GD Earth Works R2

GULF DUNES LANDSCAPING & AGRI. SERVICES LLC.,MARINA & BEACH PARK LANDSCAPE & IRRIGATION WORKS

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of 21 EXCAVATION & BACKFILLING METHOD STATEMENT

EXCAVATION & BACKFILL WORKS METHOD STATEMENTS

PREPARED BY QA/QC Engineer

REVIEWED BYProject Manager

APPROVED BY Consultant Engineer

Signature

Name

Date

Organization Gulf Dunes Gulf Dunes AECOM


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Table of Contents

1. Scope/Objectives

2. Sequence of related Activities

3. Definitions / Abbreviations

4. References

- Contract Documents- Internal Documents

5. Responsibilities

6. Procedure

7. Excavation & Sub-grade Preparation.

7.1. Backfilling & Compaction procedure.

7.3 Field Tests

8. Tolerances

9. Resource Requirements

- Manpower- Material- Plant & Equipment

10.Health, Safety, Environment (HSE) Provisions

11.Records

12.Approvals

13.Distribution


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14.Attachments.1.0. Scope / Objectives

- This Method Statement details general procedures to be followed for Excavation, trimming & Back filling for Trenches, Manholes, Paving works & Landscape works within the Project – Phase 1 Landscape Marina & Beach Park and Phase-I Landscape Early Works, Reem Island- Najmat. It includes Survey works, Excavation, Excavated area trimming for required level & sizes, Leveling, Backfilling, Compaction and area cleaning after the completion of works.

- Separate Work Method Statement, will be generated by the sub-contractor for Dewatering, Trench soil fall protection system, Pipe / Duct laying, Blinding works, Manhole construction and Paving works.

2.0. Sequence of related activities

- Excavation - Excavated area trimming- Compaction/Consolidation of formation of excavation below Pipe Bed.- 150mm Granular filling and Compaction below pipes.- Pipes/Ducts installation, Granular fill providing around pipe.- Blinding Concrete/ Manhole constructions/ Waterproofing/Backfilling.

3.0. Definitions / Abbreviations

MS - Method StatementCIR - Contractor Inspection Request RE - Resident Engineer / Consultant Engineer /Client Engineer TBM - Temporary Bench MarkMDD - Maximum Dry DensityEngineer- AECOMGD - Gulf Dunes Landscaping & Agri. Services LLC.,

4.0. References

4.1. References to Contract Documents

Contract Specifications Contract Drawings & Approved Shop Drawings.


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Specification for Earthworks & Trenches Section 2.9 & 2.10.

4.2. References to Internal Documents

No. Document1. Shop drawings2. Project Specs

5.0. Responsibilities

5.1. Gulf Dunes(GD) Project Manager has the over all responsibility for the implementation of this method statement and ensure that the approved sub contractor as well other team members are well aware of the requirements of the Method Statement.

5.2. GD Project Manager is responsible to co-ordinate with the company PRO and the local bodies for obtaining necessary and essential work permits – if any, for proceeding with the works. Such as Excavation permit & Civil Defense NOC inspection before commencing work.

5.3. GD Project Manager will ensure that the Resources are available to carry out the works as scheduled.

5.4. The Site / Project Engineer is responsible to carry out the works as per approved Shop Drawings and Materials.

5.5. The Project Engineer/Site Engineer is responsible to ensure that the work has been carried out as per Specifications & Drawings and inspections are done as per contract.

5.6. The Surveyor/Site Engineer/Supervisor is responsible for Setting out the area and measuring, monitoring and controlling the lines and levels.

5.7. The Site Engineer/ QC inspector is responsible to ensure that the work performed is in compliance with the approved Method Statement & other applicable requirements.

5.8. The Safety Officer is responsible to ensure that all safety precautions are in place and that the personnel on site possess the necessary and essential PPE.


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5.9. The Safety Officer is also responsible to ensure that the Machineries and Equipments mobilized for the job both by the company as well by the approved sub contractors are complying with relevant safety requirements & Risk assessment.

6.0. Procedure

6.1. Permissions/NOC’s & Approvals

6.1.1. Before start excavation obtain the Excavation NOC, Dewatering approvals and other necessary Permits from authorities.

