MS for Tank Installation_R1

Document Title METHOD STATEMENT FOR FRP TANK INSTALLATION WORKS

Document No. KTS/CLIENT/MS-008

Revision History

Rev Description Date Prepared by

00 Issue for Review and Approval 20/02/2014

01 Issue for Review and Approval

-Added sterilization of Pipe 08/10/2014

1. SCOPE & DESCRIPTION OF WORK

This method statement applicable for all FRP tank installation works within CLIENT project. It is set to

establish the steps for carrying out FRP tank to ensure conformance to contract and regulatory

requirements.

1.1. Responsibility

METHOD STATEMENT FOR FRP TANK INSTALLATION WORKS

Prepared by: KIM TECHNOLOGY & SYSTEMS ENGINEERING PTE LTD Page 2 Revision: 01 Date: 08 October 2014

It will be the responsibility of Project Manager to ensure all the necessary safety precautions are set in place

prior to carrying out the work. Tank installation shall be done by authorized, trained and experienced crew in

the supervision of Site Supervisors / Engineers.

2. PRELIMINARIES

All tank materials shall be inspected, accepted and shall conform to the approved material

specification and size or capacity. Refer below:

Tank Name Block / Level Size Effective Capacity

NEWater Make Up Tank D / Lower 1st 23m x 6m x 2mH 180cu.m

Domestic Water Transfer Tank D / Lower 1st 4m x 5m x 2mH 30cu.m

Domestic Water Storage Tank A / 6th Storey 4m x 5m x 2mH 27cu.m

Domestic Water Storage Tank B / Roof 3m x 3m x 3mH 16cu.m

Domestic Water Storage Tank C / Roof 5m x 4m x 3mH 47cu.m

Tank shall be constructed in accordance to the approved drawing.

Before the commencement of any cleaning and sterilization work, the licensed water service

plumber shall notify the Authority on prescribed forms of the work to be carried out.

All statutory safety requirements as well as other necessary and relevant safety measures shall be

complied with at all times to ensure that it is safe to enter the tank during cleaning

3. WORK PROCEDURE

1.1. Installation Procedure

Mark the location of the hold down bolts to be drilled into the RC stumps

Check that the holes drilled into the RC stumps are correct and vertically positioned. Insert drop in

anchors

Lift and install the steel skid base in place. Ensure that the supports are leveled and spaced

accordingly prior to tank assembly

Identify and mark the location of flange outlets

Core a hole for the openings



Layout the bottom panels and the flanges downwards on the skid base.

Assemble the bottom part of the tank first

Use PVC foam sealant to stick on the adjoining flange of one panel

Bring the two panels together

Put the bolts to the flange holes and screw the nuts with washers

Do not tighten yet, repeat the above procedure on the next panel until the bottom part is completed

After the bottom part is completed, continue the same procedure to assemble the side panels in

section of 5panels each up to the full height of tank

PVC foam sealant to be put on the junction before putting on the cleats.

For each cleat, fix the bolt inside the tank and screw on the nut with washers outside the tank and

tighten.

Connect the angle stays to the cleats as indicated in the assembly plan, but do not tighten until all

the stays are in position.

After all the plate stays have been assembled, tighten the bolts and nuts commencing with those in

the bottom followed in turn by those on each side.

Install the top panels including manhole access following the above steps

Install the cat ladders

Install its associated fittings such as the overflow pipes, air vents, nettings, tank manhole covers,

etc and ancillary equipment

Sample of Installed FRP GRP Tank

1.2. Inspection & Cleaning Procedure



Before the commencement of any cleaning and sterilization work, a joint inspection with CLIENT or

its representative shall be present to check on the condition of the water storage tank (including its

associated fittings such as the overflow pipes, air vents, nettings, tank manhole covers, etc and

ancillary equipment).

All remedial works to the tank, its associated fittings and ancillary equipment arising from the joint

inspection shall be carried out before commencement of cleaning work.

Adequate signboards shall be displayed to indicate that the water tanks are undergoing cleaning

and sterilization.

The water in the tank shall be used to around 150 to 200 mm above the bottom of the tank before

the tank is isolated and the outlet pipes shut off.

The external of the tank and the tank manhole covers shall be cleaned before the tank covers are

opened.

All tank manhole covers shall be opened to admit light and for ventilation and access. It shall be

ensured that the tank is isolated and all outlet pipes are shut.

All workers involved in the cleaning work must be certified by a medical doctor to be free from

water-borne diseases.

All workers involved in the cleaning work shall wash, clean and disinfect themselves thoroughly

before entering the tank.

