S Australia government questions Billiton desalination EIS
Desalination discharge led the list of concerns raised by the South Australia government in its submission on 24 April 2009 to BHP Billiton's environmental impact statement (EIS) related to its proposed expansion of its Olympic Dam mining operations.The submission identified hydrodynamic modelling, ecotoxicity testing and mitigation strategies for the brine discharge from the proposed 250,000 m³/d seawater desalination plant at to the Upper Spencer Gulf.
Summing up public and other reaction to the EIS, the submission lists the effluent discharge from the proposed Point Lowly desalination plant as the most prominent issue. Overall, more than 95% or 3,800 submissions included comment on the desalination proposal. Of these, around 90% or 3,400 submissions were copies of form letters from the Australian Conservation Foundation and the Wilderness Society, the latter focussed solely on desalination issues.
Billitons's draft EIS does not indicate the concentration of anti-scalant chemical likely to be released in the discharge, says the government submission, which points out that an appendix states that there is currently no specific ecotoxicity data available for the proposed anti-scalant. The government's Department of Primary Industries & Resources (PIRSA) has concerns about the possibility that the chemical could cause residue issues with the marine animals in actual and proposed nearby aquaculture farms over the long-term.
PIRSA agrees with the recommendation made by Hydrobiology P/L (who developed the report entitled Ecotoxicity of effluent from the proposed Olympic Dam desalination plant included in the appendix) that further testing must be undertaken once the plant is commissioned and the final make-up of the effluent has been determined.
Further ecotoxicity testing of antiscalant chemicals will have to be undertaken once the final make up of the effluent has been determined; testing is to include residue testing on aquaculture species within the Fitzgerald Bay area. Ideally, the EIS supplement will include results of further ecotoxicity testing of antiscalant chemicals. However, if the final make-up of the effluent has not been determined at the time of the supplement, then it must clearly detail how and when this matter is to be addressed.
Looking at impacts on individual species, the submission questions the World Health Organization (2007) guideline that an incremental level of 10% above ambient salinity is safe. "As these guidelines were not developed for already hypersaline environments, their relevance to this environment is questionable," says the SA government.
Pipefish, cuttlefish, sponges, crabs and whales are among the species that the government is seeking more impact information about.
The government expects BHP Billiton to review in detail the government submission and the range of public submissions (including the reports of Members or Committees of Parliament), and to prepare a thorough supplementary EIS accordingly.