15.project report - uwssrp1 - masvingo final draft

LLOYD F.

FENDE

CIVIL

ENGINEERING

TECHNICIAN

REHABILITATION OF WATER AND SEWAGE SYSTEMS IN MASVINGO, ZIMBABWE.

Page 1

TECHNICAL PROJECT

REPORT

October

2013

To

May 2015

Rehabilitation of Water and

Sewage Systems in

Masvingo, Zimbabwe.

REHABILITATION OF WATER

AND SEWAGE SYSTEMS IN

MASVINGO, ZIMBABWE.

Contents Page


Page 2

Chapter

Page

i. PREFACE

3

ii. ACKNOLEDGEMENTS

3

iii. INTRODUCTION

4

1. THE PROJECT 5

2. BUSHMEAD WATER TREATMENT WORKS

6

2.1. Raw Water Intake 7

2.1.1. Challenges 8

2.2. Flow Regulation 9

2.3. Flow Measurement and Aeration

9

2.4. Activated Carbon Addition 9

2.5. Coagulation 9

2.6. Flocculation and Sedimentation

10

2.7. Filtration 10

2.7.1. Challenges 11


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2.8. Chlorination 12

2.8.1. Challenges 12

2.9. Treated Water Pump Station

12

3. RAW SEWAGE PUMPING 13

3.1. Raw Sewage Pump Station No.1

13

3.2. Rujeko Raw Sewage Pump Station

14

4. MASVINGO SEWAGE TREATMENT WORKS

15

4.1. Preliminary Treatment

16

4.2. Primary Treatment

16

4.3. Secondary/ Tertiary Treatment

17

4.3.1. Biological Filtration

17

4.3.1.1. Challenges 20

4.3.2. Biological Nutrient Removal Plant

20

5. SITE ORGANISATIONAL STRUCTURE

22


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6. ROLES AND RESPONSIBILITIES

23

7. SUMMERY OF CONTRACT INFORMATION

24

8. CHALLENGES 24

9. CONCLUSSION 25


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i. PREFACE

This report is part of the requirements by the Zimbabwe Institute

of Engineers for registration as a Civil Engineering Technician. It

aims to show the relevant working experience I gained during the

implementation of Masvingo Water Supply and Sanitation

Rehabilitation Project from October 2013 to May 2015. Although

the project did not touch each and every component of

Masvingo’s Water and Sewage Treatment systems, I have included

description of the treatment processes. However, I gave more

emphasis to sections that the Project directly focused on for

example where equipment was replaced or refurbished. This

report also shows how implementation of the project had an

effect on the sewage and water treatment systems of Masvingo

City Council.

ii. ACKNOWLEDGEMENTS

Credit in preparing this report is given to all various organisations

that made it possible for me to be part of the Urgent Water Supply

and Sanitation Rehabilitation project in Masvingo City. I am

thankful of all my work colleagues for their aspiring assistance,


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invaluably beneficial criticism and friendly advice during the

course of the project and during preparation of this report.

Sincere and grateful appreciation is also given to the above

mentioned for sharing their truthful and illuminating views on a

number of issues integrated in this report.

iii. INTRODUCTION

I had just returned home to Zimbabwe for a short break from my

work in South Africa and the advertisement for position of Clerk

of Works from Brian Colquhoun Hugh O’Donnell and Partners

caught my eye. I made some further enquiries and found out what

the job entailed.


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The job was to be based in Masvingo Town where an Urgent Water

and Sanitation Rehabilitation Project was to be implemented. The

job specifications included site supervision and inspection of

civil, mechanical and electrical works related to water and sewage

treatment systems; Assisting the Resident Engineer to apply and

maintain the Contract Plan; Monitoring of work to ensure

compliance with specifications; Compiling and summarising

materials data; Measurement of the works and agreement of

quantities with the contractor; Maintenance of daily diaries and

weekly reports.

The successful candidate would report to the Resident Engineer

as well as to the Project Managers.

