the geographic information.

e.g. Title, Legend, North Arrow, Scale Bar, Neat lines, Source Information and Descriptive Text.

29.1

29.2

CARTOGRAPHIC PRODUCTION STANDARDS Introduction The GIS Section produces several different types of maps and as such the need to have standard formats to plot them is important. The following are currently used as standardize:



..1.1.1 LINE FEATURES

THEME TYPE THICKNESS COLOUR LABEL TEXT COLOUR FONT SIZE

RIVERS ALL 0.01 to 2.0 BLUE BLUE ARIAL 3.5 to 7.0ROADS MAIN 0.01 to 2.0 GRAY 80% 50% GRAY ARIAL 3.5 to 7.0ROADS ALL OTHERS 0.01 to 2.0 GRAY 50% 40% GRAY ARIAL 3.5 to 7.0WATER MAINS ALL 0.01 to 2.0 RED RED 3.5 to 7.0SEWER MAINS ALL 0.01 to 2.0 GREEN GREEN 3.5 to 7.0COAST 0.01 to 2.0 BLACK BOARDERS MAP AREA 0.25 to 5.0 BLACK LAYOUT 0.25 to 3.0 BLACK POINT FEATURES

FEATURE TYPE SIZE COLOUR SYMBOL

FILE/SYMBOL LIBRARY

BUILDINGS 2-40 GRAY

80%-30% SQUARE 1 ESRI APPURTENANCES LEGEND 1. AVL

MAN HOLE SEWER 5-10 BLACK MANHOLE WATER/WASTE

WATER

GUAGE RAINFALL 10-40 BLUE WATER

ENVIRONMENTAL

STREAM 10- BLUE CIRCLE 18 ESRI



20

WELLS OBSERVAT

IONS 5-40 GREEN

WELL DRILLED INDUS. VTILITIES

PRODUCTION 5-40 BLUE

WELL DRILLED INDUS. VTILITIES

SPRING 5-20 RED CIRCLE 21 ESRI INTAKE 5-20 GREEN TRIANGLE 7 ESRI

STORAGE TANK 10-40 BLUE

ENCLOSED STORAGE

WATER/WASTE WATER

WATER TREATMENT

PLANT 10-30 BLACK

TREATMENT PLANT

WATER/WASTEWATER

BOOSTER STATIONS

10-30 BLACK

PUMP STATION

WATER/WASTEWATER

SEWER TREATMENT

PLANT 10-30 GREEN STEP TRANS UTILITIES

SEWER PUMPING-STATION

10-30 BLACK LIFT STATION

WATER/WASTEWATER

POLYGON FEATURES

THEME Section 30 TYPE/NAME OUTLINE WIDTH

FILL COLOUR

LABEL TEXT

COLOUR FONT SIZE

BUILDINGS PRESIDENTIAL 0-1 SODALITE BLUE

COMMERCIAL 0-1 LIGHT APPLE PUBLIC 0-1 DARK AMBER GOVERNMENT 0-1 HELIOTROPE

POLICE STATION 0-1 CRETEAN BLUE

POST OFFICE 0-1 FIR GREEN FIRE STATION 0-1 MARS RED



T&TEC 0-1 SOLAR YELLOW

TSTT 0-1 PEONY PINK

SCHOOL 0-1 SAHARA SAND

RELIGIOUS 0-1 OLIVENITE GREEN

HOSPITALS/HEALTH C 0-1 SEVILLE ORANGE

INDUSTRIAL 0-1 60% GRAY

COUNTIES ST GEORGE 0.5 to 5 ROSE QUARTZ BLACK

ARIAL-BLACK 5-50

ST DAVID 0.5 to 5 LIGHT APPLE BLACK ARIAL-BLACK 5-50

ST ANDREW 0.5 to 5 30% GRAY BLACK ARIAL-BLACK 5-50

CARONI 0.5 to 5 SODALITE BLUE BLACK

ARIAL-BLACK 5-50

NARIVA 0.5 to 5 RHODOLITE ROSE BLACK

ARIAL-BLACK 5-50

VICTORIA 0.5 to 5 YUCCA YELLOW BLACK

ARIAL-BLACK 5-50

ST PATRICK 0.5 to 5 BERYL GREEN BLACK

ARIAL-BLACK 5-50

MAYARO 0.5 to 5 SUGILITE SKY BLACK ARIAL-BLACK 5-50

THEME TYPE/NAME OUTLINE WIDTH

Section 31 FILL COLOURLABEL TEXT

RED GREEN BLACK COLOUR FONT SIZE WARDS Erin 0.25 to 3.0 190 232 255 Black Arial Black 3-30 Toco 0.25 to 3.0 211 255 190 Black Arial Black 3-30 Blanchisseuse 0.25 to 3.0 178 178 178 Black Arial Black 3-30 St.Anns 0.25 to 3.0 255 190 190 Black Arial Black 3-30 Valencia 0.25 to 3.0 211 255 190 Black Arial Black 3-30





