The Mayfield Site is approximately 155 ha within the former Newcastle steel works site on the south bank of the Hunter River. Over a period of 130 years this site has housed copper smelters, steelworks and ancillary operations. Steelworks wastes (slag) have been used to fill much of the site. The most polluted part of the site is an area known as Area 1, and was previously occupied by coke ovens, gas holders, and other processes associated with steelmaking.
On 14 June 2001, under Section 21 of the Contaminated Land Management Act 1997 (CLM Act), the Environment Protection Authority (formerly EPA, now Department of Environment & Conservation – DEC) declared the former Steelworks site to be a remediation site. Under the Declaration, remedial works were required because the DEC considered the site to present a significant risk of harm to human health and the environment. In March 2003, RLMC was created by the NSW Government to manage the former Steelworks site and other crown land in the Lower Hunter Region, including remedial and redevelopment works for the site. RLMC has entered into a Voluntary Remediation Agreement with the DEC, where remediation activities are regulated under Section 26 of the CLM Act, as well as the planning approval under the Environmental Planning and Assessment Act (1979).