All workers involved in the cleaning work must observe safety measures at all times and must be

properly equipped with the necessary safety equipment and gear.

Equipment and tools used shall not have sharp edges that may damage the inside of the tank.

The equipment and tools shall be exclusively used for the cleaning of potable water tanks only and

shall be disinfected before every use.

To prevent sludge and sediments from entering the outlet pipes, all outlets of these pipes shall be

covered. The sludge and sediments shall be placed in containers for disposal at authorized

dumping grounds.

The internal of the tank including the floors, walls, roof, internal of the tank manhole covers, etc

shall then be cleaned using appropriate methods such as scrubbing, pressure jet, etc, Sediments

and solids shall be collected in containers for disposal at authorized dumping grounds.

The roof and sides of the tank walls above the overflow level shall be cleaned and disinfected too.

Chlorine solution of 200 mg/litre shall be applied onto the internal surfaces of the roof and sides of

the tank walls above the overflow level (by spraying or brushing) and left there for at least 30

minutes after they have been cleaned and washed.



The entire tank (including the roof and sides of the tank walls above the overflow level) shall be

thoroughly washed and flushed until it is clean and free from dirt, solids, chemicals or other foreign

matter which may affect the quality of water stored and supplied.

1.3. Sterilization Procedure

Once the tank has been cleaned and inspected, conduct sterilization to ensure the tank is capable

of providing fresh potable water for human consumption.

The sterilization of water storage tanks shall be undertaken by a licensed water service plumber.

After cleaning, potable water is fed into the cleaned tank up to overflow level. Sterilizing chemical

in solution form containing chlorine shall be gradually added while the tank is being filled to ensure

thorough mixing. Safety procedure for the handling of such chemical must be observed at all

times. Introduction of the sterilizing chemical into the tank in powder form is not allowed.

The chemical concentration for sterilization of the tank shall be 50 mg/litre of free chlorine (i.e. 50

ppm of free chlorine). Ordinary bleaching powder in solution form or sodium form or sodium

hypochlorite solution may be used with equivalent concentration.

While the water in the tank is being sterilized, all outlet pipes from the tank must be closed tight

and no water shall be allowed to flow into these pipes as the water under sterilization may not be

safe for human consumption.

The sterilized water shall be kept in the tank for at least 24 hours. The water in the tank is then

drained off completely through the wash out pipe and the tank refilled with potable water through

the inlet pipe. It must be ensured that all outlet pipes are closed tight before re-filling the tank with

potable water.

Main and distribution pipes must also be sterilized while the tank is being soaked using the same

concentration. Open the discharge valve and fill the pipe with chemical solution. Pipe must be filled

until the remotest fitting. Once sterilized, drain the pipe and flush with potable water.

Water samples shall then be taken from the tank sampling tap for bacteriological and chemical

analyses at an accredited laboratory.

Water samples shall be taken by a licensed water service plumber and should be sealed and

marked by CLIENT or its representative and escorted to the accredited laboratory. Alternatively,

the water samples may be taken by personnel from the accredited laboratory and sealed and

marked by CLIENT or its representative. Water samples with broken seals shall be rejected.

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The tank and the water shall only be put into use after satisfactory test reports are obtained from

the accredited laboratory. All down feed and distributing pipes from the tank shall be thoroughly

flushed until clean before water from the tank is put into use.

If the test reports from the accredited laboratory are unsatisfactory, sterilization shall have to be

carried out again.

After cleaning and sterilization have been completed, a final joint inspection with the CLIENT or its

representative to check on the condition of the water tank shall be carried out to ensure that all

remedial works have been carried out and all tank openings (such as air vents, overflow and

warning pipes, etc) have been properly screened to prevent birds, insects and other possible

contaminants from entering the water tank.

Upon completion of cleaning and sterilization work, the licensed water service plumber shall notify

the authority on prescribed forms of the completion work accompanied with the laboratory water

sample test reports within the time period stipulated by the Authority.

4. HEALTH & SAFETY MEASURES

SWMS for all activities to be established and it must be briefed to all workers who are involved in

the task

All necessary control measures should be taken as mentioned in the SWMS

Workers must complete the minimum Work At Height foundation course by Authorized Training

Provider accredited by MOM

Workmen shall wear all appropriate safety Personnel Protective Equipment such as safety helmet,

long sleeves, safety shoes, goggles, safety gloves etc. wherever required.

Other than basic PPE, workers to wear full body harness when working at height.

Sufficient lighting shall be provided at dark areas.

Wind speed and direction to be considered when assembling the FRP panels at building roof tops.

PTW shall be prepared and approved prior to start work.

MS for Tank Installation_R1

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