The historic Brukunga mine site is located at Brukunga in South Australia, 4km north of Nairne and 40km east of Adelaide in the Mt Lofty Ranges.
The mine was worked for the recovery of iron sulfide (pyrite minerals) from 1955 to 1972. The sulfur was used in the production of sulfuric acid and superphosphate fertiliser, which was used to sustain the rapid expansion in agriculture that occurred in SA during the Cold War period.
Approximately 8 million tonnes of overburden containing 2% sulfur was excavated and discarded into two large rock-dumps and 3.5 million tonnes of sand-tailings containing 1.7% sulfur.
The underflow from the metallurgical concentrating plant was hydraulically placed to fill an adjacent shallow valley. Fresh pyrite mineralisation was left exposed on the surface in the floor of the quarry.
Pyrite and pyrrhotite minerals when exposed to air, water and bacteria will oxidise and break down to form acid drainage. Acid conditions enable various heavy metals contained in minerals to dissolve and the resultant seepage contaminates the flow in Dawesley Creek as the creek passes through the mine site.
No mining has occurred at Brukunga since the mine closed on 31 May 1972.
In August 1977 the State Government accepted responsibility for rehabilitation of Brukunga and in September 1980 commissioned the lime neutralisation plant to treat acid water.
Grasses and native trees have been progressively established since 1988 in the thin layer of imported soil used to cover the once barren sand-tailings dam.
Environment Protection Agency (EPA) requirements
The Department of State Development is responsible for the management of environmental issues at the historic Brukunga Mine site.
The Brukunga Mine site is specifically prescribed in statutory legislation. The Environment Protection Act 1993 (external site) and Regulations states that the mine is ‘a prescribed activity of environmental significance’.
Hence, although the only activities performed onsite are focused toward rehabilitation and minimising environmental impact, an EPA licence is required.
The first EPA licence for Brukunga was issued to SA Water Corporation, commencing May 1995.
Water quality monitoring
The ‘Water Quality Monitoring Program’ developed by SA Water Corporation and accepted by the EPA on the 2 August 1996 comprises:
This information is used to examine the downstream contaminant levels and their seasonal variation, the load of various contaminants transported from the site, and the biological affect of seepage on macro-invertebrates along the course of the waterways.
Efforts behind the Brukunga mine site rehabilitation program include: