Method Statement of Potable Water / Firewater Network Installation and Testing

1. Purpose

This method statement of potable water / firewater networks defines the installation and testing as per specifications, procedures, & HSE requirements.

This method statement specifies the technical requirements to be followed and also acts as a reference to clearly establish defined standards for work assessment.

Moreover, this document shall provide guidelines to check that specified materials are installed and agreed procedures are implemented during the execution of work. This also defines the responsibilities for controlling the execution.

2. Scope

This Method Statement describes the sequence of activities involved in laying and testing of potable water / firewater network as per the requirements derived from the scope of work, contract specifications, codes, and standards of the project.

3. Description

All activities for earthwork, trench excavation, pipe bedding in trenches, backfilling after laying the piping, laying of marker tapes, and all associated jobs relates to civil shall be done by a civil contractor whose prequalification documents shall be forwarded to authority for approval prior to commencement of any activity whatsoever.

Work includes the construction of potable water/firewater network including installation of ductile iron piping, copper piping, valves and other appurtenances, fire hydrants, hydraulic testing of pipelines, swabbing, flushing, and disinfection.

Moreover, corrosion protection of all metallic parts of the network will be part of this MST whilst construction of the different types of valve chambers as well as other reinforced concrete structures is excluded.

4. Definitions

Supplier/Vendor – Seller of material as defined in the project

Must – Signifies a legal or statutory requirement

Shall – Signifies a requirement made mandatory by this specification

May – Signifies a feature, which is discretionary in the context in which it is applied

Will – Signifies feature that the supplier may assume to be already present

5. References

Approved material submittals

Approved shop drawings.

General Specification for Main Laying Materials for Water

General Specification for Main Laying Contracts

Main Laying Design Standards

British Standard 6920 – Testing of Non-Metallic Components with Regard to their Effect on the Quality of Water (Items which have passed full tests of effect on water quality.)

Project Specification

AWWA C600 Installation of Ductile-Iron Water Mains and Their Appurtenances

6. Abbreviations

HSE Health Safety and Environment

QA/QC Quality Assurance and Quality Control

MST Method Statement

RSK Risk Assessment

ITP Inspection and Test Plan

PQP Project Quality Plan

INR Inspection Request

PPE Personnel Protective Equipment

MEP Mechanical, Electrical & Plumbing

STARRT Safety Task Analysis Risk Reduction Talk

FF Flat Face

DI Ductile Iron

PN Nominal Pressure

DN Nominal Diameter

RF Raised Face

AWWA American Water Works Association

ASME American Society of Mechanical Engineers

ASTM American Society of Testing and Materials

MDPE Medium Density Polyethylene

WRAS Water Regulation Advisory Scheme

EPDM Ethylene Propylene Diene Monomer

NTC Non-Toxicity Certificate

BFV Butterfly Valve

GV Gate Valve

ARV Air Release Valve

DFM District Flow Meter

FCV Flow Control Valve

NRV Non-Return Valve

FH Fire Hydrant

7. Responsibilites

A. General

1. Project Manager (MEP) will be responsible to manage, executing, completing, and handover the construction activities within approved budgets and resources in compliance with project requirements as specified in project specifications. He will be overall in charge of implementing the method statement in accordance with QA/QC and HSE requirements.

2. Construction Manager will be responsible for managing construction activities and will lead and communicate site Supervision, Subcontractors and Vendors to assist them in working to the project schedule by conforming QA/QC and HSE requirements at site.

3. HSE Manager will be responsible for planning, coordinating, and implementing issues and directives within the organization. He ensures safe environmental working conditions for all employees.

4. QA/QC Manager will be responsible for supporting the project team in implementing and maintaining Quality Management System for the project through PQP, ITP, MST, and procedures in compliance with project specifications, codes, and standards.

5. HSE Officer will ensure enforcement of safety procedures in accordance with the approved HSE Plan. Will be closely monitoring the site engineer’s strict implementation of the MST and Risk Assessment, the use of proper tools and equipment to maintain safety, certifications of equipment and their adherence to safety regulations, reporting of any unsafe work or stopping work that does not comply with HSE procedures.

6. Site Engineer will be responsible for carrying out all construction-related activities with compliance to HSE and QAQC requirements as per contract specifications, drawings/documents, codes, and standards.

7. QA/QC Engineer will be responsible for conducting inspections as per PQP.

8. Supervisor/Foreman will be responsible for coordinating all works and workers related to the job.

9. Electrician / other tradesmen will be responsible for assisting his superiors during all construction work-related activities following HSE and QA/QC requirements.

10. Store In-charge receives and inspects all incoming materials and reconciles with documents; processes and distributes documentation; reports, documents and tracks damages and discrepancies.

11. Security guards will be clearly visible, vigilant, respond quickly and correctly during the crisis, observe and report, check and monitor, maintain order among workers, and offer safety warnings and tips.

B. Material Handling and Storage

All materials shall be handled/transported/stored in an optimal way that will not cause damage to them.

During transport, special care shall be taken not to damage the coating of the materials. Materials shall be cleaned from any foreign matter deposited during transport.

