WORK METHOD STATEMENT FOR SITE PREPARATION WORKS BEFORE START OF ANY MAJOR PROJECTS CONTENTS

A Vision To Clear Solutions.

1 PURPOSE
2 SCOPE
3 REFERENCES
3.1 Company Specifications
3.2 Project Specifications
3.3 Drawings and Documents
3.4 Codes and Standards
4 RESPONSIBILITIES
5 METHODS
5.1 Definitions
5.2 Preliminary Activities
5.3 Top Soil Removal
5.4 Fill Material
5.5 Fill and Compaction
5.6 Slope Erosion Protection
5.7 Testing and Inspection
5.8 Disposal
Attachment #1 Topographical Survey Results
Attachment #2 Area classification for Site Preparation
Attachment #3 Field Fill Trials Program

Purpose

The purpose of this Work Method Statement is to outline the general requirements and precautionary description of the site preparation works to be performed for any project.

SCOPE

This Work Method Statement identifies the general steps, arrangements and precautions to be followed for the execution of all activities of site preparation works before the foundation works start by consultant and contractor.

The General Scope of Work of the Contractor includes, but is not limited to supply and construction of the following:
– Site Preparation works (Top Soil Removal, Fill, Compaction and Slope Protection Works);

– Other miscellaneous site preparation works not mentioned above;

The expected period of the Site Preparation Works is approximately 8 months.

REFERENCES
The Site Preparation Works shall be designed, planned and performed in compliance with the following applicable Specifications and Codes.

In case of conflict, the order of precedence of the documents shall be:
• Client Specifications (as modified with NCR, if any)
• Project Specifications
• Design Drawings
• General Specifications and Standards
• Industry Codes and Standards

However, any discrepancies shall be brought to the attention of the Client.

Company Specifications
– Plant Layout
– General Requirements to Civil Works & Structures

Project Specifications
– Project Specification for Civil works and Earth Movements
– Project General HSE Plan

Drawings and Documents
– Site Preparation General Grading Plan
– Site Preparation Sections (1~4)
– Areas Characterization for Site Preparation
– Geotechnical Report

Codes and Standards
– ASTM D 2922 Test Methods for Density of Soil and Soil-Aggregate in Place by Nuclear Methods (Shallow Depth)
– BS 1377 Method of test for Soils for Civil Engineering Purpose
– BS 5930 Code of practice for site investigations
– BS 6031 Code of practice for earthworks
– If any local country specification

RESPONSIBILITIES

Contractor will proceed and coordinate with concerned authorities to obtain work permit, supply the construction materials and control all site activities by the personnel as follows;

Superintendent
He has overall responsibility for the site preparation management in accordance with the contract requirements.

He shall coordinate and control the execution of the Site Preparation, and ensure completion within scheduled time and the observance of HSE and quality procedures and practices in accordance with the relevant regulation of authorities.

Site HSE Supervisor
He has overall responsibility for the implementation of HSE plan according to the Project HSE Plan in this specification.
He shall investigate and report all major accident, recommend protection measures, and ensure the availability of safety equipment and first aid kits.

QA/QC Engineer
He has overall responsibility for the control and inspection of quality according to the QA/QC plan in this specification.
He shall review the Contract specifications and drawings, identify project criteria and prepare required checklist for QA/QC inspection.

TPI (Third Party Inspection)
Any organization, authority, person or persons, to which Contractor has subcontracted the execution of inspection and/or laboratory testing, related activities.

Civil Engineer
He has overall responsibility for the implementation of Site Preparation Works in this specification.

He shall arrange the manpower, equipment and materials required for the implementation of the works, coordinate with HSE officer and QA/QC Engineer involved in the tasks in accord to the method statement and reporting.

METHODS
Definitions
     General Fill

General Fill means the fill with Dune Sand and/or selected fill material, mainly this concerns the non-congested area with low density of foundations, mainly this concerns the off-site and some portions of process units. This fill will be up to local requirement of site during Site Preparation period after completion of top soil removal. This is mostly on bottom of structural fill.

    Structural Fill

Structural Fill means the fill with Structural Fill Material imported from quarry, mainly this concerns the congested area with high density of foundations, mainly this concerns the process units. This fill will be up to 1.1m during Site Preparation period after completion of top soil removal;

For the area of elevation exceeding 1.1m after completion of top soil removal, Contractor shall verify the bearing capacity and settlement and determine fill method whether the replacement will be needed or not.

