The area being tested covers the southern limit of Illawarra Coal Measures, where there are warped seams due to doming, igneous intrusives within the seam and dykes.
Longwall panels are to be mined beneath the overlying Bulli seam (30m interburden), which has been partially mined.
Additionally, the Wongawilli seam previously has been mined to the north and south of Area 1.
GHD is also assessing the impact of past mining activities in both seams and conducting hydrogeological modelling of caved and upward migrating bed separation.
GHD will attempt to predict the impact of longwall mining subsidence, valley closure and upsidence in the base of the storage reservoir and risk assessment of uncontrolled inflow into the longwall panels.
These are all in the context of obtaining approval from the NSW Dams Safety Committee for Dendrobium to mine adjacent to one of Sydney's water supply reservoirs.
In addition, Area 2 of the mine is situated adjacent to the Cordeaux Crinanite complex, upon which Upper Cordeaux No. 2 dam is situated.
Among other tasks is engineering geological mapping, which is part of GHD’s ongoing involvement to define the challenging hydrogeology of the Dendrobium project, so as to preserve the security of Sydney's water supply.
