• Construction control and reference bench marks shall be established at the site. (Refer to PMDB01SGP – Method Statement for Survey Works). These construction control and reference bench marks shall be used as reference for all surveys in the project.
• Temporary reference points shall be provided using non-corrodable pins or plates set in concrete of suitable proportions to avoid movement of the point.
• Permanent Setting Out Stations shall be accurately positioned at location as shown on the drawings and shall be adequately protected from damage during the construction of the works. Stations that are damaged or displaced shall be replaced accordingly.
• In receipt of relevant permits, site clearing shall be started by means of manpower and/or machinery in a safe and tidy manner.
• Removal of vegetation layer to an average depth of 150mm, clearing and grubbing all surface objects, trees, including brush, shrubs, debris and top soil materials.
• Levelling and trimming of top soil to required depth shall be done using mechanized equipment.
• A separate notification shall be forwarded for getting approval for cutting trees, which is with a diameter of 300 mm and over.
• The trees to be cut shall be identified and marked during joint inspection with client representative. The location, type, size of trees to be cut shall be recorded in the inspection sheet which will be certified by clients.
• Trees to be removed shall be safely cut down and their roots grubbed up.
• Tie-up trunk of the tree with tug line.
• Cut the main trunk of the tree by chainsaw.
• Dig up the earth on the front portion of the trunk until its main roots are exposed and extracted.
• With the use of backhoe, excavate the stump until it is uprooted. Ensure that the backhoe is positioned in a way that when the tree is pushed, it will fall completely to the ground without hitting or falling on other objects.
• Cut the main trunk and branches of the tree to segregate twigs and leaves.
• Trunk and main branches shall be cut into a length suited to fit the dump truck for hauling and disposal.
General Procedures of Excavation Works
• All excavations shall be barricaded using barricades and applicable warning signs. (Deep Excavation, etc.)
• All excavations beside vehicular traffic area shall be barricaded with hard barriers for safety.
• Excavation shall be executed by the use of an excavator/rock breaker, or manually, where required.
• Excavation stability shall be maintained through side sloping or shoring and bracing as per safe working practices. The sides of the excavated area shall be covered with blue sheets to avoid soil erosion during rainy days. A supply of other shoring materials will be available for instances where neither of the above methods for preventing collapses are suitable.
• As the excavation progresses, the characteristics of the soil will be monitored and decide whether a shoring is required or not. (separate methodology will be provided if and when shoring is required)
• As applicable and practicable, the preferred method of ensuring safety in Excavations will be by battering or benching.
• Loader/dump trucks shall be used to stockpile the excavated materials.
• If subsurface water accumulates in the excavation pit, dewatering shall be used.
• Possible suitable materials shall be loaded to dump trucks and placed in stockpile area for sampling, testing, evaluation and approval of client prior to use.
• Unsuitable materials shall be loaded to dump trucks and placed in the stockpile area for disposal or in a later time.
• If the pit is deep enough for the backhoe to reach it, a ramp will be constructed to be used as access of equipment in going inside the pit.
• The depth and size of excavation will be closely monitored by a survey team using survey instruments.
Top Soil Stripping
• All top soil and all debris off-site shall be removed to a maximum depth of:
• 100 mm for the outline of the general outline area. This includes former storage areas (gravelled, L1, L2, L3), Parking Area, and Office Area A.
• 300 mm for the outline of the general outline area. This includes construction area Unit 70, and 02UST01/02.
• 600 mm for the outline of the general outline area. This includes construction corridor PAB.
Hauling and Disposal
• Hauling of spoil/ unsuitable materials shall be disposed simultaneously outside the jobsite.
• Strict environmental compliance shall be implemented with regards to disposal of any materials or debris. The materials and debris shall be transported and dumped into the disposal area(s) as specified in the contract specification.
• Before use, the geotextile shall be stored in a clean, dry location out of direct sunlight, not subject to extremes of either hot or cold temperatures, and with the manufacturer’s protective cover undisturbed. Receiving, storage and handling at the jobsite shall be in accordance with the required standard.
• Geotextile must be identified and installed in such a way that its physical property values are not affected and that the design conditions are met as intended.
• The surface on which the geotextile is to be placed shall be graded to the neat lines and grades as shown on the drawings. It shall be reasonably smooth and free of loose rock and clods, holes, depressions, projections, muddy conditions and standing or flowing water.
• Installation guidelines of manufacturer shall be followed. Geotextiles must conform to the surface and placed smooth and wrinkle free with laps in either direction to at least 600mm overlap.
• Cover materials shall be placed in lifts such that no equipment is operated directly on geotextile and compacted carefully to avoid any damage, displacement or overstressing of the geotextile. The first fill layer on top the geotextile of a minimum thickness of 300mm shall compacted statically not dynamically.
Filling, Backfilling and Compaction
• Filling or backfilling shall commence upon completion of the following works:
• Acceptance of all surface areas to received filling or backfilling.
• Areas to received filling or backfilling shall be clear of top soil, rubbish, scrap material and standing water. Removal of formworks, shoring, bracing, trash and debris where applicable.
• Testing and acceptance of test results by client’s representative.
• Acceptance and approval of client’s representative.
• Survey the elevation of the exposed sub-grade (NGL). Check and ensure all required elevations are based on approved survey reference control points. Elevation of every layer shall be marked near the filling area and assure markings are not disturbed.
• Received/delivered approved filling materials must be free from debris or unsuitable components. Using backhoe, dump delivered fill materials to final location or stock pile if area is not yet ready.
• A trial tests shall be conducted in the trial area to determine how many number of passes of vibratory roller compactor required to achieved the required compaction.
• Spread fill materials using bulldozer/ backhoe or payloader (each layer thickness shall be compacted to a minimum of +150mm – 200mm = 6 – 8 inches each lift).
• Fill materials shall be compacted using mechanized vibratory roller compactor to a dry density not less than 95% of its maximum dry density as determined by ASTM D698 or equivalent. For soil not suitable for Proctor tests the corresponding relative density test ASTM D2049 is to be used.
• Field density tests on fill materials shall be in accordance with ASTM or equivalent Standards. Additional pass(es) of the vibratory roller is required if the required field density is not obtained. The frequency of these test shall be:
• Large areas of fill in excess of 5000m² : 3 tests per layer
• For areas of fill less than 5000m² : not less than 2 tests per layer.
• For road works preparation: 1 test per 100m.
• Results of all tests shall be submitted to client within 24 hours of each test. A weekly summary report of all tests shall be submitted to client.
• Top 1 inch of the lift should be scarified to promote bonding with the succeeding layer.
• Survey data must be obtained for every layer prior to filling of the next layer.
• Care of water shall be implemented in case of water ponding due to heavy rains and shallow water table.
• Joint inspection with client will be conducted and the area filled is acknowledged by accomplishing Request for Inspection RFIA form.