Procedure for Field survey, Site preparation, Setting out, Excavation, Backfilling and Compaction

 Procedure for Field survey, Site preparation, Setting out, Excavation, Backfilling and Compaction.

           

1.0	PURPOSE
	1.1	The purpose of this Procedure is to meet the minimum requirements for civil earth works as mentioned in the contract documents for the Project ”Renovation of Water Treatment facilities at Al-Khafji. ”
2.0	SCOPE
	2.1	The scope of this procedure is to meet the minimum requirements for Survey, grading, excavation, back filling and compaction as per the scope of work mentioned in contract documents for civil construction.
3.0	DEFINITIONS
		Following words utilized in this procedure are defined below.
	3.1	Company                            -
	3.2	Contractor                          -
	3.3	Sub Contractor                   -
	3.4	JV Partner                          -
4.0	REFERENCES
	4.1	Approved for construction Drawings
	4.10	ASTM – D1556- Standard test method for density & unit weight of soil in place.
	4.11	ASTM –D1557- Standard method for lab compaction characteristics of soil.
	4.12	ASTM- D 4318- Standard test method for liquid limit, plastic limit and plasticity.
5.0	ABBREVIATIONS
	5.3		PMM	-	Project Management Manual (Contractor)
	5.5		PQP	-	Project Quality Plan
	5.6		NCR	-	Non Conformance Report
	5.7		ITP	-	Inspection and Test Plan
	5.8		DO	-	Director of Operations
	5.9		PD	-	Project Director
	5.10		PM	-	Project Manager
	5.11		QR	-	Quality Representative ( QA/QC Manager-Project )
	5.14		QA	-	Quality Assurance
	5.15		QC	-	Quality Control
	5.17		AFC	-	Approved for Construction
	5.18		QAM	-	QA Manager (Division) / QA/QC Manager (Corporate)
	5.19		CM	-	Construction Manager
	5.20		DE	-	Discipline Engineer
	5.21		PIP	-	Process Industry Practices
	5.22		MSL	-	Mean Sea Level
6.0	PROCEDURE
	6.1		General Requirements
	6.1.1		Prior to commencement of any civil work safety precautions and necessary permits for the job shall be taken.
	6.1.2		Contractor shall provide and erect profile templates, boning rods,                              site barricading and properly set out proposed works from the base lines levels, co-ordinates or datum given by Company.
	6.1.3		The site shall be cleared of all rubbish and debris, trees shrubs and hedges including grubbing up roots. Remove all contaminated earth and fill the voids with compacted material in accordance with the procedures.
	6.1.4		All the inspections during field survey, Site preparation, Setting out, Excavation, Backfilling and Compaction shall be as per inspection and test plan (ITP) for earth work
	6.1.5		All the inspections shall be done as per the notification for inspection (NFI)
	6.1.6		During the construction extreme care shall be taken not to damage any of the existing facilities.
	6.1.7		All the civil construction work shall be carried out as per the approved drawings only.
	6.1.8		The Land surveyor shall be qualified, experienced person and shall be fully conversant with co-ordinates and all survey instruments.
	6.1.9		All the Survey report shall be maintained as per the Attachment No.1 survey report.
	6.2		Survey
	6.2.1		Pre-Requisites for Field survey
	6.2.1.1		The co-ordinates and datum use for surveying and constructions shall be referred from fixed Bench Marks (B.M) placed by the Company authority as per the contract.
	6.2.1.2		All surveying works shall be in accordance with contract specifications. Any Bench mark which needs shifting shall be done by coordinating with Company authority.
	6.2.1.3		All instruments such as Dumpy level / Theodolite / Total station shall be calibrated by a recognized agency and certificates made available to the Company for verification.
	6.2.2		Requisites of survey
	6.2.2.1		A minimum of 3 survey Bench marks shall be made available for easy reference.
	6.2.2.2		Sufficient pegs shall be set and maintained during progress of civil work.
	6.2.2.3		Sufficient reference points shall be made available and located such that they will not be disturbed by other operations.
	6.2.2.4		The coordinates and elevations shall be based on site survey approved drawings (latest revision)
	6.2.2.5		All survey works shall be carried out as per Notification for Inspection (NFI)
	6.2.2.6		A copy of latest site survey drawings highlighted to be submitted for approval of any inspections of surveying.
	6.2.2.7		Underground services encountered if any to be recorded in the inspection sheets and highlighted in the survey report.
	6.2.2.8		Mean Sea level which is 3.772 M height shall be the vertical datum for all elevations as per (final (Factory) coordinates of control points BM5S) highlighted document with construction Manager.
	6.2.2.9		As built surveys shall be based an actual field measurements referenced to the factory coordinates.
			References 1) SAES-A-100- Survey Co-ordinates and datums.
