Balfour Street, Dulwich Hill GPT Refurbishment

Optimal Stormwater were asked to carry out some specialist repairs to the CDS unit in Balfour Street, Dulwich Hill. Over 8 years of operation on a large flowing culvert, the device had suffered from wear and tear.


On inspection of the Balfour Street CDS unit, Optimal Stormwater observed the following issues:

  1. The fiberglass inlet chute had broken away from the Diversion Chamber which meant the pollutants weren’t necessarily going into the GPT to be trapped. This had been caused by a deformation of the screen support structure which anchored the inlet chute.
  2. In addition, all but 300mm of the outlet volute of the device has silted up, effectively blocking flow through the device.
  3. The construction of the diversion structure provided a less than efficient hydraulic conveyance for high flows.

Optimal removed three stainless steel screen panels to allow the removal of the silt from behind the screen and a thorough overall clean.
To rectify the inlet problem, stainless steel plates were cut and bolted into position to close the gaps. It was determined that to rebuild the entire screen structure was not cost effective.
Additional concrete benching was poured into the diversion structure to reduce hydraulic losses and reduce deposition of debris.

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