000A88A4.126.tif · 132003.221037

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Rainwater Tank System

It is intended that the majority of the water demand will be met via a system of individual
rainwater tanks at the eco-cabins and a main rainwater tank at the lodge/interpretive centre. It
is proposed that “topping” of these tanks will be carried out using groundwater that will be
extracted from the existing sub-artesian bore. Section 6.2 details the results of the availability
and quality of the groundwater following testing works carried out on site by Coffey Water
Studies.

It is proposed that groundwater extracted from the bore will be treated and pumped to a storage
tank adjacent to the watch-tower (i.e. the highest area available on site). An additional
groundwater storage tank will be constructed on the western area to service the lodge,
interpretive centre and other facilities. Figure 5 provides an illustration of the preliminary location
for these tanks.

A water reticulation system will be constructed to allow for the gravity supply (topping up) of the
proposed rainwater tanks. Figure 5. provides an indication of the proposed water reticulation
system.

A preliminary analysis of the expecied amount of rainwater that could be collected was carried
out. Table 6.1.1 provides indicative daily average collection amount, which has been determined
using traditional calculation methods based on the following parameters.

1. Average roof area of each eco-cabin — 100 m*.
2. Roof area of lodge accommodation, interpretive centre, café and other facilities — 5,000
2 .
m*.
3. Average annual rainfall — 1,689mm (refer Table 4.3.1).
4, Rainwaier tank capacity ~ 22,500 litres (standard rainwater tank).
5. Probability of failure — this refers to the percentage of days that the rainwater yield will

not be met.

Table 6.1.1 — Indicative Daily Average Rainwater Collection

 

 

   

 

 

 

 

 

 

 

 

; Eco-Cabins 257 220 "194 177
Lodge, interpretive Centre 43500 44000 9700 8850
and Café.

 

From the above table, 100% of average day water demand cannot be met with the supply of
rainwater alone. However it is intended that the storage capacity of the proposed rainwater
tanks will provide a higher rainwater supply capability and thereby minimise the dependency on
groundwater extraction. It should be noted that the level of groundwater extraction that can be
achieved is able to deliver average day water demand. This indicates that under a worst case
scenario of severe drought and minimal Tfainwater collection, the groundwater bore will be able
to deliver average day demands.

An optimal combination of rainwater and groundwater supply will be devised through the
development of a dynamic water network analysis model. This analysis will be carried out during -
the detailed design phase. This analysis will ensure that the maximum potential yield from
rainwater is achieved, thereby minimising the impact/dependency on groundwater extraction.

 

PETRAC LAND HOLDINGS P/L Noosa North Shore Eco-Tourism Portal September 2003
L:A7296-03\Repori\FINAL REPORT ~ 18Sept03.doc Commercial in Confidence Page 18