The tank was in a small basement at the bottom of a shaft, 4.5mtr below the ground surface. The metal liner had rusted through exposing the concrete to attack from the various caustic and acidic liquids.
It would have been virtually impossible to replace this unit due to its position so after cleaning, a wooden former was made and the best part of 2 ton of concrete was used to fill the void and rebuild the walls and floor. With a new concrete tank in place it only remained to protect it from further attack from the aggressive chemicals. This was achieved by lining the tank with woven glass fibre matting and a highly chemically resistant polyurethane resin. This is a quick setting product that allowed the system to be brought back into use very quickly.