To prepare myself for the interview, I read books and browsed the

internet for information on Water and Sanitation infrastructure

and processes. This tremendously helped me for any eventuality

in any Municipal Water Supply and Sanitation Rehabilitation work

as Technician and further helped me spruce up my otherwise

decaying knowledge on Water Supply and Sanitation that I learned

at college ten years back.


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1. THE PROJECT

I was offered the job as a Clerk of Works with an initial contract

of ten months which could be extended on condition that the

project I was to be involved in was also going to be extended.

The project entailed implementation of the Urgent Water Supply

and Sanitation Rehabilitation Project (UWSSRP) in the City of

Masvingo in Zimbabwe (the beneficiary). The original value of the

project was US$2,850.000.00 approximately and the

implementation period was 10months in the contract. The project

was funded by Zimbabwe Multi-Donor Trust Fund (Zim-Fund)

administered by the African Development Bank (ADB) and The

Crown Agents for Oversea Governments and Administrations

Limited (Crown Agents) was the Procurement Agent. I was an

employee of Brian Colquhoun Hugh o’Donnell and Partners

(BCHOD). Lahmeyer GKW Consult and its local partner Brian

Colquhoun Hugh o’Donnell and Partners (BCHOD) were mutually


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the Implementing Entity. Technofab - Gammon Joint Venture

(TGJV) was the contractor.

The project comprised of the repair and or replacement of critical

components of the water supply and sewage systems located in

Masvingo in order to restore operations and increase capacity of

services provided by the Municipality. The project focused on

rehabilitation of three sections of the water supply and sanitation

infrastructures of Masvingo City Council namely; Bushmead Water

Treatment Works, Sewage Treatment Works, Raw Sewage

Pumping Stations.

My duties were to measure works done by the contractor for

payments purposes and ensuring that the contractor executed

the works according to the contract specifications. My daily work

included progress tracking by recording daily works done and

capturing weekly progress. It was my duty to ensure that good

workmanship was achieved during work. I was responsible for

keeping records including Site diaries, instructions, progress and

programme records and keeping measurement records.

Inspection of the works, identification of defects was also part of

my work. I was also ensuring that safe methods of working were

used by the contractor by enforcing the use of proper personal

protective equipment and by assessing and reporting on


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environmental damage caused by the works. My other duties were

to capture minutes of technical meetings.

2. BUSHEMEAD WATER TREATMENT WORKS

The City of Masvingo gets its water from Lake Mutirikwi which

also provides water for the irrigation of nearby sugar plantations.

Masvingo Water Treatment Process has six main stages namely

abstraction, conveyance, sedimentation, filtration, chlorination

and pumping. Below is the process flow chart for Bushmead Water

Treatment works.


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Bushmead Water Treatment Flow Chart

2.1. RAW WATER INTAKE

Raw water is extracted from Lake Mutirikwi at the intake tower.

The design set up is that there is provision for three vertical

turbine pumps with an operational system of two on duty and one

stand-by. The purpose of the Vertical Turbine Pumps is to convey

raw water from Lake Mutirikwi to the Treatment plant through

two parallel pipelines of 300mm and 400mm diameters.

Before the Urgent Rehabilitation project, only one pump was

running. The second pump was due for services and the third


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pump was down. The Municipality was operating with only one

raw water vertical turbine pump and the City was running dry

during breakdowns.

During the Project two new raw water vertical turbine pumps with

the following characteristics; System head 66m, flow 600 m3/hr

were supplied and installed. Gate valves, non-return valves and

air release valves for the two pumps were also installed during

the project.

Installation of 400 V, 3 phase, 50 Hz main switch panel with

voltage protection unit was also installed.

Minor civil works were also done during the rehabilitation of the

intake tower and they mainly comprised of internal and external

painting works.

After installation of the pumps was complete we tested the

capacity of the pumps to check if they had the required

characteristics by use of flow meter and flow charts. The two new

pumps had an average capacity of approximately 800m^3/hr.

The picture below was captured during the installation of the

vertical turbine pumps.


