orana water utilities allian e disinfe tion of pota le

ORANA WATER UTILITIES ALLIANCE DISINFECTION OF POTABLE WATER SUPPLY ASSETS GUIDELINES

Document Register

DATE PREPARED BY DOCUMENT

August 2014 Daryl McGregor Pty Ltd, Consulting Engineers Version 1.1 – Adopted

March 2019 Alayna Gleeson, OWUA Project Officer Update – Draft 1

April 2019 Alayna Gleeson, OWUA Project Officer FINAL

Disinfection Guidelines – April 2019 Page 1 of 33

Background

Public water supply systems are vulnerable to a variety of organisms that have the potential to spread

diseases such as gastroenteritis, cryptosporidiosis, giardiasis, typhoid, dysentery and cholera to the

consumer. Sources of such contamination can include poor quality untreated water in the system,

breaks in the reticulation system (and subsequent repairs), construction of new systems or the

replacement of existing systems.

Most of these organisms are controllable by disinfection. Disinfection is considered the single most

important treatment process in the production and supply of a safe potable water supply.

The water supplies of the Orana Water Utilities Alliance Councils (OWUA) are produced and supplied

to standards set by the NSW Department of Health, the National Health and Medical Research Council

(NHMRC) and the guidelines specified within the Australian Drinking Water Guidelines (2004 –

currently being amended).

The OWUA has developed these guidelines for the disinfection of the water supply systems of its

constituent Councils.

The objectives of the document are to:

formalise processes for the disinfection of water supply systems, and

to provide guidelines and procedures for the disinfection of various components of the water

reticulation systems.

The 11 member Councils of the OWUA are:

Bogan Shire Council

Bourke Shire Council

Brewarrina Shire Council Central Darling Shire Council Cobar Shire Council Gilgandra Shire Council

Mid-Western Shire Council

Narromine Shire Council

Walgett Shire Council

Warren Shire Council

Warrumbungle Shire Council


Contents

Background .............................................................................................................................................. 1

Introduction ............................................................................................................................................. 3

1. Personnel Requirements ................................................................................................................. 4

2. Disinfection Process at Water Treatment Plants ............................................................................ 5

3. Pipelines and Associated Infrastructure .......................................................................................... 6

3.1 Preventative Measures and Construction Activities Prior to Disinfection .................................... 6

3.1.1 Keeping the Pipe/Fittings Clean and Dry ................................................................................ 6

3.2.1 Flushing of mains .................................................................................................................... 6

3.2 Disinfection Process ...................................................................................................................... 7

3.2.1 Disinfection of a Water Main after a Main Break .................................................................. 7

3.2.2 Disinfection of a New/Replacement Water Main .................................................................. 7

4. Water Supply Storage Reservoirs/Tanks ......................................................................................... 8

4.1 New Storages or Reservoirs Taken out of Service for maintenance ............................................. 8

4.1.1 Cleaning .................................................................................................................................. 8

4.1.2 Disinfection Process ............................................................................................................... 8

4.2 Disinfecting Full Reservoirs while in service ................................................................................ 11

References ............................................................................................................................................. 13

Appendices ............................................................................................................................................ 14

APPENDIX A: Monitoring and Testing Programs ......................................................................... 14

APPENDIX B: Flushing of a Burst Main – Works Report [Sample Only] ...................................... 15

APPENDIX C: Procedures for Disinfection a New/Replacement Main ........................................ 15

Typical Work Method Statements ........................................................................................................ 17

Graphs for Determining Disinfection Criteria ......................................................................................... 3


Introduction

The 11 Councils of the OWUA accept responsibility for maintaining the supply of water to standards set

by the NSW Department of Health, the National Health and Medical Research Council (NHMRC) and

the guidelines specified within the Australian Drinking Water Guidelines.

The purpose of these guidelines are to ensure that these health requirements are complied with in the

water supply reticulation systems.

The standard guidelines as specified within the Australian Drinking Water Guidelines encompass a wide

range of measurable characteristic compounds or constituents which can fall into a number of

categories, these include:

Physical (taste, odour and appearance)

Microbiological

Chemical (including inorganic chemicals, organic compounds and pesticides)

Radiological.

As part of their compliance with the Australian Drinking Water Guidelines, the Councils of OWUA have

in place programs that include daily, weekly and monthly monitoring and testing. There are also specific

monitoring and testing activities that are performed at particular times of the year. Refer to Appendix A

for more details of the monitoring and testing programs.

These guidelines are to be read in conjunction with the Requirements and Procedures specified in the

following document.


1. Personnel Requirements

All personnel working on the water treatment and reticulation systems must be appropriately licensed

and/or qualified or competent, trained or accredited in the particular type of work being undertaken.