All materials to be stored are strictly in accordance with the requirements/manufacturer storage recommendation. At all times, all corrosion protection materials shall be stored under the shade and not be exposed to direct sunlight.

Upon delivery to the contractor’s stores or site, the contractor should unpack at all times, open all crates, etc., and unload to areas as directed by the Store controller or the Site Engineer. The contractor shall provide all timbers and packing, necessary for the correct stacking of pipes, fittings, and other delivered materials.

After inspection, the contractor shall shift and stack the approved materials to areas as directed by the store controller/ site engineer.

All coated materials such as epoxy etc. shall be handled special care during transportation/loading in order to protect from accidental damage. Use hooks with special protection of plastic or rubber to avoid damage to the internal coating of the pipe.

The storage area for DI pipes and fittings has to be arranged with a leveled wooden platform. The area should be barricaded.

The DI pipes and fittings should be laid on the wooden platform, in a horizontal position only. Care to be taken that the pipes are arranged in order of dimension.

Larger-sized pipes of thicker class shall always be stacked at the bottom level.

The ends of pipes should be kept closed by means of the manufacturer-supplied plugs.

The layer of pipe stacks will be in accordance with the manufacturer’s storage and handling recommendations.

The gaskets and all other accessories/fittings should be stored in a cool and dry place and should be protected from direct sunlight and moisture. It should be stored in a normal position, free from any deformation.

The storage area shall be cleaned and is at an appropriate height from the ground level. The materials shall be stored in a shaded area to protect them from exposure to direct sunlight/rain etc. Separate areas in the storage zone must be marked for different materials.

Ensure when the transporting load for the fork should not raise more than 8 inches from the ground and the load should be titled back, never carry loose or poorly stacked loads. Never put hands or legs in the lifting.

Whenever heavy or bulky material is to be moved, the material handling needs will be evaluated in terms of weight, size, distance, and path of movement.

Each material item shall be allotted a distinct and separate reference number and mentioned on the material requisition. Make sure that material is approved/examined by the Consultant and QA/QC and associated documents/test certificates are approved.

The Store In-charge shall ensure that all approved supplies be delivered to the site as per the approved material submittal with the manufacturer’s seals, labels, or other proof of origin intact. These labels and seals shall not be removed until the material is required for use and shall be retained for inspection by the consultant and QA/QC.

The Site Engineer shall be responsible for the off-loading and handling of the materials on-site and shall ensure that materials delivered to the site are properly protected against mechanical damage.

No metallic strings or chains shall be allowed for lifting/ handling DI pipes and fittings. Only cloth or similar belts shall be used for such purpose.

Molding putty and wrapping tapes shall be kept/ stored in a cool place. Polyethylene sheets shall be dealt with in a similar way so as to avoid being degraded as a result of exposure to direct sunlight.

C. Material Inspection

For materials to be inspected after receiving at the site, the following points are to be followed:

On receipt of materials at the site, necessary precautions shall be taken for unloading, shifting, and storage.

Each material item shall be allotted a distinct and separate reference number and mentioned on the material requisition. Make sure that material is approved/examined by the Consultant and QA/QC and associated documents/test certificates are approved.

The Store In-charge shall ensure that all approved supplies be delivered to the site as per the approved material submittal; with the manufacturer’s seals, labels, or other proof of origin intact. These labels and seals shall not be removed until the material is required for use and shall be retained for inspection by the Consultant and QA/QC.

I/C Stores shall initiate material inspection for all incoming material to QA/QC and the material shall be inspected against reference documents and as per approved material submittal. Moreover, the physical condition of the material shall be checked. Afterward, an INR shall be raised by QA/QC to the consultant and inspection will be carried out by the Consultant.

Materials, which do not conform to the given specification/approved material submittal, shall be rejected. Any discrepancy or damages will be notified and reported for further action.

The material found not suitable for site use will be removed from the site and arrangements shall be made for replacement.

For any materials inspection (especially pipes, fittings, valves, other accessories), the items shall be segregated as per their type/sizes and placed items separately in racks or on different pallets.

Each rack/pallet shall have an identification posted on a laminated paper with the description of the items clearly written on it.

There shall be appropriate spaces between the pallets so that the engineer/inspector can freely go around them and inspect the materials thoroughly.

Staking the materials all over each other & in one corner is strictly not allowed.

All items shall be kept in a protective environment and shall not be kept directly on the floor; they shall have wooden pallets underneath them.

Primer/paints shall never be kept under direct sunlight or exposed to a harsh site environment. They shall be stored in an air-conditioned environment inside the warehouse.

If the items in one pallet are more in number, do not arrange them on top of one another, and provide space in between to inspect easily.

Generally, after the inspection request is approved by the consultant, an invitation to Material Engineer shall be forwarded through the Project Manager & the client for final inspection and permission to use.

8. Resources

A. Tools and Equipment

Tools

a. Mechanics Toolbox

b. Drilling Machine

c. Spirit Level

d. Grinding / Cutting Machine

e. Chain Block

f. Pipe Wrench

g. Torque Wrench

h. Feeler gauges

Equipment

a. Trailer to accommodate pipe length of 6 meters

b. 25-30 Tons Crane

c. 2-3 Tons Forklift

d. Belts

e. Chain Block

f. Hydrostatic testing equipment includes test pump and test manifolds, two calibrated pressure gauges.

