Waste water tank relining using Polyurea

THE PROBLEM

The existing HDPE liner had broken down and was allowing effluent to leak into the surrounding soil presenting an environmental hazard.


THE SOLUTION

We proposed the application of a seamless spray applied polyurea tank lining as the most suitable solution due to the materials high elasticity and tensile strength.

Removing the old lining

The existing HDPE liner was unbolted and cut into sections using reciprocating saws and removed from the tank. Due to years of leaking sewage the structure underneath was heavily contaminated and had to be thoroughly cleaned by method of high pressure washing. 

Preparing the Tank for lining

The tank internals where prepared by method of abrasive blasting to remove eroded concrete and raise a surface profile to ensure excellent adhesion of the new polyurea tank lining.

Waterproofing and repairing

Following abrasive blasting several significant cracks were exposed in the tank structure and points of groundwater ingress discovered. The active leaks were first stopped using Remmers Rapid Hardener cementitious water stop. The cracks were repaired either by epoxy injection  or using Remmers Betofix RM repair mortar applied using trowels.

To ensure that no groundwater ingress could enter in other areas the tank was waterproofed using Remmers MB2K flexible tanking system. This also served to fill blow holes and pores in the concrete that could not be filled with primer alone.

Priming the tank for relining

The tank was primed throughout using a damp tolerant epoxy primer. This was fully blinded with quartz aggregate so as to remove any concerns about exceeding the primers recoat window. This serves to provide an excellent mechanical anchor for the new polyurea tank lining.

Applying the tank lining

VIP Quickspray Industrial pure polyurea was spray applied to a thickness of 2mm using one of our WIWA PU460 plural spray units. Care was taken to spray the polyurea into the previously cut termination rebates. The lining was tested for pin holing using a DC holiday spark tester and where required repairs to the tank lining made.

The previously cut rebate was then sealed using a polyurethane jointing compound to protect the top edge of the tank lining.

VIP Quickspray Industrial pure polyurea was spray applied to a thickness of 2mm
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