They must also be of good health with no known diseases such as typhoid, cholera, etc.

All personnel required to work on water supply infrastructure, including any new works must be fully

immunised against Hepatitis A and E, Typhoid, Tuberculosis (TB), Polio and Cholera in accordance with

the NSW Department of Health criteria.

In the case of staff of each Council, the Human Resources Section of each Council will be responsible

for ensuring that all the relevant immunisations have been administered and all required

documentation is maintained.

In the case of all other personnel (contractors, sub-contractors, etc), working on a Council’s

infrastructure, documentary evidence of appropriate immunisations must be provided prior to any

work being commenced.

To comply with the NSW Occupational Health and Safety requirements all personnel are also required

to comply with the relevant Work Method Statements (WMS) developed for the various procedures

and activities associated with these guidelines.


2. Disinfection Process at Water Treatment Plants

The preferred disinfection process involves using chlorine gas injected into the treated /filtered water

prior to leaving the Water Treatment Plant but before it enters filtered water storage tanks in readiness

for delivery throughout the reticulation system.

Plants should operate on the weight of chlorine to volume of water principle. The dose rate should be

sufficient to maintain a residual chlorine concentration of 0.2 - 0.5 mg/L throughout the reticulation

system. The Australian Drinking Water Guidelines state that “in clean water, a combined available

residual level of 0.5 mg/L should be sufficient to ensure microbial control”. Typically the dose rate at

the Treatment Plant should be maintained at between 2.5 and 3.5mg/L, dependent upon the condition

of the raw water at the time. The final free chlorine residual level of the water leaving the Treatment

Plant should be 2.0 – 2.5mg/L.

A very stringent daily monitoring and testing program must be established/performed. This allows the

WTP Operators to closely monitor the operation of the Plants and the quality of water leaving the

WTPs.

Monitoring should also be established/performed to ensure chlorine levels are adequate on the edges

of the distribution system. Water travelling to outlying areas or villages may not retain sufficient

residual to be effective due to the distance or relatively low usage at the end of a single supply line.

Three methods of monitoring and testing should be used; the instantaneous ‘flow dose’ method, the

‘daily dose’ method and daily testing in the WTP Laboratory for free chlorine residual and total

chlorine. These dosing methods require the WTP Operators to record the gas dispenser value and the

weight of the chlorine drum in the chlorine room and the flow rate and the total amount of water

filtered in the main control room, and then perform some simple calculations. To complete the

laboratory testing, samples are collected and tested from water directly piped to the laboratory from

the raw water supply, the pre-treated/post-filtered water and the final discharged treated water

leaving the WTPs.

Scales should be used to indicate to the WTP Operators when a drum is nearly empty and the ‘duty’

chlorinator is manually changed over to the full drum. Each of the chlorinators are to be fitted with

manually adjusted gas dispensers set to meet the desired dose rate. Where necessary a variable speed

control unit can be used.

The preferred dosing method is for the chlorine gas to be passed through a pipe at a predetermined

rate to the filtered water dosing point on the inlet to the filtered water storage tanks.


3. Pipelines and Associated Infrastructure

3.1 Preventative Measures and Construction Activities Prior to Disinfection The effectiveness of chlorine and its derivatives in the disinfection process of water supply reticulation

infrastructure will depend on the quantities of particulate matter within the system. As this material

may contain bacteria, it is important to ensure that the pipes and their associated fittings are

thoroughly clean prior to any disinfection process occurring.

For this to occur the following must be complied with:

3.1.1 Keeping the Pipe/Fittings Clean and Dry Storage – Pipe lengths and fittings should be stored in a clean environment so as to prevent the

entrance of foreign materials. Ends should be capped, boxed or sealed with plastic wrapping or similar,

where appropriate.

Temporary Capping – During construction, seal all openings in the pipeline at the close of the day’s

work or at times when the trench is left unattended. On continuation of work after the seal has been

removed, the joint shall be disinfected in accordance with Section 3.2.3. If water accumulates in the

trench and it is determined that the seals are ineffective, keep the main dry by dewatering the trench.

3.2.1 Flushing of mains

Prior to any disinfection, mains shall be flushed in accordance with the following requirements.

A complete record of all flushing shall also be maintained and the relevant details entered onto a

‘Disinfection of a New/Replacement Water Main – Works Report’ (refer Appendix B).

All water mains in this category, whether new, existing or those which have had repairs completed

must be flushed and disinfected.

Water required to flush mains shall be supplied from the nearest point available in the existing

reticulation system via a stop valve adjacent to the section to be flushed.

The discharge point of the flushing water shall be located at the other end to the supply point of that

section being flushed. The discharge ‘stream’ of water shall be wherever possible and practicable

directed to a designated tanker. Where a tanker is not used, the ‘stream’ shall be directed so as not to

cause any damage to persons or property or the environment.