RED GREEN BLACK COLOUR FONT SIZE Diego Martin 0.25 to 3.0 255 255 190 Black Arial Black 3-30 Matura 0.25 to 3.0 255 190 232 Black Arial Black 3-30 Tacarigua 0.25 to 3.0 190 210 256 Black Arial Black 3-30 Arima 0.25 to 3.0 233 255 190 Black Arial Black 3-30 POS 0.25 to 3.0 232 190 255 Black Arial Black 3-30 Moruga 0.25 to 3.0 255 235 190 Black Arial Black 3-30 Manzanilla 0.25 to 3.0 190 255 232 Black Arial Black 3-30 Cunupia 0.25 to 3.0 156 156 156 Black Arial Black 3-30 Tamana 0.25 to 3.0 255 127 127 Black Arial Black 3-30 Cedros 0.25 to 3.0 255 255 115 Black Arial Black 3-30 Turure 0.25 to 3.0 115 255 223 Black Arial Black 3-30 San Rafael 0.25 to 3.0 223 115 255 Black Arial Black 3-30 Chaguanas 0.25 to 3.0 178 178 178 Black Arial Black 3-30 Couva 0.25 to 3.0 255 167 127 Black Arial Black 3-30 Montserrat 0.25 to 3.0 209 255 115 Black Arial Black 3-30 Charuma 0.25 to 3.0 115 223 255 Black Arial Black 3-30 Cocal 0.25 to 3.0 255 115 223 Black Arial Black 3-30 Point-A-Pierre 0.25 to 3.0 190 232 255 Black Arial Black 3-30 Guayaguayare 0.25 to 3.0 104 104 104 Black Arial Black 3-30 Savana Grande 0.25 to 3.0 211 255 190 Black Arial Black 3-30 Ontoire 0.25 to 3.0 255 255 190 Black Arial Black 3-30 Naparima 0.25 to 3.0 255 190 232 Black Arial Black 3-30 San Fernando 0.25 to 3.0 190 210 255 Black Arial Black 3-30 Trincity 0.25 to 3.0 233 255 190 Black Arial Black 3-30 La Brea 0.25 to 3.0 232 190 255 Black Arial Black 3-30 Siparia 0.25 to 3.0 255 235 190 Black Arial Black 3-30 DISTRICTS North East 0.5 to 50 190 232 255 Black Arial Black 5-50 North West 0.5 to 50 210 255 190 Black Arial Black 5-50 North Central 0.5 to 50 178 178 178 Black Arial Black 5-50 Port-of Spain 0.5 to 50 255 190 190 Black Arial Black 5-50

San Fernando/Central 0.5 to 50 211 255 190 Black Arial Black 5-50

South East 0.5 to 50 255 255 190 Black Arial Black 5-50 South West 0.5 to 50 255 190 232 Black Arial Black 5-50





RED GREEN BLACK COLOUR FONT SIZE HYDROLOGICAL North Coast 0.5 to 50 190 232 255 Black Arial Black 5-50 North Oropouche 0.5 to 50 210 255 190 Black Arial Black 5-50 West 0.5 to 50 178 178 178 Black Arial Black 5-50 Peninsula/Caroni 0.5 to 50 255 190 190 Black Arial Black 5-50 Nariva 0.5 to 50 211 255 190 Black Arial Black 5-50 Central/West Coast 0.5 to 50 255 255 190 Black Arial Black 5-50 Ortorie 0.5 to 50 255 190 232 Black Arial Black 5-50 Southern Range 0.5 to 50 190 210 255 Black Arial Black 5-50 South Oropuche 0.5 to 50 233 255 190 Black Arial Black 5-50 Cedros Peninsula 0.5 to 50 232 190 255 Black Arial Black 5-50 DISTRIBUTION Toco 0.25 to 2.0 190 232 255 Black Arial Black 2-20

San Juan-Santa Cruz 0.25 to 2.0 211 255 190 Black Arial Black 2-20

D'abadie (Arouca) 0.25 to 2.0 178 178 178 Black Arial Black 2-20

Tacarigua (Tunapuna) 0.25 to 2.0 255 190 190 Black Arial Black 2-20

Ariam (North) 0.25 to 2.0 211 255 190 Black Arial Black 2-20 Ariam (South) 0.25 to 2.0 255 255 190 Black Arial Black 2-20

Diego Martin (North) 0.25 to 2.0 255 190 232 Black Arial Black 2-20

Diego Martin (South) 0.25 to 2.0 190 210 256 Black Arial Black 2-20

Barataria/Laventille 0.25 to 2.0 233 255 190 Black Arial Black 2-20 Sangre Grande 0.25 to 2.0 232 190 255 Black Arial Black 2-20 Caroni 0.25 to 2.0 255 235 190 Black Arial Black 2-20 Central North 0.25 to 2.0 190 255 232 Black Arial Black 2-20 Central South 0.25 to 2.0 156 156 156 Black Arial Black 2-20 POS 1&2 0.25 to 2.0 255 127 127 Black Arial Black 2-20 Mayaro 0.25 to 2.0 255 255 115 Black Arial Black 2-20 N/Grant-R/Claro 0.25 to 2.0 115 255 223 Black Arial Black 2-20 P/Town- Moruga 0.25 to 2.0 223 115 255 Black Arial Black 2-20 San Fernando/PAP 0.25 to 2.0 178 178 178 Black Arial Black 2-20 Naparima 0.25 to 2.0 255 167 127 Black Arial Black 2-20





