Anglesea mine water body hits 11 per cent

THE groundwater pumping test at the former Anglesea mine that may pave the way for the Eden Project is on track, with the mine void now at more than 11 per cent of its proposed full level.

Former mine operators Alcoa are running a 12-month pumping test of the Upper Eastern View Aquifer (UEVF) and extract 1.5 gigalitres of water.

The groundwater pumping test started on May 13 and is part of the plan to have the mine void at least half full with water and thus not only enable Eden Project Anglesea but also Alcoa’s Anglesea Mine Rehabilitation and Closure Plan.

According to the latest community update on the test, covering the period May 25-June 23, the pumping rate was increased from 3.45ML per day to 4.32ML per day on June 8.

118.3ML was extracted and placed into the mine void water body, with a total of 171.9 ML extracted since the pumping test started.

The water level has increased from 20.42 metres below sea level to 19.93 metres below sea level, which represents 11.8 per cent of the proposed full volume of the water body.

“There is no significant change to groundwater levels in the upper part of the UEVF aquifer or the unconfined shallow Demons Bluff Group and Perched Water Table aquifers, which are responding to natural climate variations.”

Investigation triggers (of a defined water level and/or quality) were reached for three out of the 12 nominated trigger bores, but Alcoa says the triggers are set at conservative levels so the instances “do not represent any risk to groundwater dependent ecosystems or any other users”.

Two of the occurrences are attributed to natural climate variability and not the pumping test, while the third is believed to be due to multiple factors including climate variability, bore condition and potentially also the pumping test.

“This will continue to be monitored and the pumping rate will also be reviewed,” the update states.