Note:

All testing equipment and measuring tools to be used shall have valid calibration certificates prior to usage.

All lifting equipment and machines shall be 3rd party verified with valid certificates.

B. Materials

a. The material shall be used after being approved by approved material submittals.

b. All material to be used shall conform to the project specification and authorities regulations (where required).

C. List of Manpower

Construction Manager

Pipe installers

QA/QC Engineer

Helpers

HSE Officer

Mobile Crane Operator

Site Engineer

Trailer Driver

Supervisor

Forklift Driver

Foreman

Riggers

9. Methodology-Potable Water/Firewater Network Installation and Testing

A. Pre Installation

All activities for earthwork, trench excavation, pipe bedding in trenches, backfilling after laying the piping, laying of marker tapes, and all associated jobs related to civil discipline shall be done by the civil contractor.

Check & verify that the civil work is completed in compliance with all requirements for installation as per approved shop drawing and handed over for mechanical works. Joint inspection of the location shall be carried out by the consultant & contractor before releasing the excavated trench for installation works.

Any over-excavation adjacent to a structure or beneath the formation level of a pipeline either to be constructed under the contract or in a futures contract shall be backfilled with grade 20 SRC concrete.

If during excavation the trench width exceeds one of the values listed in the table below:

A plain or reinforced concrete cradles and/or reinforced concrete arches shall be provided to the requirements shown on the drawings and to the approval of the engineer.

Check the pipe for transport damage prior to starting with any installation work; Check that the inside of the materials is free from any foreign objects.

Transport and unload the pipe, fitting & support down to its intended installation place.

Pipe installers should be careful to prevent bending or torsion strains from being applied to flanges or flanged appurtenances.

Ensure that proper and dry trench beddings are placed.

Verify that the invert levels of the trench are correct. Check the dimensions and elevations based on the approved benchmark by the engineer.

Ensure trenches are free from obstruction, rocks, and other debris prior to laying of the ductile iron materials.

All relevant documentation approved shop drawings, and material applicable to a particular section of work will be checked by Site Engineer prior to commencement of work.

Ensure that material received is in compliance with the project specifications/authorities regulations and is approved.  Ensure that all required materials and accessories are delivered, inspected, and approved by the consultant and are readily available at the site to carry out the work.

Prior to the commencement of work, areas and access will be inspected to confirm that site is ready to commence the work and coordinated with other trades and subcontractors.

All relevant documentation (including MST and RA are approved, obtain necessary work permits, fill up STARRT cards after completion of daily toolbox talk), will be checked by Site Engineer prior to commencement of work.

The Site Engineer/Site Supervisor will give necessary instructions to mechanical tradesmen and provide necessary approved construction/shop drawings.

The Site Engineer/Site Foreman will check that proper tools and equipment are available to carry out the work and are in compliance with contract specifications.

The Site Engineer will explain to his team about HSE precautions to be observed.

The Site Engineer/Foreman ensures the cleanliness of the area.

Pre‐inspection arrangements for DI pipes, fittings, valves, and corrosion protection materials: In order to facilitate the onsite inspection for Materials Engineers, the following points are to be followed.

For any materials inspection, the items shall be segregated as per their type/sizes on different pallets.

Each pallet shall have the description of the items clearly displayed on it.

There shall be appropriate spaces between the pallets so that the engineer/inspector can freely go around them and inspect the materials thoroughly.

Staking the materials all over each other & in one corner is strictly not allowed.

All valves shall be kept under the shade away from direct sunlight. The valves shall not be kept on the floor; they shall have wooden pallets underneath them.

Corrosion protection materials shall never be kept under direct sunlight or exposed to a harsh site environment. They shall be stored inside the site warehouse.

If the items in one pallet are more than ten in number, do not arrange it on top of the others, and provide space in between to inspect easily.

B. Procedure

All necessary work permits shall be obtained prior to the commencement of any activity at the site and shall remain valid throughout the entire duration of the operation.

Work clearance forms shall be submitted and approved prior to commencement of any works at the site.

The work area shall be isolated by erecting suitable barricades.

At the completion of each day’s pipe laying, the ends of the pipe shall be covered to prevent the ingress of dirty water or debris.

Prior to the start of excavation, make sure that the pipeline coordinates and elevation have been certified by the surveyor. Pipe location, elevation, and slope shall be maintained by a surveyor. A survey report shall be made after the final installation.

For the waterlogged areas, gabbro material as gravel shall be used.

Before the start of pipe laying, the bottom of the trench shall be dry, continuous, smooth, and free of rocks and to the line and grade have shown on the drawings.

Ductile Iron Pipe Installation

Before commencing to place any side fill material, any leveling pegs or temporary supports shall be removed.

Ductile iron pipes shall be supplied in 6.0 meters. lengths; Cut to the required size using the cutting machine before lifting.

Lower the pipe into the trench. Don’t remove the lifting device (existing crane or chain hoist) before the pipe is laid and aligned in the support.

Only remove caps and dummy plugs on-site just before the pipe is laid.

