1. Purpose
2. Scope
3. Definitions
4. Responsibilities
5. Safety
5.1 Machinery and Equipment
5.2 Personal Protective Equipment
5.3 Safety Arrangement during the foundation work
6. Working Method
6.1 Preparing Work
6.2 Survey and Setting out
6.3 Excavation
6.4 Dewatering
6.5 Piles (where applicable)
6.6 Blinding Concrete
6.7 Foundation
6.7.1 Rebar
6.7.2 Formwork
6.7.3 Concrete
6.8 Embedded Items
6.9 Repair and Items
6.10 Repair and Touch-up
6.11 Pedestal
7. Allowance and Tolerance
8. References
9. Appendices
A. Activity Organization Chart
B. Emergency Action Plan
C. Sketches and Drawings
D. Foundation Location Plan Foundation Construction Sequences Foundation Schedule
10. Exhibits: Manufactures repaired product data sheets to be added
1.0 Purpose
The purpose of this general method statement is to describe the construction procedures for the isolated pile cap and pad foundations. Large raft foundations will be covered in specific foundation method statements and are not included in this document.
2.0 Scope
The works will incorporate the procedures necessary to execute the following items:
Preparing of Work
Survey And Setting Out
Excavation
Dewatering
Pile (If Applicable)
Blinding Concrete
Foundation- Rebar- Formwork- Concrete
Embedded Items
Backfill
Pedestal
3.0 Definitions
Client:
Contractor:
Responsible in the supervision of the sub-contractor who will perform the construction work and all related activities as outlined in this procedure
Sub-Contractor:
Responsible in the execution of the construction work as well as the tests required in accordance to this procedure
Sub-Subcontractor:
Responsible in the execution of Foundation Work
4.0 Responsibilities
Construction Manager and Senior Engineer:
Responsible in ensuring the implementation of construction procedure and method statement, the Quality Control of work, Supervise the work and reporting the progress of work to Site Manager.
Safety / Environmental Officer:
Responsible in ensuring that all activities are carried out safely He will responsible to patrol at the site, Establishing the site safety plan, Conducting continuous safety inspection and stop any work deemed unsafe and a risk to personal.
Taking action to rectified the unsafe condition and report to project manager and preparing the notes of safety meeting.
QA/QC Engineer:
Responsible to monitor the execution and performance of the works in relation to this method statement,
ensure approved drawings and material specifications;
detect and report non-conformance;
ensure that all non conformance products or activities identified are reported;
propose the corrective and preventive action where possible and appropriate and record the completion of the Non Conformance by using approved report format.
Site Engineer & Foreman:
Responsible to make sure that all activities on site are carried out in accordance with the schedule and the construction drawing.
Take care of all worker to make sure that they work as per their responsibilities.
Make necessary decision when some non conformance is occurring and report to senior engineer.
5. Safety
Refer to the site safety policy for general safety controls. One of the main aspects of this procedure is Safety and Health Control.
This is to control occurrence of injuries as well as damage to equipment and properties during the entire construction period.
In order to ensure a safe working environment during the entire construction period, the following safety measures will be implemented:
5.1 Machinery and Equipment:
Prior to using any machinery / equipment at site, it shall be inspected and certified by qualified person.
Periodic Preventive Maintenance shall be made on all equipment and machinery.
All operators and drivers are to be equipped with valid driver’s / operator’s license or permit from concerned government agency.
Only authorized drivers or operators will be allowed to operate machines or equipment.
Only authorized signalman shall be assigned together with the operator or driver.
All lifting equipment as well as its accessories such as sling wire, nylon sling, shackles, chain blocks crane hook and latch shall be inspected periodically.
5.2 Personal Protective Equipment:
Personal Protective Equipment (PPE) shall be issued to all workers such as safety shoes, hardhat, working gloves, earplug, safety goggles (if required) and safety belt and or safety harness for workers who will be assigned in elevated places 2.0 meter and above.
Wearing of the basic PPE shall be enforced fully.
5.3 Safety Arrangement during the Foundation Work:
Emergency Action Plan- refer to Appendix-B
All new recruits shall undergo proper orientation and safety induction before they are deployed at site for work.
6.0 Work Procedure – Method of Foundation Work
6.1 Preparation of Works:
- Foundation works will not commence until confirmation that all pre-construction planning and safety checks are completed.
- The supervisor shall be familiar with the latest construction drawings and method statements.
- Plant and equipment requirements will be assessed on a case-by-case basis for each foundation location and agreed with the Construction Manager prior to starting the works.
6.2 Survey and Setting out
Before work starts, survey department will establish baselines and benchmarks from which co-ordinates and elevations will be taken to set out the foundation works.
6.3 Excavation
- Excavations will generally be executed in open cut to the size, slope and elevation shown on the construction drawings and/or design calculations.
- Survey will verify set out and check edge slope and bottom founding level of excavation.
- Excavation will be carried out with excavator and the excavated material loaded directly into dump truck and transported to temporary stockpile area.
- A small bucket or manual digging will be used when excavating between piles.
- The final bottom founding level under each foundation will be inspected by QC and tamped or compacted as per design requirements before pouring blinding concrete.
- For a description of all related work activities refer to method statement for open-cut excavations.