WARNING: THE DISCHARGE FLOWS CAN BE OF A HIGH VELOCITY.

If valve and hydrant locations permit, flushing toward the ‘work area’ from both directions is

recommended.

Flushing shall commence as soon as the repairs/new work are completed and shall continue until

discoloured water no longer exists.

The main shall be flushed for a minimum of 30 minutes or longer as required. The flushing procedure

if using tankers will need to be modified to suit the availability of tankers.

Should the flushing not eradicate the contamination, further investigation of that section of main must

be performed.


3.2 Disinfection Process All mains which have been taken out of service for repairs or inspection, or have been made/cut into

or are new to the water supply infrastructure must be disinfected prior to being brought back into

service or becoming part of the reticulation infrastructure. Part of the disinfection process includes

flushing in accordance with Section 3.1.2.

Notification of affected customers is also an important step in this process so that persons or

businesses dependant on water or are susceptible to high Chlorine can make allowances.

A Mains Disinfection Unit (MDU) or an equivalent unit/piece of equipment may be used to complete

the disinfection process.

Only appropriate trained staff may use a MDU and all activities shall be in accordance with the

relevant Work Method Statement (WMS), the MDU’s Procedures Manual and these guidelines.

A Hach Chlorine Test Kit (with digital read-out) or an approved equivalent shall be used to measure the

chlorine residual level. (Note: this equipment only has a reading range of 0 – 4.9mg/L; any higher level

will only register 4.9mg/L.

3.2.1 Disinfection of a Water Main after a Main Break The following specifies the requirements for disinfecting a section of main that has been repaired after

a break/burst.

After repairs are completed, water in the main shall be tested for chlorine residual, using a Hach meter

or equivalent. If a satisfactory chlorine residual is not achieved after 15 minutes, then disinfection of

the main will be necessary. The section of main should be dosed with chlorine to achieve a residual of

at least 1.0 mg/L, maximum 1.5 mg/L. After this disinfection the main shall be flushed until free

chlorine residual levels of between 0.2 – 0.5 mg/L (or a level appropriate to that particular section/area

of the reticulation system) are achieved.

The flushed water is to be directed onto a grassed area or to stormwater drain.

A complete record of all flushing/disinfection shall also be maintained and the relevant details entered

onto the ‘Flushing of a Burst Main – Works Report’ (refer Appendix B).

3.2.2 Disinfection of a New/Replacement Water Main All new or replacement water mains equal to or greater than 100mm nominal diameter must be

disinfected prior to being brought into service.

The new or replacement main shall be gradually filled with potable water with a solution of 25mg/L

free chlorine.

Once filled, the chlorinated water shall be retained in the main for a minimum of 24 hours. At the end

of this period, the treated water in all portions of the main shall have a residual of not less than 5mg/L

free chlorine.

After this initial disinfection the super-chlorinated solution shall be flushed from the main until free

chlorine residual levels of between 0.2 – 0.5mg/L or a level appropriate to that particular section/area

of the reticulation system are achieved.

Upon achieving acceptable free chlorine residual levels and the water is at an aesthetically acceptable

level (clear, no odours, etc) the section of main can be brought into service.

A complete record of all disinfection shall also be maintained and the relevant details entered onto the

‘Disinfection of a New/Replacement Main – Works Report’


4. Water Supply Storage Reservoirs/Tanks

4.1 New Storages or Reservoirs Taken out of Service for maintenance All storage reservoirs/tanks taken out of service for inspection, painting/coating, cleaning or any

other activity that might lead to contamination of the water supply must be disinfected before

refilling and returning to service.

The same requirement for disinfection also applies for new storage facilities prior to them being placed

in service.

4.1.1 Cleaning All scaffolding, planks, tools rags and any other materials not part of the structure or operating facilities

shall be removed.

The surfaces of the walls, floor, overflow pipes and operating facilities of the storage facility shall be

cleaned thoroughly using a high pressure water jet, sweeping, scrubbing and/or any other equally

effective means to remove dirt and loose material.

4.1.2 Disinfection Process There are three (3) methods of disinfecting which are acceptable for storage reservoirs. Typically, only

one method will be used for a given storage reservoir, however, combinations of the methods may be

used. All methods can use chlorine gas, sodium hypochlorite or calcium hypochlorite.

Method 1

The storage reservoir is filled to the overflow level with potable water. Sufficient amounts of chlorine

are then added to provide a free chlorine residual of not less than 10mg/L at the end of the appropriate

‘retention period’. This period is dependent upon the type of chlorine used and the method in which

it has been added.

