BHP Billiton is making some improvements following the release of its environmental assessment.
The miner says that it plans to treat and burry contaminated waste from the Hunter River in an around-the-clock operation taking between 18 months and two years. Some contaminants are believed to have been released through leaks, spills and disposal in waste pits.
The mining company’s environmental report identified the main contaminants of concern as polycyclic aromatic hydrocarbons (PAHs), in particular, naphthalene derived from coking coal. Other contaminants included ammonia, cyanide, total petroleum hydrocarbons (TPH), benzene, toluene, ethylbenzene, and xylenes (BTEX) and trace metals.
The contaminated material would be dredged from the river and mixed with cement and blast furnace slag at a treatment plant on the former steelworks site, before being hauled and buried.
The treat-and-haul approach means sediments would typically be dredged, treated and placed at the emplacement cell within 24 to 48 hours. This method can reportedly handle between 30,000 and 40,000 cubic metres a week.
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