The controversy over Wingecarribee Council's back flip on support for the Medway coal mine expansion is set to re-surface after claims the future of the Berrima Cement works is at risk.

Last week councillors narrowly approved a notice of motion from Clr Larry Whipper reversing its support for a doubling of output at Medway by Boral,  to more than 400,000 tonnes a year, following claims heavy metals were being discharged into local waterways.

Clr Duncan Gair has lodged a rescission motion aimed at over turning  the decision and will argue that council should have given the resources giant an opportunity to respond to the allegations before withdrawing its support.

Boral employee, Clr Graham McLaughlin has warned of job losses and the possible closure of the Berrima Cement works if the expansion application is not approved by the state government.

Clr Gair says he is disappointed that council did not inform Boral of its intentions.

Meantime Boral has reject claims it is discharging high levels of " heavy metals " into local waterways.

The company says weekly independent testing is undertaken at the discharge point into the Wingecarribee River.

Operations Manager Stuart Hutchings says the tests have consistently shown levels of all minerals are within the regulatory limits.

Testing is also undertaken upstream and downstream of the mine to test the potential effects of any discharges.