Site Preparation & Earthwork Procedure

Scope of Work Land Preparation & Work Procedure which I will explain in this article is used for work as follows:
  1. Demolition, clearing and grubbing
  2. Top Soil Stripping
  3. Top Soil Stock pilling and respreading
  4. Disposal of surplus material
  5. Stake out (Survey)
  6. Bulk Excavation 
  7. Open drain construction
  8. Excavation for footings, foundations, and slabs
  9. Trench excavation for services
  10. De - Watering
  11. Backfilling
  12. Compacting
  13. Testing
  14. Site Grading and restoration
  15. Embankment construction
  16. Dust suppression
  17. Geotextile
1 Demolition, Clearing and Grubbing 
Demolition 
Demolition shall include the removal of all specified existing structures, foundations, if any, and pavement. Demolition work shall be limited to the area and objects designated by the Company. The Contractor shall protect benchmark, baseline monuments, property corners and other temporary or permanent surveys marker in the vicinity of the work from destruction or disturbance. The demolition work shall use appropriate equipment as per HSE requirements based on adequate capacity and number for hauling dirt materials. 

Clearing and Grubbing 
The work consists of clearing, grubbing, and disposing of trees, snags, logs, root, stump, shrubs, and rubbish from the designated areas. 

The limits of the area(s) to be cleared and grubbed will be marked by stakes, flags, tree markings, or other suitable methods. 

All trees not marked for preservation and all snags, logs, roots, stumps, shrubs, rubbish, and similar materials shall be cleared from within the limits of the designated areas. Unless otherwise specified, all stumps, roots, and root clusters that have a diameter of 200 mm or larger shall be grubbed out to a depth of at least 600 mm below subgrade for concrete structures and 300 mm below the ground surface at embankment sites and other designated areas. 

2 Top Soil Stripping 
Undisturbed topsoil is off limits to all equipment and vehicles except when such topsoil is being stripped. This will keep disturbances to a minimum and eliminate topsoil contamination. 

All stripped organic soils shall be stock piled adjacent to site and along roadways as appropriate on land provided by Company or Company designated area. 

3 Top Soil Stock pilling and respreading 
Topsoil stripped from an area prior to mining is preserved for later use in a topsoil stockpile. Regulations may require that topsoil not promptly redistributed be stockpiled in such a manner so as to minimize wind and water erosion and unnecessary compaction. The limits of topsoil stockpiles are field staked prior to placement of topsoil. Roads to and from stockpiles need to be stripped of topsoil prior to use. Stockpiles must be marked with a topsoil sign before stockpiling is begun. 

Construction of a ditch or berm should precede any activities associated with material placement in the stockpile. The topsoil stockpile is completely enclosed with this ditch or berm, which should be approximately 1.5 feet high, or higher as needed for sediment control and topsoil conservation. If a sediment control structure is required, the ditch or berm will need to be constructed to ensure drainage to the structure. 

Topsoil stockpile slopes should not exceed 5H:1V, to allow for seeding necessary to prevent erosion. When stockpiling is completed, the stockpile may be scarified parallel to the contour to minimize wind and water erosion. Large rocks uncovered during final grading activities should be removed. 

4 Disposal of surplus material 
All waste materials shall be removed from the project site and legally disposed of in recycling facility. No onsite burning of materials allowed. 

Location of disposal areas and access route are the responsibility of Contractor. No Disposal areas available from Company, unless otherwise specified by Company at the time of execution. Disposal areas of all cleared and grubbed material, and access route of hauling shall be proposed by Contractor and approved by the Company, prior to disposal work by the Contractor. 

5 Stake out (Survey) 
The scope of work under this section includes furnishing labour, technicians, qualified professional surveyors, surveying equipment required to perform all surveying work, setting out and calculations required for construction to establish the accurate location of pipeline route and all gas receiving facilities equipment. 

The Contractor shall performed all survey work and setting out required during contruction stage to establish the accurate location of pipeline route and all gas receiving facilities equipment. 

The Contractor shall set out, construct, establish and maintance the benchmarks in stable areas at the Site for his work. The survey for his bench mark grid shall only be based on approved triangulation points of the national grid. The Contractor shall submit calculations and drawings for the triangulation work done to establish the bench marks. 

