NIWA - National Institute of Water & Atmospheric Research
We were called in, to remove the bitumen coating from walls and floor of the tank, using a high pressure industrial soda blasting unit, which was achieved blasting wet. This was not an easy task as it was an enclosed/confined space, so all safety precautions were put in place as the team had to work in full body suits and use full mask and breathing apparatus. On the floor of the tank the bitumen was so thick that this had to be removed with a jack hammer. Then a water soluble solvent was applied to ensure that all oil residue and contaminants were removed and neutralized. We then had to repair some of the structure, as over the years, the concrete had become soft.
The final stage was to apply two coats of Aquella Waterproof Coating to the walls and floor of the tank and then an epoxy coating.
NIWA also asked us to look at the two large in-ground tanks, which were painted, but in very poor condition. Once again the soda blaster was put into use, but this time dry. The floors of the tanks were abraded using the Klindex 750 Expander, which also removed the imperfections in the floors. Once this was achieved and cleaned up, we then had to chase out large areas of soft hollow concrete, rust and cracks around the internal structural steel, these were then filled with the Krystol Bari-Coat, to all open areas in the concrete.
The same application as the mushroom tank was applied and the EPAR 226 epoxy coating as the final membrane.
Posted: Thursday 2 January 2014