RED GREEN BLACK COLOUR FONT SIZE La Brea/Fyzabad 0.25 to 2.0 209 255 115 Black Arial Black 2-20 Debe/Erin 0.25 to 2.0 115 223 255 Black Arial Black 2-20 Pt. Fortin/Cedros 0.25 to 2.0 255 115 223 Black Arial Black 2-20 Blanchisseuse 0.25 to 2.0 190 232 255 Black Arial Black 2-20 St.Joseph 0.25 to 2.0 104 104 104 Black Arial Black 2-20 BILLING Pt.Fortin/Cedros 0.25 to 2.0 190 232 255 Black Arial Black 2-20 Toco 0.25 to 2.0 211 255 190 Black Arial Black 2-20 Blanchisseuse 0.25 to 2.0 178 178 178 Black Arial Black 2-20 S/Juan-Laventille 0.25 to 2.0 255 190 190 Black Arial Black 2-20 Sangre Grande 0.25 to 2.0 211 255 190 Black Arial Black 2-20 Dibe/Maraval 0.25 to 2.0 255 255 190 Black Arial Black 2-20 Carenage-D/Martin 0.25 to 2.0 255 190 232 Black Arial Black 2-20 Santa Cruz 0.25 to 2.0 190 210 256 Black Arial Black 2-20 D'abadie/Tacarigua 0.25 to 2.0 233 255 190 Black Arial Black 2-20 O'mera/Malabar 0.25 to 2.0 232 190 255 Black Arial Black 2-20 POS 0.25 to 2.0 255 235 190 Black Arial Black 2-20 Arima 0.25 to 2.0 190 255 232 Black Arial Black 2-20 Maturita 0.25 to 2.0 156 156 156 Black Arial Black 2-20 Central North 0.25 to 2.0 255 127 127 Black Arial Black 2-20 Central South 0.25 to 2.0 255 255 115 Black Arial Black 2-20 Caroni 0.25 to 2.0 115 255 223 Black Arial Black 2-20 Cumuto 0.25 to 2.0 223 115 255 Black Arial Black 2-20 Rio Claro 0.25 to 2.0 178 178 178 Black Arial Black 2-20 Biche 0.25 to 2.0 255 167 127 Black Arial Black 2-20 Princess Town 0.25 to 2.0 209 255 115 Black Arial Black 2-20 Naparima 0.25 to 2.0 115 223 255 Black Arial Black 2-20 Mayaro 0.25 to 2.0 255 115 223 Black Arial Black 2-20 San Fernando 0.25 to 2.0 190 232 255 Black Arial Black 2-20 La Brea/ Pt.Fortin 0.25 to 2.0 104 104 104 Black Arial Black 2-20 Penal/Erin 0.25 to 2.0 211 255 190 Black Arial Black 2-20 Moruga 0.25 to 2.0 255 255 190 Black Arial Black 2-20 Cedros 0.25 to 2.0 255 190 232 Black Arial Black 2-20



Each Layout should display:

1. Cardinal Points (must North, South, East and West 2. Scale Bar: Double Alternating 3. Scale Text: Optional 4. WASA logo: Symbol Code- 0=Blank, 1=Black, colour = 5 (0, 168, 135) (RBG) 5. Title: Rockwell Extra Bold (18pts – 200pts) 6. Reference Grid 7. Map Data:

a. Grid: UTM ZoneN, Datum: Naparima 1955, Projection: Transverse Mercator, Units of Measurement: Metre, Spheroid: International

b. Grid: Tobago, Projection: Cassini, Unit of Measurement: Metre, Spheroid: Clarke 1858

c. Grid: UTM Zone 20N, Datum: WGS 84, Projection Transverse Mercator, Units of Measurement: Metre

8. Legend: Title Arial, (0.5pts – 100pts), Labels Arial (0.5pts – 80pts) 9. Legend order: points, line, polygon, text 10. Sea Label: Times New Roman 11. Map must also show the following information usually placed under the Company Logo:

WATER AND SEWERAGE AUTHORITY

Section 32 Systems optimization GIS Section

File Path (Net Id, Location on PC, file extension) Date (date/month in text/year)

32.1 CADE STANDARDS

The Water And Sewerage Authority, Systems Optimization Department, CAD/E Section produces various types of drawings that are categorized as ‘Design’ and ‘As-Built’ drawings: Civil, Mechanical, Electrical, Architectural and Survey Works.

32.2

..1.1 Types of Drawings Design (Proposed) and As-Built Drawings for:

• Civil Engineering Works Water and Sewer Pipeline Systems, Bridges, roads section and details, dams, intakes etc

• Mechanical Engineering Works Vat and Flange details, pumps, steel supports, piping arrangements, layouts and details Value

chamber details. Thrust blocks, Pressure indicator, Jim Pole detail, Plinth detail, spool piece etc.

• Electrical Engineering Works



Schematic and block diagrams, schedules, floor plans, electrical site plans, motors, instrument panel detail arrangement, panel assembly, panel support details etc.

• Architectural and Structural Works • Elevations, floor plans, foundation plans and details, roof plans and details, section or

buildings, fence post and hinge details etc. • Land and Engineering Surveying

Profiles, Cadastral, Traverses, Site Plans, Location Plans, Vicinity Plans etc

32.3 Miscellaneous Drawings

All drawings that are not categorized with the types mentioned above are considered miscellaneous drawings. Examples are: Organizational Structural Charts, Sketches, Schematic Drawings and Diagrams, Signs, Report Covers etc.