The Contractor shall submit in sufficient advance, for approval by the Owner, the methods he intends to apply for the surveying work. 

A survey based on fixed triangulation, polygon points and bench marks both for onshore and offshore survey has been performed by the Owner. The Contractor may use it for his surveying and setting out as reference during construction stage 

The Contractor will obtain plans containing the basic survey with all necessary information. Should the Contractor have any objection to this basic survey and the relevant drawings, he shall inform the Owner in writing within two weeks of this handling over by the Owner. 

Protection of Bench Marks 
The Contractor shall protect, preserve and keep accessible the bench marks of the basic survey and any provided by himself. Any damage or removal of bench marks, shall be avoided as far as possible. Any accidental damage to any bench mark shall immediately be brought to the attention of the Owner. It is expressly understood that the Contractor will be held responsible for damage to the bench marks and the resulting consequences. He shall thus take preventive measures subject to approval in order to minimize the possibility of destroying bench marks. Bench marks must be of stainless steel or cast iron. 

The steel bolt shall be embedded in an absolutely stable concrete block of suitable size subject to approval of the Owner. Inscriptions shall be durable and clearly legible. Intermediate points of the Contractor's triangulation survey used in establishing bench marks may be marked by steel pipes or other pegs, subject to the Owner's approval. Every new bench mark shall be double- checked, as far as possible in relation to points other than those which served to establish the point in question. 

Verification Of Work 
All relevant elements of survey and set out may be checked by the Owner. The Contractor shall notify Owner for this check sufficiently in advance of performing the work. In addition, the Contractor shall assist, if required, the Owner at any time in the performance of the verification work. The Contractor shall keep clear all marks and sightliness required for this purpose. 

Checks will usually be made during work breaks, but in cases of urgency, the Contractor shall restrict or stop affected work without being entitled to extra payment. Any control by the Owner shall not relieve the Contractor of his full responsibility for the accuracy of the position and dimensions of the work and parts there of. 

Personnel and Equipment 
The Contractor shall entrust the surveying only to such persons who by their training and experience have sufficient qualification and knowledge to ensure proper fulfillment of the survey tasks assigned to them. If requested, they shall give the Owner any information relating to the survey. For the performance of the survey, the Contractor shall have a sufficient number of reliable, accurate and well adjusted instruments, the type and quality of which will be subject to the approval of the Owner. 

6 Bulk Excavation 
Unless otherwise indicated unsuitable by the Company, excavated material, which is free from organic materials, may be used for construction fill. The material class ML of ASTM D2478 can be used for fill under engineering control at site and material may need to be tested at Company’s request. 

Upon request by Company, Contractor shall reserve any selected material from excavation, stock pile them within working area limit for future Company usage. 

Excavation work should include remove rock encountered in areas requiring excavation using mechanical methods such as using ripper or other suitable equipment. 

7 Open drain construction 
  1. The storm water shall be drained ditches provided on both sides of the concrete roads. Requirement for placement and earth drainage slope shall conform to soil investigation report. Drainage shall be made of reinforced concrete 
  2. The Contractor shall conduct field design of all water crossing considering maximum discharge capacity of the approval of the Company. Design shall be based upon available meteorological rain fall data 5 years period or site visual record of highest water level. 
  3. The bottom of Structure Bridge, crossing with non-navigated water shall be at minimum clearance 600 mm above maximum water level and shall be not damaged or reached by rising water. 
  4. Catchment area for drainage design shall be accordance to topographical survey and/or shall be visual record on site. 
  5. Culvert shall be installed for road crossing with all buried pipe and other service. The setting of Culvert as water road crossing shall be design avoids neither erosion nor sedimentation 
  6. Bridges that non-navigated water shall be constructed of reinforcement concrete, structural steel, precast concrete or composite materials may be used with guard railing shall be installed at the sides of all bridges. 
8 Excavation for footings, foundations, and slabs 
  • Dugouts for pipes, sewers or drainage concrete and excavations for the Foundation of a bridge or other structure, shall be sufficient in size to allow installation of the material correctly, compaction must be performed after the landfill under and around the job. 
  • The Cofferdam, a shoring and bracing or other action to eject the water must be in place for the creation and examination of the terms of reference and to allow the pumping of outside references. Cofferdam or supporter or confessor who ever been replaced or moved sideways during the excavations and would work in the repair, restored his position and strengthened to ensure freedom of space and safety required during implementation. 
  • The Cofferdam, shoring and bracing made to the Foundation of other structures is placed such that does not cause erosion, cliffs or riverbanks. 
  • If excavations and trenches for sewers or other done on new embankment, then the heap is done to elevation is required, then the trench excavations carried out by the sides match the soil conditions. 
  • When used pile foundation, excavation had been completed until basic elevation of footing before starting erection. 
9 Trench excavation for services 
Under no circumstances will approval be given if it is possible to easily lay the pipe, etc, beneath or around the roots. Trenches for underground services shall be excavated in a straight line using a mechanical excavator or similar approved means. The trench width shall be 300 mm wider than the service to be laid and shall be excavated to the depths shown on Figures 1 to 5 attached. Wider trenches may be approved by the Grounds and Landscape Manager but only where the space is necessary for personnel to enter the trench to connect services. 

