The purpose of this article is to define the procedure for sequence of works in preparation for the foundation up to the level of blinding concrete, considering all safety and quality requirements. Preparation of foundation works at site involves water proofing, screed and casting of foundations including column and lift pit footings.
Prior to commencement of activities ensure that all personal are safety inducted and aware of the nature of work and the risk assessment. Appropriate safety gear i.e. PPE shall be provided, and the workforce shall be instructed to use it properly.
In areas where deep excavation has been carried out, safe and secured, ladders shall be provided to access the bottom of the excavation. Fall protection shall be provided all around the main excavation area. Warning tape and warning signs will be provided to the surrounding of Lift pits or other deep excavations.
Roles & Responsibilities
Project Manager
Ensure that the Project Works are carried out in accordance with Company policies & Project Quality Plan.
To ensure the full compliance of sub-contractors with the requirements of this Quality plan.
To ensure that all the required equipment to execute the works according to the construction program are available, in good condition, and provide any additional equipment that might be required.
To co-ordinate with the Construction Manager, Project Engineer, Safety Engineer, Surveyor and Foreman for the safe and proper execution of the works.
Construction Manager
Ensure the area is ready and safe to start the works.
Set up the required equipment and allocate required manpower through discussion with the Project Manager and Project Engineer / Works Foreman.
Ensure the works are carried out according to the specification, quality plan, approved shop drawings and the construction program.
Provide Risk Assessment for the works in hand.
Provide sufficient and safe access for operatives, trucks and pumps.
Ensure that all the works are carried out in accordance with approved procedures and drawings.
Project Engineer
The Project Engineer shall carry out his duties in a manner that shall be coordinated by the Project Manager on a daily basis with the relevant subcontractors.
Ensure proper distribution of workforce and equipment at required locations.
Ensure that the works are carried out according to the approved sequence and to inform the QC Engineer / Inspector for the areas ready for inspection.
QA/QC Engineer / Inspector
Ensure that Consultant/ Client inspection requests are implemented as per project quality plan.
Compilation of all necessary quality control check lists.
The control of work performance by means of checking the work before consultant’s inspection and issuing RFI’s, punch lists and assisting consultant during the inspections.
Completion of documentation to verify the work performed.
Controlling all inspection activities on site in line with ITP’s.
Ensuring that all test equipment including surveying equipment is calibrated and suitable for use at site.
Surveyor
To establish bench marks from agreed reference points, provide required setting out and level markings and follow up with regular checks.
Co-ordinate with Project Engineer and foreman to ensure the location of works carried out according to the approved shop drawings/construction drawings.
Maintain survey details and report, periodically check the progressing works and notify the Project Manager if any deviation from the drawings.
HSE Engineer/Officer
To ensure implementation of all safety measures related to the nature of works being carried out, and in accordance with the Project Safety Plan.
To ensure all the persons involved in the works are aware of their responsibilities, and they have enough understanding of the safety procedures.
The safety officer in coordination with Project Manager shall ensure that all the safety measures implemented are effective enough to maintain safe working at site.
To maintain continuous inspection of site activities, advise and train persons on a daily basis to prevent accidents and personal injury.
To ensure all the relevant safety sign boards for different works are in place, and to give special concern to housekeeping, and ensure that the site is maintained clean & tidy.
Foremen/ Works Supervisor
Ensure the works are progressed in the sequence as agreed with the Project Manager.
Liaise with construction manager / project engineer for required plants/ materials and allocation of manpower.
Ensure with Project Engineer / QC Inspector the works are inspected and approved by Engineer prior to proceeding with next stage of construction.
Necessary Equipment’s and Tools
- Excavators
- JCB
- Total Stations & Auto Levels
- Water proofing tools
- Masonry Tools
- Dozers
Notification to Start Activity (NSA)
Prior to starting any new activity, a ‘Notification to Start Activity’ (NSA) form shall be submitted for approval.
Excavation
General excavation shall be carried out by using dozers/ shovels/ excavators / jack hammers / shovels, and the excavation shall be completed with hand tools like pickaxe, hand shovel etc., according to the approved excavation method statement up to the bottom level of raft / slab on grade.
Setting Out
The limit of the working space may be set-out on the ground (the limit shall include working space around the foundation for casting retaining walls and waterproofing works). Or shall be marked temporary structures such as a side rail as reference, in accordance with the approved drawings.
Over-excavation
Care shall be taken not to excavate below the required level (the excavation shall include 11cm for the thickness of blinding, approved waterproof system and protection screed).
Compaction
The bottom of the excavation shall be cleared from debris and extraneous material.
The formation level shall be sprinkled with water to achieve the required O.M.C for the soil, which shall be then compacted by means of a vibrating compacting roller or a vibrating plate compactor.
The compacted area shall be tested to determine the degree of compaction (i.e. not less than 95% of M.D.D). The method shall be in accordance with the ASTM D 1557.
To determine the Safe bearing pressure of soil under footing Plate Load Test shall be conducted as instructed by the consultant engineer.
Consultant’s Approval
No permanent works activities shall be carried-on in the compacted areas, prior to receiving approval from the Engineer.
Anti-termite Treatment
Anti-termite treatment shall be applied according to the applicators approved method statement and covered with one layer of 1000 gauge polythene sheet.
Blinding Concrete
Blinding concrete to the approved mix design shall be poured to thickness of 50mm in all horizontal areas.
The blinding shall be finished to a uniform level. The surface of the blinding concrete shall be steel float finished, and smooth enough to receive the approved water-proofing membrane.
Block Work
Block wall (C.M.U) around the footing shall be built to an internal dimension 25mm larger than footing sizes (for thickness of waterproofing), up to the bottom level of blinding for slab on grade.
Waterproofing
Waterproofing shall be carried out to the horizontal and vertical sides according the approved waterproofing method statement, and protection board / screed shall be completed prior to the placement of footing reinforcement. Adequate lap length of water proofing membrane shall be left for the continuation.
Backfilling
The surrounding area of footing shall be back filled in layers not exceeding 200mm, using approved material and compacted not less than 95% of M.D.D. up to the bottom level of blinding of slab on grade. If the footing can be excavated approximately to the required dimensions the gap between excavation & block wall can be filled with mortar.
Preparation of Lift Pits
Follow steps above for: surveying, anti-termite treatment and blinding.
Waterproofing
The water proofing shall be continued from footing to the bottom level of slab on grade after the casting the Lift Pit footing and walls, and protection board / screed shall be provided as required
Backfilling & Compaction
The surrounding area of lift pit shall be back filled in layers not exceeding 20 cm, using approved material and compacted not less than 95% of M.D.D. up to the bottom level of blinding under slab on grade.
Anti-termite Treatment & Blinding
Complete the compaction and grading works at bottom of slab on grade level. Anti termite treatment shall be applied and covered with one layer of 1000 gauge polythene sheet.
Blinding concrete to the approved mix design shall be poured to thickness of 50mm in all horizontal areas up to the lift wall, and up to top of block wall in column footings.
The blinding shall be finished to a uniform level. The surface of the blinding concrete shall be steel float finished, and smooth enough to receive the approved water-proofing membrane.
Waterproofing
Waterproofing shall be carried out on the blinding according to approved method statement which shall lap with the lift wall / column footing waterproofing.
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