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

5.13.6.1 Within 20 second after the last application of solvent cement, insert the pipe into socket in a single steady and every controlled but forceful action. Press it infully until it bottoms. No. hammer blows should be used. If there is any sign ofdrying of the cement coat before insertion; the surface should be re-coated,avoiding application of excess cement in the socket. Once the insertion iscomplete, hold in place for 1 min without shifting the pipe in the socket.5.13.7 Immediately after assembly, wipe the excess solvent cement from the pipe atthe end of the socket. A properly made joint will have a uniform bead around itsentire perimeter. Any gaps in this bead may be indicative of an improper jointdue to insufficient cement or the use of a lighter-bodied cement than the onerecommended.5.14 Trench:-(See Drawing No.-3)5.14.1 Location: Drinking water pipelines should not be located below seweragepipelines. Where a pipeline runs parallel to other pipelines or cables, thedistance between them should not be less than 0.4 m.5.14.2 At points of congestion, a distance of 0.2 m should be maintained unless stepsare taken to prevent direct contact.5.14.3 Width: Trenches should be of adequate width to allow the burial of pipe, whilebeing as narrow as practical. If expansion and contraction are not problemsand snaking of pipe is not required, minimum trench widths may be obtained byjointing the pipe outside the trench and then lowering the piping into the trenchafter the testing. A trench width of two or three times the pipe diameter is agood rule of thumb. Narrow (unsupported) trench width and supported trenchwidth shall be as given under:Nominal pipe size(Diameter in mm)Table No.5.6Unsupported NarrowTrench Width (Minimum)Number ofpipe Diameter Width (mm)Supported Trench Width,(Minimum)Number of pipe WidthDiameter (mm)90 5.0 450 10.0 900110 4.0 450 8.2 900125 4.0 500 7.2 900140 3.9 550 6.4 900160 3.5 560 5.6 900180 3.2 580 5.0 900200 3.0 600 4.5 9005.14.4 Where necessary to prevent cave-ins, trench excavations in unstable soil shallbe adequately supported. As backfill is placed and sheeting withdrawn, the voidleft by the withdrawn sheeting shall be filled and compacted before withdrawingthe next increment.Urban Administration & Development Department Page 61