WORKING METHOD AND PROCEDURE FOR EARTH WORKS
Excavation
Equipment
All heavy equipment, as mentioned hereunder, required for excavation works will be supplied by company.
• Backhoe Excavators (+Buckets, Hydraulic hammers)
• Wheel Loaders
• Dump Trucks
Mini Skid Loaders
• Bobcat
• Roller compacter
• Water Tanks Trucks
• Air Compressor
Contractor will utilize supplied equipment operated by certified operator for the excavation works.
All previous equipment will be provided by Proximity Warning Alert System except air compressor.
Excavators with bucket will be used for soft and/ or rock excavation.
Excavators attached with hydraulic rock breakers (hammer) will be used for rock excavation. Hydraulic hammer will break rocks into pieces would be collected by the Buckets and load them into dump trucks for transport (if needed).
Excavation permit is a designated work permit process and Gas testing will be done by approved vendor if the depth of excavation exceeds 1 .2 m.
Excavation Execution
• Setting-out will be done in accordance with the IFC drawings. Prior to the commencement, reference benchmark position shall be verified and limits/centerlines of excavation shall be marked. All benchmarks shall be maintained for future check/verification.
• Precise survey instruments will be used for setting-out.
• Excavation dimensions at the ground level will be calculated based on the dimensions of the structure, working space, depth of the excavation & slope to be maintained etc.
• Safety at workplace is to be ensured.
• Excavators attached with buckets will excavate soft soil strata
• As per as dump trucks can reach near the excavator, excavated soil will directly loaded into the dump trucks and transported to the dumping area. This helps to maintain a tidy site.
• Proper access for dump trucks will be maintained.
• When excavation reaches to harder strata where the buckets don’t work, remove buckets and fix
hydraulic jack hammers.
• Jackhammers will break rocks into smaller pieces.
• Collect rock pieces by excavators attached with bucket. Transport by dump trucks.
• Excavation will be done in layers.
• Excavate to grades as required to accommodate the works and provide adequate working space
around the foundations, but not less than 1.2 meters.
• Excavated material which is suitable for General fill shall be stockpiled for future use.
• Care shall be taken to avoid any disturbance to the bottom of excavation. If the bottom is disturbed, the loose material shall be removed.
• When several close excavations are needed, the entire adjoining area may be excavated.
• Adequate access for vehicles to the bottom, if needed, shall be maintained.
• Ensure that all sides of open excavations are maintained in a safe and stable condition by shoring or adequate slopes.
• All Necessary requirements will be taken consideration if the excavation around or near any existing
structure according to Engineer instruction.
• Excavation shall not allow below the existing structures.
• Excavation should be done up to the level shown on the approved drawings.
• Once excavation reaches to sub-grade elevation, make the sub-grade smooth, and free from loose earth.
Backfill
Selection of backfill Material
Backfill Material shall be selected in compliance with SAES-A-114 Para 6.2.
Regardless of the source of supply, any fill material shall be sampled and test by approved Independent Laboratory in order to verify its compliance with SAES-A-114 Para 6.2 standard.
General Fill
General fill material shall be selected from common excavation material which is free from organic
material and debris. It shall contain no rock over 75mm in greatest dimension and shall be capable of being compacted in accordance with the requirements of Project Specifications.