PREPARATION, GENERAL FILL AND COMPACTION
1.0 OBJECTIVE
1.1 Is to define the procedure for mix, lead, lay, spread and compaction of backfill materials for the contract no GTC.101/ED/01 Engineering, Procurement, Installation and Commissioning (EPIC) of Ras Laffan Utilization Project –Buildings and utilities and support service Phase 1-Utilities.
2.0 SCOPE
2.1 For the backfilling in Service Base Area.
3.0 REFERENCE
Project Approved Drawings
Qatar Petroleum Standard Specification for Civil Works Vol. I, Section 13
British Standards BS 1377, part 2, 3, 12, 13, 15B, 15C.
Qatar Construction Specification Vol. II, Section 12
4.0 PROCEDURE
4.1 SITE CLEARANCE
4.1.1 Prior to commencement of work, the contractor shall obtain the relevant work permits from QP/RLC
4.1.2 The contractor shall under take clearing of site in order to remove any existing vegetation; steel, concrete, unused buildings identified for demolition, piping debris, loose wind blown sand and other foreign materials.
4.1.3. All existing structures, foundations, etc. as indicated above shall be entirely demolished, removed, transported and disposed of by the contractor to a debris yard designated by Qatar Petroleum. All soft spots left shall be filled with suitable material and compacted as per specification.
4.1.4 Excavated material, if any, and suitable and approved by Qatar Petroleum for backfilling shall be transported and placed in fill areas with in the limits of the work.
4.2 SITE PREPARATION
4.2.1 After clearing, grubbing and removal of all unsuitable material from the surface, soil sample will be taken from the existing ground and tested for Maximum Dry Density and Optimum Moisture Content of the existing soil. Then the ground shall be scarified, watered, leveled and compacted. The compacted ground is tested for Field Dry Density test by means of Nuclear Gauge Method so that the upper 250 mm of the compacted subsoil material has a minimum density equal to 95% of the Maximum Dry Density as defined in the BS 1377 part 13.
4.3 FILL MATERIALS-DESERT FILL
4.3.1 Desert fill is a natural well-graded sand/gravel material. The characteristic of desert fill material to be used shall be in accordance with QP Standard Specification Clause 13.9.1
4.3.2 Maximum water-soluble salt contents shall be 2% by dry weight. Plasticity Index shall be limited to a maximum value of 6 as measured in accordance with BS 1377 part 2. It shall not contain an excess of fine or in excess of 2% organic materials as defined in BS 1377 part 3.
4.3.3 Suitable materials shall include unless and otherwise shown in contract drawings, desert fill as described above shall be used exclusively as fill material.
4.3.4 The contractor shall take material approval for the fill materials from Qatar Petroleum prior to transportation of fill materials. Rock fragments in excess of 100 mm, which may exist in natural desert fill material, shall be removed by screening at site or by other appropriate method in order to comply with the gradation limits indicated in QP Standard Specification Clause 13.9.1
4.4 MIXING, SPREADING AND COMPACTION:
4.4.1 Fill materials shall be transported to site, stacked in heap. Water from QP approved source is to be added and mixed thoroughly such that the moisture content of the filling material is with in ±3% of the Optimum Moisture Content. The mixed filling material shall then be spread in layers on the fill area by means of shovels and graders. The first layer shall be maximum of 200 mm thickness of loose materials and the subsequent layers shall be of 250 mm compacted thickness. The spreaded fill material is compacted by single drum vibrating roller with adequate number of passes to achieve the required compaction. The compacted area shall then be tested for required Field Dry Density. Desert fill shall be compacted to a maximum density equal to 95% of Maximum Dry Density as determined by BS 1377 part 13.
4.5 TESTING FREQUENCY:
4.5 .1 Field tests shall be carried out at the following frequency:
4.5.1.1 Density and moisture content (as determined by BS 1377 test 15B or 15C) one test per 500 cu.m of compacted fill.
4.5.1.2 The frequency of insitu compaction testing by means of Nuclear Gauge Method shall be of one test per 2000sq. m of compacted area.
4.5.2 No individual value of density shall be acceptable, if MDD is less than 95%
5.0 RECORDS
5.1 Lab test report of existing soil.
5.2 Lab test report of fill material
5.3 Inspection Reports
5.4 Lab results for insitu Field Dry Density Test
5.5 ITP/Checklist
