Illawarra Coal is part of Carbon Steel Materials that is in turn part of the BHP Billiton organization. Illawarra Coal operates five underground coal mines, viz Appin, Tower, West Cliff, Cordeaux and Elouera. One of these mines is Cordeaux Mine which ceased production in April 2001 and is currently being operated on a care and maintenance basis until its ultimate future is decided. Approval for a new mine, Dendrobium, has been granted and construction has commenced with the aim of replacing dwindling Elouera Mine production and reserves by 2004. Appin, Tower and West Cliff mine from the Bulli or No. 1 Seam of the Illawarra Coal Measures. This seam is considered very gassy by world standards and each mine has extensive underground gas drainage systems in place to control both gas emissions and the outburst hazard. Seam gas present is predominantly methane but some areas of the mines encounter high carbon dioxide levels, generally localised around geological structures within the seam.