Bowral STP Detailed Design

  • ASpect’s Client: Hunter H2O
  • Head Client: Wingecarribee Shire Council
  • Plant Configuration: FSB
  • Plant Size: 21,000 EP
  • Project Value: $30M (ASpect Fee $110k)
  • Project Duration: March 2020 to Current

Bowral STP Detailed Design, with Hunter H2O for Wingecarribee Shire Council (NSW).

Wingecarribee Shire Council (WSC) own and operate a number of STPs in the NSW Southern Highlands Region.  This is a growing region in the south west corridor out of Sydney.  The region is characterised by a number of large towns and cities in a cool climate, situated in the drinking water catchment of Sydney.  The location within the catchment places a number of constraints on discharge from the STPs.  One of these is that the load of pollutants, including nutrients, are capped at historical quanta.  Therefore, all amplifications and upgrades must achieve a neutral or beneficial effect (NorBE) on the recieving waters.  As the population increases, the performance targets tighten.  Bowral STP also suffers from tight site constraints and the encroachment of residences.  The existing STP was already overloaded, making construction and commissioning sequences more complex.  The original concept, prepared by others, involves the expansion of the STP using existing IDEA style bioreactors.  The NorBE requirements were proposed to be met by post IDEA add on technologies.  During the proposal, ASpect identified shortfalls in this approach, particularly with regard to total nitrogen removal.  ASpect also identified an alternative concept, utilising the existing IDEA as an aerobic digester, that would save capital costs, improve redundancy and increase the buffer to local residents.  After award, further options investigations resulted in the replacement of the IDEA concept with continuous flow bioreactors.  These could be operated as MLE or four stage bardenpho (FSB) as NorBE limits tightened.  The MLE configuration could be used in the interim, utilising the spare capacity to provide a very high wet weather treatment capacity.  This concept was shown to be of lower NorBE risk, offered further capital cost benefits, simpler construction and commmissioning and simpler operation than the IDEA equivalent.  ASpect’s role in the project was to determine current and future loads, review the existing concept, help Hunter H2O prepare alternative options, undertake the process design compenent of the revised concept and detailed design, draft P&IDs, write the functional description and the prepare the process designer’s report.