Eurobodalla Integrated Water Cycle Management Strategy

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Eurobodalla Integrated Water Cycle Management Strategy
Medium to Long Term Water Cycle Management Opportunities
The medium to long term opportunities are related to enhancing the sustainability of the
water cycle, protecting the public health and environment and improving the service
standards.
As part of a long term strategy, the water quality and quantity of the Broulee aquifer needs
to be managed so that the environment and current water users can continue to enjoy this
resource in a sustainable manner. Options include:
Reduce or ration the volume of water extracted from the aquifer.
Inject and store highly treated reclaimed water from the Tomakin STP into the
aquifer such that a balance is maintained between extraction and injection. If more
local users take-up this option within sustainability limits, it has the potential to
reduce demand on the regional water supply scheme and increase the secure yield
of the regional supply infrastructure.
Mossy Point and Broulee areas receive town water supplied through the regional water
supply scheme. Water is supplied through the 4.6 ML Mossy Point Reservoir. There is
sufficient capacity for all future growth. Some residents in Broulee use groundwater for nonpotable
external use.
Table 9-20 Costing of Management Opportunities presents the water cycle management
opportunities, their relative capital and present value costs over a 30-year period at an
annual discount rate of 7%. Whilst the costs are indicative only, the relative cost difference
between the opportunities should be similar.
Table 9-20 Costing of Management Opportunities in Tomakin and Surrounds
Costs ($)
Opportunity
Capital NPV @ 7%
Process optimisation strategy 1
Enhance
capability of
1.7 M 1.64 M
existing STP Construct a parallel process train 2.85 M 2.3 M
Stormwater quantity and quality control measures for
high priority sub-catchments
Stormwater quantity and quality control measures for low
priority sub-catchments
1.72 1.8
0.5 0.53
Enhance the Biological and Hydraulic Capability of the Existing Tomakin Sewage
Treatment Plant
The Tomakin STP has a nominal biological capacity of 8 000 EP however the reactor and
clarifier has been assessed to have a treatment capacity able to process double this
biological load (3.7 ML/d or 15 000 EP) with minor modification. This is due to past
conservativeness in design and improved design techniques. The biological treatment
capacity of the reactor and clarifier could be further increased to about 4.9 ML/d
(20 000 EP) by the addition of chemicals provided the pipeline linking the various treatment
process units are adequate. It is an accepted practice under these circumstances to bypass
the secondary treatment, and only apply disinfection, as the strength of the sewage is
very weak.
An alternate to the process optimisation strategy is the traditional strategy including a
parallel process train with similar capacity to the current plant is built.