This article is about Backfilling Work, Material, Foundation requirement, Backfilling Equipment, Compaction Requirement after backfilling, Risk assessment and Hazard Control for this activity as per international standard and codes.
- SCOPE.
- REFERENCES.
- RESPONSIBILITIES.
- GENERAL.
- WORK PROCEDURE.
- MOCK-UP TO IMPROVE BACKFILLING THICKNESS.
- QUALITY CONTROL.
- SAFETY CONTROL.
- TOOLS AND EQUIPMENT.
- ATTACHMENT.
- JOB SAFETY ANALYSIS, FDT RESULT, MOCK-UP PICTURE.
METHOD STATEMENT FOR PROPOSED BACKFILL WORKS
1.Scope
The scope of this procedure / method statement is to improve progress for backfilling works of trench for Under Ground Piping with adjacent layer of backfilling works from 200 mm to 300 mm in all area of commercial buildings, plants and refinery projects.
2, References
Saudi Aramco Engineering Standards
1. SAES-A-111 Borrow Pit Requirements.
2. SAES-A-114 Excavation and Backfill.
3. SAES-S-070 Installation of Utility Piping Systems.
4. IFC drawings.
3. Responsibilities
1. Site Manager
Site manager is entirely responsible for all authorized works related to construction, quality and safety plans and guidelines. He is responsible for the overall direction, coordination and control of the activities attached and related works prior to commencement of work and implementation of HSE Plan in accordance to Project Safety Plan and Standards, but he can delegate this activity.
2. Construction Manager
Construction Manager shall be responsible for the overall implementation and monitoring of all the activities involved. He shall be responsible for safe and productive work culture. He shall be dealing with construction team for implementing work in correct procedure at site.
3. Safety Manager
Safety Manager review construction company formulates and implements policies, procedures and programs on construction safety that comply with OHSA regulations. He has broad knowledge of local, state and federal regulations. He should also be familiar with all relevant environmental laws prior to start of the work and HSE plan must be implemented and abide.
4. QC Manager
QC Manager shall be responsible to ensure that all backfill works are in accordance with SAUDI ARAMCO standard & Project Specification as well implementation of quality control procedure. He is responsible to review work activity and provide related SATIP & SAIC. He ensures that the proposed method of backfill is approved by COMPANY prior to start of work.
5. Civil Engineer
Civil supervisor shall be directly involved in the planning and executions of backfill works. He shall ensure the implementation of quality plans and also responsible Obtaining PTW prior to commencement of work. HSE Plan must be implemented and observed during earthworks.
6. QC Inspector
QC Inspector shall be responsible to raise RFI to CONTRACTOR & COMPANY ones the work is ready. QC inspector of GU SAN will inform test schedule to technician of third party laboratory.
7. Foreman/Leadsman
Foreman shall be responsible for the direct execution of earthworks according to the plan and shall directly control and give instruction to the working personnel. He is responsible forth usage of Proper tools /equipment, personal protection equipment’s and housekeeping.
8. Direct/Skilled Worker
Responsible in implementation of general works on site in different category for direct execution of work according to the instruction of foreman. The required manpower lineup shall be determined accordingly.
4. BACKFILL WORKS GENERAL
1. Backfill and Compaction
a) Backfilling will be done in uniform horizontal layers not exceeding 350mm loose thickness. Each layer will be compacted depending on the area of working. When clean sand material is used, it will be compacted to a firm and stable condition using an appropriate compacting device.
b) Backfilling will proceed symmetrically around the structure, whenever possible to do so.
c) The water for the compaction will be sprayed uniformly. Then fill material will be sprinkled to uniform water content before compacting, care will be taken to see to it that the layer thickness does not exceed as specified.
2. Inspection & Testing Agency
a) Testing shall be performed by Saudi Aramco-approved independent testing agency.
3. Submittals
a) The Contractor shall be responsible for transmitting the following submittals to the Saudi Aramco Company Representative:
b) Soil sample test report & field test reports shall Include density and moisture content test logs indicating location by coordinates and Elevation/Layer.
4. Safety
a) Any construction or maintenance work which restricts the full use of a pedestrian or Vehicular
Roadway shall comply with Gl-1021.000, Street and Road Closure: Excavation, Reinstatement
and Traffic Controls.
