Scientific committee raises concerns about modelled Goulburn River mine water flows into the Hunter River

The Hunter River’s water is worth bottling, but for how long Production: Coal stacks at Moolarben Coal Mine between Denman and Mudgee, which has applied to increase annual coal yield from 13 million to 16 million tonnes of coal per year. Picture: Cathy Toby.
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Increase: Trucks at the Moolarben coal Mine site. An independent scientific committee has raised concerns about proposed water discharges into the Goulburn River. Picture: Cathy Toby.

Discharges: Ulan Coal Mine near Moolarben Coal Mine. Modelling shows a total of up to 50 megalitres of treated mine water per day could be discharged into the Goulburn River from the mines under certain scenarios. Picture: Cathy Toby.

Concerns: Ulan Coal Mine. A scientific committee has backed the need for major mines between Denman and Mudgee to be assessed in terms of the cumulative impact on the Goulburn River. Picture: Cathy Toby.

Impacts: A section of the man-made Goulburn River Diversion on Ulan Coal land. Four kilometres of the river was diverted to the mine’s southern and eastern boundaries to make way for an open cut operation. Picture: Cathy Toby.

TweetFacebookWater quality assessment has to consider cumulative impacts of other mines in the area, such as in elevating salinity in the upper Goulburn River, and how the altered water quality and volumes of discharged water influence the aims of the Hunter River Salinity Trading Scheme.

Independent Expert Scientific Committee on Moolarben Coal expansion

The impacts of the Moolarben expansion “cannot be considered adequately without the context of water discharges and water quality impacts from other mines”, the committee said.

The mine is approved to run four open cut and three underground mining areas until 2038. The mine has applied to lift its allowable daily discharges into Goulburn River from 10 megalitres of treated mine water per day to 20 megalitres. This is despite the mine only discharging mine water into the river on one occasion since 2010.

The scientific committee report backs calls by community and environment groups for a full independent study of groundand surface water impacts of the three huge underground and open cut coal mine complexes between Denman and Mudgee, including the Peabody Wilpinjong mine that produces coal for domestic energy generation at Bayswater power station.

The scientific committeeraised concerns that under certain modelled conditions there would be discharges from Moolarben to the river on most days between 2024-2026. It was also concerned that discharges of 20 megalitres per day from Moolarben could impact aquatic plants in the neighbouring Ulan Coal Mine Goulburn River Diversion, where four kilometres of the Goulburn River was diverted to the mine boundaries in the early 1980s to allow open cut mining.

Any impact on the aquatic plants raised the risk of disturbing sediments potentially containing high concentrations of heavy metals “given the history of mine water discharge” into the diversion channel, the committee warned.

The scientific committee said Moolarben’s environmental assessment did not adequately assess the potential downstream impacts of large volumes of uncontrolled discharges into the Goulburn River under certain modelled scenarios. The committee has previously told the NSW and federal environmentdepartments that uncontrolled discharges from the proposed Bylong mine and the Wilpinjong mine extension had been “inadequately assessed”.

In a submission to the Department of Planning, the Environment Protection Authority rejected a Moolarben proposal to store up to 2.5 megalitres per day of brine –a waste product of mine water treatment –in underground mine voids.

The Department of Primary Industries and Crown Lands and Water questioned why Moolarben needed to lift its potential Goulburn River discharge from 10 megalitres per day to 20 megalitres per day when its groundwater assessment said the proposed expansion would result in a negligible increase in groundwater entering the mine.

Moolarben said the proposed annual yield increase from 13 to 16 million tonnes of coal per year would improve productivityand “security of the continued employment of the existing workforce” and return an additional $80 million in royalties to the state.

It said a water treatment facility would control water quality discharges to the Goulburn River. It said modelling predicted “no adverse impacts to downstreamwater quality” and “negligible impacts to downstream aquatic ecology”.