6.1.2. Obtaining of Bench mark Certificate from Bunya and Existing underground services location from client/Bunya.

6.1.3. Location of the dumping area and disposal of dewater shall be finalized before the commencement of works and obtain NOC if require.

6.1.4. Dewatering disposal and Construction debris shall be dumped in the approved Municipality dumping / disposal area.

6.1.5. Excavation and Back fill levels shop drawing should be approved from Consultants.

6.1.6. Third party Testing laboratory approval shall be approved by Consultants.

6.2. General :

6.2.1. Before of the work, ascertain the nature and location of all existing above and underground services on site by visual survey and making trial pits or by reviewing the service layout drawing (if available).

6.2.2. If any protection, rerouting, termination or removal of services is required for the smooth progress of work, it shall be discussed and written approval shall be obtained from Client/Engineer as appropriate.


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6.2.3. Ensure Shoring, Bracing/Battered & Dewatering installation where required, shall be carried out subcontractor as per approved shop drawings.

6.2.4. A warning tape shall be tied along the perimeter of excavation at a distance of 1 meter from the edge of excavation as a warning sign to restrict the movement of equipment. Flash lights will be provided when working at night as required.

6.2.5. All testing shall be done as required in the project specification and contract documents by the approved accredited testing lab.

6.3. Survey

6.3.1. Establish and protect sufficient number of stations to re-establish the stations if they are disturbed during earthwork excavation.

6.3.2. Mark the location and levels & Line which is approved sub-grade for Excavation & backfill works.

7.0. Excavation & Sub-grade Preparation procedure: All excavation levels & lines in regards of particular approved drawings of Storm water, Sewerage, Irrigation and Hard/Softscape works.

7.1.1. After fulfill above requirement GD will be conduct all excavations by mechanically and Manual wherever required as per approved shop drawing mentioned level & line. Storm water/Sewer line trench width care to be take without exceeding pile dia +300mm.

7.1.2. More than 1.5m deep excavations or necessary areas fall protection shoring will in installed and necessary precaution will take to prevent slips and falls of earth or other materials. Temporary works supports will not remove till complete the final backfill and consultants approval.

7.1.3. All excavation shall be kept free of water. Stability of the excavated area shall be maintained with required slope at the sides of the excavation. Do the necessary bracing where sloping is not possible. Excavation in restricted areas shall be carried out by hands.


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7.1.4. Dewatering system will be installed where ever required and dewatering will be carried till complete the works.

7.1.5. Final sub grade level will be done by hand trim excavation and remove loose matters such as lumped subsoil, boulders and rocks and dimensions as shown on the drawings within the tolerance.

7.1.6. Excavated material approved for back filling shall be stockpiled at a safe distance 3 feet away from the trench with adequate angle of repose and to protect the excavation and approved by Engineer before using for backfill.

7.1.7. Over excavation, if any, shall be backfilled with satisfactory soil material only when acceptable to Engineer. Moisture of backfill material shall be controlled within +/-3% of optimum moisture content as per the requirement of specification. And shall be compacted to not less than 95% of Proctor Density test or relative density as applicable.

7.1.8. The elevation of any point and the line of any edge or center of earthworks shall be as per the drawing shown and within acceptable tolerances and as straight as to top edge of the trench

7.1.9. CIR will be raised & Inspection shall be carried out by the Engineer, when excavation has reached the required sub grade elevations. Iinsitu density tests shall be carried out for pavements & Sumpts/Manholes as per RE required. Insitu density test not required below pipe/Ducts for Trenches..

7.1.10. Trench excavation will be organized without exceeding total excavation 500 meters length for one time. Second excavation will be started after completion of first 500 m backfilled & approved. Pubic areas and Private gardens trench battered will not exceed 30 meter length and trench should not be excavated more than 7days prior to pipe laying.

7.1.11. Irrigation system main pipe trench shall be 1m depth from crown of the pipe to the finish grade and lateral pipe depth shall be 600mm to be maintain as specifications 13.1.


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7.1.12. Tree & Palm pits excavation sizes: palm pit 2.0 x 2.0 x1.5m (Concrete dimensions);Palm Pit-1.5 1.5 x 1.5m ; Tree pits-1.2 x1.2 x 1.2m; Large shrub pits- 1.0 x 1.0 x 0.5m; Shurb beds – 600mm deep; Ground Cover beds- 300mm deep; Lawn -150mm deep.