    Boundary between Congested and Non-Congested Area

Boundary area between congested and non-congested area means a boundary with different elevations, mainly this concerns the slope stability during construction period. These areas will be overlapped with General and Structural Fill Material to the extent of app. 3.2 m of width and 1.6 m of height in order to secure the stability of slope. The drawing in outline of this area is as below;

Preliminary Activities
Existing Service

Contractor shall make his own investigation to establish the exact location of existing services which may affect or be affected by the construction of the Works. In addition, Contractor shall before carry out adequate preliminary investigations using any suitable means to verify the location of existing services.

Surveying

A topographical survey supervised by Contractor has been carried out so as to commence the Site Preparation Works. Contractor has installed the Control Points to set out the locations at good controlled places along the Site. For more details, refer to attachment #1 Topographical Survey Report.

Dimensions and levels shall be pre-established from drawings prior to construction. During construction period of the Works, surveying team will indicate and maintain the boundaries of the areas, especially the cut and fill area by putting temporary signs at the exact positions using total station and auto level instruments.

Contractor will establish a number of permanent settings out station from which to set out the Plant and establish and record their co-ordinates on the site grid.

All surveying reports shall be submitted to Company after inspection by Contractor.

Site clearance

All work areas shall be cleared of refuse, vegetation and deleterious material with all necessary authorizations. Unsuitable materials shall be removed from Site in an area approved by authorities.

Unsuitable materials and suitable material not intended for re-use shall be removed from the work site and disposed in accordance with local and national laws and regulations.

Top Soil Removal
Area classification and Work Sequence

The area classification and work sequence for Top Soil Removal Works is as below;
(1) The Site will be classified by 7 divisions as shown in the attachment #2 Area Classification for Site Preparation according to the construction schedule.
(2) To meet the requirement for Specification, each division will be sectioned by various levels according to the site ground condition.
(3) Considering the natural ground conditions and workability of equipment, each section will be stepped and graded as shown in the attachment #2 Area Classification for Site Preparation.
(4) The Contractor can secure a stockpile of topsoil placed in a limited area for disposal or reuse after approval of Company.
(5) After finishing the top soil removal work, the area will be finally leveled and compacted in order to prepare for fill works.
(6) The sequence of each unit will be according to the given Site Preparation Schedule

Work Methodology

• Prior to the work, Contractor shall obtain the Work Permit and request for Waste Transportation and Disposal from authorities as per related regulations.
• Before starting the work, all bushes, vegetation, debris, materials or any other obstruction will be removed by means of required equipment and machinery.
• The removed soil should be transported to the disposal area designated by authorities.
• The work will be performed on the basis of the soil nature which shall be stripped down to 200mm app. below the existing ground level for both areas
• The stripped soil will be heaped for further loading and transported to stockpile on the identified area.
• Adequate loading will be made within the allowable truck load and shall not be exceeded.
• Truck will use the approved access road by authorities complying with local regulations and practices.

Fill Material
Suitable Fill material

All fill material shall be either suitable excavated material or suitable imported material.
The suitability of materials shall be in accordance with the following

(1) Suitable material for earthworks shall be approved soil with a liquid limit not exceeding 40%. The material passing the 0.075mm sieve shall not exceed 20% and the organic matter content shall not exceed 2% (as determined by BS 1377-Part 3).

(2) Where excavated rock is to be used as fill material elsewhere on the site, the Contractor is responsible for ensuring that the excavated rock meets the requirement of the Specification for fill material.

(3) The Contractor is responsible for mixing the excavated rock with suitable fill material imported and/or excavated from within the site should it be necessary in order to produce a suitable fill material that complies with the requirements of the Specification.

Contractor shall supply suitable material and carry out such tests as required, to demonstrate the suitability of the fill, especially with respect to compacting.

Contractor shall submit geotechnical test reports on dune sand, structural fill material and selected fill material specification for Company’s review.

General Fill Material

1.     Dune sand can be used as general fill.

2.     Structural Fill Material

When structural fill material imported from borrow pits, it shall comply with the following requirements as minimum:
1) Particle Size : 75mm max.
2) Gradation
Sieve Size % of Mass Passing
75 mm 100
28 mm 65 to 95
10 mm 30 to 75
5 mm 25 to 60
2 mm 15 to 45
0.425 mm 8 to 30
3) Fines content : 20% max.
4) Liquid limit : 40 max.