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Installation of vertical turbine pumps

2.1.1. Challenges

During the installation of the two new vertical turbine pumps, one

of the challenges that we faced was that the two new pumps and

motors were bigger than the existing pumps and motors. This

caused the new equipment not to fit in the space within the tower.

To resolve this problem, the overhead slab above the pumps were

trimmed in order to accommodate the protruding motors. The

other challenge was that flanges on the existing pipework did not

match with some flanges on the new equipment. They had

different number and size of holes. This delayed the installation

time frames and conclusively installation of pump and

components being completed outside shut down periods.

Thorough checking of all components to be installed had to be

done to compare with the existing equipment in order to limit


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delays due to incompatibility of new and existing components.

Personally I had challenges in the inspection of electrical

components of the control panels since I do not have a typical

electrical bare ground. This was a challenge and a learning point

throughout the whole project.

2.2. FLOW REGULATION

The vertical turbine pumps convey raw water up to the inlet

control valve. The system design at Bushmead Water Treatment

Works has one butterfly valve used for controlling or regulating

the flow of raw water into the inlet channel. The existing butterfly

valve which was out of order was replaced with a new butterfly

valve. Removal of the existing control valve was a challenge since

it had been worn out and dilapidated for years.

2.3. FLOW MEASUREMENT AND AERATION

From the flow regulation chamber, the raw water passes through

another chamber with a V-Notch which serves the purpose of

measuring discharge into the inlet channel. Turbulences in this


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chamber also have an aeration effect to the raw water before it

enters the inlet channel. This is the initial stage in the treatment

process of the raw water at Bushmead were oxygen is added.

2.4. ACTIVATED CARBON ADDITION

Originally the water treatment system at Bushmead did not

incorporate activated carbon addition. However, this is

improvised during periods of high pollution in Lake Mutirikwi. To

tailor the high pollution periods, activated carbon is manually

dosed at the mouth of the inlet channel. Activated carbon

removes the bad odours that are caused by high pollution of the

water source.

2.5. COAGULATION

Coagulation is the addition of a coagulant to capture impurities

and stick them into larger particles. At Bushmead Water

Treatment Plant aluminium sulphate is added at the inlet channel

for this process. The municipality has improvised some buffers

along the channel to create turbulences that create a uniform

mixing effect of the coagulant and the raw water before it reaches

the sedimentation tanks.


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2.6. FLOCULATION AND SEDIMENTATION

After addition of the coagulant at the inlet channel, the water

passes through conical basins. This is where the impurities stick

together into larger particles due to the effects of the coagulant.

The larger particle that form during this process are called flocs

and the process is known as flocculation. The flocs become

heavier and sink at the bottom in a process called sedimentation.

There are ten sedimentation tanks at Bushmead water treatment

works. At the Masvingo Water Treatment Plant the heavier flocs

are collected from the bottom of the basins as sludge and are

disposed into a small pond before being dumped on a small

Banana field. Water is collected from the top section of the basins

and is conveyed to the filter beds for further treatment processes.

2.7. FILTRATION

Water collected from the top side of the sedimentation tanks

passes through eight filter beds for the next stage of treatment.

At this stage water travels through large filter beds of sand to

remove any remaining microscopic particles or micro-organisms.

At Bushmead Water Treatment Works, water is pre-chlorinated

before passing through the filter beds if the pollution levels of

the raw water are higher than normal. Aeration and backwashing


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systems are used to cleanse the filter materials of sludge that

clogs during the filtration process. The main components of the

filtration process are the filter beds, air-blowers and backwash

pumps. During the project, two new horizontal, single end –

suction, centrifugal pumps were supplied and installed with

motors. They had a head 10m and flow of 1000m^3/hr. Four cast

iron gate valves and two check valves were also installed.

One rotary piston roots type air-blower with motor was also

supplied and installed to replace the existing broken down one.