5. Entering Confined Spaces
a) No one may enter any deep excavation or manhole without specific approval and a current work Permit. Prior to entering any vessel, deep excavation or deep manhole, gas test and instruments are required.
b) No new activity shall be introduced into a confined space without the permission and Signed
approval of the permit to work issuing authority.
c) Subcontractors shall not enter or commence work in any deep excavation, deep Manhole, deep excavation, pipe or chamber or other enclosed space, until a valid permit to work has been
issued. Where Subcontractor operations may result in a dangerous atmosphere arising during the work activity the permit to work issuing authority shall be made aware of this before permit
issue.
5. Backfilling Work Procedure
1. Procedure for Proposed Backfilling Layer The backfilling material is spread to a loose depth of the backfilling layer with 350 mm (Clean Sand) and after compaction, the final thickness shall be equal or less than 300mm.
2. Procedure for backfill using Clean Sand Subgrade is prepared for the proposed backfilling area at site. FDT is conducted at the required number of points as per SAES A-114.
3. Using Roller Compactor/ Rammer / Plate Compactor.
Clean Sand is spread in layer of loose depth of 350mm and water is sprinkled until saturated. Compaction is carried out using Roller Compactor/ Rammer or Plate Compactor.
4. After Compaction. The compacted backfilled layer should be less than 300mm and FDT will conduct by third party technician once the test result passed then backfilling can proceed to next layer.
5. The relevant Mock-up Test was conducted with QC, PID, PMT and 3rd Party on 28″ Feb., 2016 at site as shown in attachment 3. The result was very satisfactory.
6. Mock-Up to Improve Backfilling Thickness
Purpose: Establish sticks with marking elevation (350 loose / 300 compacted)
Procedure:
1st lift @ 150 thick of clean sand filled on duly prepared surface by a backhoe. Uniformly spread on surface and saturate with water for 5mns. approximate 100 litres /m². Compaction by plate compactor with 2 uniform passes on surface.
2nd and final lift placement (including levelling)
Uniformly Spread on surface and saturate with water for 5mns. approximate 100ltrs. /m². Compaction by plate compactor with 2 uniform passes on surface. After 2 mns. recompact by plate compactor with 2 uniform passes on surface.
7. Quality Control
1. QC Inspections
a) Conduct site surveillance on his designated area
b) Monitor construction activity and verify if the area is ready for inspection.
c) Raise RFI to Contractor and Company.
d) Coordinate to third party lab. technician
e) Witness testing for compaction and verify the result passing or failing.
f) If result is satisfactory then construction can proceed to next layer.
g) RFI will be accepted and signed by Contractor and Company.
8. Safety Control
1. Contractor Safety officers shall carry out the safety site inspections to ensure that safety requirements laid out in the safe work plan are being followed during and after the excavation work. Safety Manager/ Supervisor shall review Safety Action Plan and secure Work Permit if necessary prior to start of any activities job safe analysis will be strictly followed.
2. Barricading of excavation and “swing” areas of equipment shall be checked prior to the commencement of work.
3. Prior to work commencing, TSTI shall be conducted by the Foreman / supervisor. Review and comments to be generated by contractor civil supervisor and safety supervisor to carry through safe practice.
4. Persons involved in Excavation work shall be provided with and use the necessary PPE and as a standard each person shall wear a Safety Helmet and Safety footwear. The requirement for additional PPE shall be identified may include the use of the following:
a) Eye protection.
b) Hand Protection.
c) Dust masks.
d) Reflective jackets if working in the vicinity of moving traffic.
e) And any other necessary PPE
9. Equipment and Tools
a) Excavator
b) Long arm Excavator.
c) JCB Back Hoe.
d) Bobcat.
e) Dump truck.
f) Vibrating roller compactor 1/3 ton.
g) Vibrating plate compactor.
h) Rammer.
i) Water Truck.
j) Fuel Tank.
k) Wheel barrows and hand shovels.
10. Attachment
1. Job Safety Analysis.
2. FDT Result.
3. Pictures for Mock-up Test.
Check out more information in following article.