Water for Compaction

Fresh water or ground water (brackish) shall be used for the fill operations. Water used for compaction of fill material shall be reasonably free of salts, oil, acid, alkalis, organic matter, or other deleterious substances, and imported from outside authorized source.

Fill and Compaction
Flow Chart

The flow chart for fill and compaction is as below;

Field Fill Trials

Before the commencement of the fill and compaction work, field fill trials shall be carried out in order to determine optimum properties of compacted fill and shall include;
• Layer thickness
• Compaction methods
• Number of passes
• Amount of watering
• Type of Equipment

Compaction shall be performed with equipment compatible with fill type according to the results of Field Fill Trials.

 The Field Fill Trials will be carried out according to the attachment #3.

Fill and Compaction

General Fill and Compaction

General fill may be used to raise certain areas of the site to the required grades. These areas shall be limited to locations where no structures, pipelines, utilities are to be constructed.

Contractor will perform the works in non-congested area in accordance with the following sequence:

CASE 1:
The non-congested areas inside “process areas Contractor will perform the works in accordance approximately with the following sequence:
1. Clearing, grubbing and minimum 200 mm soil stripping on area defined on design drawings
2. Compaction of the sub-grade to at least 90% of maximum density
3. Spreading, grading and compacting each fill layer with general fill material
4. Consecutive general fill and compaction up to established grade levels

CASE 2:

The non-congested areas into “non process areas”, could be directly backfilled up to that is the elevation to receive the final finishing (concrete paving/asphalt or gravel), with dune sand including the last layer of structural fill material.

In those areas, the roads will be prepared up to EL. +99,40 providing sub-grade with dune sand and sub-base with structural fill material, according to Drawing.

As a minimum, at least one field density test must be performed on every layer of fill and further placement shall not be allowed until the required density has been achieved.

General fill shall be placed in layers according to the results of Field Fill Trials. Each layer shall be compacted with approved equipment to a minimum density of 95 % of the maximum density obtained in BS 1377 or equivalent.

The surface of each layer, to be tested, shall be in accordance with specification.

Structural Fill and Compaction

Structural fill shall be used to raise the site to the required grades. Wherever unsuitable soil is found it shall be removed and replaced with material suitable for support of the Works.

Contractor will perform the works in congested area in accordance with the following sequence:
(1) Clearing, grubbing and soil stripping on area defined on design drawings
(2) Compaction of the sub-grade to at least 90% of maximum density
(3) Spreading, grading and compacting each fill layer with structural fill material
(4) Consecutive structural fill and compaction up to elevation +98.000

Structural fill shall be placed in layers according to the results of Field Fill Trials and each layer shall be compacted with approved equipment to the densities specified herein. Areas not meeting the required compaction shall be scarified and re-compacted until the specified density is obtained. If the top of a layer has crusted, the Contractor shall scarify the surface to ensure good bond with the following layer.

Each layer of Structural Fill shall be compacted to a minimum dry density of 95 % of the maximum dry density obtained in BS 1377 or equivalent.

Tolerance

These earthworks shall be undertaken to obtain the final surfaces, elevations, and slopes in the various areas as shown on drawings with tolerances +I- 30 mm.

Compacted surfaces of fill shall be finish graded to the cross sections, lines, grades, and elevations as indicated on the approved drawings.

Slope Erosion Protection
General

A layer of minimum 50 mm thickness of bituminous mix accordingly to project specification shall be applied for slopes in order to provide erosion protection. Special care shall be placed at construction stage to avoid all situations where concentrated flows may take place over unprotected slopes.

Material

An application of liquid asphalt primer or similar approved material shall be sprayed at the rate of 1.5 kg/m2 to the surface.

The bitumen mix shall be made with a well graded aggregate, and the maximum size of the aggregate shall be within 10 mm.

The percentage of bitumen to be mixed shall vary from 4.5% to 6.0% by weight of aggregates.

Placing

For placing of slope protection, the surface to be placed shall be leveled according to the design elevations and shall have the established slopes according to the drawings.

An application of liquid asphalt primer or similar approved material shall be sprayed at specified rate to the surface, and before proceeding with the covering work, an appropriate weed-killer must be applied in accordance with the Suppliers instructions.