Check the horizontal level of the pipe longitudinally and in the cross direction.

Accurate axial alignment of the mating pipes prior to jointing will be done.

Pipe straightness will be achieved using cotton or nylon thread.

Install appropriate pipe thrust blocks where required. The excavation for thrust blocks shall be carried out prior to laying the pipes except that a trimming margin of not less than 150 mm shall be left to be removed by hand excavation. No pressure shall be applied to the thrust blocks until the concrete has matured for at least seven days.

All activities related to the thrust block shall be performed by the civil contractors. All concrete thrust blocks shall be cast against undisturbed soil.

All joints shall be kept exposed until satisfactory completion of the hydraulic pressure test.

If trench dewatering is necessary, no pipe installation shall start until the design of the dewatering system has been approved.

The wrapping operation shall preferably take place where low temperature can be maintained in the summer heat period so as to avoid the tape degrading due to the high temperature of the coated pipes.

The maximum time between wrapping of the pipe and installation/ laying into the trench will be as per project specification and manufacturer recommendation.

Sluice valves, fire hydrants, air, and washout valves shall be installed as per approved manufacturer recommendations/instructions, approved shop drawings, and project specifications.

All equipment and accessories required for testing shall be calibrated and certified by an approved third-party agency for its accuracy and shall process valid calibration certification.

Step of Works

The installation operations to be adopted for connecting the DI pipe shall be in accordance with the project requirements and as per manufacturer recommendations. Installation operations shall be done by trained DI pipefitters.

The DI materials shall be suitable for use with the range of chemical characteristics of the water and comply with guidelines suitable for using and storing in the environmental condition and normal working water temperature at 50 degrees centigrade.

All the potable water DI pipes shall be from approved manufacturers and the engineer’s approval.

All the material shall be stored in accordance with the manufacturer’s storage recommendations.

Prior to installation, the material shall be protected as per general specification for the main laying contract:

Protection of Materials before installation:

Pipes

A suitable storage area shall be arranged for the duration of the project and subject to approval.

The pipes shall be stacked neatly on timber battens in parallel method with spigots and sockets laid to alternative ends and using wooden battens between rows (size and location of battens shall be as manufacture specification) and the maximum recommended number of layers as manufacture specification.

Valves & Fittings

Valves & fittings of any type shall be arranged in a suitable storage area and shall take every care to prevent damage to valves & fittings and their ancillary equipment. These items must not be in contact with the ground but shall be placed on timbers or planks and provide adequate wedging between each fitting in the base layer and at the sides.

Valve headstocks, motor gearing, or indicators shall be adequately labeled for identification stored carefully in weatherproof premises and be reconnected after the erection of the valves.

Electrical equipment shall be protected from the dampness and the dampproofing seals shall remain intact until the electrician is ready to connect up the equipment.

Air valves are to be stored under cover, in a vertical position with the top of the valve uppermost. Under no circumstances are air valves to be stored such that the ball is subjected to sunlight. Resilient seated sluice valves are to be stored in the same fashion as air valves.

Other Materials

Rubber seatings, gaskets, polyethylene film, wrapping tape, adhesive tape, PVC coated copper pipe, copper fitting, PVC duct, and other anti-corrosion materials and all other equipment and materials liable to be adversely affected by the heat and sunlight are all to be stored in end door cool place. Bolt, nut, the washer should be stored under cover in dry conditions and before used should be lubricated.

All material like rubber seating, gaskets, adhesive tape, wrapping tape, and other anti-corrosion materials shall be stored indoors and in an air-conditioned space prior to starting installation.

All the interfacing of tie-in points with other packages shall be done according to project specification and shall be as per approved shop drawings with coordination with Engineer’s representative.

Corrosion protection shall be applied to the ductile Iron pipes, clean the surface from dust then apply the primer to the pipe surface and wrap the pipe with approved color self-adhesive wrapping tape.

Corrosion Protection

All buried pipes and related fittings shall be protected from corrosion by the application of a PVC / bituminous corrosion protection tape and sleeving.

All pipes and fittings shall have the appropriate external corrosion protection.

Wrapping of Pipe Barrel

The entire external surface of the pipe shall be clean, dry, and free from all rust, dust, grease, or any other deleterious matter.

Only touch up shall be done at the site.

No grit blasting or sandblasting shall be done at the site.

The clean, dry, primed prepared pipe surface is to be machine wrapped with the approved tape.

The tape is to be applied spirally with a minimum of 25 mm overlap for the normal area and 55% overlap for the waterlogged area using sufficient tension to ensure the tape conforms and adheres to the pipe surface. End laps between successive rolls to be a minimum of 200 mm. The wrapping shall extend as close to each end of the pipe as practicable, so the pipe can be jointed in the trench damage to the wrapping.

After the pipes are jointed the step between the spigot and socket area is to be shaped up with the tape manufacturer’s to give a smooth surface profile for wrapping. The joints shall then be wrapped as described above and the joint wrap to extend a minimum

150 mm onto the existing wrap on either side of the joint. Any transit damage to the wrapping tape will be repaired before the pipe is wrapped in the sleeve and laid in the trench.