Under no circumstances shall trenches be less than 150 mm wide as this will prevent adequate compaction of the backfilling. Where the depth of trenches is to exceed 1.2 m and personnel need to enter the trench, adequate measures shall be taken by the contractor to provide support for the trench. This may require shoring or battering the excavation at a suitable angle depending upon the type of material through which the trench is excavated. The contractor shall comply with all Work Cover requirements for trench support. 

All soft, yielding or other unsuitable material shall be removed and replaced with compacted clean, low plasticity soils or stabilized sand. Unsuitable material shall be removed from the site at full cost of the contractor. 

10 Dewatering 
The installation of horizontal dewatering systems, a trencher installs first an unperformed pipe followed by a synthetic or organic wrapped perforated pipe. The drain length is determined by the drain diameter, soil-conditions and the water table. In general drain lengths of 50 meter is common. After installation of the drainpipe a pump is connected to the drain and water can be pumped out. After the water table has been lowered the intended construction can start. After the construction is finished the pumps are stopped and the water table will rise again. Installation depths up to 6 meter are common. 

11 Backfilling 
Contractor is required to locate suitable sources for filling, back filling and banking materials. 
No borrow pit is available from Company. The source selected by Contractor must be outside Company property areas and approved by Company. 
Filling materials are classified as silty clay or sandy silt or classified by United Soil Classification System/USCS as CL, ML or SM which approved by Company as filling materials. 
Prior to the start of soil embankment or back filling, a bedding surface shall be well prepared, free from any organic material, dry and compacted using the same effort with compaction for the overlaying fill material as required by this specification. 
The furnishing of borrow, when sufficient quantity of suitable backfill materials is not available from on site sources. Backfill materials will be inspected, possibly tested and approved by the Company prior to being installed. 
Filling procedure and compaction requirement shall be made in accordance with attachment 4 of this specification filling and compaction procedure shall be layer by layer with thickness ± 30 cm. Before to next layer should be tested accordance with requipment of dencity and compact each layer to a firm and stable condition using vibratory or impact compaction equipment suitable for the materials, except for the fill and compaction work at live plant as per Company instructions. 
Adjust the moisture content as necessary to archive a condition suitable for compaction. For cohesive materials, the moisture content at the time of compaction shall be within 2 percentage points of optimum. 

12 Compacting 
Where soil has been softened or eroded by water or rain, the Contractor shall remove the fill from the damaged areas and replace the fill and re-compact it. Back fill materials have a uniform dry density and are accordance to ASTM D1557. The density of compacted soil shall be more than 95 % of the Modified Proctor density. 

Compacted clay of 60 cm minimum thickness shall be put on non woven geotextile type. The Company reserves the right to order random compaction tests when in his opinion a sign of compliance failure is observed. In the case that compaction test proof failure to reach required density, the Contractor shall correct soil water content by replacing the soil or air drying and carry out further compaction of the dried soil. 

The Contractor shall take priority to repair any compaction work that does not meet the density requirement in this specification and as specified by result of trial compaction test. 

Adjust the moisture content as necessary to archive a condition suitable for compaction. For cohesive materials, the moisture content at the time of compaction shall be within 2 percentage points of optimum. 