The spreading of the material must be made at a temperature of 120°C approx. and spreading is carried out manually and the thickness of the loose layer shall correspond to a finished thickness of 50mm.

Rolling is performed with a hand operated roller when the material is still hot, in order to reach a satisfactory compaction. The layer thickness must be uniform and homogeneous over the entire area covered, and the surface must be perfectly even.

Temporary Slope Protection

In accordance to Clause 5.5.3 in this specification, it will be necessary to protect the slope of dune sand layer between the areas at different elevation using fabric material such as non-woven geotextile (PET short fibre needle punched, 100g/m2) fixed on base and top with a layer of structural fill material or equivalent.

Testing and Inspection
Testing

Testing shall be provided in order to adequately demonstrate the suitability and acceptability of al fill materials. The testing shall also demonstrate that required compaction requirements are met. Trials shall be carried out to confirm the adequacy of al materials and methods prior to commencement of site fill operations.

Gradation, density, and moisture content control tests shall be performed at the following minimum frequencies; one standard sieve analysis and one Modified Proctor Test per BS 1377 or equivalent with corresponding Proctor curve performed for each type of fill material.

Contractor shall also perform the above tests every day during filling work until the Company’s approval of decrease in the frequency.

In-situ density and moisture content of soils shall be determined by the sand-cone method per BS 1377 or equivalent and/or nuclear method per ASTM D2922.

Acceptance testing of in-situ density and moisture content (field density testing) on compacted fill will be performed every 500m2 of the fill area. The layers will be deemed suitably compacted if they meet the requirements of 95% maximum dry density.

The number of tests shall be increased if a visual inspection determines that the moisture content is not uniform or if the compacting effort is variable and not considered sufficient to attain the specified density.

Inspection

The required inspection for each activity will be monitored by Contractor in proper as per the General Earthwork specification.

An authorized and certificated TPI (Third Party Inspection) shall be carried out the testing inspection and related activities during construction.

All inspection report shall be submitted to Company accordingly to specification requirement as above mentioned.

Disposal
Unsuitable Material

Debris resulting from site clearance, stripped top soil which is not acceptable for use as fill material shall be removed from the Site by the Contractor and disposed of in areas allocated and/or acceptable to the responsible authorities. Arrangements for such disposal shall be the responsibility of the Contractor.

Excess Material

Any excess soil resulting from the Site shall be removed from the work site and disposed in local tips. Materials shall be disposed of in accordance with local and national laws and regulations.

Areas used for temporary stockpiling shall be kept clean and tidy and shall be restored to their original condition on completion of works.

Topographical Survey Results

1. Survey Details

2 Survey Location

3 Control Point Setting Out

4 Area classification for Site Preparation

Attachment #3 Field Fill Trials Program
Field Fill Trials Program

1. Purpose

This plan describes the method and procedure to determine fill materials, compaction equipment and compaction method etc. to meet the requirements of the Specification.

2. Flow Chart
The flow chart for Field Fill Trials is as below;

Execution Plan

Trial Area and Equipment Proposed
1) Trial Area : Width 6 m, Length 180 m, 5 Blocks (5 Cases), Total Area 5,400 m2
2) Equipment Proposed (to be used for the work)
• Tripper Truck (40ton) : 6 nos
• Loader (3.5~4.0m3) : 2 nos
• Grader (W=3.6m) : 2 nos
• Vibratory Roller (10ton) : 2 nos
• Water Spray Truck (20ton) : 2 nos

Materials and Mixing Method
1) Materials
• Dune Sand :from Dune Sand stock Area of MIC
• Structural Fill Material : from Quarry to be used
2) Mixing Method (if required)
• Equipment : Loader
• Mixing Ratio Weighing : by Volume of Tripper trucks with same loading capacity

Test Plan

Items Description Frequency Remarks

Reporting

Fill Trial Method and Measurement Results
• Thickness before Grading
• Equipment used
• Compaction Times
• Moisture Content
• Dry Density
• Compaction Degree
• Load-Settlement Curve
• Thickness after Compaction
• Visual Inspection

Analysis and Conclusion
• Determination of Fill Materials to be used for its purpose
• Determination of Compaction Thickness of a layer
• Determination of Compaction Times
• Determination of Optimized Moisture Content
• Review of Load-Settlement Relation
• Conclusion

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