The backwash system was designed for two pumps operating as

one duty one standby and the air blower system was designed to

operate as one duty and one standby. Two new electric panels for

the air blowers and back wash pumps were installed with starter

switches, emergency stop switches, voltage protection and surge

protection units.

2.7.1. Challenges

Most of the challenges on the back-wash pumps and the air-

blower were faced during the testing phase. The main challenge

we faced with the back-wash pumps was the breaking of

couplings between the motor and the pump. This problem caused

numeral breakdowns and shut downs of water supply to the

users. The main cause of this problem was identified to be miss-


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alignment of the pump and the motor. To rectify this problem a

more accurate method of aligning i.e. laser alignment was used

instead of the traditional manual alignment. The air blower also

had challenges tripping and cutting airflow during the testing

period. This hindered the normal procedure for filter media

backwashing. The main cause of this problem was identified to

be the small air release valve and a larger size of valve was

installed to solve this problem.


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2.8. CHLORINATION

The existing chlorination system at Bushmead Water Treatment

Plant was failing to dose the water during times of high pollution

levels in the source river. To cater for these periods of high

pollution the municipality had improvised a pre-chlorination

method by use of a tank a hose pipe dosing directly into the

channel before the filters. The existing chlorinator had a capacity

of 4mg/l. A new standby chlorinator and control panel with a

capacity of 20mg/l was supplied and installed. Chlorine cylinder

tank, liquid trap, gas detector, emergency kit and other related

items were supplied/ installed. Refurbishment of the chlorinator

room was also done to upgrade the facility. Refurbishment

included painting, installation of ventilators and chlorine

detectors.

2.8.1. Challenges

The main challenge that we faced during installation and testing

of the chlorinator was that the existing water pipe system feeding

the chlorinator was of a smaller size and did not have enough

pressure required by the new chlorinator. This reduced the

dosing capacity specified in the contract. To rectify this problem


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a variation was made to install 50mm diameter pipe work to feed

the new chlorinator in order archive the specified dosing capacity.

2.9. TREATED WATER PUMP STATION

The project included supply and installation of one new set of

high lift pump unit, actuated suction and discharge valves with

bypass valves, two new actuated delivery valves with bypass

valves for the existing high lift pump units. Electric panels for the

high lift pumps, air-blowers and back wash pumps and low lift

pumps at the intake tower. Suction and delivery pressure gauges

for the new pump were also installed during the project.

High Lift Pump Installation

The electrical works comprised of installation of control panel and

motor starters. Replacement of 250W flood lights was done for

the whole treatment plant to improve lighting.


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3. RAW SEWAGE PUMPING

There are two raw sewage pump stations in Masvingo namely

Rujeko Pump Station and Pump Station No.1.

3.1. RAW SEWAGE PUMP STATION NO.1

Raw Sewage Pump Station No. 1 was designed to operate with two

pumps on duty and one on standby. Before the ZIMfund/ AfDB

project, all three pumps were not operational and had been

dismantled and removed from the pump room. The UNICEF

contract had supplied two new pumps however installations had

not been done.

The civil works included survey works & designs for remedial

works to correct overflow problems and modification to the pump

station overflow to prevent premature spillages into Mucheke

River. The works involved levelling of the overflow structures.

Upgrading of the pump station building was done during the

project and comprised of interior wall painting, installation of new

windows, new doors, new gutters & down- pipes and new site

fencing. Surface treatment of all metal works comprising of hand

- railings, walkways, chequer plates etc. was also part of the civil

works package.


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Supply and installation of a new horizontal, single end-suction,

centrifugal pump with 40 m head and 700 m3/h flow was done

at the pump station complete with a motor, two gate valves and

one check valve. The two pumps that had been supplied under

the UNICEF contract were also installed during project.

A new electric panel was also supplied and installed complete

with motor starters, emergency stop switches and protection

units.

3.2. RUJEKO RAW SEWAGE PUMP STATION

Rujeko Pump station was designed with three raw sewage pumps

operating as two on duty and one on standby. Only one pump

was operational before the AfDB project and raw sewage often

spilled into the nearby Mucheke river.