6.4 Dewatering
- From the site soil report the relative groundwater level is approx. -2.2 m below existing ground level
- During excavation and after reaching the required excavation level a dewatering system will be installed as required and any water discharged to the vicinity drainage pits
- For a description of all related work activities refer to method statement for dewatering excavations.
6.5 Piles (where applicable)
- Following final excavation the piles will be cut down to design pile cut off level.
- Removed sections will be lifted out and taken to designated disposal area.
- After cleaning, the pile head treatment will be done to connect pile to foundation.
- For a description of all related work activities refer to method statement for pile cut-off.
6.6 Blinding Concrete
- Bottom of the excavation should be dry and tamped or compacted to a uniform level before pouring the 50 mm thick lean concrete blinding layer.
- For a description of all related work activities refer to method statement for concrete.
6.7 Foundation
After QC inspection of the prepared founding level and lean concrete base layer then construction of the foundation will follow.
6.7.1 Rebar
- Rebars will be cut and bent on site in line with the agreed construction sequence.
- Installation of rebar will begin as soon as blinding concrete has hardened enough for trafficking (normally 12 hours)
- A mobile truck crane and/or manual workers will be used for rebar installation.
- Rebar placement sequence will follow the latest rebar construction shop drawings.
- Suitable concrete spacers will be used to achieve the desired covers and additional rebar spacers will be installed to maintain support of top steel and any cast-in items.
- All pedestal column starter bars and cast-in anchor bolts will be accurately located and securely fixed in the correct position.
- Location, spacing, verticality and cover shall be checked during the installation process and QC will make a final inspection prior to calling up concrete.
- For a full description of all work activities refer to Method Statement for Rebar.
6.7.2 Formwork
- The formwork system to be adopted for each foundation type and size will be as specified in approved calculations prepared by the Temporary Works Design Engineer. The different types of formwork for site installation purposes are summarized in Table in Appendix.
- Plywood sheathing with timber and steel props will be used for formwork and manual labor will be used for lifting and placing according to survey-lines of the foundation outline.
- Approved form release agent is applied prior to lifting-in and erection of the clean forms.
- Forms are connected tightly together and braced to the excavation profile or waling in the case of a sheet pile wall.
- For a full description of all work activities refer to method Statement for Formwork.
6.7.3 Concrete
- Concrete pump will be available (with back-up pump) for placing concrete at a rate of around 3540 m3/hr. In some cases pouring concrete will be done by bucket and 25T mobile crane at a rate of 10-15 hr.
- A minimum of 4nos of 50mm vibrators shall be used for compaction.
- Unless agreed otherwise the foundations will be poured at one time in layers, starting from the centre and spreading out to each side.
- Keep concrete alive without performing any cold joints.
- Manual tools and float are used to finish the top surface.
- For a full description of all work activities refer to method statement for Concrete.
6.8 Embedded Items
- All embedded items and cast-in anchor bolts shall be placed to the specified installation tolerances shown on the construction drawings.
- Special care will be taken to place and maintain embedded materials to the proper setting location to prevent movement during the progress of the work and to tamp concrete thoroughly around them.
- For a full description of all work activities refer to method statement for embedded items.
6.9 Repair and Touch-up
- After striking of forms a QC inspection will be conducted to decide whether any repairs to the concrete surfaces are necessary.
- For a full description of concrete repair procedures and materials to be used refer to method statement for concrete repair and touch-up.
6.10 Backfilling
- Backfilling operations will be executed in two (2) stages using suitable excavated sand material.
- The first stage fill will be placed up to the top of foundation level and will commence as soon as formwork has been removed and QC inspection of foundation is approved. NOTE: If this method is adopted then curing of the foundation will be done using suitable curing compound.
- Backfilling will be done in loose layers not more than 250 mm in thickness.
- Suitable vibrator plate/rollers and/or water will be used to achieve the compaction requirements for each layer field density test will be performed to check the soil compaction to 95% maximum dry density.
- Any embedded cable way conduits and earthing/grounding wires, drainage pipes and trenches etc. should be installed simultaneously with the back filling layers.
- After completion of the concrete pedestal then the second stage fill will be carried out up to grade level below proposed finished ground level
6.11 Pedestal
- Pedestal columns vary in height
- Heights exceeding specific value will be cast in two(2) lifts
- Formwork will be made using plywood form panels in sizes to suit manual installation and dismantling.
- All construction joints will be properly prepared at location indicated on the construction shop drawings.
- For general construction details and work procedures refer to method Statements for Rebar, formwork and concrete.
7.0 Tolerances
As per final design drawings and/or Main Contractors instructions.
8.0 References
- Specification: Client’s Technical Specification for Civil Works
- Safety provisions: Refer to Site Safety Plan.
- Related Method Statements:
- General Method Statement of Concrete
- General Method Statement of Reinforcement
- General Method Statement of Formwork
- General Method Statement of Concrete Repair and Touch up
- Drawings: Refer to latest “Issued For Construction” drawing list.
9.0 Appendices
Appendix A: Activity Organization Chart
Appendix B: Emergency Action Plan
Appendix C:
1. Foundation Location Plan
2. Foundation Schedule
3. Foundation Construction Sequences
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