32.4 STANDARDS

For any organization to function efficiently, it must be guided by appropriate standards. This document contains information on the various components of drawing production that is currently used by the Systems Optimization Department. Updates to this document will be made only with the approval of the Manager, Systems Optimization Department. Quality Production of Drawing

• All drawings must have a ‘Titled Border’ and unless specified otherwise, use the appropriate standard ‘Title Blocks’ (Borders) available.

• Show the Drawing’s Title in the space provided in the Title Block of the standard border. It must say specifically what the drawing is representing.

• Yellow should be used at a minimum, if it must be used in drawings. Black should be the predominant colour in the entire drawing. Center lines and dimensions lines in their standard colours.

• Ensure all words are spelt correctly. Design (Proposed) and As-built Drawings These drawings should consist of the following:

• Ground (alignment) and street names • Existing and Proposed mains and sizes • Appurtenances • Detail of interconnection • Street name, North sign, mains and sizes must be included in each viewport • Viewport scale 1/500 • Location/ File Path in Title Block • As-built sheet (see sample page 6)

CAD File Specifications



Layers

32.4.1 LAYERS

32.4.2

32.4.3

USE (In order of pen weight from light to dark)

groundplan Black Continuous Light Lines

waterwa Blue Continuous Dark Lines

Detail Circle Cyan Continuous Light Lines

Matchline Red Dashdot Dark Lines Text Black

Chainage Red Continuous Light Lines

Text Styles

32.4.4 TEXT NAME

32.4.5 TEXT STYLE

32.4.6 USE

1 Simplex Narrow Generally used for labelling of Chainage

2 RomanD 32.5 Narrow For general text headings Road Name E.g. COCONUT DRIVE.

3 Txt.shx Arial Narrow or Bold

Generally used for Size Main NEW 100mm PVC main



Section 33

As-Built Sample Template

33.1.1.1 Civil Engineering Works

Already setup with Land Development Desktop software. Colour, Linetype etc. Survey Drawings Layers



Land and Engineering Surveying Cadastral (Surveys Drawing) A Cadastral Drawing shows the location, identification and legal description of the, access, appurtenances, encumbrances, improvements or other conditions that may affect a property for the title company. The quantification of appurtenances, encumbrances and total areas of the property required by the appraisers to assist in validating the purchase price and the inventory of parcels and the identification/perpetuation of lines and corners of the property for land management purposes. Use Standard cadastral Sheet • Buildings to be hatch in gray • North Arrow in Cyan at the Top Right of the Viewport

33.1.2 LAYERS 33.1.3 COLOUR

33.1.4 LINE TYPE

USE (in order of pen weight from 0.00-2.11)

Road Outline BLACK Continuous 0.00 Major Contours GREEN Continuous 0.00 Minor Contours GREY Continuous 0.00 Stations BLACK Circle 0.00 Iron put/Iron Found RED Circle 0.00 Wire Fence GREEN Dashed X 0.20 Trees BLACK Continuous 0.00 Text BLACK Continuous 0.00 Electricity Pole BLACK Circle 0.00 Telephone Pole BLACK Circle 0.00 Retaining Wall BLACK Dashed-Dot 0.00 Colour of Road BROWN

(255,214,160) Continuous 0.00

Colour of Parcel PINK (255,219,237)

Continuous 0.00

Colour of Drain Reserve, River and the Sea

BLUE (210’226,240)

Continuous 0.00

Houses Black Continuous 0.00 Earthen Drain BLACK Arrow 0.00



Text Styles

33.1.5 TEXT NAME

33.1.6 TEXT STYLE

33.1.7 USE

1 Simplex Regular Bearings, Distances, Ir. put, Ir. Fd.

2 Arial black 33.2 Regular

Road Name, Neighbors

Drawing Scales 33.2.2 33.2.3 C

IRCLE

(Ir. Put/Ir. Put)

33.2.4 TEXT HEIGHT

33.2.5 NEIGHBOUR

(Adjoining Parcels)

1 1/500 0.4 0.75 1.0 2 1/750 0.6 1.13 1.5 3 1/1000 0.8 1.5 2.0



4 1/1250 33.3 1.0 1.88 2.5

5 1/1500 1.2 2.25 3.0 6 1/2000 1.6 3.0 4.0 7 1/2500 2.0 3.75 5.0 7 1/2500 2.0 3.75 5.0

Architectural and Structural Works These drawings should consist of the following: • Elevations • Floor Plans • Foundation Plan & Beam and Column Details • Roof Plan & Details • Sections of Building • Fence Post & Details • Site Plan/Location • Drainage Details • Standard Drawing Block/Sheet (see Page 12) CAD File Specifications Layers


33.3.3 LINE TYPE

USE (in order of pen weight from light to dark)

Hatch, Plants, Tiles, etc. COLOUR 9 Continuous Light Lines Centre Lines/Section Lines, Grid lines, Hidden Detail Lines, Stairs, Dimension, Roof Sheeting, RC Columns, Roof Outline etc.

