T-242 - Method Statement for Excavation & Backfill

PROJECT : EPC PACKAGE SEWAGE TREATMENT PLANT, STAGE 1 Project N°

Contract N°

 AR 05/13

122-C01R

Date

08/02/2014

Document N°

Rev

0 Sheet

1

from

7

METHOD OF STATEMENT Excavation and Backfill

ROYAL COMMISSION FOR JUBAIL AND YANBU  JUBAIL, KSA 

0

23/11/13

First issue

REV

DATE

Designation

NAME

Issued by

 VISA

NAME

Verified by

VISA

NAME

Approved by

VISA

Date: 08/02/2014

Method of Statement for Excavation & Backfill Page: 2 of 7

TABLE OF CONTENT 1) Scope ..........................................................................................................3 2) Purpose.......................................................................................................3 3) Reference....................................................................................................3 4) Safety Requirements..................................................................................3 5) Responsibilities..........................................................................................4 6) Tools and Equipments..............................................................................4 7) Materials to be Used..................................................................................4 8) Construction Procedure.............................................................................5&6 9) Inspection and Testing Requirements.....................................................7 10) Records......................................................................................................7

Date: 08/02/2014

Method of Statement for Formwork & Concrete Page: 3 of 7

1) SCOPE This Method Statement is to define and describe the procedure of Excavation and Backfill for all concrete structures for the EPC Package Sewage Treatment Plant - Ras Al Khair.

2)PURPOSE This method statement describes the procedure and inspection instructions to be followed during the Excavation and Backfill for all concrete structures in EPC Package Sewage Treatment Plant - Ras Al Khair, KSA. This has to ensure that all activities are in full compliance with Royal Commission Specification

3)REFERENCES •

Royal Commission Standards: Section 02315 Excavation and Fill.

 Approved IFC Drawings

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 Al Jazea safety manual

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Royal Commission safety manual

4)SAFETY REQUIREMENTS  All risks involved in Excavation and Backfill will be indicated in risk assessment sheet.

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 All construction work will be undertaken in accordance with RC and Al Jazea safety manual.

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Permits will be obtained (when required) prior to any work being carried out and work will commence in accordance with specific measure itemized on the permit.

 All necessary (PPE) Personal Protection Equipment will be provided and worn in accordance with Procedure of RC and Al Jazea safety manual.

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 All Access/Exit points shall be maintained free from obstacles, material or equipment etc.

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Temporary safety signs shall be provided at all working areas where needed.

 At site all the work activities will be kept in a clean and tidy manner.

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Signal man must be provided for equipments on site.

Date: 08/02/2014

Method of Statement for Formwork & Concrete Page: 4 of 7

5)RESPONSIBILITIES: Foremen – Co-ordinate day-to-day activities of direct Labor and Sub-Contractors and responsible for the on-going Quality and production at the work face.

Site Engineer – Provide technical information and overseas on the basis of day-to-day activities of field supervision.

QC Engineer – witness all tests performed in his designated area and carry out detailed inspection prior to raising an RFI. All such tests should be signed and certified by the individual performing the test. Perform daily surveillance Inspection of workmanship and documentation activities.

Site manager – manages and directs project construction activities performed by the project team composed of personal assigned by the various functional departments.

6)TOOLS AND EQUIPMENTS:

No.

Equipment

1

Excavator

Excavation & Fill

2

Loader

Excavation & Fill

3

Roller Compactor

Compaction

4

Plate Compactor

4

Jumper

5

Water Tank

7)MATERIALS TO BE USED: •

Existing Material

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Base Coarse

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Select Fill

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Sand

Type

Compaction Compaction Compaction

Quantity

Date: 08/02/2014

Method of Statement for Formwork & Concrete Page: 5 of 7

8)CONSTRUCTION PROCEDURE:  All work activities highlighted in the method statement of Excavation and Backfill work applies to this method statement, in addition to following: EXCAVATION •

Excavations shall comply with all structural drawings of EPC Sewage Treatment Plant Package.

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Excavation boundary work shall be set out in accordance with the Approved IFC Drawings. A clear space of at least 1m shall be maintained on all sides of excavation to allow circulation and setting of formwork

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 All excavation will be adequately protected for safety. All local excavation will be hard barricaded at sufficient distance from the edge of excavation (1.0m). Banks more than 1.5 shall be shored on laid back.  All trench of 1.5m in depth or more than will be provided by sufficient egresses and proper side slopes will be provided .And maximum allowable angle of slope is 45 degrees.