Civil works the we carried out included upgrading of the site

buildings comprising of interior wall painting, installation of new

windows, new doors, painting of the existing site fencing,

upgrading of the site new facility, surface treatment of metal

works like hand - railings, walkways, chequer plates etc.

Supply and installation of two new horizontal, single end-suction,

centrifugal pumps with electric motor drives was done during the

project. The two pumps had characteristics of 40 m system head


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and 750 m3/h flow. All the accessory valves were also supplied

and installed.

A new electric panel was supplied and installed complete with

motor starters, emergency stop switches and protection units.

A new standby generator was Supplied and installed. The

generator was a 400V, 150KVA complete with weather proof

enclosure and changeover switch to feed pump No. 3.

4. MASVINGO SEWAGE TREATMENT WORKS

Masvingo Sewage Treatment Plant was designed to treat raw

sewage from the residential area. The raw sewage is pumped

from two pump stations namely Sewage Pump Station No.1 and

Rujeko Pump Station. Raw sewage from a nearby Army Barrack is

also treated at the plant.


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Masvingo Sewage Treatment works has four main stages namely

Preliminary, Primary, secondary/ Tertiary and Effluent disposal.

4.1. PRELIMINERY TREATMENT


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The preliminary stage comprises of; inlet works that collect raw

sewage from Barracks, Rujeko and Sewage Pump Station No.1;

Course and fine screens that remove debris, rags, papers,

plastics, bottles and other large materials that may cause damage

or blockages in pipes; Grit channels that remove heavy organic

suspended solids (grit) from the waste water. Only installation of

handrails (60m) on the grit channels was done during the project.

4.2. PRIMARY TREATMENT

This stage comprises of the primary sedimentation tanks.

Masvingo sewage treatment plant has four primary sedimentation

tanks. The purpose of these tanks is to separate solid organic

matter from the liquid waste. Solid matter settles at the bottom

and the liquid waste floats on top.

During the project, all four primary sedimentation tanks were

rehabilitated since they were not operational. Rehabilitation

included desludging of the tanks, supply and installation of gate

valves, penstock gates, scum pipes, weir plates, pipe work and

protective coating.


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4.3. SECONDARY/ TERTIARY TREATMENT

The main purpose of tertiary treatment is to restore waste water

to a state where it can be safely disposed back to the water course

or ground. This is basically achieved by reducing the levels of

nitrates and phosphates. At Masvingo Sewage Treatment Plant

there are three types of tertiary treatment namely; anaerobic

digestion, biological filtration and biological nutrient removal.

Raw sewage from the grit channels at Masvingo Sewage

Treatment is diverted to the Biological Nutrient Removal Plant for

tertiary treatment and/or to the primary sedimentation tanks.

Sludge collected from the bottom of the primary sedimentation

tanks is diverted to the anaerobic digesters for tertiary treatment

as well. Liquid waste collected from the top of the sedimentation


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is conveyed to the trickling filters for tertiary treatment. For the

purposes of this project report, I will emphasis on the biological

filtration and biological nutrient removal components where

rehabilitation works where involved.

4.3.1. Biological Filtration

Masvingo has three trickling filters for processing liquid waste

from the sedimentation tanks. Liquid waste or supernatant from

the primary sedimentation tanks is sprinkled on to the trickling

filter media (stones). Micro-organisms that culture on the

surfaces of the filter media basically feed on nitrogen, organic

carbon compounds and phosphates releasing water, carbon

dioxide, humus sludge and nitrogen compounds there by treating

the liquid waste. The treated water (effluent) is collected from the

bottom of the tanks and is used for irrigating a nearby farm, the

sewage works area and is also recirculated back to the primary

sedimentation tanks for the removal of scum.

The three trickling filters had not been operational before the

project and were clogged with sludge. The distribution arms,

centre pivots and components had been corroded and

dilapidated.