COLOUR 8 Centre, Dashdot, Hidden, Continuous

Light Lines

Fixtures BROWN 30 Continuous Medium Lines Windows, Railing, Roof CYAN Continuous Medium Lines Walls, Details, Foundation

MAGENTA Continuous Medium Lines

Doors BROWN 41 Continuous Medium Lines Electrical, Rafters RED Continuous Medium Lines



Ring Beam, Reinforcement

BLUE Continuous Dark Lines

All Text WHITE Continuous Dark Lines DIMENSIONS CYAN Continuous Dark Lines

Text Styles

33.3.4 TEXT NAME

33.3.5 TEXT STYLE

33.3.6 USE

1 Simplex Narrow Generally used for labelling of building fixtures. E.g. WC, FB, SH etc.

2 Romantic 33.4 Narrow

For general text headings i.e. room names, room numbers, etc. E.g. MASTER BEDROOM, etc.

3 Arial Arial Narrow or Bold

Generally used for dimensions and drawing names E.g. FLOOR PLAN, etc.



Architectural and Structural Works Sample Template

33.4.2 Electrical Engineering Works • Text and Dim Line in Blue. • Text Roman Simplex. Oblique 15. Height 1.75mm or 2mm • Sub-title, Roman Duplex; Height 2.5mm or 3mm • Lines are Color-Coded

R Red



Y Yellow B Blue N Green

• Rest of line work in Black/White • Symbol in Blue. Symbols are to be created in accordance to the nature of the drawings and must be specified in a menu box which must be usable at all times. CAD File Specifications Layers

33.4.3 LAYERS

33.4.4 COLOUR

33.4.5 LINE TYPE

33.4.6 LINE SIZES

Ground wire Green Continuous Set as Default Positive wire Red Continuous Set as Default Negative wire Black Continuous Set as Default Positive wire Yellow Continuous Set as Default

Text Styles

33.4.7 TEXT NAME

33.4.8 TEXT STYLE

33.4.9 TEXT SIZE

33.4.10 USE

1 Simplex Narrow 5mm Generally used for labelling of streets and street names.

2 Romantic 33.5 Narrow 33.6 6 Headings and labeling of all drawings.



mm


3 mm Appurtenance

33.7 Schematics

The drawings should comply with the following: • The Schematic diagram block sheet must be used for all Schematic drawings. • All data required on the sheet must be entered. • All symbols used in the Schematic diagram must be from the block symbols set for

Schematic diagram only, unless otherwise stated. • All symbols used in the Schematic diagram must be included as part of the Symbol Key in

the sheet. • Street names should be indicated in blue using text style Romans.shx, for example,

WARREN STREET. • The height of the street name in the view port should be between 2.5 – 3 mm. • The main size and the type of main are to be labeled in red using Romans.shx. for example,

100 PVC. • All existing mains to be indicated in black/white continuous lines. • All proposed Appurtenances, Mains etc are to be indicated in green. • Whenever the Schematic diagram is modified, the revised date must be entered on the

Schematic sheet. CAD File Specifications Layers




33.7.3 LINE TYPE

USE (in order of pen weight from light to dark)

Street name Blue Continuous Medium Lines Appurtenances Red Continuous Medium Lines Proposed Appurtenances Green Continuous Medium Lines Size Red Continuous Light Lines Existing main Black Continuous Dark Lines Proposed mains Green Continuous Dark Lines Proposed mains size Green Continuous Light Lines

Schematic Sample Template

..1.1 Sketches These drawings are not drawn to scale, they are consistently used to specify areas in which work is to be done or in drafting terms (Proposed work to be done). These drawings are not to be used for accurate measurement; they are only for proposals. Drawing standards that have been set are to be met at all times to ensure proper quality control is maintained and kept.



CAD File Specifications Layers

33.7.4 LAYERS

33.7.5 COLOUR

33.7.6 LINE TYPE

33.7.7 LINE SIZES

Roadway Black Continuous Default Pipelines Blue Polylines 1.3mm Appurtenances Red Continuous Default

Text Styles

33.7.8 TEXT NAME

33.7.9 TEXT STYLE

33.7.10 TEXT SIZE

33.7.11 USE

1 Simplex Narrow 5mm Generally used for labelling of streets and street names.

2 Romantic 33.8 Narrow 33.9 65 mm

Headings and labeling of all drawings.


3 mm Appurtenance



Section 34 Symbology

The following standards are used when producing surveying type drawings WATER SYMBOLS - SCALE 1: 500



BLOCK NAME

BLOCK ALIAS

BLOCK DESCRIPTION

DEFAULT SCALE

FACTOR

ASSOCIATED LAYER COLOUR

MAP 3 SP Stand Pipe 1.5 W-SYM RED 1 FIREH FH Fire Hydrant 1.5 W-SYM RED 1

VALVE 1 SV Gate Valve 1.8 W-SYM RED 1 VALVE 2 V2 Gate Valve 1.8 W-SYM RED 1 AVALVE AV Air Valve 1.2 W-SYM RED 1 WVALVE WO Washout Valve 2.5 W-SYM RED 1

RED R Reducer 1.8 W-SYM RED 1 RVALVE RV Reflux Valve 1.8 W-SYM RED 1

PVALVE PRV Pressure Reducing Valve 1.8 W-SYM RED 1

BVALVE BV Butterfly Valve 1.6 W-SYM RED 1 METER M Meter 1.5 W-SYM RED 1 PUMP PRV Pump Set 2 W-SYM RED 1 PDN PD Pipe Down 1 W-SYM RED 1 PUP PU Pipe Up 1 W-SYM RED 1