Chlorine shall be introduced progressively with the water as the reservoir is filled. This can be achieved

using portable chlorination pumping equipment. This equipment shall include liquid chlorine cylinder,

gas flow chlorinator, chlorine injector, appropriate tubing to cater for high concentration chlorine and

appropriate safety equipment. If this method is used the delivery tubing shall be located in close

proximity to the inlet pipe such that the chlorine solution will mix readily with the incoming water. For

amounts of chlorine to use and the retention period refer to Tables 2 and 3 respectively.

Using sodium hypochlorite:

The sodium hypochlorite can be either introduced in the same manner as described above for liquid

chlorine or added in bulk amounts to the water in the reservoir. Should the latter be adopted the water

level in the reservoir should be in the range of 0.3 – 0.9m deep. For the amounts of chlorine to use and

the retention period refer to Tables 2 and 3 respectively.

Using calcium hypochlorite (not recommended):

Calcium hypochlorite tablets should be crushed or broken to sizes not larger than 6mm maximum and

dispersed over the floor of the reservoir prior to filling it. The location of the tablets should be such

that the inflowing water will ensure a current of water circulation through the tablets, dissolving them

as it fills. WARNING: THE RESERVOIR FLOOR SHOULD BE COMPLETELY DRY WHILST DISTRIBUTING THE

CRUSHED TABLETS UNLESS PROTECTIVE BREATHING APPARATUS IS BEING WORN. IF THE TABLETS


BECOME WET/DAMP THEY REACT AND BEGIN TO GIVE OFF POISONOUS CHLORINE VAPOURS. For the

amounts of chlorine to use and the retention period refer to Table 2 and 3 respectively.

Table 2: Amount of Chlorine Required

(for 1,000 litres of water at a chlorine concentration of 10mg/L) Chlorine Gas

Sodium Hypochlorite Calcium Hypochlorite (65% Available Chlorine)

5% Available Chlorine



0.01 kg 0.2 L 0.1 L 0.07 L 0.015 kg

After the storage reservoir has been completely filled, it shall remain full for the period of time as

defined in Table 3. The time is dependent upon the type of chlorine used and the method by which it

was added to the reservoir.

Table 3: Retention Time Type of Chlorine Used and Method of Dosing Retention Time

Chlorine gas dosed progressively 6 hours

Sodium hypochlorite dosed progressively 6 hours

Sodium hypochlorite dosed in one large amount 24 hours

Calcium hypochlorite crushed and distributed inside the reservoir prior to filling 24 hours

On completion of the retention period, samples shall be taken to measure free chlorine levels (using a

Hach Chlorine Test Kit) and to conduct bacteriological tests. The free chlorine level should be no higher

than 2mg/L and the results of bacteriological testing should be ‘compliant’.

Should the chlorine level be in the range of 2 – 10mg/L the reservoir shall remain out of service until

the chlorine dissipates. Once the free chlorine level has reached or is below 2mg/L and the water is at

an aesthetically acceptable level (clear, no odours, etc) the reservoir can be brought back into service.

An alternative (not recommended) to keeping the reservoir out of service while the chlorine level drops

to the acceptable level is to pump out the reservoir into tankers and transport the contents to the

Sewage Treatment Plant. The reservoir shall then be immediately refilled with potable water from the

reticulation system.

HOWEVER, THE REFILLED RESERVOIR SHALL STILL BE TESTED FOR CHLORINE LEVELS, WHICH MUST BE

LESS THAN 2mg/L BEFORE BEING BROUGHT BACK INTO SERVICE.

If it is proposed that the chlorinated water is to be tankered to the STP, it must not exceed a

concentration of 10 mg/l and a volume of 5000 l/day. If either is to be exceeded, trade waste approval

will be required, with an application to NSW Office of Water for approval to discharge.


Method 2

If using this method, a solution of 200mg/L available chlorine is applied directly to the surfaces of all

parts of the storage facility that will come into contact with the water when the storage reservoir is

full to the overflow level. Table 4 provides details of the amount of various forms of chlorine required

to produce 1,000 L of a 200mg/L solution.


(to produce 1,000 litres of water at a chlorine concentration of 200mg/L) Chlorine Gas





0.25 kg 4.0 L 2.0 L 1.5 L 0.36 kg

The solution is applied with suitable brushes or spray equipment. The solution shall thoroughly coat

all surfaces to be treated.

WARNING: USING THIS METHOD REQUIRES PERSONNEL TO WEAR APPROPRIATE BREATHING

APPARATUS DUE TO THE POISONOUS CHLORINE VAPOURS THAT WILL BE GIVEN OFF BY THE

SOLUTION.

The disinfected surfaces shall remain in ‘contact’ with the strong chlorine solution for a minimum of

30 minutes, after which time potable water shall be admitted and the reservoir filled.