7.2. Method of Backfill and Compaction: (Approved Shop drawing to be followed for location & levels and thickness of granular back fill).

7.2.1. Storm Water / Sewerage Trenches/Manhole Backfill: After the excavation, offer the inspection to Consultants Engineer/Client Engineer(RE) for Sub-grade status approval and obtain approval to start granular bed for trenches.


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The bottom of the trench shall be trimmed to a depth below the invert level to allow for the thickness of bedding material and compacted. Trench backfill should be layer wise, shown following typical sketch for Storm water / Sewer line trench backfill.

If the excavated material suitable as agreed by RE, can be used for backfill, other wise imported granular material to be used for 150mm thick bedding below the pipe and more than 10mm size stone to be removed/separated.


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Imported material for bedding and surrounding shall be following as specified in specifications section 7.6, page 233.

For 110mm size pipe 10mm nominal single sized aggregate, 160mm size pipe 5 to 14 mm size graded aggregate and for 225mm and over size pipes 5 to 20mm graded aggregate can be used.

Initially lay the 150mm thick bedding approved material below the pipe and compact mechanically by passing not more than 4 time of plate compactor and sprinkle the water during compaction.

After installation pipe and approved by RE, fill the back fill 150mm thick around the pipe and compact manually by sprinkling water and obtain the RE approval and total filled to be maintain 300mm thick above the pipe with same material.

Second and Third to be filled each layer 150mm with Subka or granular fill size not more than 40mm and necessary mechanical compaction to be done by sprinkling water. Each layer inspection will be done by RE after compaction and agreed.

Further all lifts 300mm thick will be filled with Subka/Granular fill size not more than 40mm and mechanical compaction will be done by sprinkling water and same system will repeat till reach necessary level or ground level.

Moisture in compacted fill or backfill material shall be maintained within 3% above at 90% maximum dry density for under the traffic flooring areas.

Detectable 150mm wide Warning Tape will be placed over the back fill of service pipe with caution note 300mm below finish grade level for Sewer pipes – Yellow colour, Drainage pipes-Orange colour.

Selected excavated / stockpiled materials or borrowed material soil classification tests shall be carried out to establish its suitability from approved independent laboratory and approved by CE.


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All test reports will be forward to Consultants prior to laying of further layer / blinding concrete. Failed test points will be re-compacted and tested with the witness of consultant. This procedure will followed till achieve the required compaction / approved by consultants.

All excavation & compaction levels should be followed as per approved shop drawing or Contract drawings. Approved area will be handovered to casting team for blinding concrete process/Manhole installation.

7.2.2. Portable water/ Irrigation trenches backfill: (As per approved shop drawings and specification section 13.1 page 281)

Initial backfill shall be by hand in 300 mm lifts and carried in such a manner as to ensure adequate support under the pipe and distributed evenly to ensure there are no voids under and around the sides of the pipe and backfill material as following. Under the pipe bed and

surround pipe backfill should be sand shall not more than 5mm size aggregate

TYPICAL IRRIGATION SYSTEM PIPE BACKFILLING SKETCH


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For 3” dia pipe, backfill material shall be clean sand and shall not

contain any particles larger than 5mm and backfill shall be placed in 300mm lifts and consolidated without mechanical compaction by flooding the trench with irrigation water.

For the pipe Size 4” dia and above, back fill material shall be deposited in 300mm first lift in general areas and compacted in 90% by water sprinkle tamping . In paved area lift shall be 150mm and backfill shall be compacted manually. Mechanical compactor shall not be used until there is a minimum of 300mm above the crown of the pipe.

Second lift backfill above pipe will be done with250mm thickness by spreading approved subka/granular fill not more than 40mm size. And same procedure will be applied to reach the trench top level. All layer necessary moisture will be maintained will manual compaction.

Detectable 150mm wide Warning Tape will be placed over the back fill of service pipe with caution note 300mm below finish grade level for Irrigation Mains-Yellow, Drainage pipes-Orange colour, Electrical cables-Red, Water line- Blue colour.

TYPICAL BACKFILL DETAILS FOR WATER LINE


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Finally C.I.R. for correct elevation and test request/reports to be raised and approved by the engineer.

