Method Statement Template for Backfilling Work
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Method Statement Template for Backfilling Work

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Method Statement Template for Backfilling Work


Scope of Works.

The purpose of this Method of Statement for backfilling is to outline the materials and labor required to undertake the works in a safe and controlled manner, compiling with relevant legislation, standards, and codes of practice etc.

The method statement shall be briefed to all appropriate operatives to ensure that they are aware of the sequence of activities and any Client/Consultant project specific requirements.

A constant monitoring and supervision duty shall be undertaken by main contractor to ensure work activities are carried out in accordance with the method statement. Any irregularities shall be immediately actioned.

This method statement describes the working procedures for backfilling and all related activities. This will include surface preparation, application, testing, and post application.

General.

Prior to works commencing, the Site Engineer shall ensure that the following activities have been completed and signed-off by the Consultant:

  • Drawing must be approved for construction by the Consultant.
  • Materials Submittals for backfilling is approved by consultant.
  • The Site Engineer shall ensure that the necessary Statutory Authorities approvals have been received.

Reference.

  •  Approved drawings for construction.
  •  Project specification Section D20 (Excavating and Filling).
  •  Approve project quality & safety plan.
  •  Approved back filling materials.
  •  Approved Inspection of Damp Proofing (if required).

Backfilling Procedures.

If excavated materials intended for fill & backfill, test will be conducted to make sure that it is satisfactory materials as required in Technical Specification and approved by the Engineer.

After the excavation is completed up to formation, the formation shall be flooded, and heavy compaction shall be carried out. Any soft areas found during compaction shall be rectified and allowed for drying.

Ensure that the test result of approved materials is available, reviewed and approved by consultant.

Ensure that the backfill material to be used is identical to sample being approved.

Backfilling material must be stored in designated area and shall be inspected if suitable backfill material    based in the project specification requirements.

All rubbish, debris and other foreign material must be removed (sieving can be applied to remove excessive foreign material).

Backfilling of designated area can only be start if the activities (Damp proofing if required, screed protection for the concrete etc.)  prior to backfilling are approved by consultant, plastic protection was provided, and notification / clearance was approved from the side of QA/ QC team.

Compaction of backfilling material will be done every layer using vibratory compactor with corresponding test (FDT) to be witnessed by consultant and the test will be conducted by third party laboratory.

In case that in some point where the compaction did not reach the percentage requirement, re-compaction and retest will be conducted until the compaction reached required percentage as per specification. Note that next layer will be hold until the completion of present layer done with test result approval.

For area near the existing concrete core walls, columns etc. plate compactor will be used to ensure that the compaction will reach the 98 % at the same time to ensure that no damages will be found in the existing part of the structure.

For area with waterproofing or damp proofing, ensure that protection was provided prior to proceed with backfilling to avoid any damage to the waterproofing or damp proofing

Backfilling and compaction will be done up to the required level.

MEP provision to be provided by proper setting out and cutting out of backfill material if required. Note that casting of concrete for protection of embedded MEP material will be done as per approved MEP drawing. 

Benching in filling, if during filling the difference in level between adjacent areas of filling exceed 600 mm, cut into edge of higher filling to form benches 600 mm minimum width and height equivalent to depth of the layer of compacted filling. Spread the new filling and compact to ensure maximum continuity with the previous filling. Where filling is to be placed at sloping ground, the surface of the ground shall bench in steps to enable melding of the fill with existing slope.

Compaction of fill material, all filling material used in earthworks shall be compacted to specification and the enabling works contractor shall submit to the Engineer for approval. Suitable fill material shall be compacted to 95 % maximum dry density, shall be placed within 300 mm of formation level.

Compaction of hardcore filling, granular sub-base material will be compacted to 150 mm thickness to the required grade using water to maintain optimum moisture content. The sub-base shall be compacted to not less than 98 % of the maximum dry density. This for the construction of raft sub-base.

Top layer of the compacted fill must be smooth, level was verified, compaction test was done, application of anti-termite was done (if required) and plastic protection was provided prior to proceed with preparation for blinding concrete.

Testing.



FDT test for every 1500 – 3000 mm layer with 95 % or 98 % degree of compaction with the frequency of 3 test for every 2000 square meter as per project specification.

CBR, Particle size distribution, chemical analysis randomly as per discretion of Engineer / Consultant).

Testing will be conducted by approved third-party laboratory.

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