Do you know that GRP lining is the material we used inside the water tank of mostly high-rise buildings?
The purpose of GRP lining is to prevent the leakage of the tank because the water tank is just made of concrete. So to prevent water from leaking this material is advisable to apply.
In this method statement, I will show you how to properly install a GRP lining even if you are a newbie applicator.
Method Statement for Installation of GRP Lining to Water Tank at Basement
The purpose of this method statement is to describe the measures and system, a procedure that will be adopted for GRP lining installation to the basement water tank. This method statement has been prepared based on the method statement from the specialist included in the material submittal n0. (place your number here) already approved by the engineer,
• Polyester resin
• Chopped strand matt
• Catalyst M-50
4.1 Before lamination or lining works the concrete surface preparation work would be carried out by removing any loose particles laitance, dust, oils, grease (if any) to the satisfaction of the specialist subcontractor for this works. Any honeycomb or segregation would be repaired with approved materials as per manufacturers’ recommendations. All corners would be made curved (acceptable to the specialist subcontractor) before applying GRP lining.
4.2 GRP lamination works would be carried out in the sequence of ceiling, then wall, and finally the floor.
4.3 After removing the dust and cleaning the surface, for first layer putty filling would be done and resin coating would be applied as undercoat.
4.4. For 2nd layer, 450mm chopped strand mat would be laminated by applying with unsaturated polyester risen to obtain 1 mm thickness.
4.5 For 3rd layer the same procedure would be followed (1 mm thickness).
4.6 For 4th layer the same procedure would be followed (1 mm thickness).
4.7 For 5th layer thick white gel coat would be applied for filling the pinholes as a final coating (1.0 mm thick) and would be allowed to dry. The total thickness of GRP lining would be an average of 4 mm.
4.8 General lap length for the lamination process would be 10cm. At corners between floor or wall and wall or ceiling, the strand mat sheet (120 cm width) would be laid centrally with 60cm on either side. No other special treatment is required at corners as advised by the specialist.
4.9 Lining around the pipes inside the tank would be as per the attached sketch.
4.10 All necessary MEP services would be installed and related clearance would be obtained prior to commencement f the lamination work.
4.11 Inspection request would be submitted to the engineer before and after completion of GRP lining works inside the tank.
5. Filling water in the tank
5.1 After approval of the engineer and after receipt of the inspection request the filling of water can then commence.
5.2 Full curing time of the lining in the normal temperature is 24 to 48 hours but as this is the underground tank, it is recommended to fill water 3 to 4 days after the completion of laminations works.
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6.1 Confined space work permit system would be strictly implemented and followed as per the company’s project safety plan.
6.2 The health risk involved in working with these materials in confined spaces (such as suffocation, exposure to material vapor or fumes, etc.) would be given priority while making safety arrangements.
• All persons entering inside water tank would be briefed (every time) regarding safety precautions and hazards.
• Proper ventilation would be provided with an exhaust fan near the opening.
• Near entrance or exit extra person would be deployed to keep a continuous watch inside and maintain communication with the person working inside.
6.3 Skin and eye contact should be prevented by providing rubber gloves, eye goggles, protective clothing to the crews.
6.4 Only experienced applicators under the supervision of an experienced supervisor would carry out the works.
6.5 Proper scaffolding and lighting would be arranged.
6.6 Company safety crew would be always alert and present outside the tank during the activity in order to adopt necessary urgent action in case any worker becomes sick or ill inside the tank.
If you are a quality engineer you have to make sure that the above method statement is followed by the subcontractor or applicator.
If you are a client and if you want to ensure the quality of the application of GRP lining you can hire a quality engineer or consultant to see to it that the works are as per approved drawing and as per related documents such as method statement, inspection and test plan, checklist, project quality plan , etc.