Coal wash is obtained from the processing of raw coal in a coal preparation plant. The coal wash product is a non-coal material from the coal seam and material cut from the seam roof and floor during mining. The coal wash generally consists of a mixture of carbonaceous shale and mudstone with minor proportions of sandstone. Small quantities of low-quality coal can also be present.

The CWEA is the designated and approved facility which will accept large quantities of coal wash over an extended period of time.

The Coal wash emplacement area (CWEA) receives coal wash primarily from the West Clift Coal Preparation Plant (WCCPP) and from the Dendrobium Coal Preparation Plant (DCPP).

The facility has been designed to progress gradually down the Brennans Creek Valley within the contained Brennans Creek Dam catchment, approximately 25 kilometres (km) north-west of Wollongong in New South Wales.

Coal wash is placed in the valleys within the CWEA and is rehabilitated, changing the overall landform of the area.

The design of the CWEA is developed to minimise environmental impacts to sites of Aboriginal cultural significance and threatened flora and fauna species. The alignment and location of haul roads, construction roads, drainage works, and emplacement ponds have been carefully chosen to avoid threatened flora species, sensitive habitat and Aboriginal sites where possible.

Due to the long life of the emplacement, detailed final designs are prepared progressively and for stages.

Wollondilly Shire Council (WSC) granted development consent for West Cliff Mine in 1975, which included the deposition of coal wash in Brennans Creek Valley (now known as the Stage 1 CWEA). The consent was conditional on each phase of the emplacement facility complying with legislation administered by relevant government authorities.

Approval for Stage 2 of the CWEA comprised of several approvals and various conditions. Approval for commencement of coal wash deposition in Stage 2 was granted in 1999 by the then Department of Mineral Resources.

Emplacement of coal wash in Stage 1 and 2 is complete and these areas are now rehabilitating.

Approval for Stage 3 of the CWEA was issued by the Minister for Planning on 20 December 2007. Emplacement of coal wash in Stage 3 is currently underway.

For Stage 4 CWEA the specific approvals in place are:

- approval under the EPBC Act 1999 (EPBC Approval 2010/5350);

- approval under Section 75J of the EP&A Act 1979 (the Project Approval).

Stage 4 is scheduled to commence in approximately five (5) years.

Coal wash can be re-used and re-purposed in road construction by substituting it for quarried rock and aggregate where appropriate.

By re-using it in this way, IMC is diverting coal wash from the CWEA while producing an essential product for construction and reducing the need for mining and quarrying natural rock.