Excavation –
- Trenches shall be dug to exact width of foundation and to the maximum should be vertical (vertically especially to maximum height as the thickness of lean concrete is 8 to 10 inches.
- In case of loose soil, extra payment for shoring may be required to retain the soil.
- Material shall be placed minimum 1m away from trench.
- Normal lift and lead are 1.5m and 30m respectively.
- If contractors digs the trench more than required then the extra depth has to be refilled with earth or concrete. Rammers of 6kg and area 200 sq. cm. are used.
- Both directions of the trench have to be levelled.
- In case if there are any organic material, these materials should be taken out and replaced with good quality soil in layers of 200mm and the compacted.
- During excavation if any of historic materials like coins, fossils, etc. are found, they must be handed over to the government.
- In case if ground water table is very high, extra payment is made to the contractor for dewatering.
- During rains, if trenches are filled with water as he has not put any covering, he will have to pump out the water.
- While refilling, good quality soil should be used.
Dimensions – width of lean concrete and depth of foundation is set according to the design.
Rates – cost of tools and equipments, labor required, lift and lead and proper margins are considered.
Verry thanks for inf.