Once filled, samples shall be taken to measure free chlorine levels (using a Hach Chlorine Test Kit) and

to conduct bacteriological tests. The free chlorine level should be no higher than 2mg/L and the results

of bacteriological testing should be ‘compliant’.

If the chlorine level is in the range of 2 – 10mg/L the reservoir shall remain out of service until the

chlorine dissipates. Once the free chlorine level has reached or is below 2mg/L and the water is at an

aesthetically acceptable level (clear, no odours, etc) the reservoir can be brought into service.

An alternative to keeping the reservoir out of service while the chlorine level drops to the acceptable

level, it to pump out the reservoir into tankers and transport the contents to the Sewage Treatment

Plant. The reservoir shall then be immediately refilled with potable water from the reticulation system.

HOWEVER, THE REFILLED TANK SHALL STILL BE TESTED FOR CHLORINE LEVELS, WHICH MUST BE LESS

THAN 2mg/L BEFORE BEING BROUGHT BACK INTO SERVICE.





Method 3

The procedure when using this method is to fill the storage reservoir to approximately 5% of capacity

with a water/chlorine solution, such that the available chlorine level is 50mg/L. Table 5 provides details

of the amount of various forms of chlorine required to produce 1,000 L of a 50mg/L solution.


(to produce 1,000 litres of water at a chlorine concentration of 50mg/L) Chlorine Gas





0.05 kg 1.0 L 0.5 L 0.33 L 0.08 kg

This solution shall be held in the storage reservoir for a period of not less than 6 hours.

The storage reservoir is then filled with potable water to the overflow level. On completion of filling

the reservoir, it shall be held for another 12-hour period. Following this procedure samples shall be

taken to measure free chlorine levels and to conduct bacteriological tests. The free chlorine level

should be no higher than 2mg/L and the results of bacteriological testing should be ‘compliant’.

If the chlorine level is in the range of 2-10mg/L the reservoir shall remain out of service until the

chlorine dissipates. Once the free chlorine level has reached or is below 2mg/L and the water is at an

aesthetically acceptable level (clear, no odours, etc) the reservoir can be brought back into service.

An alternative to keeping the reservoir out of service while the chlorine level drops to the acceptable

level is to pump out the reservoir into tankers and transport the contents to the Sewage Treatment

Plant. The reservoir shall then be immediately refilled with potable water from the reticulation system.




HOWEVER, THE REFILLED TANK MUST STILL BE TESTED FOR CHLORINE LEVELS, WHICH MUST BE LESS

THAN 2mg/L BEFORE BEING BROUGHT BACK INTO SERVICE.

4.2 Disinfecting Full Reservoirs while in service Existing service reservoirs may require chlorine dosing if an E. Coli alert is detected in the reticulation

system.

It is important to regularly inspect reservoirs and test for residual chlorine concentrations. The chlorine

residual in these reservoirs can dissipate if the water is stored for extended periods, especially during

hot weather or demand is low. Service reservoirs should be operated to ensure turn-over the water

during periods of hot weather.

Samples shall be taken from the top of the reservoir and it is also important to record the temperature

of the water.

All reservoirs should also be checked regularly for bird and vermin access. The bird proofing may need

repair or replacement to ensure that entry is denied.

Inspection of Service Reservoirs shall be carried at minimum monthly periods, chlorine levels taken

and recorded and any maintenance work carried out shall be similarly recorded.

You should also check your storages for sludge accumulation every 2 years.


Chlorination – if required:

Enough chlorine should be added to provide a free chlorine residual of around 0.5 milligrams per litre

(mg/L) after 30 minutes. As a general guide, an initial dose of 5 mg/L of chlorine will provide this

residual (see box below). The residual should be checked using a Hach meter or equivalent.

To work out how much chlorine to add to your tank to provide an initial dose of 5 mg/L:

1. Calculate the volume of water in the storage (in kilolitres)

For a cylindrical tank the volume of water (in kilolitres) = D2 x H x 0.785; where D = tank diameter

(in metres) & H = depth of water (in metres)

Where D = diameter of the tank (in metres), and H = depth of water in the tank (in metres).

To check your calculation, compare this volume with the maximum capacity of your tank.

2. For every kilolitre (1,000 litres) of water in your tank, add either:

• 40 mL of chlorine (sodium hypochlorite - 12.5% available chlorine), or

• 8 grams of granular chlorine (calcium hypochlorite – 65% available chlorine).

Note: Appropriate PPE equipment must be worn at all times when handling chlorine.