Wrapping of Buried Flanges, Valves, and Other Fittings

Buried flanges, valves, and fittings shall be protected by approved PVC / bituminous protection wrapping tape, plus primer and putty supplied by the tape manufacturer.

All exposed metal surfaces of the object to be protected and existing protective coating at each extremely to be cleaned free of all rust, weld spatter, mill scale, dirt, dust, lime wash, and other deleterious matter.

The clean, dry, prepared surface is to be brush primed with one thin continuous coat of quick-drying primer and allowed to dry completely.

All pipe and fittings shall be wrapped with an approved polyethylene sleeve if required by project specification.

The polyethylene film will be supplied in tubular form and it is to be placed around the barrel of the pipe or fittings and fixed with sufficient overlaps as required and taped with an approved tape of a minimum of 50 mm width.

All such sleeving is to be done before the pipes and fittings are lowered into the trench.

After the pipes and fittings have been lowered into the trench and jointed, the polyethylene film shall be folded over the joints with an overlap of 300 mm.

Polyethylene Sleeving

All pipes and fittings shall be wrapped with an approved polyethylene sleeve if required by the specification. The polyethylene film will be supplied in tubular form and it is to be placed around the barrel of the pipes or fittings and fixed with sufficient overlaps and taped with an approved tape of the minimum width of 50mm.

All such sleeving is to be done before the pipes and fittings are lowered into the trench.

After the pipes and fittings have been lowered into the trench and jointed, the polyethylene film shall be folded over the joints with an overlap as directed by the consultant.

The contractor is to ensure that the fold is positioned such that it is on the crown up the pipe. The contractor is to ensure that there is a continuous film of polyethylene between pipes and fittings and the surrounding backfill material. No backfilling of the pipe is to take place until it has been checked and passed the integrity of the polyethylene protection.

Before the pipes are laid, they are to be carefully brushed before the pipes through to remove any soil, stones, or other matter, which has entered.

After the trench has been excavated and required elevation achieved, obtaining approval to proceed with granular bedding and compacted as per project specification for the main laying as follow: (Will be done by civil contractor)

i. Imported granular material shall comprise crushed clean hard limestone. The crushed limestone shall be obtained from an approved source.

ii. Granular material shall contain no excessive quantities of dust, soft or flaky particles, shells congealed lumps, nodules of soft clay, shell, alkali, or other contamination likely to affect adversely the compaction of the material or to cause damage to pipes.

iii. Prior to commencement and during the progress of works the contractor shall provide samples of the proposed granular material to be used in the works. This sample will be retained for comparison with deliveries to the site during the works.

iv. The grading of fine aggregate, when determined by the method described in BS 812 (British Standard 812), shall lie within the respective limits specified.

Ensure that pipes and fittings to be joined are of the same nominal size, pressure, and type, making sure that no stones or sharp ends in the bedding.

Special attention needs to be given to the bedding, side filling, and backfilling of the trench. This provides the necessary support for the pipes.

The pipes shall be laid according to the coordinates and elevations specified in the approved drawing. The tolerances for elevation shall be strictly followed.

Before the pipes are socketed the joint shall be carefully cleaned and dried. No dirt or water is to be allowed to enter before the joint is made. No packing of any kind shall be used to locate the pipes in position in the trench.

All precautions shall be taken to avoid any foreign material from entering the pipe during installation. Ensure no debris, tools, clothing, or other materials shall be left inside the pipe.

Pipe installation shall start at low points and towards high points.

Pipes will be lowered in the trench and installed/jointed in the specified slope, level, and coordinates as per the approved shop drawings, seal the open ends of the pipes with caps after completion of activities according to project specification of laying contracts.

Sealing Ends of Pipes

Immediately after laying, the open ends of the pipes shall be sealed with unperforated wooden plugs of appropriate size or approved expanding stoppers to prevent the entry of extraneous matter or water which might contaminate or damage or affect the working of the system.

These plugs are not to be removed until the end in question is no longer classified as an open end.

Pipes, valves, fittings, and other materials shall be handled, moved, lifted, or lowered, connected with the least possible impact, and handling equipment using slings with a third-party inspection certificate.

Valves (washout, air release, etc.) and all fittings (tees, bends, reducer, etc.), and other related materials (fire hydrants) shall be fixed according to manufacturer recommendation, specification, and approved shop drawings.

All pipes, valves, fittings, and their ancillary equipment shall be protected before and after erection against the collapse of earthworks, falls of materials, concrete and cement droppings, wood, and other shavings, and all deleterious material.

When setting and assembling flange work, care shall be taken to ensure that the flanges and bolts are correctly positioned and bolts are evenly tightened up in the correct sequence.

Immediately after laying, open ends of the pipes shall be sealed with imperforated wooden plugs or approved expanding stoppers to prevent the entry of extraneous matter or water which might contaminate or damage and affect the working of the system.

At curves on the pipelines; horizontal, vertical, or a combination of both bends and elsewhere shall be provided with the thrust blocks, supports blocks, etc. as per approved detailed shop drawings and requirements.

As-built surveying shall be taken and recorded prior to surrounding, the pipe surround shall not be less than 250 mm above the pipe crown.

