Procedure for Earth Backfilling Works At Site

This procedure describes the steps to be taken and sequence of events necessary to enable satisfactory completion of each activity.

1.Ensure that all IFC and reference drawings have been issued to responsible personnel handling the work.

 2.Project END document control section provides all relevant personnel approved procedures associated with backfilling works in control manner.

 3.The Civil Supervisor shall verify availability of approved compaction equipment and operators. Secure work permits and check work areas accessibility to Dump trucks that hauling the backfill / fill materials and other filling equipments. Use only fillIing materials that are approved by OWNER. When excavated material can be utilized for backfilling, the same with imported materials it shall be placed / laid at layer not more than 150 mm thick structural fill. Each layer shall be fully compacted and tested to the required density. 

 4.The Safety officer shall ensure erect barriers / tapes, caution boards, and other necessary warning sign. (Reference Approved Project Safety Plan).

 5.The Engineering Department.shall prepare and submit plan / work procedure and fill materials (except for excavated materials) for approval of OWNER / GENCON. 

 6.Civil Operation Section shall execute the filling / backfilling work in accordance SES C02-S02 and YPC-C02-S02 and ensure the following are being taken as a minimum: 

• a )Areas to receive fill materials shall be free of water, roots, trash, and other for foreign materials.
• b )Use only fill materials that are approved by OWNER. 
• c )Compaction shall begin only after the fill or backfill has been properly placed, and the material to be compacted is shall be within ± 2 percent of OMC (Optimum Moisture Content).
• d )All compaction equipment shall be suitable for the entire lift being compacted and the type of fill material being compacted. The type and size of hand-operated vibratory compactor and power tampers for use in restricted areas shall be suitable to perform the required compaction.
• e )Fill & backfill adjacent to structures (i.e. retaining walls, pits, and basements) shall not be compacted with heavy equipment. It shall be compacted with hand operated equipment up to a distance of 1.2 m (4 ft.) beyond the side of structures. 
• f )Structural fill or backfill placed beneath footing, grade beams, mat foundation, or any settlement sensitive structures shall be compacted to at least 95 % of the maximum dry density as determined by ASTM D 1557.

g )Backfill adjacent to structures not supporting any footing, grade beams or mat footing shall be compacted and then tested at least 90 % of the maximum dry density as determined by ASTM D 1557.

h )For base course for roads, parking areas and paved areas to be surfaced, it shall be prepared as follows:

• h.1 The existing ground, up to the toe of fill slopes shall be cleared, grubbed and stripped in accordance with SES C02- S01.
• h.2 Fill for the base coursed shall comply with paragraph 4 and 8.2 of specification SES C02-S01.
• h.3  The base course shall be graded and finished to within a vertical tolerance of (+) or (-) 10 or 15 mm of the elevations as indicated on the Approved for Construction Drawings.

i )For Bedding & Backfilling of Piping Underground (i.e. GRP, FRP,  C.S. Steel Pipe): 

• i.1 .Pipe bedding materials shall be compacted to minimum 90 % of maximum dry density per ASTM D-1577.
• i.2 .The finish bed shall be plane, of the minimum depth shown in drawing and shall provide uniform and continuous support for the pipe. Prior to pipe placement, slightly loosen the compacted bed at the invert location to a depth 25 to 50mm so the pipe when position into the trench seat well into the bed. Civil section shall inspect over excavation of the bed at each coupling joint location to insure that pipe will have continuous support.
• i.3 Bedding and backfilling materials in the pipe zone shall be cleaned sand conforming to ASTM C 33. Native soil shall only be used for backfill above the pipe zone backfill.
• i.4 .The backfill material shall not be frozen or contaminated with debris or other foreign matter that could damage the pipe or cause loss of side support.
• i.5.A board or other blunt tools shall be used to push and compact backfill under the pipe.
• i.6.Proper backfilling for pipe shall be done as follows:

- For pipe smaller pipe less than 300 mm, each lift height to be half the pipe diameter or 110 mm which ever is greater.

-.For larger diameter pipe more than 300 mm, each lift height to be 150 mm to 300 mm depending on backfill material and compaction method.

j ) Compacted surfaces of fill and backfill shall be finish graded to the cross sections, lines, grades and elevations as indicated on the approved construction drawings, within a vertical tolerance of (+) or (-) 15mm.

7. QC Civil Inspector shall check the following items before start inspection:

a) Appropriate use of the latest IFC drawings.

b) All other civil related works are completed and accepted.

c) Ensure that measuring instruments are in current state of calibration and being used in the prescribe manners.

8. Civil Supervisor shall submit request for inspection (RFI) to site QC section. 

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1. Purpose

2. Scope of Work

3. Definition

4. References

5. Responsibilities

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