SMH SMH Sewer Main Hole 1 S-SYM GREEN 3



SURVEYING/MAPPING LINE TYPES - SCALE - 1:500 UTILITY SERVICE LINE TYPES- SCALE - 1:500

LINE SYMBOL

LINE TYPE

LINE DESCRIPTI

ON ASSOCIATED LAYER

BLOCK INSERTI

ON SPACING

THICK-

NESSCOLO

UR COLOUR CODE

Continuous

Polyline

Water Main (Proposed/AS-

Built) PW-LIN 0.5 Blue 5

Dashed Polyline

Water Main Existing AW-LIN 0.5 Blue 5

Continuous

Polyine

Sewer Main (Proposed/AS-

Built) PS-LIN 0.5 Brown 9

Dashed Polyline

Sewer Main (Existing) XS-LINE 0.3 Brown 9

Border

Polyline Electricity

Cable E-LIN 0 Yellow 2

Phantom Polyline

Telephone Cable T-LIN 0

Magenta A 6

LINE SYMBOL

Section 35 LINE TYPE

LINE DESCRIPTION

ASSOCIATED LAYER

BLOCK INSERTION SPACING

THICK-NESS COLOUR COLOUR

CODE

Converted Dashed Polyline Earthen Drain Drains 1 0 Cyan 4

Dimension Leader Kerb and Slipper Drain Drains 1 Cyan 4

Converted Dashed Polyline Cutting Ground 0 White 7

Converted Dashed Polyline Cliff Ground 0 White 7

Converted Dashed Polyline Wire Fence Property 0 White 7



Divide

Polyline Gas/Oil Line G-LIN 0 Red 1 SURVEYING/MAPPING SYMBOLS - SCALE - 1:500

BLOCK NAME

BLOCK ALIAS

BLOCK DESCRIPTIO

N

DEFAULT SCALE

FACTOR ASSOCIATE

D LAYER COLO

UR COLOUR

CODE Map 1

Map 2

S Survey Station 0.85 Control White 7

UP Utility Pole 0.9 Utility White 7 Map 4 4 White 7

Map 5 5 White 7

Map 6 6 White 7

Map 7 FP Fence Post 0.9 Property White 7

Map 8 White 7

Map 9 White 7

Sign SGN Sign 3.5 Ground White 7

TVS TVS Traverse Station Control White 7

TGS TGS Trig Station Control White 7

MM MM Mile Mark Control White 7

BM BM Bench Mark Control White 7

T1 Tree 4 Vegetation Green 3






SURVEYING/MAPPING ABBREVATION DICTIONARY

..1.1.1.1 ABBREVIATION MEANING

ABT ABUTMENT AVE AVENUE

b CORNER OF BUILDING

B BOTTOM BM BENCH MARK BEG BEGINNING BE BOTTOM EDGE BR BRIDGE

BDR BOX DRAIN BF BLOCK FENCE

BV BUTTERFLY

VALVE CI CAST IRON

CONC CONCRETE CL CENTRE LINE

CTR CENTRELINE OF

TRACE

CRD CENTRELINE OF

ROAD CP CONCRETE




PAVEMENT KRB KERB

KSDR KERB AND

SLIPPER DRAIN CULV CULVERT

DI DUCTILE IRON DRN DRAIN DW DRIVEWAY EOR EDGE OF ROAD EDG EDGE EDT EDGE OF TRACE EDR EARTHEN DRAIN

E EAST

EP ELECTRICITY

POLE FH FIRE HYDRANT GP GATE POST GS GROUND SHOT

h CORNER OF

HOUSE IDR INVERT DRAIN

I INVERT IR FD IRON FOUND IR PT IRON PUT JCT JUNCTION LP LAMP POST

SDR SLIPPER DRAIN L LEFT

MM MILE MARK mm MILLIMETER M METER N NORTH

PRV PRESSURE

REDUCING VALVE PS PUMP SET

PD PIPE

DOWNWARDS PR PIPELINE ROUTE PU PIPE UPWARDS




PVC POLY VINYL CHLORIDE

R RIGHT RW RETAINING WALL RED REDUCER RD ROAD RV REFLUX VALVE RIV RIVER

RCP REINFORCED

CONCRETE PIPE S SOUTH

STL STEEL SV SLUICE VALVE SP STAND PIPE

SPK FD SPIKE FOUND SPK DT SPIKE PUT

ST STREET STM STREAM SGN SIGN

SMH SEWER MAIN

HOLE T TOP

TBM TEMPORARY BENCH MARK

TP TELEPHONE POLE TR TRACE

T2, T5, .. TREE W WEST w WIDE

WO WASHOUT VALVE WF WIRE FENCE

VRG GRASS VERGE X CROSSING

INT INTERSECTION AV AIR VALVE PL PROPERTY LINE

SWK SIDEWALK SOF SOFFIT



PLUS EMHFIREHVALVE1AVALVEWVALVEREDRVALVEPVALVEBVALVEMETERPUMPPDNPUPSMHMAP1MAP2MAP7SIGNTRITGSCIRPLPRHOTREE1TREE2TREE3TREE4

GIS SURVEYS

TOPOGRAPHICAL SURVEY AND MAPPING SYMBOLS LIBRARY

SHEMHFHSVAVWORDRVPRVBVMPPDPUSMHSUPBPSGNTVSTGSKMBMT1T2T3T4

GRAPHICSYMBOL

BLOCK FILENAME

FIELD CODE

DEFAULT SCALEFACTOR

1:000 1:500ASSOCIATED

LAYERLAYER COLOURBLOCK DESCRIPTION

0.30000.00300.00300.00550.00350.00850.00550.00550.00550.00500.00450.00600.00230.00230.00200.00180.00200.00250.00700.45000.42000.38000.550.00900.00900.00950.0090

