Method Statement for Underground Drainage Pipes & Fittings – Installation & Testing. Construction / MEP teams and Subcontractors are fully responsible for all aspects of Quality and Safety, and QA/QC and HSE teams roles are to provide training, advise, guidance, and to conduct ad hoc Monitoring, Surveillance and random Inspections (as defined in ITAP).
Method Statement for Underground Drainage Pipes & Fittings – Installation & Testing
- UPVC Pipe
- Fittings Such As:
- 45 Deg elbows
- 90 Deg elbows
- MIR to be used to ensure that materials are matching with the approval.
Tools – Equipment
- Screw Drivers.
- Spirit levels
- Wire Cutters.
- Hacksaw Frame.
- Sand Paper and Files.
- Measuring Tape.
- Risk Mitigation
- Steel wires.
Read Also: Method Statement for Above Ground Drainage Pipes
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Sequence of Works
- To outline the quality system to be implemented. It contains a work procedure, which is applicable with the specified works for underground drainage.
- This method is design to give guidance to those who have the responsibility of performing the specified task Scope This method statement covers the detailed procedure for installation & inspection of uPVC pipes for below grade drainage services. This procedure defines the Method used to ensure that the installation and inspection of uPVC pipes for below grade drainage services are carried out as per the contract specification and Approved drawing.
- The Entire drainage system network is connected through the internal building Manhole, gully traps, vented & connected to the External Drainage system as per city drainage regulations. Basement waste water pumps out by sump pump to pressure breaker chamber & drain into the manhole.
- Water’s drainage pipes of all toilets are connected to the soil stacks and shall be connected direct to the manholes, which is not in the basement of the Project.
- Kitchen, dish washer and washing machine, discharge is connected to waste stack and shall be connected to gully trap before Manhole. Apartment shower, bathtub & lavatory sink pipe shall be discharge to Grey Water Tank.
- AII wet areas shall be provided with floor drains and gratings with covers, as per approved material submittal and shop drawings.
- Catch basin and grating outlets in u/g shall be connected to waste water line then sump pits in basement and then pumped out to the drainage manholes.
- Drainage stacks running with standards slope to maintain flow of drainage water from 1st point to last point in either sump pit or FIC Manhole.
- Supports will be installed for drainage pipes as per project specification and engineer observation as required to keep piping in neat work man ship manner.
- Level of pipes and drainage fixture as per latest approved shop drawing to last manhole, Sum pit.
- Services will be installed based on latest approved layout and shop drawing and coordination to achieve desired routs of pipe.
- Required concrete encasements for the drainage below grade will be applied as per project specification.
- Test of drainage stacks will be applied to ensure that the network is no leakage.
Pre-Installation Check: –
- Ensure that all safety requirements are in pace in accordance with project safety plan. All the working crews are safety inducted.
- On receipt of the material at site, QA/QC Engineer site Engineer shall inspect the material internally and inspection shall be offered to the Engineer for Approval in MIR (Material Inspection Request) form.
- Ensure all the materials used, have passed receiving inspection in accordance with QA procedures and are not damaged or defective. Any nonconforming Materials must be labelled by storekeeper and returned to quarantine area in accordance with procedure. Ensure that all the materials are Stored staked properly in the store as per the manufacture’s storage recommendation.
- Ensure that all plumbers and helpers are aware of the correct materials handling and installation procedure to ensure best quality of workmanship training shall be provided by site engineers, Supervisor as and when required
- All drainage pipes and fittings shall be cleaned by approved cleaning agent before installation.
- The main contractor to ensure that prior to installation of pipes, all building surfaces to which raceways or brackets are fixed and completed to acceptable tolerance and are in a suitably clean and dry condition. Any unsatisfactory conditions are to be reported to project manager and installation shall not proceed until corrective action measures have been taken by him.
- Prior to start the work, plumbing engineer, Supervisor from all execution team shall ensure that the latest approved shop drawings and approved method of statement (hard copy) at installation location
- Supervisor shall ensure equipment and correct tools are available for installation-operation and to achieve compliance with contract requirement.
- Rotate equipment and power tools must have HSE inspected color coding.
Installation of uPVC Drainage Pipes Underground
- Prior to start of work, supervisor and plumbing engineer assigned for the execution of this activity shall be provided with latest approved construction drawing for site implementation.
- The supervisors will ensure correct tools and equipment are suitable for installation- operation and to achieve compliance with contract requirements.