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During the project, the filter media was removed up to a depth of

2m, cleaned to wash away sludge and replaced back into the

tanks. Remedial works to spalling concrete and exposed rusting

reinforcement was also done to the tanks. The distribution arms

and stay rods were replaced with new ones. The centre pivots

were repaired. Repair of broken down hand rails and protective

coating was done on the trickling filters.

Effluent from the trickling filter is collected from the bottom of

the tanks and conveyed to the effluent ponds at the treatment

works. This effluent is used for irrigating a nearby farm in

Masvingo and also for irrigating the plant’s area. Some of the

effluent is recirculated back to the primary sedimentation tanks

for scum removal. Effluent recirculation and discharge is done at

the effluent pump station.


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Before the project, all two effluent discharge pumps and two

effluent recirculation pumps where broken down. Raw liquid

waste was just passing through inlet works, PSTs, Trickling filters,

effluent pond and finding its ways to the nearby stream since all

pumps were down.

The two effluent disposal pumps were replaced with two new

vertical centrifugal pumps and motors with characteristics of 80m

system head and 250 m3/hr flow together with two gate valves,

check valves and air release valves. The effluent recirculation

pumps were also replaced with two new vertical centrifugal

pumps and motors with characteristics of 10m head and

62m^3/hr flow together with gate valves, check valves and air

release valves.


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New control panels for effluent disposal and recirculation pumps

were also supplied and installed with motor starters, emergency

stop switches, voltage protection, surge protectors and float

switches.

The pump house was rehabilitated by painting and repairing

broken down windows and doors. Installation of 10 new pole

mounted flood lights was done and 8 existing pole mounted flood

lights were refurbished. All internal lighting for the pant buildings

was also refurbished during the project.

Before & After Rehabilitation of the Effluent Pump Station

4.3.1.1. Challenges


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The main challenge that was faced during rehabilitation of the

filtration process was during cleaning of the filter media. There

were no drawings for the trickling filter to refer to during our

work. This delayed our work since extra care had to be taken in

order not to damage unforeseen components within the media.

However, with the assistance and consultation from the

Municipality’s staff we were able to overcome this problem. The

other challenge was that it was difficult to use heavy equipment

operating from ground due to the height of the tanks (3m) and

operation with manual labour delayed progress as well. We had

to erect ramps and platforms on the tanks so that the equipment

would be able to remove the media without damaging it.

4.3.2. BIOLOGICAL NUTRIENT REMOVAL PLANT

The third tertiary treatment of sewage in Masvingo is the Bio-

Nutrient Removal process. This process removes nitrogen and

phosphorous before disposal into the nearby stream, Shagashi.

Removing nitrogen and phosphorous also reduces the bio-

oxygen demand by reducing the amount of organic substances

that consume oxygen. At Masvingo Sewage Treatment Plant, this

is the only process that produces a blue category of effluent

which may be disposed directly into the stream.


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The Bio-Nutrient Removal Plant mainly consists of three zones

namely the aerobic zone, anaerobic zone and anoxic zone.

Aerobic bacteria develop in the aerobic zone and decomposes

almost all of the dissolved organic matter in the waste water. The

aerobic zone is adjacent to an anoxic zone, where most of the

nitrification occurs. The anaerobic zone is where digestion of

waste takes place in the absence of oxygen. The content of the

tank is kept homogenous by using large mixers and aerators, and

the sewage is re-circulated numerous times between the three

zones to attain maximum treatment using Return Activated

Sludge pumps. The resultant liquid is taken from the top layer of

the BNR basin and collected into secondary sedimentation tanks

(clarifiers) to separate the liquid from the solids.

Supernatant liquor will form on the top layer of the clarifier ready

for disposal into the river.

Sludge will settle at the bottom of the clarifier and is re-circulated

or pumped back into the BNR system to maintain the amounts of

cultured micro-organisms. This is known as the Return Activated

Sludge.