BLACKMAGENTAREDREDREDREDREDREDREDREDREDRED

RED

REDREDGREENGREENGREENGREEN

REDRED

TOPO-SPOTSELECT-MHW-SYMW-SYMW-SYMW-SYMW-SYMW-SYMW-SYMW-SYMW-SYMW-SYMW-SYM

S-SYMCONTROLUTILITYPROPERTYSIGNCONTROLCONTROLCONTROL

VEGETATIONVEGETATIONVEGETATIONVEGETATION

CONTROL

TOPO SPOTSELECTRICAL MANHOLEFIRE HYDRANTSLUICE VALVEAIR VALVEWASHOUT VALVEREDUCERRELUX VALVEPRESSURE REDUCING VALVEBUTTERFLY VALVEMETERPUMP SETPIPE END DOWN

SEWER MANHOLESURVEY STATIONUTILITY POLEBOUNDARY POSTSIGNTRAVERSE STATIONTRIG STATIONKILOMETER MARKBENCH MARKTREEPALM TREEMANGO TREETREE

PIPE END UP W-SYM REDRED



NAME PATTERNSYMBOL

LINEDESCRIPTION

GLELMLTVWFNONENONENONENONENONENONENONENONETLBF

COLOURLAYER

1(RED)23(GREEN)2207777141BLUE3040CYANMAGENTA7

G-LINE-LINM-LINCABLETVPROPERTYGROUNDGRONDDRAINS1DRAINS2XW-LINXS-LINHOUSESBUILDINGST-LINPROPERTY

LINETYPE

PATTERN LINEPATTERN LINEPATTERN LINEPATTERN LINEPATTERN LINECONTINOUSCONTINOUSCONTINOUSDASHEDDASHEDPHANTOM2CONTINOUSCONTINOUSPATTERN LINE PATTERN LINE

LINETYPE

GIS SURVEYS

TOPOGRAPHICAL SURVEY AND MAPPING SYMBOLS LIBRARY

GLELMLTVWFR1R2D1D2XWXSHBTLBL

GAS LINEELECTRICAL LINEMETHANOL LINECABLE TV LINE WIRE FENCEROAD EDGEROAD EDGECONC.DRAINEARTHEN DRAINEXIST. WATER LINEEXIST.SEWER LINEHOUSEBUILDINGTELEPHONE LINEBLOCK FENCE



The following are symbols used for Schematic Drawing



The following are symbols used for the Emergency Evacuation Drawing

1. Additional symbols may be needed for the Emergency Evacuation drawings symbol set.

2. The text style used for labeling the symbols is Stencil



35.2 10 Golden Draughting Rules

1. Never draw a line unless you understand what it represents. 2. A drawing should be laid out to allow clear interpretation of the data. 3. Sections/Elevations should be drawn as projections of the plan whenever possible; the plan

grid should line up with the elevation grids for easy reference. 4. Sections/details should all be lined up so that the floors can be easily identified and related. 5. Annotation should be kept to a minimum and always be orientated so that it reads from the

bottom or the right-hand side of the drawing. 6. Annotation should be as close to the information to which it relates, but clear of linework.

Note arrows (leaders) should never cross. 7. The use of abbreviations should be avoided unless space on the drawing dictates otherwise. 8. Always ensure that the drawing is independently checked and approved before issuing. 9. Symbols should be consistent on all drawings. 10. Certain standards notes should always be considered.

35.3

35.4 Standard Title Block Data Entry

The following are lists of instructions to be used when editing the title block information

35.5 Project Title

• Here the name of the project should be entered. • Note: Text should be all CAPS. • E.g. MARAVAL WATER TREATMENT BUILDING UPGRADE WORKS

35.6 Job Title

• Here the name of the drawing should be entered. • Note: Text should be all CAPS. • E.g. PROPOSED GROUND FLOOR LAYOUT



35.7 Sheet

• Here the sheet number is entered. If the project consists of more than one drawing the total amount of drawings should be indicated on each sheet.

• E.g. Sheet # 5 Of 13

35.8 Drafted By

• Here the drafting technician should enter his/her name. • E.g. F. Wellington

Note: If the drawing is modified, the drawing should be saved as another version. In the example the figure two indicates that the drawing has been updated.

• E.g. ARC-PRO-FPLAN-MARAVAL-MARAVALWATERTREATMENTPLANT-2

35.9 Designed By

• Here the designer of the proposed drawing should include his/her name. Checked By

• Here the drawing should be check and the person checking the drawing should indicate his/her name.

35.10 Approved By

• Here the person or body that is responsible for the works being done, should sign here indicating that the drawings has meet the required standards.

35.11 Scale

• The scale of the drawing on the present sheet should be indicated here. 35.12

35.13 File Path

• Here the location where the drawing could be found should be indicated by the use of a file path.