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Blasting shall not be permitted without prior approval.

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Rocker breakers will be used in hard strata where excavators and /or shovel loaders are efficient, immediately after the company approval.

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Excavation material that is suitable for backfilling either will be placed so as minimize any inconvenience to vehicular traffic and other construction activities or stockpiled in an agreed unconstructive location for later use.

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If unsuitable material beneath the specified depth is encountered. The unsuitable material will be remove (over excavate) as directed by company. Resultant excavation will be filled with approval suitable material is loose layers not exceeding specified thickness foe each type of fill material.

 All excavation across existing roads, accesses paving will be carried out in a manner with no disturbance to the other executing works in the area.

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The width of all trenches for culvert and underground utilities shall be sufficient to allow inspection of  pipe, pipe joints and proper compaction of backfill at bottom section of lines. DEWATERING

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The purpose of dewatering is to ensure good condition of soil during excavation and backfilling operations within the scope of work

 All work shall be kept well drained at all times and shall ensure that all work is carried out in the dry conditions

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Remove water to prevent softening of foundation bottoms, undercutting footings, and soil changes, detrimental to stability of sub grades and foundations, and shall convey water removed from excavations and rain water to collecting or run-off area

Date: 08/02/2014

Method of Statement for Formwork & Concrete Page: 6 of 7

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Once the excavation reaches below the water table and depending on the dimension of the pit, side ditches will then be excavated submersible pump will be placed for pumping out the water. Discharge water shall be pump through flat hoses to a final water discharge location approved by RC and  within moderate distance. Dewatering progress will continue till the backfilling activity is completed.

 Adequate measure shall be taken to deal with the presence of water and inflow of water when placing the fill.

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BACKFILLING AND COMPACTION •

In general the placement and compaction of all classes of fill material shall be constructed to the lines and levels as indicated on the drawings.

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Curing must be exercised during the placement of fill against buried pre-cast units, vessels, or a structure to ensure that uneven placement of fill on one side does not move or destabilize the unit.

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Fill material belonging to a particular class shall well graded placed, spread and compacted in a uniform layers of equal thickness a maximum size of 100mm and shall be free of deleterious, debris, vegetation, organic and foreign material and shall comply with RC requirement:

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Type I 1) Graded sands and gravel, gravel-sand or silty-sand mixtures, crushed graded rock; little or no fines, no  well-defined moisture versus maximum density relationship (GW, SW, GP, SP). 2) Plasticity Index: NP to 5. 3) Gradation: Less than 12% passing No. 200 sieve.

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Type II 1) Clayey gravels and sands, poorly graded mixture of sand, gravel and clay, clays (inorganic) of low to medium plasticity, sandy clays, silty clays, lean clays (CM, SM, GC, SC, CL). 2) Liquid Limit: 20 to 50. 3) Plasticity Index: 5 to 22 maximum

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Prior to placing fill material the civil inspector shall inspect the excavation for clean lines and must ensure that backfilling location is dry ad clear form foreign matter (free paper ,wood ,rags and other organic matter). The backfilling operation will not commence unless the area to be filled has been inspected and approved by company supervisor.

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Fill material shall be mixed at stock with fresh water to the moisture content within+/-2% of the optimum moisture content using wheel loader. This will be controlled by visual and FDT respectively.

Date: 08/02/2014

Method of Statement for Formwork & Concrete Page: 7 of 7

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For paved areas, dune sand fill material around cables shall be used.

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For unpaved areas, dune sand fill material shall be used from bottom of trench up to 100mm above cables.

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The site foreman shall be responsible for applying the required number of passes by compaction equipment in use.

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Results of compaction achieved will be confirmed by necessary soil tests required by earthwork.

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Soil testing (field density, water content, classification etc) in general, shall be carried out at frequency stated in “Earth work”

9)INSPECTION AND TESTING REQUIREMENTS: •

Work execution, material approval and test shall be monitored, witnessed and recorded as per requirements.

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Contractor will issue a written RFI 24 hour in advance of test/inspection to permit Al Jazea QC Engineer to verify the readiness of the test inspection.

 Verbal notices of readiness for inspection are not acceptable.

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Soil testing (field density, water content, classification etc) in general and construction tests shall be conducted as per Royal Commission Specification and required international codes.

10)RECORDS:  All Records will be maintained and keep save in Al Jazea Document control Section.

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