When the water must added, distributed it uniformly over the surface of the layer, and thoroughly incorporates it into the soil to achieve a uniform distribution of moisture throughout the material. When the moisture content is excessive defer compaction until the material has dried to suitable moisture content. 

The work shall be including the performance of all calculations, and the setting of all mark and stakes necessary to ensure that the fill work conform to the requires lines, grade and dimensions, and measured to survey control momentums and benchmarks identified on the drawing or other documents. 

13 Testing 
Compaction Trial Test 
  • Compaction trial test shall be carried out to define optimum moisture content and maximum dry density. 
  • Compaction trial test shall be perform every 1000 cubic meter or whenever material visibly change color, grain, size and plasticity. 
Field Density Test 
Field density test shall be perform one point per 100 m2, the test point should represert the area. 
Next layer embankment is not allowed before the density test result in accordance with the specification. Record of test should include: 
  • Number of compacting passing 
  • Optimum moisture Content (OMC) and Maximum Dry Density (MDD) 
  • Times, Level, and Coordinat 
Equipment Test 
Type, availability, calibration certification and calibration procedure shall be prepared in procedure. 

14 Site Grading and restoration 
Grading work shall conform to any environmental requirements regarding surface runoff, spillage and leaks which should be contained. All other areas of the plant site that are unlikely to be contaminated; runoff shall be diverted away from the processing areas to drain separately and designed to prevent soil erosion and/or sedimentation. 

Remove coal seam encountered in areas requiring excavation to a depth not less than 30 cm below the indicated grade as shown in the drawing. Backfill undercut area with as bedding layer used suitable soils and compacted in accordance with the fill and embankment requirements using suitable equipment. Drainage required to avoid potential water pocketed on any concrete and foundation surface. Drainage function is for avoid direct contact between acid water and concrete, which is potential to concrete damage. When the coal seam excavation must be exposed for an extended period time, during which time inclement weather, water and air (Oxygen) may possible inflected coal compound and potential bitten into concrete, the exposed excavation shall backfill with suitable soils. The grading design encountered in coal seam crop shall consider to the elevation of bottom foundation. The bottom foundation design shall be placed at more than 30 cm above the maximum water level and shall be provide with drainage system. 

15 Embankment construction 
The requirements of density control are as followed : 
  • Unless otherwise specified, all embankments are compacted to at least 95 % of their maximum dry density. 
  • The moisture content is controlled within -2 and +1 percentage points of optimum moisture content. 
  • When type soil are silts, silty loams encountered and used in embankment construction, the moisture content is controlled within -3 percent of optimum and the optimum moisture content. 
  • If the embankment material is too wet, the material is aerated to remove excess moisture. 
  • If the embankment material is too dry, the material is watered and disked to increase the moisture content. 
  • The embankment material is placed in uniform level layers, and compacted with approved compacting equipment. 
  • Compacting equipment is required to include at least a three-wheel roller or other compacting equipment capable of providing a smooth and even surface. 
  • Where a tamping roller is used, the loose depth of lift is required to not exceed the length of the tamper feet. The surface area of the end of each foot of the tamping roller is required to be no less than 5 in2. 
  • Field compaction tests are required to be conducted on each lift, and the required compaction obtained on each lift before the next lift is placed. 
  • The moisture content for sandy soil or a sand and gravel soil, having at least 80 % sand and gravel size particles, is required to be such that the soils may be compacted to the specified density, which is normally several percentage points below optimum or as directed. 
16 Dust suppression 
The use of polymer binders during the road maintenance process (grading and rolling) can improve the stability and compaction of the road, reducing dust and also reducing the frequency of road maintenance. 

17 Geotextile 
Onshore receiving facility area, inspection road at Pipeline ROW Butun Area, and access road to flare stack shall be equipped with layer of non woven geotextile with minimum thickness of 2,5 mm to prevent entrainment of particles in the ground water flow and to prevent the mixing of a single layer of material with other material, a protective layer of non woven geotextile shall be installed. 

Procedure for Instalation Geotextile 
  • Geotextile installation was held on the ground without waves or wrinkles 
  • Requirement for splicing and overlapping Geotextile 
  • Geotextile is placed in the bend in the road must line curve. 
  • Do not create overlapping or stitches in the region in line with the wheel load (traffic load).

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