Licence conditions for pollution studies and reduction program


  

Licence conditions for pollution studies and reduction programs

Summary
 
Licence number: 2504
Title: PRP18 - Modification to Brennans Creek Dam off-take
Start date: 18 Mar 2013
 
Licence Condition
The aim of this PRP is to improve the overall quality of, and reduce the ecological risks due to, discharges from Brennans Creek Dam (BCD) via discharge point 10 by changing the configuration of discharge point 10 to a floating off take. Prior to 2004 discharges from BCD were taken from the surface waters of BCD via a spillway. The discharge waters using this configuration did not always comply with licence pH limits of 6.5-9.0. ‘PRP 7 Brennans Creek Discharge Trial’ was completed in March 2006 and trialled discharging ‘bottom’ waters from BCD. This trial was aimed at reducing the number of uncontrolled releases from BCD via the spillway, and optimizing the pH and salinity in controlled discharges via discharge point 10. An outcome of this PRP was to alter the BCD discharge configuration from the spillway, to a pipe discharging from the bottom of BCD via discharge point 10. The pH licence compliance achieved by changing the BCD off take configuration are temporary, as pH in the discharge waters increases downstream of discharge point 10 due to carbon dioxide out gassing. On balance, and considering the science and investigations undertaken into BCD, the EPA agrees with the licensee that there will be an overall reduction in ecological risks by changing the configuration of the BCD off take to a floating off take. In particular, ammonia and salinity in the discharge waters will be reduced.  Coupled with this change, the EPA will temporarily change the pH limit for discharge point 10 to 6.5-9.3. In making this change the EPA notes: ·  This change is temporary until completion of ‘PRP 19 Water Quality Discharge Improvement to Upper Georges River via discharge point 10,’ and ·  The change to pH limits will not in effect represent any increase in environmental impact, due to carbon dioxide out gassing in the discharge waters that causes the pH to increase downstream of discharge point 10, compared to the pH measured at discharge point 10. The licensee must change the configuration of discharge point 10 from a pipe discharging from the bottom of BCD to a floating off take, so that water discharged from that discharge point is taken from the surface water of BCD and not the ‘bottom’ waters. DUE DATE: 30 JUNE 2013 COMPLETED: 28 JUNE 2013