In November 2014, Brisbane’s Southern Star reported on community concerns surrounding plans to drain toxic water that had collected at the disused Pine Mountain Road Quarry at Mount Gravatt through Salvin Creek.
According to the newspaper, volunteers that had been working to restore bushland in the area had believed the water might impact upon the nearby vegetation.
At the time, Quarry spoke with Wayne Scott, past IQA president and inspector of small mines at the Queensland Department of Natural Resources and Mines, who pointed out that draining the quarry lake would help minimise risks for trespassers.
“Unauthorised access is a major hazard for all quarries,” he explained. “Once quarrying is completed, the risks increase, particularly where water-filled voids are present. From a safety perspective, the draining of these voids does reduce the risk of injury to those who break into these sites.”
Mark Dekker, the general manager of BMI Group, the owner of the 34ha site, told Quarry it was necessary to drain the quarry as continued rainfall would have eventually caused the water to overflow. He added that there had also been potential for some acid mine drainage issues to cause environmental impact.
“Boral, the previous owner of the site, indicated to residents that water would be sent to the sewer system,” Dekker explained, “but that’s not possible.”
Effective water management
To address the issue, BMI Group worked with a wastewater consultancy to treat the quarry void water, removing its metal content and bringing its pH levels back in line. A discharge structure was constructed into a concrete-lined portion of Salvin Creek and downstream erosion protection measures were established to facilitate draining. The company also organised for the installation of a polishing system that could detect the water quality and halt pumping if those attributes fell outside of pre-set parameters.
BMI Group began pumping treated water from the quarry in November, and Dekker stated that although there had been some “initial teething problems”, the system was now operating well.
“The water released is cleaner than the water in the creek itself and meets the ANZECC [Australian and New Zealand Environment Conservation Council] guidelines for the creek classification,” he said, adding that BMI Group had not received any further community complaints since draining began.
Dekker noted that the company was keeping a close eye on the operation’s environmental impact. “We have been undertaking background environmental monitoring, which is based on chemical and biological assessment of the state of the creek, impacts of flora and sediment sampling.”
In addition, BMI Group was maintaining public transparency with regards to its environmental findings. “The polishing unit provides real-time feedback on all parameters which will be posted to the website we have established to provide information to residents: www.pinemountainroad.com.au,” Dekker explained. “We have also established an information board at the discharge end to inform passers-by of the process.”
In total, Dekker said he expected the pumping operation would take 18 months and that following rehabilitation, the quarry was likely to be utilised for residential purposes.
Pine Mountain Road Quarry produced hard rock from 1964 to 1991 under the operation of Boral before being sold to BMI Group in 2013. It gained preliminary approval for residential infill from Brisbane City Council in January 2008, which continued to apply following the transfer of ownership.
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