2.3.4.2 Water management for coal resource development

In the Gloucester subregion there are two existing coal mines with expansion plans (Duralie Coal Mine and Stratford Mining Complex), one proposed coal mine (Rocky Hill, currently on hold as of 15 November 2015) and a CSG project (AGL’s Gloucester Gas Project, under development).

2.3.4.2.1 Duralie Coal Mine

The information summarised in this section was obtained from Duralie Coal Mine Water Management Plan (Duralie Coal Mine, 2013) and Heritage Computing (2009).

Duralie Coal Mine (DCM) water management is designed and operates to control water generated from surface development areas via on-site water permanent and temporary storage structures. The other objective of the DCM Water Management Plan is to prevent overflow of dirty water generated within the mine workings, waste rock emplacements, water storage areas and runoff from areas where coal is handled, to the neighbouring water bodies Coal Shaft Creek or Mammy Johnsons River. The total on-site water storage capacity is about 4609 ML with approved capacity up to 4805 ML. Once mining in the Weismantel Extension open pit is complete (as of 30 June 2015, progressive backfilling with waste rock is occurring and water is allowed to accumulate in the pit (Yancoal, 2015a)), the remaining void will be used as a water storage. The storage capacity is estimated to be 1900 ML. The stored dirty water is used on site for dust mitigation and irrigation of a mixture of pasture, woodland and cropping within the approved irrigation areas. On average, DCM operates in surplus yielding more water from the mine and mine infrastructure catchments than needed for the mining and processing operations. Excess water is disposed through on-site irrigation.

2.3.4.2.2 Stratford Mining Complex

The information summarised in this section was obtained from Stratford Coal Mine Water Management Plan (Stratford Coal Mine, 2012) and Heritage Computing (2012).

Stratford Mining Complex (SCM) water management is designed and operated to achieve no overflow from on-site water storages (Stratford East Dam, Stratford Main Pit, Return Water Dam) to the downstream watercourses including Avondale Creek, Dog Trap Creek and the Avon River. Total on-site storage water capacity of existing dam is about 40,350 ML. Once mine operations are completed in the Bowen Road North Open Cut (BRNOC) (where, as of 30 June 2015, mining ceased (Yancoal, 2015b)) and in the Avon North Open Cut (where, as of 30 June 2015, no activities had commenced in the Avon North Pit, part of the Stratford Extension Project (Yancoal, 2015b)), the voids will also be used as contained water storages.

Run-of-mine (ROM) coal from the DCM is transported by rail to the SCM, where it is processed along with ROM coal from the SCM and BRNOC. The majority of water used on site is for the coal handling processing plant (CHPP) and for dust suppression. On average the site has operated in surplus yielding more water from the mine and mine infrastructure catchments than has been needed to supply the mining and processing operations. This excess has been managed by containment in the Stratford East Dam, storage in Stratford Main Pit and historically controlled release to Avondale Creek under Environment Protection Licence No. 5161. Irrigation of water from the Stratford East Dam over approximately 23 ha of a rehabilitated portion of the Stratford Waste Emplacement area will occur to reduce stored water on site and to assist the current pasture cropping programme on the rehabilitated emplacement.

2.3.4.2.3 Rocky Hill Coal Project

As of November 2015, the NSW Department of Planning and Environment placed the Rocky Hill Coal Project on hold. The information summarised in this section was obtained from the Rocky Hill Coal Project Environmental Impact Statement (RW Corkery & Co Pty Ltd, 2012a; 2012b) and the Rocky Hill Coal Project Groundwater Assessment (Australasian Groundwater and Environmental Pty Ltd, 2013).

As of June 2015, there was no water management plan for the Rocky Hill Coal Project. Gloucester Resources Limited (GRL) is planning to manage the dirty water through on-site storage areas with no outflow to the downstream watercourses. On-site water storage includes three environmental dams with a total storage capacity of approximately 2300 ML and refilled mining pits. The majority of water used on site is for the CHPP and for dust suppression. According to the site water balance estimated by WRM Water and Environment Pty Ltd (2013), there would be occasional excess quantities of saline water throughout the proposed 21-year life of the project.

2.3.4.2.4 Gloucester Gas Project

The information summarised in this section was obtained from various AGL water management plans (AGL Energy Limited, 2012; 2014b; 2014c; 2014d), produced water factsheets (AGL Energy Limited, 2014a) and AGL’s Review of Environmental Factors – Waukivory Pilot Project (AGL Upstream Investments Pty Limited, 2014).

During the fracture stimulation of a CSG well, the volume of water required for fracture treatment is estimated to be between 0.9 ML and 2.4 ML per well (AGL Upstream Investments Pty Limited, 2014). It is expected that all flowback water (i.e. 0.9 ML and 2.4 ML per well) and 0.04 ML/day per well of produced water to be maximum at the commencement of fracturing/testing but quickly diminishing to much lesser volumes (typically an order of magnitude lower) (AGL Energy Limited, 2014b; 2014c).

According to AGL’s Produced Water Management Plan (2014c), the produced water strategy is:

Produced water, flowback water and natural groundwater generated during the fracture stimulation of CSG wells will be stored on the site in above ground tanks (75,000 L capacity) or open top tanks (40,000 L capacity) and then transferred by road tanker to the Tiedman dams for either industrial use or blended water irrigation. As part of the Gloucester Gas Project, AGL is planning to treat produced water using reverse osmosis, a desalination technology to reduce the amount of salt in the produced water and to be used for irrigation or returned to the environment (AGL Energy Limited, 2014a). Salt produced during the reverse osmosis process is crystallised to a mixed solid salt, bagged and removed to suitably licensed landfill sites (AGL Energy Limited, 2014a).