Eurobodalla Integrated Water Cycle Management Strategy

Eurobodalla Integrated Water Cycle Management Strategy
margins are compromised and during wet weather flows plant by-pass will continue to
occur, albeit the frequency may be lower with the proposed inflow reduction management.
The by-pass of raw diluted sewage could be avoided by installing additional clarifiers to
settle the solids and provide some treatment. To reduce public health risk an artificial UV
irradiation plant could be installed at the outlet of the maturation pond, which could be used
to disinfect the effluent prior to discharge through the ocean outfall, and the reclaimed water
used at the golf club. The other works necessary for plant capacity augmentation include:
New inlet works
Minor process modifications
Additional aeration capacity and/or an aerated balancing storage at the inlet, and
Overall OH&S improvement for the plant.
An alternative to this process optimisation strategy is to build a parallel process train with
similar capacity to the current plant.
To overcome the incidence of sewage overflows from the coastal area, a dedicated pipeline
along Spine Road alignment could also be installed to convey sewage from the northern
catchment to the treatment plant.
A New Sewage Treatment Plant to Serve the North Batemans Bay Catchment
In this strategy, a new STP with an initial biological capacity of 5 000 EP would be built
north of Clyde River to treat all the sewage generated from the northern catchment. The
plant would be located on Council owned land. The reclaimed water from the plant would be
conveyed via the proposed Spine Road sewage main to the existing outfall. The advantage
of this strategy is the conveyance of reclaimed water across the Clyde River and up to the
existing plant as opposed to the conveyance of raw sewage. Another benefit may be the
reduction and/or elimination in the wet weather storage capacities within the existing sewer
network. In this strategy the existing STP would still need new inlet works and other minor
rehabilitation works to meet OH&S requirements. The reclaimed water discharged from
both STPs would be artificially disinfected using a common UV facility at the existing STP.
Transfer of Southern Catchment Sewage Load to Tomakin Sewage Treatment Plant
In this strategy, the sewage from the southern catchment would be transferred to the
existing Tomakin STP. Reversing the flow from the main southern pump station and
constructing a rising/gravity main to the Tomakin plant could achieve this. The benefit of
this strategy option is that the new rising/gravity main could be integrated with the proposed
rising/gravity main to serve the Rosedale and Guerilla Bay areas. Further, this opportunity
also maximises the utilisation of the currently under loaded Tomakin plant and discharges
the reclaimed water through a relatively better performing ocean outfall (verbal advice from
NSW EPA). In this opportunity the existing Batemans Bay plant would still require new inlet
works and other minor rehabilitation work to meet OH&S requirements. The reclaimed
water discharged from both STPs would be artificially disinfected using UV facilities located
at the respective STPs. The Tomakin plant would need minor upgrades to meet the
increased loads. Preliminary analysis shows that the performance of the plant could be
enhanced by optimising the treatment process and by dosing chemicals during periods of
peak holiday loads.
Assessment of Medium to Long term Water Cycle Management Opportunity
The TBL assessment in Table 9-11 provides the comparative environmental and social
benefits of the sewerage management component of the water cycle management
opportunities for Batemans Bay.
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