Q. What is the scheduled use of overburden in the rehabilitation program?
A. Placement and shaping of overburden will be undertaken to create slopes with gradients up to 10 degrees. Overburden and other waste materials (selectively backfilled or blended) will be covered with a suitable medium to allow for the placement of intermediate soil and topsoil materials prior to revegetation in accordance with relevant technical documents.
For an open cut mining operation, settlement and surface instability can occur on the post mining landform. By selectively placing materials within the reinstated landform and tailoring the shaping methodologies and timing of this emplacement, settlement can be minimised. In this regard, any vegetation established on the progressively developed final landform is unlikely to be adversely impacted. However, as a precautionary measure, periodic monitoring for areas of excessive settlement and other areas where initial attempts to establish vegetation were not successful will be undertaken throughout the life of the Project.
Q. What is the topsoil resource available for the rehabilitation of the final landform for agricultural purposes?
A. Consistent with the strategy for the Project, Class III land will be rehabilitated on the final landform that is planned to be dedicated for future agricultural purposes. The volumes of topsoil available for rehabilitation of the site are adequate to allow the requirements for development of Class III lands as per the Land and Soil Capability Assessment Scheme – Second Approximation (OEH, 2013b). Published peer review information demonstrates the viability of successfully rehabilitating mined land for agricultural purposes.
Q. What is proposed for rehabilitation of native woodland communities on the final landform?
A. Approximately 2,384 ha will be rehabilitated in the Disturbance Boundary with a focus on re-establishing native woodland, associated grassland and Koala habitat.
It is recognised that native woodland rehabilitation will not have the same complement of native herbs and grasses as the original communities. However, published peer review research demonstrates that it is viable to recreate and establish a self-sustaining post mining landscape that resembles the pre-mining vegetation communities and is able to support a diverse range of viable flora and fauna populations, in particular a Koala population.
Q. What are the rehabilitation and management plans for the final void?
A. A final residual void will be present within the Western Mining Area. The low wall will be stabilised by means of battering to a gradient of 10 degrees and construction of drainage and erosion control structures. The majority of the highwall will be blasted back to improve its long term safety and stability. The remaining area of the highwall will be capped with at least 3 m of inert material from the crest above the highest coal seams and rehabilitated.
Surface water runoff and groundwater seepage generated off the final landform will fill the Western Mining Area void thereby creating a lake. The open void will remain a permanent sink for groundwater flow and the saline water that will develop within the void lake will not be able to flow to the adjacent alluvial aquifers or affect its associated water quality.
Where practicable, efforts will be made during consultation and preparation of a Mine Closure Management Plan to reduce the size, depth, batter grades and address groundwater performance of the final void.