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Effluent Pit Lining, Chesire

THE PROBLEM

The trade effluent pit was suffering from degradation and as part of the planned site upgrade works a suitable tank lining solution was required.

THE SOLUTION

With the pit being below ground we proposed the application of Sikagard®-7000 CR. This system offers the following benefits;

  • Vapor permeable, reducing the risk of osmotic blistering which is a critical consideration in buried concrete/masonry structures which might not have external waterproofing in place.
  • Crack bridging making it ideal for aged concrete and masonry structures where some future movement may occur.
  • Highly chemical resistant
  • Fast curing – ideal for short outages such as this project
  • Highly moisture tolerant

Initially the pit was prepared by method of high pressure water jetting using our 10,000 psi jetting unit to ensure excellent adhesion of the new tank lining.

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Following preparation this fully exposed the level of degradation that had occurred to the pointing within the pit, with nearly all mortar joints requiring repair.

Dehumidification equipment was introduced to dry out the chamber prior to testing and recording the moisture content of the substrates on to which the tank lining was to be applied as part of our standard quality assurance.

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The ambient conditions with regard to relative humidity and dew point were also tested and recorded to ensure compliance with the manufacturers recommendations as part of our tank lining quality assurance.

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All surfaces were primed using Sikagard® M 790 highly damp tolerant polyurethane primer by method of brush and roller. Because of the short duration of the shutdown it was not possible to make good the substrate using cementitious materials. Instead a repair mortar was made by mixing Sikagard® M 790 with blended kiln dried quartz. This was applied into the tacky primer by trowel to provided a continuous surface suitable for tank lining application.

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The first coat of Sikagard® M 790 was applied by method of brush and roller in a red colour

To accelerate the cure of this material heating was introduced and the chamber enclosed.

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The second coat of Sikagard® M 790 was then applied by method of brush and roller in a grey colour as per best tank lining practice

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As per our standard tank lining quality assurance the cured coating was checked for pin holing using a DC Holiday spark tester as a single pin hole is a point of tank lining failure which will allow aggressive chemicals to reach the substrate and attack recommence.

Any pin holes identified were marked prior to making good using the same material applied by brush.

The entire project was completed in less than a week within the client tight shutdown programme.