Specifications Part 1 - Water Supply, Sewerage and Tube Well Works

5.17.3 Where concrete would be in direct contact with the pipe or fittings, these shouldbe wrapped with a compressible material, for example rubber sheet or foamedpolyethylene sheet, to accommodate creep and prevent the occurrence of highlocal stress concentrations.5.18 Back-filling5.18.1 The first side fill or hunching layer should be placed by hand and compacted inlayers under the lower quadrants of the pipe up to the spring level (half thevertical diameter) of the pipe.5.18.2 Compaction can be done by careful trampling with the feet or with tramplingtool.5.18.3 Care should be taken to leave adequate area around the joint free of backfill toallow for inspection during testing of the pipeline.5.18.4 Successive layers of backfill of 75 mm thickness may then be placed over andcompacted to a height above the crown of not less than 150 mm. Lightvibrating machinery may be used, but not directly above the pipe.5.18.5 On completion of the surround to the pipe, suitable excavated material may bethen replaced as backfill in 250 mm compacted layers up to the top of thetrench.5.18.6 No heavy compaction equipment to be employed until there is at least 300mmof fill above the crown of the pipe.15.19 Measurement15.19.1 The net length of pipes as laid or installed shall be measured in running meterscorrect to a cm. Specials shall be excluded and enumerated and paidseparately under the relevant item. The portion of pipe at the joints (inside thejoint) shall not be included in the length of the pipe work. Excavation, refilling,masonry and concrete work (as required) shall be measured and paid forseparately under relevant item of work.15.20 Rates:The rate shall include the cast of the material and labour involvedin all the operation described in the item.Urban Administration & Development Department Page 63