Backfilling of the trench, after obtaining approval from the Engineer shall proceed immediately after satisfactory completing of work. No backfill layer shall be covered by the next layer of construction until it has been inspected, tested, and approved by the Engineer.

Approved PVC marker tape shall be laid directly above the water main, 300 mm below-finished ground level, and 200 mm below the service connection line. Under carriageways, marker tape shall be laid on top of the concrete protection to the water main or as directed by the Engineer.

The remaining depth of trench above sand layers can be backfilled with approved excavated material in layers of not less than 200 mm compacted thickness, each layer will be compacted by roller or plate compactor. The final layer will be tested to 95% proctor.

For the scenarios for pipe crossing new road work and other utilities.

Laying, Jointing Pipes and Fittings

Pipes and special castings will have flange joints, couplings, bolted glands, joints, or similar. Before the pipes are laid they are to be carefully brushed before the pipes through to remove any soil, stones, or other matter, which has entered.

Pipe laying shall commence at low points, i.e., washout branches, and proceed towards summits, i.e., air valve location. Pipes are to be lowered singly into the trench brought to proper inclination, firmly bedded, and made to rest throughout their whole length as specified.

Before the pipes are socketed the joint shall be carefully cleaned and dried. No dirt or water is to be allowed to enter before the joint is made. No packing of any kind shall be used to locate the pipes in position in the trench.

Pipes, valves, fittings, and other materials shall be handled, moved, lifted, or lowered, connected with the least possible impact, and handling equipment using slings made of terylene, nylon, or other suitable synthetic fibers capable of withstanding the required loads.

Joints

When setting and assembling flange work care shall be taken to ensure that the flanges are correctly positioned as required that the component parts of the joints are clean and dry that the faces and bolt holes are brought firmly together that the bolts are evenly tightened up in the correct sequence and that the protection of the flanges is made good.

All jointing out strictly in accordance with the manufacturer’s instructions and prior to jointing a demonstration may be given by the manufacturer’s supplied skilled pipe jointer/representative or a trained pipe jointer of the contractor.

Flexible Mechanical Joints

The spigots and sockets of all types of flexible jointed pipes shall be thoroughly cleaned before jointing rings are placed and jointing completed.

Notwithstanding any flexibility provided in the pipe joints, pipes must be securely positioned to prevent movement during and after the making of the joints and no person shall be employed on the jointing of pipes who is not thoroughly experienced and skilled in the particular work in hand.

No deviation from a straight line will be allowed without approval. Any such deviation shall be provided with thrust blocks if so instructed.

Cutting Pipes

Pipes shall be cut by a method, which provides a clean square cut of pipe and lining and then chamfered where required without being shattered or separated.

All cut or trimmed ends and the parts of any pipe on which the coating may have suffered damage shall be re-coated as per manufacture specification.

Collars and Closers

Where loose collars are used to join pipes cut for closers special tools shall be employed to keep the inside of the pipes flush and the collars concentric with the pipes while the joint is being made.

Sluice Valves and Fire Hydrants

Faces and Seating

Gunmetal faces and seatings of all sluice valves shall be kept clean and free of dirt. No valve shall be laid and operated without first wiping the gunmetal faces with a clean cloth dipped in clean non-mineral oil.

After such cleaning, every care is to be taken to ensure that no extraneous matter enters the valve during the laying process.

The gate groove in the base of the valve is to be thoroughly cleaned by hand before laying the valve. Should bitumen, cement, or any other matter be deposited on the gunmetal faces or seatings it shall be dissolved using proprietary solvents or carefully removed by methods that do not involve scraping the gunmetal faces.

Oiling of equipment

Before any sluice valve or hydrant is commissioned, all gears, bearings, and spindles should be oiled with approved oil as recommended by the valve manufacturer. Oil baths are topped up to the appropriate levels and all grease nipples are charged with the grease of the approved manufacturer.

Stuffing Boxes

Every stuffing box shall be examined when the main is under pressure test and leaking boxes shall be adjusted or repacked with square plaited lubricated packing, or ‘O’ rings of approved manufacture. The stuffing box shall not be so tightly adjusted or packed as to materially affect the friction of the packing on the spindle.

Air Valves

Air valves shall be checked before the main is tested to ensure that the balls and faces are not damaged and that there is no dirt or other deleterious material in the cavities of the body.

All air nozzles shall be probed to see that they are clean. Air relief valve assemblies shall not be installed directly to any storm drain or sanitary sewers system.

Connections to Existing Live Water Mains

Where no tee has been left for future development, the connection shall be made using an approved cutter or under-pressure drilling tee and drilling machine.

The pipe where is to be fitted will be clean, dry, and free from all rust, dust, grease, wrapping tape, or any other deleterious matter and shall be painted with the quick-drying primer. After fitting and drilling the whole tee shall be protected as per specifications.

Protection of Equipment during Laying

All pipes, valves, fittings, and their ancillary equipment shall be protected before and after erection against the collapse of earthworks, falls of materials, concrete and cement droppings, wood and other shavings, and all deleterious material.

