Eurobodalla Integrated Water Cycle Management Strategy

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Eurobodalla Integrated Water Cycle Management Strategy
Another alternative is to upgrade the septic system to one that achieves nutrient removal
and therefore results in a higher quality effluent discharge (e.g. aerated tanks). This would
increase the potential uses of the treated effluent.
Both these options would minimise the potential of environmental degradation as well as
reducing the likelihood of public health issues and odour complaints.
Centralised Management of Effluent from On-site Facilities
As an alternative to providing a full reticulated sewage system, the effluent from existing onsite
systems (e.g. septic tanks) could be collected and transported to a central treatment
facility. This type of system relies on smaller pipes than those required for a conventional
reticulated sewerage system. Pipes can be laid in the ground at a lesser gradient and at a
more shallow depth than that of conventional gravity sewerage, as the solids are captured
by the on-site system and the pipes only need to carry liquid wastewater.
Appendix P provides a description of the available effluent transport and local treatment
options. The effluent could also be transported to Narooma STP for treatment.
The reclaimed water could also be managed in a number of ways, if the effluent was
treated at a local treatment facility. Appendix C provides a detailed description of the
available management options. Preliminary appraisal suggests dunal infiltration and
agricultural reuse are suitable disposal methods. Costs in Table 14.1 are based on
Centralised effluent drainage (CED) for transport, a reed bed system for treatment and
dunal infiltration as an opportunity or transfer to the Kianga STP as an alternative.
Provision of Full Reticulated Sewerage System
An alternative to on-site sewerage treatment facilities is to transfer wastewater through a
centralised sewer transport network to either a local package treatment facility or to Kianga
STP.
Unlike in the previous opportunity the sewer transport pipes would be larger and possibly
installed at greater depths.
Appendix P provides a detailed description of the available transport and local treatment
options. The shortlisted reclaimed water management options are the same as those
discussed for the above opportunity.
Costs in Table 9-39 are based on a modified gravity transport system, a local package
extended aeration treatment plant and dunal infiltration.
Provision of a Full reticulated sewerage system with greywater reuse and roof water
harvesting
On-site systems that achieve a suitable level of treatment for greywater would be
maintained, and blackwater only would be transported to the STP using the reticulation
systems described above. The resulting greywater could then be utilised for a variety of
outdoor uses and for toilet flushing. Maintaining current aerated systems in Mystery Bay for
greywater reuse would reduce the volume of wastewater requiring treatment by 3.35 ML/a.
This in addition to reducing the volume of imported of reticulated water required for Mystery
Bay, would reduce the hydraulic load on the Kianga STP. With the implementation of
appropriate monitoring systems, long term environmental and water resource sustainability
and public health protection could be achieved.
Systems that are not suitable for greywater reuse (e.g. septic tanks) would be de-sludged
and disinfected and used to collect roofwater for non-potable uses including garden
watering and toilet flushing. This would result in an additional 2.32 ML/a of wastewater not
requiring transportation and treatment at the Kianga STP. Together with greywater reuse
from aerated systems, a total of 5.67 ML/a could be saved.