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

15.17.5.11 During excavation, large stones and rubble shall be separated and removedfrom the excavated soil and stacked separately. The material from excavationshall be deposited on either side of the trench leaving adequate clear distancefrom the edges of the trench and pit or as may be necessary to prevent thesides of the trench / pit to slip or fall or at such a distance and in such a mannerso as to avoid covering fire hydrants, sluice valves, manhole cover, etc. and soas to avoid abutting the wall or structure or causing inconvenience to the publicand other service organization or otherwise as engineer may direct.15.17.5.12.1 Water pipes, drains, sewers, etc. if met with during excavation shall be properlymaintained by contractor, by means of shoring, strutting, planking over,padding or otherwise as engineer may direct, and shall be protected bycontractor from damage during the progress of the work.15.17.5.13. Wherever extra width of excavation shall be necessary for shoring andstrutting, of the trenches on account of the nature of the soil, such extra widthrequired to accommodate the shoring boards shall not be paid for separatelyand the rates quoted for trench work shall be deemed to be inclusive of all suchincidental work.15.17.5.14. All precautions shall be taken during excavation and laying operations to guardagainst possible damage to any existing structures/pipelines of water, gas,sewage etc.15.17.5.15. Utmost care shall be taken to see that the width of the trench at the top of pipeis not more than [External diameter of pipe in mm + 600 mm] + [ 400 mm forevery 1500 mm Depth of cutting] or as specified in the cross section Drawing(in case there is any difference, the latter shall prevail).15.17.5.16. In case additional width is required it shall be provided only in the top portionfrom the ground level up to 300 mm above the crown of pipe. If any extra widthis provided in the area below this portion, Contractor shall have to provideremedial measures in the form of lime concrete or rubble masonry or otherwiseat the discretion and to the satisfaction of Engineer.15.17.5.17 If rock is met with, it shall be removed to 15 cm below the bottom of pipes andfittings / specials and the space resulting shall be refilled with lean cementconcrete of adequate depth, properly consolidated to give the curved seating.15.17.5.17.1 The bottom of the trench shall be properly trimmed to permit even bedding ofthe pipeline. Bottom of trenches / pits shall be saturated with water and wellrammed wherever Engineer may consider it necessary to do so.15.17.5.18 For laying of pipes larger than 1200 mm in diameter, in earth and moorum, thecurvature of the bottom of the trench should match the curvature of the pipe asfar as possible, subtending an angle of 120 degrees at the centre of the pipe.Urban Administration & Development Department Page 187