Sealing Ends of Pipes

Immediately after laying, the open ends of the pipes shall be sealed with unperforated wooden plugs of appropriate size or approved expanding stoppers to prevent the entry of extraneous matter or water which might contaminate or damage, or affect the working of the system. These plugs are not to be removed until the end in question is no longer classified as an open end.

Anchor Blocks, Thrust Blocks, Support Blocks, etc.

At curves on the pipelines, either horizontal, vertical or a combination of both bends or elsewhere, the pipes must have thrust blocks of concrete Grade SRC 20 to the dimensions shown on the drawing.

Concrete work shall be done by civil discipline.

Thrust blocks shall be cast against un-disturbed soil and shall be cast at all socketed bends, tees, and tapers/ reducers.

Service Connections

This specification covers the laying of MDPE pipes with associated fittings for the size range 20 mm (1/2”) up to 63 mm (2”) underground and aboveground.

Excavation & Backfilling

Excavation and backfilling for MDPE service connection will be in accordance with general specifications for main laying contracts noting that pipe depth shall be 600 mm as detailed in the specifications of the project.

MDPE service pipe shall have 100 mm sand bedding, 150 mm selected backfill material with 100% compaction, and backfill material of varied depth up to ground level, all in accordance with road depth highways maintenance section requirements.

The minimum width of trench excavation is to be service pipe duct diameter (either 100 mm or 150 mm) used plus 200 mm and the maximum width of trench excavation is to be service pipe duct diameter used plus 300 mm.

Materials

All materials supplied shall conform to the project specification for materials used in pipe-laying construction and service connection work.

Service connection size

The sizes of service connections will differ, in no circumstances shall the sizes of the connection exceed the following values:

MDPE pipes and fittings Installation Instructions

Trench marker tape with an aluminum strip in the middle shall be laid at a minimum 450 mm depth below ground level along the route of pipe.

The contractor shall tap the distribution main at depth of a minimum of 900 mm and bring MDPE pipe from ferrule to a higher elevation without the use of any fittings, as far as possible, so that MDPE the pipe could be laid at a minimum depth of 600 mm from ground level, from the distribution main till it reaches customer boundary wall.

When laid above ground along with customer wall premises or elsewhere, polyethylene pipe shall be protected with GRP duct of minimum thickness 3 mm.

Two sizes are allowed; 2” duct for 20mm (1l2”), 25mm (3/4”), 32mm (1”) & 40mm (1 ¼”) and 3” duct for 50mm (1 ½”) & 63mm (2”).

The GRP duct shall start from ground level and be extended to an appropriate height to secure the exposed MDPE pipe near the water meter service cabinet. The GRP duct shall be of a semi-circular shape and be firmly fixed to the wall with brackets.

Hydraulic Testing

The pipelines are to be subjected to the following hydraulic tests:

Test to a pressure of one and half time the working pressure or to a pressure of 9 bars which is the greater and is to be carried out on the section of main during laying.

After completion of all sections of similar diameter, a test shall be carried out at the specified pressure on the completed pipeline.

After completion of service connection, a test of 6 bars shall be carried out on the completed pipeline.

The first test is to be to a pressure of 9 bars and is to be carried out on sections of the main during laying. The second test (final) is to be 6 bars, carried out on the competed pipeline, and is designed to test the service connections. However, in case no service connections are installed, the second test (final test) shall be 9 bars, not 6 bars.

In general, testing should not be carried out against closed valves, the final 9-bar test can be carried out in sections against closed valves.

Initial Test

This test will be carried out on a short section of the main, maximum length to be 1.5 km with joints left exposed, with in-service connections installed, and against proper stop-ends. Under no circumstances this test be carried out against closed valves.

Each section of the pipeline is to be tested to a specified pressure, such pressure being recorded at the lowest point on the test section.

The contractor is to supply all necessary pumps, water, approved blank suitably drilled and tapped for use as the temporary test ends, small bore pipework to fill the main supplying the test hand, pressure gauges, isolating cocks, measuring vessels for measuring the quantity of water lost during the test period and all other materials necessary to ensure successfully testing of the section.

Final Testing

This test will be carried out when the pipeline has been fully completed i.e., all service connections made fully backfilled and reinstated, all valve chambers complete, etc.

The pipeline is to be tested to a specified pressure, such pressure being recorded at the lowest point on the test section.

Testing Method

Where pipes are being tested by sections, each section must be properly sealed off with a stop and securely anchored to prevent any movement. Unless otherwise specified, the maximum thrust on the stop ends for the 9 bar test shall be as per project specification for the main laying as shown below.

If the anchor is to be made of concrete, testing must not start until the concrete has developed adequate strength.

After the contractor is satisfied that all stop-ends are adequately anchored, the section under test is to be filled with water taking care that all air is displaced either through vents at the high points or by using a swab.

After filling the pipeline, must be left under operating pressure for a period to permit the lining to absorb water, pipeline movements, the release of any air still remaining in the section, etc.

The test will last for a period of 24 hours after which time the pressure will be noted and the seals removed.

If a drop in pressure occurs, the quantity of water added in order to re-establish the test pressure should be carefully measured. Unless otherwise specified this quantity should not exceed 0.1 liters per millimeter of pipe diameter per kilometer of pipeline 24 hours for each 30m head of pressure applied.