Excess sludge or Waste Activated Sludge is collected in the two

settlement tanks for thickening and then pumped by diaphragm

pumps and disposed onto the Town Council’s gumtree


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plantation. Some of the waste sludge is pumped back to the BNR

to increase or maintain the number of micro-organisms. The

liquid collected from the top of the thickeners is conveyed to the

effluent pump station. Contents from the thickener are not

disposed directly into the river since they have micro-organisms

that will reduce oxygen levels in the water there by killing life.

Before the project, the BNR plant was not operational and sludge

had settled and solidified at the bottom. Some sections had

floating islands with fully grown grass and reeds within the BNR

plant. The aerators and mixers could not rotate in these

conditions. During the project, removal and disposal of the

sludge in the plant was the only work done on the BNR plant.


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Disludging of the BNR Plant

Surface treatment, painting and protective coating of all metal

works like hand railings, walkways and bridges was done on the

clarifiers.

Two new axial flow Propeller pumps with motors for return

activated sludge with 0.4 m system head and 156 l/s flow were

supplied and installed during the project.

A new control panel with motor starters, emergency stop

switches, voltage and surge protection units for the RAS pump

control room was supplied and installed.

For the thickeners, two new variable speed air operated

diaphragm pumps with 27m head and 2.5l/s flow where supplied

and installed complete with 2 gate valves and check valves. A new

compressor with a capacity of 3.4m^3/min was also supplied and

installed complete with a motor for the treatment plant. A control

panel for the diaphragm pumps was also supplied and installed

complete with motor starters, emergency stop switches and

protection units.

5. SITE ORGANISATIONAL STRUCTURE


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6. ROLES AND RESPONSIBILITIES

As a Clerk of Works, my main duties at site are summarised

below.

Maintaining daily records of work done by the contractor.

Measuring and agreeing with Contractor daily quantities of

sludge removed and disposed during the rehabilitation of


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the BNR plant and calculating total quantities after

completion of works.

Measuring and agreeing with the Contractor daily quantities

of filter media removed, cleansed and replaced during the

rehabilitation of three trickling filters at the Sewage

Treatment Works.

Ensuring that steel pipes were properly treated to prevent

corrosion before being used and monitoring the

workmanship and general finishes of mechanical works to

detect irregularities.

Ensuring that the correct number and size of gate valves,

non-return valves, air release valves, pumps and motors for

each work station has been supplied and installed and

keeping record thereof.

Ensuring that materials are stored properly at site i.e. pipe,

valves and pumps.

Monitoring of all civil, mechanical and electrical works to

ensure compliance with specification.

Ensuring that the correct type, number and size of tools and

equipment were being handed over to the Masvingo City

Council.

Measuring the capacity of pumps after completion of

installation works.


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Recording and reporting to the Resident Engineer on daily

progress at site.

Participating in technical meetings and keeping records of

the meetings.

Keeping records of site diaries, instructions, progress,

progress photos and measurement of works.

Reporting to the Resident Engineer describing plant and

labour used in each section of work, location, type and

extent of work carried out, stoppages and any unusual

events noted at site.

Assisting the Resident Engineer to assess and report on

environmental damages or damages to existing structures

caused by the works and ensuring that the contractor adopt

safe, healthy and environmentally friendly practices at site.

Assisting the Resident Engineer with final inspections of

works and issuing snags to the contractor before handing

over of structures to the end user.

7. SUMMERY OF CONTRACT INFORMATION

The original value of the contract was US$2,847,391.00 and the

commencement date was 17 May 2013. The contractor was

handed over the site 02 June 2013 and the original contract

duration was 300days however works exceeded this period by


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more than 250 days mainly due to late deliveries of materials

imported from India. The contractor incurred some liquidated

damages of approximately US$143,000.00 due to delays in

completing the contract within the specified timeframe. The

original contract was exceeded by approximately US$550,000.00

mainly due to additional works that had to be done in order to

commission some of the works. The defects liability period was

for a duration of one year from the issuing of the completion

certificate in May 2015. Snags highlighted on the completion

certificate included repainting of handrails at Pump Station No.1,

replacement of a burnt coil on the generator switch over box for

Rujeko Pump Station and replacement of a soft starter display unit

for pump No.3 at the Effluent Pump Station at the Sewage

Treatment Plant.

