Pipe Laying – General operations
1 Roads & Places Approval for the Location of Sewage Pipe Trace
Before the commencement of any sort of excavation on roads or any other places, the approval should be obtained from relevant Authorities with the assistance of the Engineer.
2 Identifying underground services
Details of existing underground services such as power, telecom and water etc. are ascertained from respective institutions and further by trial pits.
3 Transporting, Handling and Storage of Sewage Pipes
Precautionary actions are initiated to prevent damage of pipes in transportation, handling and storage when required. They will be lifted by means of mechanical forklift or similar equipment. Belt slings will be applied at the correct lifting points along the length with tackle suitably padded to prevent damage to the coating.
Pipes will be stocked on timber cradles on level ground, so that there will be no any damage to any part of the pipe. During stacking and removal operations, safe access to the top of the stack will be provided. Stacking type and the maximum stacking height will be done in accordance with manufacturer’s recommendations.
4 Trench Excavation
Trench excavation for lying of pipes shall be open cut and will be done according to the approved drawings and specifications provided. Either backhoe loaders or mini excavators will be used for the excavation work and for narrow roads and stretchers where machinery cannot travel, manual excavation will be done. All surplus excavated material and materials arising from site clearance will be disposed from the site to a selected dumping yard.
Before commencing trench excavations, the route of the trench will be determined accurately. Trial holes will be excavated ahead of the trench excavation to determine and confirm the alignment for the trench where necessary and for the detection of underground services.
Excavated surfaces too steep to be safe and stable if unsupported and to safeguard the work & workmen, to prevent sliding or settling of the adjacent ground and to avoid damaging existing structures or whatever, either steel or timber shoring will be provided to meet safety requirements where necessary.
Catch pits will be prepared in the trenches for the purpose of dewatering if water logged. Either submersible or centrifugal sludge pumps will be used for this purpose.
When the excavated soil, suitable for backfilling is insufficient, additional soil will be imported from approved borrow pits.
In backfilling, Trench will be filled with specified material in approximately horizontal layers and compacted by mechanical compactors to achieve the expected compaction, here necessary vibrator roller will be used. w
5 Pipeline Installations
In handling pipes every care will be taken to avoid distortion or other damage to pipes. Pipes will not be allowed to drop or strike objects & will be lifted by means of the mobile crane & belts will be used at the correct lifting points of the pipe.
As far as possible, pipes will be lowered into trench by using either crane or excavator. No pipe will be rolled from place to place or into trench except over suitable timber planking free from roughness likely to damage coating. If the prepared bed is disturbed for any reason, the pipe will be raised and the bed is made good before pipe laying is continued.
Pipe installation with push-in joints will be in accordance with the manufacturer’s
recommendations. Sockets and spigots will be thoroughly cleaned prior to making the joint. The lubricant recommended by the manufacturer will be used.
6 Concrete Works
Normally, concrete pipe bedding for sewage pipe should be applied before the pipe installation according to the design. No pipe should be installed before the hardening of the concrete.
The sewage line between two chambers will be hydrostatically tested according to the approved method. All tests will be conducted on the pipelines before the trench is fully backfilled.
All precautions will be taken to prevent the damage either to human or property. To identify the excavation area, sign boards and barricade tapes will be displayed. With regard to human safety, workers involved in trenching will wear safety helmets and boots. Workers will not be allowed to work under heavy machineries such as Cranes, Excavators, and Boom Trucks etc.
For night work, sufficient illumination will be provided. Exposed live wires will not be placed without proper insulation.
Sufficient number of traffic cones, barricade tapes, warning boards and lamps and signalmen are deployed to control traffic flow, so that the work can be performed maintaining safety and perfect- ness.
Depending on situation, traffic diversions are introduced with proper approval.
10 “As-Built” Drawings
“As-built” drawings are produced as specified on each portion of work when completed.
11 Handing Over of the Works
Handing over the Project to the Employer will be effected exactly as per the specifications.