References

ANSI/AWWA C651-92: AWWA Standard for Disinfecting Water Mains

ANSI/AWWA C652-92: AWWA Standard for Disinfecting Water Storage Facilities

Australian Drinking water Guidelines, 2004 (or as amended)

Chlorine course notes for the Water Industry Training Package, Certificate 11 and 111 in

Water Industry Operations

ICI Australia Operations Pty Ltd, Chlorine Handbook

Water Industry Technical Standards Specification No 95-092.1


Appendices

APPENDIX A: Monitoring and Testing Programs All sampling and testing shall be carried out in accordance with the requirements of the current

Australian Drinking Water Guidelines. The following monitoring and testing programs are

recommended for the water supply systems of the OWUA Councils.:

1. Daily

Samples of the raw and filtered water (at the Treatment Plant) are tested for the following:

pH

Alkalinity Apparent colour Turbidity Suspended solids Samples collected by Council’s WTP Operator Total Dissolved Solids Total Chlorine Some testing may be performed by Council’s WTP Operator. Free Chlorine The remaining testing is completed by a NATA Carbon Dioxide Registered laboratory. Fluoride Alum residual Iron Copper Conductivity Salinity

2. Weekly

Council’s Sampling Officer collects samples from locations around the town (the number of locations

will vary for each Council).

These are microbiologically tested by Council’s preferred laboratory and tested for chemical

composition by the WTP Operators.

3. Monthly

Samples are collected from locations around the town by Council’s Sampling Officer for testing.

Testing is to be carried out for pH, Alkalinity, Turbidity and Free Chlorine.

4. Monthly

The WTP Operator collects samples of filtered water leaving the Water Treatment Plant and a full

chemical analysis is completed jointly by the WTP Operator and Council’s preferred laboratory.

5. Testing for MIB & Geosmin (summer months only)

Samples of raw and filtered water and backwash water from sludge lagoons at Water Filtration Plants

may be collected by the WTP Operator to be tested for methylisoborneol (MIB) and geosmin.

AWT at the Australian Water Quality Centre in Adelaide can test for MIB & Geosmin.


APPENDIX B: Flushing of a Burst Main – Works Report [Sample Only]

Location

W&S Date Sheet Reference Plan

Table 1: Volume (Litres) of Water to be Disinfected

Nom Dia. of Main (mm)

Length of

Main (m)

Volume of Water to be

Disinfected (L)

(from Graphs 1 to 10)

Flushing Time

(minutes)

Total Volume to be Disinfected (transfer to Table 2)

Free Chlorine Residual at Completion of Disinfection:

Mg/L

Super Chlorinated water disposed of at STP:

Litres

Attended by:

Signature:

Date:

Comments:

APPENDIX C: Procedures for Disinfection a New/Replacement Main


1. DETERMINE THE TOTAL LENGTH OF MAIN TO BE DISINFECTED

Measure the approximate length of each section of main for each of the diameters and

complete the details on the DISINFECTION OF A NEW/REPLACEMENT MAIN – WORKS

REPORT

You will need the relevant Water Data Plans to identify the size of each main.

2. FROM THE APPROPRIATE ‘VOLUME OF WATER v LENGTH OF MAIN’ GRAPHS (GRAPHS 1-10)

DETERMINE THE VOLUME OF WATER TO BE DISINFECTED.

3. FROM THE ‘TIME TO PUMP GRAPH’ (GRAPH 12) DETERMINE THE TIME TO OPERATE THE MDU

TO DOSE THE CORRECT AMOUNT OF SODIUM HYPOCHLORITE FOR THE SECTION OF MAIN TO

BE DISINFECTED.

4. DETERMINE THE DISCHARGE POINT AND INSTALL A HYDRANT STANDPIPE.

5. DISINFECT THE MAIN FOR THE TIME DETERMINED AND ENTERED INTO THE ‘DISINFECTION OF

A NEW/REPLACEMENT MAIN – WORKS REPORT’

6. COMPLETE FINAL FLUSHING PROCESS, INCLUDING TESTING.


Typical Work Method Statements Examples only – documents to be developed by each Local Water Utility

WORK METHOD STATEMENT (Part 1)

COUNCIL: Page 1 of 2

ITEM: CHANGEOVER OF 920KG CHLORINE DRUM (Water Filtration Plant) ITEM No.

DESCRIPTION: PROCEDURE IN STEPS: (including Possible Hazards & Safety Controls)

This requires a new 920kg drum to be connected. 1. Switch on the fan in the Chlorine Room and operate for at least two minutes before entering.

QUALITY STANDARD:

The task is to be completed in accordance with established procedures for the

handling and use of chlorine without risk to self and others.

SAFETY CONTROLS:

Check gas alarms are not operating before entry – DO NOT ENTER IF

ALARMS ARE ON

Wear over-shoulder portable air respirator.