• E.g. GIS103/STAFF/ARCHITECTURAL/ ARC-PRO-FPLAN-MARAVAL-ARAVALWATERTREATMENTPLANT-2.DWG

35.14 FILE NAMING CONVENTION

Naming Convention was developed to enable anyone to identify the contents of a CAD file without actually opening the file. This is important so that anyone who is aware of the convention rules can easily identify files when necessary.



e naming rules developed were modeled after one used by the Connecticut Department of Transportation whose approach seemed to best fit our needs. A series of discussions were held with the major stakeholders (CAD/E and IT Staff) to determine the specific requirements of our CAD file name and the working model is described below.

re two major categories of file names; General and Block.

al Name neral Name would be applied to any drawing file used as a working drawing. These would fall into the categories of

Architectural, Mechanical, Electrical, Survey or Schematic, which are defined later.

ype/Sub-Type/Sub-Sub Type/Location/Location-Type(Facililty)/Version.dwg

FILE NAME

COMPONENT

DESCRIPTION

CAD Type General Grouping of CAD drawings

Sub-Type Division of the CAD type (adding more

specificity)

Sub-Sub Type Further division of the sub-type (adding

more specificity)

Location Geographic place of the drawing contents

e.g. Arima

Location-Type (Facility) Area office or other facility e.g. Booster

Version Checkpoint of currency of drawing

35.14.1 35.14.2 Block Name

The Block Name would be applied to any drawing used as a block or in a symbol library. A block is any collection of related, scalable, CAD Objects that can be used in many drawings of the same type.

Syntax: CAD Type/Blk/BlockName/User-DefinedIdentifier.dwg

FILE NAME

COMPONENT

DESCRIPTION

CAD Type General Grouping of Cad drawings



Blk Block

Block Name Name of the Block

User-Defined Identifier Identifier devised by user to define the

block contents

Section 36 The following diagrams illustrate the categories of CAD files (CAD Type) and their sub classifications (Sub-Type).

Section 37 Main CAD Types

• Architectural – any drawing related to a building • Schematic – line model of linear type network • Survey – drawing from field survey data • Engineering – design of networks or other infrastructure • Electrical – any drawing related to an electrical configuration that pertains to

mechanical, engineering and architectural works Key

CAD TYPE

SUB-TYPE

SUB SUB-TYPE



Section 38 ARCHITECTURAL

Architectural

Proposed

Existing

Plumbing

Electrical

Complete

Floor Plan

Elevation

Roof Plan

3-D

Structural

Location Plan

Site Plan

Plumbing

Electrical

Complete

Floor Plan

Elevation

Roof Plan

3-D

Structural

Location Plan

Site Plan



Section 39 SCHEMATIC

Schematic

Proposed

Existing



Section 40 SURVEY

Survey

Surveys

GPS



Section 41 ENGINEERING

Engineering

Network

Infrastructure

Mechanical

Waste Water

Water

Miscellaneous (Pipe Fitting)

Reservoir

Building

Booster Station

Pump & Vat Details

Pipe Arrangements

Appurtenance Details



Section 42 ELECTRICAL

Electrical

Existing

Schematic

Block

Schematic

Block

Wiring

Wiring

Proposed



• After some testing and research, it was agreed by all that in the case of the Location component of the file name, the whole place name would be used to avoid confusion.

• A list of common abbreviations was developed to help reduce the amount of typing. Both the CAD application and Operating System are able to handle the long names.

• It was assumed that this trend could be applied to present and future incarnations of the applications.

CADTYPE CODE LOCATION PRE FIX/SUB FIX CODE

ARCHITECTURAL ARC AVENUE AVE

SCHEMATIC SCH BOULEVARD BLVD

SURVEYING SUV CENTRAL CNTRL

ENGINEERING ENG DRIVE DR ELECTRICAL ELEC EAST EST GARDENS GDNS

SUBTYPE CODE JUNCTION JUCT

PROPOSED PRO LOWER LWR EXISTING EXT MOUNT MT BLOCK BLK NORTH NRT SURVEYS SUV NUMBER NO GPS GPS PARK PRK NETWORK NTW PHASE PHS



INFRASTRUCTURE INF ROAD RD

MECHANICAL MEC SAINT SNT

SETTLEMENT STLMT

..1.1.1.1 SUB-SUBTYPE

CODE STREET STR

3D 3D SOUTH STH

COMPLETE COMPL TOWN TWN

ELECTRICAL ELECT TRACE TR ELEVATION ELEVA UPPER UPR FLOORPLAN FPLAN VALLEY VLY ROOFPLAN RPLAN VILLAGE VILL

PLUMBING PLUMB WEST WST

WATER WATER

SITEPLAN SPLAN

CADASTRAL CADAS

TOPOGRAPHIC TOPOG ASLAID ASLAD

SEWER SEWER

BUILDING BLDG RESERVOIR RESEV BOOSTERSTATION BSTAT

MISCELLANEOUS MSCEL

WIRING WIR

Section 43 EXAMPLE

CADType-SUBType-SUBSUBType-LOCATION-USERIdentifie -Version.dwg xxx-xxx-xxxxx-Location-Identifier-#.dwg

e.g. ARC-PRO-COMPL-FOURROADS-PUMPINGSTATION-1.dwg = Complete set of architectural drawings for the Four Roads Pumping Station (elevations, site plan, floor plan, electrical etc)

wasa wastewater and potable water design requirements

Engineering

new section

design standards

design requirements

design guidelines

design construction

tobago water

sewerage authority wasa

design approach approvals