			2) Approved Engg. Drawings
	6.3		Grading
	6.3.1		Grading shall be to the line and levels indicated on the drawing or as instructed by Company officials.
	6.3.2		Bottom of all grading shall be graded true to level, inspected and approved by Company. Contractor shall notify Company in writing when formation levels are reached stating the date and time that such formation is ready for inspection.
	6.3.3		Any depressions made by clearing and grubbing operations shall be filled with suitable material and compacted to confirm the adjacent surface of the original ground.
	6.3.4		The top soil excavated shall be removed and disposed off to the designated approved areas by Company.
	6.3.5		Reusable material if any shall be stock piled in the designated area. Building areas shall be excavated to the elevations shown in contract documents.
	6.3.6		The Earth works operations shall be suspended at times of incessant rail fall and due to inclement weather.
	6.4		Excavation
	6.4.1		Excavation (Structural)
	6.4.1.1		Excavation shall be done to the lines and levels as indicated on the drawings or as instructed by Company. Where excavating work is carried out by machine sufficient depth shall be left unexcavated to enable the exact depth required to be obtained during manual excavation.
	6.4.1.2		When vertical work against which concrete is to be placed without shuttering excavation shall be done by machine. Sufficient margin shall be allowed to make required finishing of such faces by manual excavation.
	6.4.1.3		Bottom of all excavations will be graded true to level, inspected and approved by Company before foundations or pipes laid. Contractor shall notify Company in writing when formation levels are reached stating the date and time for inspection through Notification for Inspection.
	6.4.1.4		If any excavation made below the level of the referenced drawings in order to obtain solid bottom or as instructed by the Company, the excess depth of excavation shall be filled with lean concrete with minimum strength of 150 Kg/cm2 under the direct supervision of the client.
	6.4.1.5		The disposal of excess excavated material shall be placed in Company designated areas or as per approval of Company authorities.
	6.4.1.6		When loose soil is excavated shall be removed till full depth of the salvaged soil completed and stored in stock pile as per the discretion of Company.
	6.4.1.7		Hand excavation shall be carried instead of mechanical means near existing structures and at places where machine operation is not feasible. Mechanical excavation only in the area of new road and new tanks. (Sketches shall be submitted along with applicable method statement)
	6.4.1.8		Protection of existing foundations & structures. Foundation for heavy machinery shall be independent of adjacent locations and buildings. Concrete slab or paving adjacent to foundations shall have a 12 mm isolation joint around the foundation using approved joint filler with sealant at top. Preformed expansion joint filler shall be of the full thickness and depth of joint with splicing only on the length. Depending upon the surrounding soil near the foundations a spacing of 2.5 times the width of smallest foundations is recommended. Otherwise consideration shall be given to apply soft board on the adjacent sides of the foundations.
	6.4.1.9		Priority of excavation of adjacent areas in regard to foundation levels (lowest / highest) shall be illustrated with sketches by the execution team upon the consent of the Company representative.
	6.4.2		Earthen Structures
	6.4.2.1		Excavation for ponds Canal or ditches shall be made to the lines and levels indicated on the drawings or as instructed by the Company.
	6.4.2.2		The sloped excavations shall be cut true and straight to the cross sections of the bottom of excavations, shall be graded true to level and will be inspected by Company. Unstable soils in the slopes shall be removed & slopes properly prepared. The bottom of excavations shall be graded to the elevations and configurations as shown on the drawings.(Sketches shall be submitted along with applicable method statement)
	6.4.2.3		Excavation below the designated level shall be filled with suitable material and compacted to at least 90% of maximum standard proctor density for cohesive soil and 70% relative density for sand.
	6.4.3		Rock Excavations
	6.4.3.1		For trenches and other excavations when rock is encountered shall be carried out by heavy back hoes. The excavation includes for soft rocks weathered                   or fractured which does not require blasting or pneumatic rock breakers upon prior approval of Company.
	6.4.4		Disposal of Materials
	6.4.4.1		All the excavated materials not fit for re-use as backfill or fill or that which is surplus shall be immediately disposed off at locations designated by Company.
	6.4.5		Trenching
	6.4.5.1		During trenching if any ground water percolates in the trench, dewatering is necessary upon prior approval from the company for dewatering systems and disposal of the same. Under no circumstances the discharge shall be done in to open areas or existing sewers or new sewers.
	6.4.5.2		The bottom of the trench shall be dry and sufficiently drained so that there is no standing water before the installation of pipe.
	6.4.5.3		The depth of the trench shall be dug enough to provide a minimum ground cover of 600 mm to 900 mm depending up on the size of RTR pipes and a ground bed of at least 150mm in depth below the bottom of the pipe.
	6.4.5.4		The width of the trench should be wide enough to allow room for jointing the minimum width for RTR pipes shall be OD + 300 mm  – OD + 600 mm
	6.4.5.5		A bedding layer of clean sand 150 mm in depth is required for all trenches
	6.4.5.6		The sand shall be free or debris and rock and compacted to 70% relative density as per ASTM D 4253 & ASTM D4254. Compaction by water flooding shall be allowed for clean sand.