The requirements per kilometer per day shall be as per project specification for main laying contracts or project specification and as shown below.

9 Bar Test Quantity of Water

6 BarTest Quantity of Water

If the test is not satisfactory i.e., the amount of water to be pumped in to bring the pressure back to the test pressure is greater than the quantities given in the tables above, the fault is to be found and rectified.

Where there is difficulty in locating faults, the section under test, where it is in the initial test should be sub-divided and each part tested separately. For the final test, such sub-division can be done by closing valves. All fittings and other materials required for re-testing are the responsibility of the contractor.

If no faults can be found, then one of the following methods can be utilized to find the leak:

1. Visual inspection of each point not backfilled.

2. Use of a bar probe to detect signs of water in the vicinity of backfilled joints.

3. Aural inspection using a stethoscope or listening stick in contact with the pipeline.

4. Use of an electronic listening device, which detects and amplifies the sound of any escaping fluid.

5. Injection of dye into the test water (only for use in the waterlogged ground).

6. Introduction of nitrous oxide into the test water and using an infra-red gas concentration indicator to detect the pressure of any nitrous oxide that has escaped through the leak.

All pressure tests on mains will be done using water pressure tests and under no circumstances will pneumatic testing be permitted.

Swabbing and Sterilization

Before the final commissioning of the pipeline, the contractor shall swab and scour the pipeline to ensure that this is free from obstructions, debris, and sediment.

Swabbing

One of the following methods shall be used to swab the pipeline.

Hydraulic swabbing

A foam plastic cylinder swab shall be inserted into the pipeline and driven by hydraulic pressure through the pipeline. The dimensions of the swab shall be as follows:

a. Pipe diameter less than 300 m

Swab diameter = 1.25 x pipe diameter

Swab length = 2 x diameter

b. Pipe diameter greater than 300 m

Swab diameter = pipe diameter + 75 mm

Swab length = 1.5 x diameter

The pipe shall be swabbed in one length or in a series of sections.

Should the swab jam at any point, it will be the contractor’s responsibility to either dislodge the swab or to locate it and remove a section of pipeline adjacent to facilitate the removal of both the swab and the blockage. Swabbing will be continued until such time as all obstructions are removed and swab freely through the main.

Dry Swabbing

A form plastic cylinder swab shall be inserted into the pipeline at the beginning of pipe laying and pulled through each pipe as it is laid by means of the rope, thus providing an effective dry swab.

To avoid contamination and infestation, an expandable plug shall be fitted at the end of the pipe at each break in the working day and when pipe laying is suspended. The swab shall be replaced at regular intervals to ensure a tight all-around fit.

Scouring

After the pipeline has been successfully swabbed, the pipeline is to be flushed with clean water.

The scouring shall be continued until the water runs clear and the contractor shall ensure that no erosion or silting occurs in the watercourses or drains into which the water is discharged.

Sterilization of Water Mains

After the mains have been tested and approved, swabbed, and flushed out, the mains shall be slowly filled with clean water containing a chlorine solution injected.

In general hypochlorite solution will be added to the water passing into the main such that the measured chlorine residual is 20 mg/l (ppm). After all the mains to be sterilized have been filled, the mains shall be left full of chlorinated water for a period of 24 hours.

After the period the main is to be emptied, filled with clean water, and left for a further period of 24 hours. Then the biological test is to be carried out and the sample shall be taken from the front points of the main as measured from the level of chlorine residual.

If the tests fail, the procedure is repeated until satisfactory results are achieved.

10. Quality Assurance and Quality Control

A. Quality Assurance Requirements

The contractor shall provide the required documents for the consultant’s approval prior to initiating the execution of this activity as per project specification.

The Quality Control requirement shall include related ITPs and other related documents as applicable.

Refer to Inspection Test Plan.

B. Quality Assurance Process

The contractor shall notify the Engineer 24 hours in advance prior to the start of activity and comments from the Site Instruction will be complied with the satisfaction of the consultant.

The contractor shall consult the public utility authorities not less than one month before it is proposed to commence work to ascertain whether any underground installations will be affected by the proposed work, in which event the contractor shall make all necessary arrangements with the public utility authorities to safeguard the installation.

C. Follow-up and Evaluation

Follow-up on quality performance shall be carried out through an in-house monitoring system such as progress reporting to the planning department, daily, weekly, and monthly reports generated by the planning department to closely monitor site performance.

All of the above shall be conducted in close coordination with the quality department to monitor any deviations from the Quality Management System requirement and induce corrective actions whenever required to eliminate non-conformance or quality deviations.

D. Records

Checklists (CKL)

Inspection Request (INR)

Inspection and Test Record (ITR)

11. Attachments-Method Statement of Potable Water/Firewater Network Installation and Testing

Appendices

Appendix A: HSE Risk Assessment for Installation and Testing of Potable/Firewater Network

Appendix B: Inspection and Test Plan Installation and Testing of Potable/Firewater Network

Appendix C: Checklist for Installation and Testing of Potable/Firewater Network

Appendix D: Ductile Iron Piping Leak Test

Appendix E: Ductile Iron Pipe Disinfection Checklist