Method Statement for Excavation Compaction and Back-filling | Construction Engineering | Field Compaction Test | Excavation Safety Work | Civil Works
In this article we will discuss about Method Statement for Excavation Compaction and Backfilling | Civil Works | Construction Engineering | Field Compaction Test | Excavation Safety Work | Inspection and Testing.
SCOPE OF WORK: Method Statement for Excavation Compaction and Back-filling
This procedure is issued to describe the work processes involved in construction of the excavation of concrete structure foundations, and other facilities for (Project Name) at (City Name). The latest revision of the PROJECT specifications shall be used as references and is part of this Method Statement in the execution of work.
Method Statement for Excavation Compaction and Back-filling, Civil Works
- An open cut type of excavation shall be applied with safe side slopes.
- Shoring and bracing system shall be used whenever required to protect adjacent structure if any, in an excavation site or when the excavation side slope is steeper than those mention below.
- Suitable and appropriate excavator and compacting equipment shall be used to carry out the works.
- Safe angle and clearance of excavation: Method Statement for Excavation Compaction and Backfilling
The entire excavation slope shall be as per project specification of excavation specification. Angle =45° is applied to major soil strata found in the Plant site. Clearance of 1.0 meter from excavation top edge to barricade shall always be kept.
- Excavated soil material will be removed immediately from the work site and equipment shall be kept away from the excavation top edge.
- All access walkways, Ramps, Stair & Bridges shall be equipped with guard rails. All Walkway crossings shall be equipped with tightly secured uniformly sized planking. There shall always be a safe access way for entry and exit. For excavations that are long, there shall be an access way as per requirements. Construction Engineering
DUTIES AND RESPONSIBILITIES:
Civil Superintendent: Method Statement for Excavation Compaction and Back-filling
The Civil Superintendent shall be responsible for the over-all direction, monitoring coordination and control of all the construction activities attached and related to the excavation works.
The QA/QC Inspector shall be responsible for the necessary inspections and tests to be carried out for all the activities involved in the excavation, such as excavation bottom compaction test and as per the Inspection Test Plan (ITP).
The Site Supervisor shall be directly involved in the planning and execution of the activities involved in the excavation. He shall be responsible for the preparation of excavation plan, Safety Action Plan and job safe analysis (JSA). Safe work plan application for work permits is required prior to commence of any excavation. Supervisor to develop a JSA on a weekly basis and update is necessary when conditions change. Construction Engineering
The Excavation/Equipment Foreman shall be responsible for the direct execution of works involved in the excavation process according to the plan and shall directly control and give instruction to the working personnel. He shall also ensure that works are performed with proper tools/equipment, PPE and good housekeeping around the working area and that all equipment has been safety checked and registered in the log. Inspection and Testing
Safety Manager or Supervisor shall review prior to the start of the work Safe Work Plan and work permit is required, prior to submittal to the SD that must be implemented and observed during the excavation works. Field Compaction Test
TOOLS AND EQUIPMENT’S:
• Backhoe (power excavator)
• Dump truck
• Fuel Truck
• Water Truck
• Roller Compactor, Plate Compactor, Ram Compactor ,Hand Shovel
• Shoring Materials
- Verify the detail of excavation according to the latest Issued For Construction (IFC) drawing before the start of the work. Conduct a survey and mark the location and the limits of the area to be excavated. Allowance should be provided to have enough working space between the foundation to be constructed and the edge of the bottom of the excavation for the personnel and forms, bracing and supports to be installed. In marking the excavation limits, consideration should also be given for additional area to accommodate side slopes of the excavation. Inspection and Testing
- Determine the depth of the excavation from the existing ground taking reference from the latest IFC drawing.
- Coordinate with other disciplines involved, to verify any existing service/utility lines such as water line, power line and telephone line running through boundaries of excavation is mandatory before starting work.
- All excavations shall be hard barricaded at all times.
- Set up barricades and signboards around the area to prevent unwanted persons from entering the excavation site. Before starting excavation, verify under ground services if any is existing.
- Report immediately to the company any unknown underground installation encountered during excavation. Stop work and wait for further instructions.
- Excavate trial pits where required and as instructed by company when existing utility lines or facilities are encountered, to establish the exact location. The excavation shall be done manually and carefully in order not to damage the utility lines or facilities.
Start the excavation carefully:
- Use mechanical excavator whenever possible and if the site condition permits. Excavation permit will be obtained before starting the work. Excavate manually around existing structure or in congested area where the use of power machines are not possible.
- Barricade shall be placed around the machine operation area.
- Where the excavation site is close to the existing structures, sufficient shoring and bracing system shall be planned and approved by Safety Department and then built against the excavation wall to prevent any possible collapse of the excavation slope and also damage to the structures. Where the excavation extends below the foundation of existing adjacent structures well planned and approved measures to protect that structure must be provided. Inspection and Testing
- Excavate up to the desired level, width and length as required to conform to the latest IFC drawing. The vertical tolerance shall be as per specification.
- When the desired bottom elevation is reached, level and compact the ground by using an appropriate machine such as roller, jumper or plate compactors up to the required density to confirm with the Project Specification requirement.
- Remove and replace with compacted suitable fill, any sort of contaminated soil, if any, found at excavation bottom.
BACK-FILL AND COMPACTION:
Back-filling will be carried out by following the norms as set out hereunder column:
- Back-filling will commence only after completion of inspection and test of below grade structures is complete.
- Structural fill or back-fill placed beneath footings, grade beams, mat foundations, or any settlement sensitive structures shall be compacted to at least 95 percent of the maximum dry density as determined by ASTM D 1557.
- Back-fill adjacent to structures and not supporting any footing, grade beams or mat foundations, shall be compacted and then tested for in-place density in accordance with ASTM D 1556. The tested density shall be at least 90 percent of the maximum dry density as determined by ASTM D 1557.
- The moisture content of the material being compacted shall be within ercent of the optimum moisture content as determined by ASTM D 1557.
- Structural fill or back-fill adjacent to structures shall be placed in 150 mm (6 in), compacted layers, or less if necessary to develop specified density. shall be at least 95 percent of the maximum dry density, as determined by ASTM D 1557.
- Back-filling will be done using the approved fill material or select granular material as per drawings. Each layer will be compacted to a dry density, depending on the area of working. When granular material is used, it will be compacted to a firm and stable condition using an appropriate compacting device. Back-fill material shall conform to relevant project specifications.
- Back-filling will proceed symmetrically about the structure, whenever possible to do so.
- The concrete sides will not be back-filled until the specified coatings are applied and fully cured on the concrete surface.
- The water for the compaction will be added uniformly. If required, the fill material will be ploughed to uniform water content before compacting. If drying is required, the same will be done by way of natural drying. In case additional dry material is added for drying, care will be taken to see that the layer thickness does not exceed that specified.
Inspection shall be based on approved ITP, QC Plan and Project Specifications listed in under Technical Specification or as stated on the latest IFC drawing.
Safety of men and materials is a high priority. All safety measures will be observed during the entire works. Brief account of the safety strategy is given under:
- All the activities will be envisaged a week in advance and job safety requirements will be worked out by analyzing the likely hazards and resorting to preventive.
- Proper house keeping at the end of the day is a part of the mandatory tasks assigned to workers to avoid accidents due to littered tools and materials.
- Flagmen will be engaged to control the movement of trailers, cranes, pumps and other mobile equipment’s.
- Weekly tool box talk will be conducted and brief safety measures required for the ensuing days will be discussed.
- First aid facility will be available entire the period in the work site.