Civil Engineering Reference
In-Depth Information
Government household tank rebate is estimated to deliver water at
a cost of $ AUD 0.54/kilolitres. The advantage of wide-scale decen-
tralised rainwater harvesting, by these calculations, is from five to 18
times the cost benefit for the Water Grid. Even if the Government
absorbed 100% of the cost of household rainwater harvesting instal-
lations, according to White (2009: 398) it would still be among the
cheapest options for water supply. With improved demand management
and localised supplies, an estimated 30% of potable water consumption
within the commercial and industrial sectors could be saved at attractive
payback periods (5-10 years), at less TBL cost than centralised energy-
consumptive alternatives such as desalination plants (Werner and
Hauber-Davidson 2008).
While indirect recycled water from treated sewage has been used
successfully elsewhere for potable use, public acceptability is a major
constraint affected by level of trust and risk management (Po
et al
.,
2003; Nancarrow
et al
., 2007). Impediments to investment in recycled
water also include development and energy costs, lack of financial incen-
tives, risk of cross-contamination, complexity, and liability (Martin and
Hill 2006).
Desalination plants have the second highest cost of development
and operation but can yield a reliable long-term water supply with
the flexibility to be decommissioned if not needed. However, a high
proportion of growth in SEQ is inland, whereas plants are proposed to
be located on the coast. More conclusive data comparing energy use and
greenhouse gas emissions of recycled water treatment with desalination
would add to options analysis.
A proposal to dam the Mary River would have used the 'Mary River
Reserve'. Once the Traveston Crossing Dam was over-ruled by the
Commonwealth government, the reserve was intended to be used as
part of the northern interconnector of the Water Grid to pump Mary
River water to Brisbane if needed. While the Grid had its benefits, the
energy costs and greenhouse gas emissions of operation and moving
water, water losses as well as potential risks from inter-basin transfers
would need to be taken into account. The proposed Traveston Crossing
Dam had only just been rejected, so it was included in this report
as it had already been assessed. Of all the new water supply options,
the assessment shows the disallowed Traveston Crossing Dam rated
the poorest: it is most vulnerable to climate change due to variable
streamflow, runoff and evaporation (from the shallow dam). At an early
estimate of $ AUD 1.7 billion (QWI 2007), it was by far the most
costly option to build even without considering indirect/embedded
energy costs of dam materials, purchase cost and loss of prime agricul-
tural land close to Brisbane, costs and energy related to a pipeline for
