Licence conditions for pollution studies and reduction program


  

Licence conditions for pollution studies and reduction programs

Summary
 
Licence number: 767
Title: PRP17: Options Assessment - Prevent or Minimise Turkey's Nest Dam Discharges
Start date: 15 May 2023
 
Licence Condition
Background The water management system at the premises captures contaminated stormwater that runs off coal stockpiles and coal handling areas.  The stormwater collection system includes two main catchment areas with 6 stockpiles and 2 sediment retention basins: the “Settling Pond” and the “Turkey’s Nest Dam” (the Dams).  Contaminated water from coal processing areas, stockpiles, and stockpiling areas reports to the dams.  Contaminated water from the mine’s underground workings is also pumped to the dams. Stormwater runoff water and underground water contain suspended solids (herein called coal fines) and dissolved salts including dissolved metals and bicarbonate.  Contaminated water in the dams is treated by filtration to remove suspended solids before discharge from LDP 7.   During wet weather, untreated water may overflow from the Turkey’s Nest Dam spillway (LDP 8) to Camp Gully Creek. The Turkey’s Nest Dam discharged during wet weather periods in 2021 and 2022.  Coal fines that had deposited in the dams reduced the volume of stormwater runoff that was able to be captured and treated prior to discharge.  The removal of coal fines from the dams was limited by the ability of the washery plant to accept and process the fines.  The result was a series of discharges where quantities of coal material entered Camp Gully Creek and the Hacking River.  The EPA contends that actions could have been taken to reduce the level of coal fines in the dams and prevent or minimise the incidents. The aim of this PRP is to engage a suitably qualified and experienced professional or company to investigate all reasonable and feasible options to avoid discharges occurring through point 8 in the first instance and then if discharges are unavoidable, to reduce the frequency of any discharges. Requirements Unless otherwise agreed in writing by the EPA: 1.  By the 23 June 2023 the licensee must propose a suitably qualified professional/s or company/ies (expert/s) to the EPA with experience in mine stockpile and stormwater management to undertake the required investigations. (DOC23/529876) 2.   The approved expert/s must investigate all reasonable and feasible options to avoid discharges and if discharges are unavoidable, reduce the frequency of discharges that occur from the Turkey’s Nest Dam (point 8) during wet weather events.   The options examined must include but not be limited to the following: a) Increased capacity to capture and store rainfall runoff. The expert/s must assess options to increase the water storage capacity to capture a greater volume of run-off.  This must include, but may not be limited to, expanding or deepening the existing storage basins, finding new areas for water storage, and maintaining contingency storage in the old mine workings. b) Reduction in coal fines runoff and contaminated stormwater generated. The expert/s must assess options for each stockpile to minimise the generation of water contaminated with coal fines when exposed to rainfall or stormwater runoff. The options must include, but are not limited to, diverting or piping stormwater flows around stockpiles, covering or installing roofs over stockpiles (particularly highly ranked stockpiles), constructing enclosures or sheds, applying binders to any longer term or less active stockpiles, and installing stormwater diversions around stockpiles. The licensee must also assess options to minimise the volume of contaminated water that reports to the dams.  The options must include but may not be limited to direct reuse in surface equipment, retention underground, diversion back to mine workings, or treatment prior to storage in the dams. The licensee must assess the feasibility of each option with consideration of factors including reduced sediment load, cost, and impediment to site operations. c) Increased rate of removal of water and coal fines from the dams. The expert/s must assess options to increase the rate of removal and processing of coal fines and water from the dams.  The options must include but are not limited to: coal handling plant upgrade(s) to increase the maximum slurry transfer rate; examination of the increased rate of transfer of contaminated water from the dams for treatment in the water treatment plant; processing systems that are separate to the coal handling plant to remove and dewater coal fines and combine them with exported product coal.  These should include, for example, belt presses and drying beds used in combination with mixing mill(s). 3. Water Balance Model A water balance model using a daily timestep analysis must be prepared to compare the effectiveness of the options identified (above 2a – 2c) with: •  The baseline water management system that was in place on 31 December 2022 •  A type D sediment basin in a sensitive receiving catchment following 'Managing Urban Stormwater: Soils and Construction (vol 1)' and 'Mines and Quarries (vol 2E). A report which details the above works and assesses the feasibility of implementing the identified options must be submitted to the EPA by the due date. Due Date:  To be determined with consideration of Expert advice.