Rapid Gravity Filter Tanks

Stonbury were recently contracted to carry out refurbishment works to 22 Rapid Gravity Filter tanks and outfall channels.

Refurbishment work included high pressure water jetting to the walls, floors and outfall channels to remove any loose debris and aggregates in preparation for concrete repairs and coatings to tanks. The HPWJ was carried out using a turbo nozzle with the pressure up to 3000psi, leaving a sound and suitable substrate to apply elastomeric coatings.

The next stage of the refurbishment was to repair the floors using a DWI approved mortar, these concrete repairs were to infill nozzle fixing holes to the floor slabs which were left as a result of the pipework being removed. Mortar fillets were installed at wall to floor interface. The floor repairs were needed to level out the area prior to the coating works.

Due to the nature of the confined space within the channel itself, the waterproof elastomeric coating was applied by brush and roller, the remaining RGF tanks also received the same coating but using the airless spray method to the total thickness of 2mm. The first coat of 1mm grey was spray applied and the then brushed into the substrate to ensure full adhesion. The second 1mm coat of white was applied by the spray method and finished off with a soft brush to leave a smooth surface. The use of these tanks as rapid Gravity Filters has now come to an end and they will be re-used in the future as storage or holding tanks.

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