	6.4.5.7		The ground bed shall be uniform and adequate support and drainage along the entire length of piping. In subkha areas a base support layer of crushed stone of 150 mm thick is required. Alternatively, double layer of sand bags may be used for a base support layer upon the approval of the Company.
	6.4.5.8		Trenches containing fire water line a non-oven geo textile (130 gm / m2) should enclose the  clean sand bedding layer and back fill material with a minimum over lap of 200 mm
	6.4.5.9		The trench bottom shall be continuous smooth to the line and grade as per drawing continuously supported and care should be taken not to rest on joints for RTR pipes the trench contour shall not cause the joint angular deflection and shall follow the manufactures limit for pipe bending radius.
	6.4.5.10		Sheeting or shoring shall be in accordance with Saudi Aramco construction safety manual section II. Necessary under pinning, bracing and shoring is pre-requisite to protect existing buildings, fences, walls, utilities and other structures. More fully described in the HSE document “Loss prevention plan”
	6.4.5.11		Piping shall have steel sleeves at road crossings in accordance with Saudi Aramco standard drawing AC-0366660 & AB-036880 alternatively the piping shall be protected by reinforced concrete slab or metallic casing in accordance with SAES-L-460. Prior approval shall be taken from the Company.
	6.4.5.12		Pipeline right of way (ROW). The ROW shall be graded to a flat surface accessible with 4 wheel drive vehicle on one side of the pipeline route. The final finished ROW shall be at least 5 Mtrs. wide from edge of pipeline berm to permit routine operations and maintenance access.
	6.5		Fill and Back fill
	6.5.1		Fill and back fill material shall be from designated borrow pits. Any borrow pit source shall be approved by Company and shall confirm to geo technical report.
	6.5.2		The back fill material shall consists of gravel, sand or marl and free from organic matter, trash or chunks of clay or other deleterious material. The maximum size of the material shall not exceed 75 mm.
	6.5.3		Select fill material shall be inorganic in nature and shall have 100% passing 2” sieve. 0-20% passing No. 200 sieve. The percentage passing No. 40 sieve shall have maximum liquid limit of 35 and maximum plasticity index of 12 and as per ASTM D 4318.
	6.5.4		Water quality for fill material with TDS more than 10000 ppm is not allowed and shall be free from salts, oil organic matter or other substances. Use of brackish water, sea water or water from ground pits should be verified by the Company authority.
	6.6		Requirements for placing back fill
	6.6.1		Areas to receive fill for foundations pavements and other concrete structures shall be prepared as per contract drawings and free from foreign material, stripping, clearing and grubbing to be completed prior to place the back fill material.
	6.6.2		The area to be backfilled shall be proof rolled by roller compactor and inspected.
	6.6.3		All loose spots shall be filled with firm soil and compacted.
	6.6.4		150 mm top area shall be scarified and re-compacted for foundations and pavement and other structural supports. The compacted area shall be 90% of maximum proctor density and 70% relative density for cohesion less soils.
	6.7		Compaction
	6.7.1		Compaction to be performed by compatible equipment after placing of proper moisture content material.
	6.7.2		The material to be placed shall not exceed 200 mm thick.
	6.7.3		Hand operated Machinery to be used near concrete structures maintaining a minimum distance of 1.2 Mtrs.  And all efforts shall be made to prevent filling / compaction adjacent to existing structures in order to minimize eccentric loading to structures.
	6.7.4		For heavy machinery, vibratory, asphalt and concrete pavement foundations the fill material to be compacted to 95% of maximum density for cohesive soils and 85% relative density for cohesion less soil.
	6.7.5		All other fill material to be compacted to a density as shown on the drawings.
	6.7.6		The Moisture content of the fill material shall be within 3% + of the optimum moisture content and as per the ASTM D 1557.
	6.7.7		Flooding or compaction by water jetting is not permitted for cohesive soils flooding for cohesion less material may be used.
	6.7.8		If clean sand or dune sand is used as fill material, the final layer shall be cohesive material 150-300mm thick. The cohesive material shall have between 11-35% passing the No. 200 sieve and having maximum liquid limit of 35 and plasticity index of 12. The maximum size of cohesive material shall be 75mm.
	6.7.9		Compaction on slopes > 20% is not allowed i.e on slopes greater than 1 (V) to 5 (H). If any slope encountered clause 6.3.2.9 of SAES-A-114 shall be followed.
	6.7.10		In place density and moisture content of soils shall be determined by sand cone method as per ASTM D 1556 and other tests as detailed in SAES-A-114 clause 6.3.3.2.
7.0	ATTACHMENTS
	7.1		Attachment No. 1 - Survey Report
	7.2		Attachment No. 2 - Checklist for excavation
	7.3		Attachment No.3 - Checklist for Backfilling & compaction
	7.4		Attachment No.4 - Checklist for Grading
	7.5		Attachment No.5 – Notification for inspection