HAZARD IDENTIFICATION OR RISK ASSESSMENT:

Operation of overhead crane

Chlorine gas and handling chemicals and dangerous goods

Slips and falls

2. Complete maintenance checks as per established routine/procedures.

3. Confirm compliance with Work Method Statement.

4. Switch off all valves from drum to chlorinator.

5. Manually start chlorinator and drain the gas line.

6. Disconnect the line from the drum, cap and cover the drum.

7. Use crane to lift off existing drum from scales and replace it with the new drum.

8. Remove the drum cover and cap.

9. Reconnect the gas line and switch the valve ON.

SAFETY CONTROL:

Always use a new washer when reconnecting the gas line.

SAFETY CONTROLS:

Wear all necessary PPE, including eye protection clothing, gloves and

safety helmet.

Carry over-shoulder portable air respirator.

Use safe lifting techniques to move any equipment/materials.

Keep clear of suspended drums DO NOT WORK UNDER.

Maintain neat and tidy work area.

10. Test the chlorine flow and check for joint leaks.

11. Exit and lock the room, test the alarm operation.



ITEM: CHANGEOVER OF 920KG CHLORINE DRUM (Water Filtration Plant) ITEM No:

PERSONNEL QUALIFICATIONS AND

EXPERIENCE:

PERSONNEL, DUTIES AND RESPONSIBILITIES: TRAINING REQUIRED TO COMPLETE WORK:

Certificate in Water Treatment Operation

Certificate in the Handling and Use of Chlorine

Confined Space Entry Certificate.

Complete safety checks onsite

Check First Aid Kits (that they are complete), Fire

Extinguishers (are charged) and all safety gear,

especially the over-shoulder portable air

respirator (which must be currently certified), is

in good order.

Instruction under the supervision of an

experienced employee

Handling and use of chlorine

Confined Spaces instruction.

ENGINEERING DETAIL/CERTIFICATES/WORKCOVER APPROVALS: CODES OF PRACTICE, LEGISLATION:

Confined Space Entry Documentation OHS Act (2000) and OH&S Regulations (2001)

Confined Spaces Regulations

Council Policies and Procedures

WorkCover Regulations and Codes of Practice.

OTHER PLANT/EQUIPMENT: MAINTENANCE CHECKS:

Source all items required to complete the entire job. Service and check items before starting, including Completing the Maintenance

Check List developed.

SIGNED OFF: DATE: AUTHORISED:

AREA: VALID UNTIL: APPROVED BY:

DATE:



ITEM: LABORATORY TESTING (Water Filtration Plant) ITEM No:


1. Confirm compliance with Work Method Statement.

2. Jar testing (to determine the appropriate chemical dosing for the effective

operations of the WTP).

3. pH – test raw and filtered water.

4. Alkalinity – test raw and filtered water.

5. Colour apparent – use Hach Spectrometer.

6. True colour test – use Hach Spectrometer.

7. Turbidity – use bench mounted turbidity meter.

8. Conductivity – measure salt content.

9. Total Dissolved Solids.

10. Temperature.

11. Suspended Solids.

12. Total Chlorine.

13. Free Chlorine.

14. Fluoride.

15. Residual Alum.

16. Total Hardness.

A comprehensive range of tests are to be completed on a daily basis.

QUALITY STANDARD:

All tests should meet the National Health & Medical Research Council

(NHMRC) Guidelines.

HAZARD IDENTIFICATION OR RISK ASSESSMENT:

Glass

Chemicals

Acids

Powder Reagents

SAFETY CONTROLS:

Wear your work uniform.

Wear eye protection.

Wear protective clothing including gloves as required.

NOTE:

All tests are completed as per standard methods (see Manual) using the various

equipment available.

All tests should meet Australian Drinking Water Guidelines.

If a test exceeds the standard, advise Supervisor for appropriate action

Where possible modify treatment to correct the problem.



ITEM: LABORATORY TESTING (Water Filtration Plant) ITEM No. ……


EXPERIENCE:


Chlorine Certificate

Fluoride Certificate

Water Treatment Certificate.



Extinguishers (are charged) and all safety gear is in

good order.


experienced employee.


Confined Space Entry Documentation OHS Act (2000) and OH&S Regulations (2001)




Source other plant required to support the job. Service and check all plant items daily before starting, including completing the

Maintenance Check List developed.



DATE:



ITEM: CLEANING & DISINFECTION OF WATER STORAGE TANKS/RESERVOIRS ITEM No. ……


Each storage tank is scheduled to be cleaned (at least every 2 to 3 years) and

disinfected. THIS IS A 3-PERSON (MINIMUM) ACTIVITY 1 PERSON MUST REMAIN OUTSIDE

THE STORAGE TANK/RESERVOIR OBSERVING ENTERED ACTIVITIES FROM

ABOVE. QUALITY STANDARD:

The cleaning and disinfection tasks are completed in accordance with Council’s

Policy and Procedures, within the stated time schedule and without risk to self

and others. 1. Confirm compliance with relevant Work Method Statements.

