Eurobodalla Integrated Water Cycle Management Strategy

Eurobodalla Integrated Water Cycle Management Strategy
Connecting Nelligen to the region’s water supply from Batemans Bay would require a pipe
extension of 7.2 km from Batemans Bay along the existing road line. The average annual
and peak reticulated water demands for the full development situation would be about
28 ML/a and 0.20 ML/d respectively.
The scheme facilities necessary to provide a full reticulated water supply to Nelligen would
be similar to those required for a supplemented reticulated supply as discussed previously.
The facility and component sizes will, however, need to be slightly larger. The provision of
larger pipes and facilities enables the provision of fire fighting services at minimal extra
cost.
Improved Management of Existing On-site Wastewater Facilities
Sewage in Nelligen is currently treated by on-site systems. It is recommended that Council
consider the management options for sewage treatment for the village. The seepage from
existing on-site wastewater management systems could be reduced by regularly emptying
the contents of the septic tanks and installing monitoring systems to prevent septic tank
overflows and to assess the integrity of the tanks. Regular pumpouts and monitoring have
the potential to minimise many of the environmental and public health impacts associated
with the operation of septic systems.
A single contract could be arranged by the Council or by the community such that the septic
tanks are pumped at set time intervals. This would cover both effluent and sullage
pumpout. The cost of this pumpout could be evenly split between the residents. To facilitate
pumping every tank would require a smaller holding tank or pumpout facility.
Although this opportunity would reduce the potential of waterway and aquifer contamination,
it may result in additional community impacts, such as odour complaints associated with
pumpouts and the movement of trucks in the neighbourhood.
Enhanced Management of Existing On-site Wastewater Facilities
There are several options available to upgrade the existing on-site wastewater
management systems to achieve greater public health and environmental outcomes. The
first option is to retain the existing septic tank and upgrade the on-site effluent management
system. An example of this would be the replacement of the adsorption trenches with lined
evapotranspiration beds, which achieve a higher level of water and nutrient uptake through
plants.
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 available to the resulting treated effluent.
Both these options would minimise the potential of groundwater contamination and its
associated environmental problems, 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 pipes carry only
entrained solids thus having minimal self-cleaning velocity requirements.
The effluent could be treated locally or transported to Batemans Bay STP. Appendix P
provides information on the various effluent transport and local treatment options.
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