8. CHALLENGES

The late delivery of mainly mechanical and electrical materials

was one of the major challenges faced during the project. This

was the main cause of delay since the project mainly targeted

installation of mechanical and electrical equipment. Late

deliveries may have been caused by poor planning and inefficient

communication before concluding materials schedules. Labour


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shortages were also encountered from time to time during the

course of the project. This had effects on the quality of mainly

civil works and the overall finishing of mechanical and electrical

works. The main challenge related to labour was the difficulty in

finding the right sub-contractors to execute the available works

at the main contractor’s rates. Labour related challenges also led

to most of the works being completed beyond scheduled time

frames. The main reasons for labour challenges could have been

due to differences in socio-economic costs differences between

the main contractor’s origin and the local sub-contractors.

Shortages of tools and equipment were also encountered during

civil works i.e. during cleaning of trickling filter media and

disludging of Bio-Nutrient Reactor plant. This also led to late

completion of works with some taking more than four times the

scheduled periods. Poor workmanship was another challenge

faced during the project. This was associated mainly with the

sub-contractors’ labour and probably an effect of the labour

shortages contributing to defective works.

9. CONCLUSSION

The installation of new pumps at Bushmead intake tower ensured

a continuous supply of raw water for treatment thereby having a


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positive effect on the quantity of clean water supplied to the

community of Masvingo Town. An average capacity of

860m^3/hr. of raw water could be pumped from each new pump

for treatment. Installation of new equipment like backwash

pumps, air-blower and chlorinator unit at Bushmead water

treatment plant had a positive effect on the quality of water

supplied to the community by the municipality. The new

chlorinator unit that was installed under the AfDB project could

inject up to 20mg/l compared to the 4mg/l capacity on the

existing chlorinator ensuring enough chlorination even in times

of high pollution of the water source. Work done at the two raw

sewage pump stations i.e. supply and installation off pumps and

a generator had a positive effect mainly on the environment and

the community at large. The new pumps insured that no pollution

of the environment would be done due to raw sewage overflowing

into the river/ stream. The generator supplied by the project also

ensured that there would be limited pollution of the river even

during periods of power shortages. At Masvingo Sewage

Treatment Works, the rehabilitation of PSTs, trickling filters and

Desludging of the BNR re-established the treatment of waste

water thereby controlling the quality of effluent being disposed

into the river and environment. Effluent in the blue category was

now being disposed into the river system after the project in


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comparison to the red category effluent before implementing the

AfDB project. This also limited the community from contracting

water borne diseases. The new pumps supplied and installed at

the effluent pump station ensured that there is constant supply

of nutritious effluent to the beneficial nearby farm. This boosted

the agricultural production on this relative farm.

In conclusion, the ZIMfund/ AfDB project improved the water

quality and quantity supplied to the community of Masvingo. The

project also significantly reduced the pollution of water sources

and the environment at large in Masvingo town. In short the

project had a good impact in providing a good living environment

to the community of Masvingo town.

Future projects should also work on the distribution systems of

treated water and sewerage systems. Improvements on the water

distribution systems will limit the amounts of water lost due

leakages and burst pipes. Improvements on the sewerage system

will limit pollution due to leakages and bursts on sewage

pipelines.

In relation to the challenges encountered during the projects

adequate planning should be done before drafting materials

schedules to avoid unrealistic project duration. The implementing

entity should be directly involved in the hiring of sub-contractors


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to avoid poor workmanship. The type of equipment to be used on

various work sections should be carefully chosen in order to avoid

using wrong equipment for certain works and prolong project

duration.

During the project I managed to learn more about construction

supervision and inspection, progress tracking, quality control and

the basics of project management. I also managed to learn more

about health, safety and environment at work sites and the

importance of hazard identification and assessments of risks

before executing work.

15.project report - uwssrp1 - masvingo final draft

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