Mine Dewatering Project at Phosphate Hill

Future mining at Phosphate Hill depends on deepening pits to extract higher quality ore that is located below the current water table. In order to access the ore, the mine has recently embarked on a dewatering program aimed at lowering the water table within the Duchess Embayment Aquifer by nine metres by the middle of 2008. This entails pumping around 45,000 Megalitres from the contained aquifer over a four-year period. Almost half of this water will be utilised by the operations.

Various possible uses for the water were considered, but it was concluded that the only viable option was to discharge the water into nearby Kolar Creek. As this is an ephemeral stream with a deep bed of sands and gravels. Investigation into potential cropping activity is being assessed by the local landholder to utilise some of the discharge water.

Ecological surveys of Kolar Creek were conducted during 2003 and 2004. These baseline assessments surveyed aquatic habitat and fauna, as well as riparian and terrestrial vegetation. The studies demonstrated that even though the discharge of groundwater to Kolar Creek would result in temporary alterations to the creek's flow and ecological characteristics, potential problems with exotic flora and fauna could be readily controlled. Management plans have been developed to ensure the creek ecosystem returns to its current condition at the completion of the dewatering program.

Two separate sets of approvals were required for the dewatering program; one for discharging groundwater into Kolar Creek, and the other for increasing the rate at which water is extracted from the aquifer.

In October 2003, QFO lodged an application with the Queensland Environmental Protection Authority (EPA) to amend the Environmental Authority (EA) to allow discharge of groundwater into Kolar Creek. The application was considered and received the support of the EPA. As part of the process, a public notification of the proposal resulted in objections being lodged by four parties. The issues of concern included possible flooding, downstream water contamination and feral infestations, cultural heritage issues, waste of natural resources, potential impact of surrounding aquifers and an objection to mining.

In order to resolve the objections, QFO held a public meeting to discuss the objectors concerns, and invited each objector to the site to familiarize the parties with the reasons why dewatering was necessary to continue operation. The monitoring programs that were being developed were also explained.

All objections were withdrawn by the objectors prior to the matter being heard by the Land and Resources Tribunal. The amendment application was issued in July 2004 as originally proposed.

Early in 2004, QFO applied to the Department of Natural Resources and Mines (DNRM) to increase total water allocation from 7,000 megalitres per annum to 16,000 megalitres per annum. This increase allowed for possible project delays that may have required a higher rate of extraction to meet the 2008 target. As a result of public consultation, we organized a meeting with Desert Channels Queensland, (a Government group that manages the Georgina Diamantina catchments), with representatives from the Department of Primary Industries (DPI), EPA, DNRM, and Lake Eyre Basin Ministerial Forum Advisory Committee. The conclusion from the meeting was that WMC has no choice but to extract and discharge extra water in order to continue to operate. The DNRM subsequently approved the increase in extraction of water from the aquifer.

In September 2004, QFO began pumping excess water from six groundwater bores to the Discharge Outlet at Kolar Creek. The groundwater discharges into a basin constructed from rock filled gabions and mattresses which slow down the discharging water as it exits the open ended pipe and minimises any scouring effect on the natural creek bed.

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