Specification Part 3 - Road & Bridge Works - Urban Administration ...

304.4 Measurements for Payment
Excavation for structures shall be measured in cu.m for each class of material encountered, limited to
the dimensions shown on the drawings or as directed by the Engineer. Excavation over increased width,
cutting of slopes, production /support to the existing structures shoring, shuttering and planking shall be
deemed as convenience for the Contractor in executing the work and shall not be measured and paid
separately.
Preparation of rock foundation shall be measured in square metres. Foundation sealing, dewatering,
including pumping shall be deemed to be incidental to the work unless separate provision is made for in
the Contract. In the latter case, payment shall be on lumpsum basis as provided in the Bill of
Quantities.
304.5 Rates
304.5.1 The Contract unit rate for the items of excavation for structures shall be payment in full for
carrying out the required operations including full compensation for:
i) Setting out;
ii) Construction of necessary cofferdams, cribs\sheeting, shoring and bracing and their subsequent
removal;
iii) Removal of all logs, stumps, grubs and other deleterious matter and obstructions, for placing
the foundations including trimming of bottoms of excavations;
iv) Foundation sealing, dewatering including pumping when no separate provision for it is made in
the Contract:
v) Backfilling, clearing up the site and disposal of all surplus material with all lifts and leads or as
otherwise specified; and
vi) All labour, materials, tools, equipment, safety measures, diversion of traffic and incidentals
necessary to complete the work to Specifications.
304.5.2 The Contract unit rate for preparation of rock foundation shall be full compensation for cutting,
trimming and cleaning the foundation surface and filling/sealing of all seams with cement grout or mortar
including all materials, labour and incidentals required for completing the work.
304.5.3 Summary of excavation work in brief
1. After site clearance, the limits of excavation should be set out true to lines, curves, slopes,
grades and cross-sections as shown on the drawings by constructing reference pillars, back cutting
lines, reference lines.
2. If directed, the top soil shall be stripped to specified depths and stockpiled for reuse.
3. Excavation shall be done manually or mechanically using machine. After excavation, the sides
of excavated area should be trimmed and the area contoured to minimise erosion and ponding, allowing
natural drainage to take place.
4. The cut formation, which will serve as sub-grade, should be checked for its field dry density and
if the field dry density of the material in the top 500 mm portion is less as compared to table No.-300-3,
the formation material shall be loosened to a depth of 500 mm and compacted in layer to achive dry
density as per Table No.- 300-3.
5. In hilly areas, cutting should be done from top to bottom. Special attention should also be paid
to side slopes.
6. Rock when encountered in road excavation shall be removed upto the formation level. Where
unstable shales or other unsuitable materials are encountered at the formation level, these shall be
excavated to the extent of 500 mm below the formation level.
7. In rocky formation, the surface irregularities shall be corrected with granular base material to
achieve the specified profile and levels.
8. Classification of Excavation shall be done as per clause 301.2.
9. Blasting Operation shall be done as per Clause 302.
10. Presplitting Rock Excavation Slopes shall be done as per Clause 303.