SAFETY CONTROLS: Lock-out and tag all inlet and outlet supply valves.:

HAZARD IDENTIFICATION OR RISK ASSESSMENT: 2. Drain the tank.

Confined space

Contact with chemicals and hazardous materials (Chlorine gas or

compounds)

Oxygen level

Working at heights

Slips and falls (using access stairs and when working at heights)

Exposure to noise

Contact with high pressure water jets.

SAFETY CONTROLS:

Test for confined space hazards.

Implement confined space procedures.

3. Set up and use air blowers as a precautionary measure to remove any vapours or fumes in the tank.

4. Continue to monitor the confined space.

5. Before entering the tank, test for a safe level of Oxygen.

6. Wearing appropriate PPE, enter the tank to clean and/or disinfect.

(Cleaning and disinfection shall be in accordance with the Policy and Procedures for the Disinfection of Potable Water Supply Assets and/or any specific

instructions issued by the appropriate Manager).

SAFETY CONTROLS:

Wear protective clothing and equipment, including hats and sunscreen, hearing and eye protection, chemical resistant gloves and SCBA (Self-contained Breathing Apparatus).

Comply with Council’s Confined Spaces requirements. Use of safe lifting techniques to move any equipment or materials. Comply with all chemical MSDS procedures and instructions. Ensure all working platforms are securely fixed and fitted with handrails, etc.

and all ladders are secured to prevent movement. Maintain a neat and tidy worksite at all times. Check that all pressure hoses used are in good condition and safety

couplings/pins are inserted when in use. Lock-out and tag all inlet and outlet supply valves.

SAFETY CONTROLS:

Implement confined space procedures.

OBSERVER/SAFETY PERSON TO REMAIN AT THE ENTRANCE TO THE

TANK AT ALL TIMES.

The air blowers shall be in operation while the tank is occupied.

MINIMUM OF 2 PERSONS IN THE TANK AT ANY ONE TIME.



ITEM: CLEANING & DISINFECTION OF WATER STORAGE TANKS/RESERVOIRS ITEM No. ……


EXPERIENCE:


Farm Chemical Users Certificate.

Confined Space Entry Certificate.




good order.



Handling and use of Chlorine (and its derivatives).



Confined Space Entry Documentation.

Completion of relevant ‘Works Reports’.

OHS Act (2000) and OH&S Regulations (2001)





All items required to complete the entire job, particularly PPE equipment for

measuring LEL, O2 and CO, and air blowers: refer also to the Policy and

Procedures for the Disinfection of Potable Water Supply Assets.

Service and check all items before starting.



DATE:



ITEM: MANUAL CLEANING OF 600MM NOM. DIA. OR LARGER WATER PIPES (Prior to disinfecting) ITEM No. ……


Prior to disinfecting water mains they have to be cleaned. For 600mm Nom.

Dia. or larger pipes this will require workers to enter the pipe which is classified

as a Confined Space.

THIS IS A CONFINED SPACE TASK & COUNCIL’S CONFINED SPACES

REQUIREMENTS MUST BE STRICTLY FOLLOWED.

QUALITY STANDARD:

The cleaning shall be completed in accordance with Council’s Policy and

Procedures, PARTICULARLY THE COMPLIANCE WITH COUNCIL’S

CONFINED SPACES REQUIREMENTS.

THIS ACTIVITY APPLIES TO NEW PIPES ONLY.

THE CLEANING PERSON IS ONLY PERMITTED TO ENTER THE PIPE FOR A

MAXIMUM DISTANCE OF 2 FULL PIPE LENGTHS (11m MAX.)

1. Confirm compliance with relevant Work Method Statements.

HAZARD IDENTIFICATION OR RISK ASSESSMENT: SAFETY CONTROLS:

Confined space. Lock-out and tag all supply valves to the pipeline in question.

2. Sweep and clean inside of pipe as necessary to provide a clean internal

lining.

3. Complete all relevant documentation.

SAFETY CONTROLS:

Comply with Council’s Confined Spaces requirements.

Wear protective clothing, including eye protection and hard hat.



ITEM: MANUAL CLEANING OF 600MM NOM. DIA. OR LARGER WATER PIPES (Prior to disinfecting) ITEM No. ……


EXPERIENCE:


Confined Space Entry Certificate. Complete safety checks onsite



good order.





Confined Space Entry Documentation.

Lock-out documentation/notices (where applicable).

OHS Act (2000) and OH&S Regulations (2001)





All items required to complete the entire job, particularly PPE equipment and

confined spaces equipment.

Service and check all items before starting.



DATE:

Graphs for Determining Disinfection Criteria

orana water utilities allian e disinfe tion of pota le

Documents