BHP Billiton asked to rethink desalination plant site

The Parliament of South Australia's Environment, Resources & Development Committee has recommended mining company BHP Billiton reconsider its proposed site for a 250,000 m³/d seawater desalination plant at Port Bonython in the upper Spencer Gulf.

In its final report, published on 5 August 2009, the committee states that, "The site ... is within a region believed to experience slow turnover and also recognised as the site of the only known mass aggregation of spawning Giant Australian Cuttlefish (Sepia apama) in the world, the eggs of which would be impacted by increased salinity".

The committee believes that further investigations are required into alternative siting of the desalination plant and that this process requires a regional engagement strategy with an emphasis on local, regional, company and Governmental collaboration.

BHP Billiton has proposed the plant in order to supply increased demands for fresh processing water required by the expansion of the Olympic Dam mine at Roxby Downs to the north. This would entail a total volume of 580,000 m³/d being drawn from Spencer Gulf, with a 350,000 m³/d brine stream returned to the gulf at a concentration of 70-80 ppt.

Due to what it calls "the paucity of information" in the environmental impact statement (EIS), the committee expressed concerns regarding the dispersive behaviour of the brine stream during the twice monthly event of "dodge tides", and recommended stringent monitoring should take place during these periods to obtain actual live data to validate the modelling that has been used as the basis for the current plant design. The original proposal discussed the option of storing "return water" on land during these periods of low dispersion, but no mention of this occurred in the current EIS, the report said.

The committee also said that it believed that, given the likely increase in interest in desalination plants, that reforms were needed to environmental legislation and policies to ensure that proponents had clear direction as to appropriate locations and operation of future desalination plants in South Australia, and that a framework should be established with explicit site selection criteria that includes the assessment of environmental, economic and social factors.

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