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

esults in unsuitable sub grade conditions, and which well require any specialfoundations as directed by the Engineer, such foundations shall be placed atthe entire cost of the contractor and will not be measured or paid for asseparate pay items.15.17.9.5 If the contractor selects to under cut the trench and use gravel or tile bailing,drainage of well pointing, the additional work will be considered as incidentalwork and additional compensation will not be allowed.15.17.10 Special foundation in poor soil15.17.10.1 Where the bottom of the trench at sub grade is found to consist of materialwhich is unstable to such a degree that in the opinion of Engineer, it cannot beremoved and replaced with approved material thoroughly compacted in placeto support the pipe properly, a suitable foundation for the pipes, consisting ofpiling, timbers or other materials, in accordance with relevant drawings and asinstructed by Engineer shall be constructed.15.17.10.2 During the progress of the work, should the foundation for the pipeline be insoft, yielding or spongy materials which are unsuitable for the sub grade of thepipeline and which is not the result of theproper provisions for adequate drainage of the excavation, the contractor shallremove such unsuitable sub grade materials to the depth directed by theengineer. The contractor shall fill the excavated depth in the mannerhereinafter described or as directed by the Engineer.15.17.10.3 The contract unit for foundation shall be one cubic meter. The foundation willbe measured for payment complete in place. The contract unit price shall bethe total compensation for furnishing all labour, tools, materials, equipment andincidentals necessary to complete the work, including all excavation anddisposal of surplus material.15.17.10.4 Gravel Foundation15.17.10.4.1 The space resulting from removal of unsuitable materials shall be filled withgravel. No extra payments will be made on this account, except for leadcharges if any beyond 50m15.17.10.5 Rock Foundation15.17.10.5.1 The space resulting from the removal of unsuitable materials shall be filled withcrushed stone, local lime stone rock, free from loamy soil, clay and vegetablematter, graded in size from 25 mm to 30 mm in general.15.17.11. Wooden shoring15.17.11.1 Contractor shall suitably design polling boards, walling and struts to meetdifferent soil conditions that might be encountered in excavating trenches / pits.The horizontal and vertical spacing of struts shall be such that not only thesides of trenches shall be prevented from collapse but also easy lowering ofpipe in trenches shall be ensured without creating undue obstructions for theexcavation of the work.15.17.11.2 Any inconvenience and / or delay that might be caused in lowering pipes intrenches as a result of adopting improper spacing of struts by contractor shallbe his sole responsibility. While taking out shoring planks the hollows of anyform must simultaneously be filled in with soft earth well rammed with rammersand with water.Urban Administration & Development Department Page 190