Soft Landscape Back fill: For soft landscape backfill shall be followed as per approved shop drawing and specifications suitable to plantation. Some of typical soft scape back fill sketches are shown below and should be followed according to plants / trees requirement.


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Paving area Back fill : GD labour will Trim the excavated areas manually and make the surface proper leveling and compact with 10 ton roller compaction will be done for traffic paving areas with vibration by passing adequate time while sprinkling water.


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After subgrade approval 150mm high granular sub base will be filled for and necessary compaction will be done. This sub base fill material size shall not more than 40mm size and compaction test will be conducted.

Second layer 100mm backfill will be spreaded, compacted by sprinkling water.

Raise C.I.R for selecting for compaction approval prior to mortar bedding and after RE approval mortar bedding will be started.

Walk ways : Pedestrian paving area also sub grade will be trimmed and all loose material will be removed and compacted with plate compactor.

After approval of subgrade preparation 150mm thick sub base granular fill will be filled and well compacted with sprinkling water sub base material size shall not exceed 20mm thick.

Final layer 30mm thick sand bed will layed and well compacted to receive pavers.


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Granite Tile paving area shall be following sketch and all layer shall be well compacted and approved by consultants.

7.3. Field Testing

7.3.1. For Trenches

7.3.2. Every 100 linear meters or each manhole to manhole 1 test for trenches each layer of backfilling. Two FDD tests for each manhole.


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7.3.3. For Paving area

7.4.2.1. In each competed fill layer make at least one field density test for every 1000 Sq.mtr.

7.3. Borrowed Material (Granular fill / Aggregate)

7.3.1. Routine test for each type of borrow pit materials shall be done as required in Contract specifications. One test of Grading, Maximum Dry Density, CBR and Loss by abrasion for every 1500 Cu.m imported material.

8.0. Tolerances

8.1. Excavate / Trim final required grade elevation and dimension as shown on the drawings within a tolerance of +/- 20mm at sub grade level pavements and 10mm for granular sub-base beds.

8.2. Top surface of general backfillings +/- 25 mm.

9.0. Resource Requirements

9.1 Manpower

- Project Manager- QC Engineer- Site Engineer / Foreman-Helpers (Skilled & Unskilled)

9.2 Material

- Approved & Imported back fill Road Base - Lime Powder, String Line Rolls- Steel pins

9.3 Plant & Equipment

- Total Station - Loader - Bob Cat, JCB - Tipper Trucks


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- 10 ton Roller - Hand tools like shovel, rake, etc.- Plate Compactor - Water Tanker- Air Compressor with Jack Hammers (if required)

10.Health , Safety, Environment (HSE):

10.1. The entire works will be carried out as per the guidelines established in the Project Specific HSE Plan, conforming to Abu Dubai Municipality Safety and BUNYA regulations.

10.2. Utmost importance shall be given to safety of personnel and protection of existing above / under ground services. It will be ensured that the personnel involved are thoroughly aware of the GD Engineers Safety regulations.

10.3. Tool Box Meetings will be conducted before starting the works.

10.4. HSE audits on site shall be carried out every fortnightly and report submitted in approved format.

10.5. All personnel will be provided with suitable Personal Protective Equipment.

10.6. Required permits will be obtained from the concerned authorities before starting the works.

10.7. Plant & Equipments shall be fully tested for safety compliance Third party test certificate and RTA license shall be submitted.

10.8. Excavations shall be adequately barricaded and warning signs and lights shall be posted in line with the safety requirements.

10.9. Safe measures of getting in to and out of excavation pits shall be provided.

10.10.Underground and above the ground services will be identified, rerouted or isolated (as appropriate) prior to the commencement of the excavation.


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10.11. Location of the dumping area shall be finalized before the commencement of works if any excavation.

10.12.Construction debris shall be dumped in the approved Municipality dumping area.

11. Records

No. Document1. Inspection Request2. Material Test Reports3. Non Conformance Reports4. Material Approvals5. Field Testing Reports

12. Approvals

Consultant Engineer

13.Distribution

Safety staff QA-QC staff Construction Team

14. Attachments

Check list Inspection & Test Plan Soil classification format Project Specifications.

GD Earth Works R2

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