Method Statement for Application of GRP Lining Inside Water Tank

If your project has a water tank located at the first or second basement then you will be needing to apply GRP lining. And so, therefore, a method statement for installation of GRP lining inside the water tank is inevitable to develop.

1. Title

Method Statement for Application of GRP Lining Inside Water Tank


2. Purpose & Scope

This method statement is for the purpose of installing or applying Glass Reinforced Plastic known throughout this document as GRP.

The method statement for the application of grp lining will particularly cover water tanks, sewage pipes, and manholes together with stormwater drainage systems and underground water tanks.

The scope involves covering water tanks to the specified 7mm thickness of GRP.

3. Reference

3.1 Civil Specification – Division 1, Section 014344 – Underground Water Tank GRP lining
3.2 Approved shop drawings
3.3 Material Submittal (Reference no. 0000)
3.4 Inspection and Test Plan

4. Material for the Application of GRP Lining

• Polyester Resin-Polypol-1003.
• Gelcoat Norpol GS.
• Glass fiber mat- E or Chopped strand mat
• Catalyst Dispenser

5. Equipment & Tools

• Mohair rollers
• Steel rollers
• Measuring tape
• Brushes
• Scrappers
• Grinders

6. Responsibilities

6.1 Site Manager

• Documentation must be submitted to the relevant parties in compliance with the works to be undertaken. Documents and permits will be submitted in a timely professional way.

• The site manager will make certain the work is performed in line with the method statement before GRP installation commences.

6.2 Site Engineer

• Site engineer will prepare for the appropriate work to be undertaken to the prescribed standards for the GRP lining of underground water tanks. The installation will be in line with the method statement and specifications supplied under the designated job order.

• Site engineer will manage the sub-contractor agent to acquire all necessary materials as specified for the job order.

• Site engineer will ensure together with the sub-contractor sufficient materials are available on site to complete the work as scheduled.

• Site engineer will make sure that the installation area is prepared and ready for the GRP lining application to be applied in a specified manner.

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• The site engineer will be in possession of MSDSs and be fully conversant with the said MSDSs for all materials utilized in the application of the GRP lining.

• The site engineer will ensure adequate health and safety compliance is adhered to such as ventilation and material storage and handling.

6.3 Subcontractor supervision

• The subcontractor will follow the method statement and apply the lining as specified.

• The subcontractor will designate labor to ensure the work is carried out as specified and in a timely manner.

• The subcontractor will continually liaise with the site engineer and proceed with the site engineer’s instructions to comply with the method statement.

• Continuous checking will be conducted to ensure the specification of 7mm of GRP is being met with in accordance with the specification. Remedial actions should be undertaken if required to comply with specifications.

• The subcontractor will ensure he has contact with the health and safety officer and provides a safe working environment for the installation team.

• It will be the responsibility of the subcontractor to provide adequate training to the installation team and to provide the required PPE.

• The subcontractor will provide a clean and clear working surface free from protrusions, voids, and debris, dust, and moisture prior to GRP application.

• The subcontractor will provide the required lighting with sufficient illumination for the installation team to work unhindered. In addition, sufficient ventilation must be provided to clear fumes and noxious odors’ from the working area.

6.4 Quality Control and Quality Assurance Engineer

• Will be qualified and have experience of overseeing similar projects.

• Will make sure the method statement for the application of grp lining is being adhered to in all aspects.

• QA/QC will make the subcontractor aware of specifications and provide job order drawings before the application of the GRP lining commences.

• It will be the responsibility of the QA/QC to check the supply of materials that meet the required specification before the GRP lining work commences.

• QA/QC will monitor the handling and distribution of the GRP materials in compliance with the site engineer’s instructions and MSDSs.

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• QA/QC will verify that the surface working area is in compliance with the GRP installation method statement.

• QA/QC will verify all members of the installation team are qualified and briefed of the procedures of the installation.

• QA/QC will inspect the GRP lining for visual deviations.

• QA/QC will check the GRP lining for integrity and areas, not in compliance will undergo remedial repairs to ensure specifications are met and comply with the customer’s order.

• QA/QC will monitor the depth of the GRP lining and ensure the 7mm depth is in overall compliance with the job order and method statement.

7. Methodology

7.1 The working area will be clear and free of all contaminants. Moisture must be eliminated from the working area for a successful GRP application. All hydrocarbon substances such as oils and lubricants will be removed for perfect adhesion. Any other surface impurities will also be removed.

7.2 Cleaning may include brooms brushes vacuum cleaners for the removal of heavy and fine particles.

7.3 Materials will be stored in a manner to avoid spills causing staining.

7.4 Edges will chamfer and corners rounded with the prescribed filler before the lining is applied. Imperfections will be rectified with the use of resins suitable for the GRP application.

7.5 A bonding coat such as (NORPOL 720-8001) will be applied thinly to the working area to assist the chopped strands mat adherence to the working surface.

7.6 After the bonding coat is cured, the chopped mat strands will be applied to make sure that the CSM is sufficiently wet for good application. Ensure sufficient impregnation of the CSM to avoid the exothermic heat.

7.7 A second layer of the CSM can be applied again using the steel roller when the first layer is sufficiently cured.

7.8 Approximately six layers will be required to achieve the depth of 7mm GRP.

7. 9 It is recommended to use 50mm overlapping for the laminating process.

7.10 When complete and sufficiently cured the surface will be inspected for anomalies such as air pockets and exposed matting. Remedial work should be conducted using sanders if required.

7.11 When complete and signed off as complete and in compliance by the QA/QC a final gel coat will be applied using glass fiber tissue.

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7.12 The gel coat should have the properties of anti-corrosion properties and provide a smooth surface in compliance with the job order.

7.13 The covering slap will require just two coatings of the gel coat to provide adequate protection.

7.14 When the installation is complete and working materials such as tool and access platforms will be removed from the working area.

7.15 The floor application of the GRP will now follow the same protocol as the walls.

7.16 Drainage systems and catchment areas will be also GRP lined to a depth of 7mm in compliance with the original drawings.


Related articles:

  1. Method Statement for Application of Waterproofing Membrane
  2. Method Statement for Liquide Applied Bituminous Waterproofing
  3. 7 Actionable Steps to Avoid Water Leakage for Your Underground Structures


8. Safety

• Approved Method Statement and Risk assessment for the application of grp lining should be brief, communicated, and implemented properly and available on the site at all times.

• Manlift should be 3rd party certified.

• All plant/machinery operators to be 3rd party certified.

• Pre-task briefing to be completed daily by the site/project engineer prior to any task starts. Foremen to conduct a pre-task briefing for teams every morning clearly outlining the safe work method steps, roles, and responsibilities.

• Full job-specific PPE (appropriate respirator, chemical resistant overall, gloves, googles etc.) to be worn at all times and inspected, verified and approved prior to use by the main contractor authorized personnel on a daily basis.

• All subcontractors will be inducted and fully aware of site emergency procedures.


  1. The QA/QC Engineer should check every layer of the application of grp lining.
  2. Ensure the thickness of the application of grp lining is in compliance with the approved material submittal.
  3. After the application of grp lining, there should be a water test.
  4. The inspection request for the application of grp lining should be submitted every layer.
End of Method Statement
Do you follow the method statement for the application of GRP Lining inside the water tank as stated above? Please share your thoughts.


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