Eurobodalla Integrated Water Cycle Management Strategy

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Eurobodalla Integrated Water Cycle Management Strategy
The high rainfall within the Eurobodalla Shire would restrict the reuse opportunities available
particularly for cropping in natural environment systems. The high rainfall and the highly
seasonal nature of the NSW south coast climate means that the reuse potential for
cropping under natural conditions is highest during the dry season in late spring and early
summer. Therefore it may be likely that there will be lengthy periods during the wet season
from December to April when little or no reuse is viable. Thus, practical reuse strategies
should aim to reuse a high percentage of dry weather flows, in combination with appropriate
alternative arrangements to treat all wet weather flows to a standard suitable for direct
discharge to the environment.
Two regional schemes could be developed based on opportunistic reuse (i.e. when there is
a demand). These scheme options are discussed below. However, it should be noted that
there are a number of significant constraints to agricultural reuse in the natural environment
such as:
Landforms and land slopes
High water tables on many areas of the floodplain
Shallow acid sulfate soils
Large environmental protection zones
The potential for elevated sodicity to cause deterioration in soil structure.
Northern Region Scheme
In the northern scheme, the dairy area around Moruya River could be supplied with
reclaimed water produced from the sewage treatment plants located north of Moruya. The
shire-wide reuse study proposed to use a dedicated main to transfer reclaimed water from
the Batemans Bay and Tomakin sewage treatment plants to this area. The shire-wide study
also considered a wet weather/peak demand balancing storage near Moruya to manage the
supply and demand peaks.
A review of the shire-wide reuse study within the integrated water management context
indicated that an alternative option to constructing a new main from Batemans Bay would
be to utilise the existing old 250 mm water supply main. This water main runs parallel to the
new 450 mm main and could be used for transporting the reclaimed water. The disused
Catalina 1 reservoir could then be used as the balancing storage if required. The hydraulic
analysis of the regional water supply indicates that the water supply demands could be met
through the existing 450 mm main and no augmentation to the 450 mm main would be
required if the northern water filtration plant was located near Denhams Beach Reservoir.
The schematic of this scheme concept is shown in Figure 8-5.