- Before the installation of drainage pipes, trenches shall be prepared, if required. The trenches should not be excavated too far in advance of pipe laying and should be ensured that backfilled done as per civil engineer’s recommendation as soon as possible. Trench widths should be as narrow as Practicable as but not less than the pipe 00 plus 300mm to enable proper compaction of side fill.
- Trench preparation shall be as per the manufacturer’s recommendations & DM regulation based on the laying depth which should also be read along with the approved drawings.
- For deep excavations, the sides of the excavations shall be adequately supported where required to prevent slips or subsidence. Ensure that trench Excavation is according to civil Engineer’s recommendation and approval. The main contractor safety department has to ensure that barriers, warning tapes and necessary warning signs are placed in the excavates. All the permits formalities are to be followed.
- Pipes will be laid on with concrete encasement around tied in for the drainage pipe protection below the raft slab in Basement.
- Pipe will be laid on sand and will be fixed by steel rod in ground floor where we have compaction area and will be hang by clamp in ground floor low level where basement floor below.
- The pipes shall be cut to required lengths by PVC cutter and ends shall be chamfered to remove burrs.
- Before making the joint, ensure that both pipes end and the sealing ring in the socket are clean.
- Push – fit system: suitable type of lubricant as recommended by the manufacturer shall be applied evenly, with a brush over the pipe end and inside the rubber ring socket of fitting to be jointed. Ensure that the components to be joined are correctly aligned, then push the spigot fully in to the socket. The joining of larger diameters is generally accomplished by Appling leverage to the following socket and using a timber block to prevent damage. To allow for expansion, mark the spigot at the socket face and then withdraw the spigot by a minimum of 12mm, if the spigot is already marked with depth of entry, push the spigot home until the mark is just visible.
- The setting out of soil pipe and waste pipe should be set as per the reference grid lines shown in the drawings. Consider the alignment with reference to parking drain, block walls and other drains. In case of any discrepancies found in the drawing, co – ordinate with the architect for the change of location.
- Drainage pipes of approved sizes shall be installed as explained above in proper location as shown on the shop drawings.
- The slope of the drainage pipe shall be maintained as per approved shop drawing which will be checked using spirit level or surveyor level machine or by marking with chalk and stretching the string at both ends as a reference.
- Drain pipe work installed below building & roads shall be provided with 15cm concrete encasement.
- Location where the pipe enters manhole should be such that the location and slope of the pipe entering and exiting the manhole matches perfectly with that of the benching provided inside the manhole.
- Clean outs shall be installed at changes of direction of drainage pipes inside building and where indicated on the drawings. Clean outs shall be not more than 15m apart in horizontal lines for pipe diameters of 100mm and smaller, and 30m apart for larger pipes.
Testing of Underground Drainage Pipes & Fittings
- The whole pipe work as one system and lor the part of the complete pipe work as highlighted in the concerned areas based on the concrete pour progress and site conditions will be tested in accordance with the following points.
- Test plugs are inserted at the lower end of the drain or sewer and the head of any connections.
- A suitable bend together with a vertical length of pipe is fitted at the head of the sewer of drain to provide the necessary test head. The system is then filled with water from top.
- A test pressure of 1.5-meter head above the crown of the pipe is applied at the higher end of the drain or sewer ensuring that the resultant head at the lower end does not exceed 4.0 meter.
- The sewer or drain under test should be filled with water for 8 hours.
- The loss of water over a period of 8 hours should not exceed the equivalent 1 litre per hour, in case any defect is noticed during the test, the nature of this defect shall be identified. If the fittings are cracked or defective, the same shall be replaced. In this case the above test shall be repeated with the engineer witness for conformance.
- Above test shall be carried out by the discipline engineer, checked and offered for witnessing by the engineer.
- Remove the water from the system by removing the test plug slowly to avoid spillage after the test.
- After test is completed, all open ends shall be protected by end caps and to be removed only when adjoin section to be installed.
Read Also: Method Statement for Installation of Earthing and Lighting Protection
Safety – Underground Drainage Pipes & Fittings
Implementation of health & safety machines and check shall be done as per contract agreement & the approved safety manual. The safety office shall carryout the necessary routine inspection.
- Ensure only trained persons shall operate the power tools.
- Ensure all concerned personals shall be PPE and all other items as required.
- Make sure adequate lighting is provided in the working area at night time.
- Ensure service shaft opening are provided with barricade, tape, safety nets.
- All other precautionary measures must be in accordance with HSE requirement.
- Necessary work permit shall be obtained prior to start of any work.
List of Safety Tool Box Talks to be given
- Safety Shoes.
- Hand Gloves
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