The clean-up of the former Newcastle gasworks has been completed.
The $11.5million project used cap and contain methodology to secure contamination on the site, which operated as a gasworks between 1913 and 1985.
Work undertaken throughout the remediation project involved the installation of a 510 metre subterranean wall to redirect groundwater flow away from contaminated materials.
Jemena acquired the 7.5 hectare Hamilton North site from AGL in 2006.
Project Director, Oliver King, said the project would move into a monitoring phase.
"Our next step is to demobilise the site, retaining a skeleton staff who will monitor the effectiveness of the controls we've put in place," he said.
The monitoring data will be provided to the independent EPA-accredited Site Auditor as part of the Statutory Audit process."
The site has been remediated to a commercial-industrial standard.
Mr King said that while Jemena has not yet made any plans in relation to the future use of the site, it was open to discussing with local businesses or developers how the site could be repurposed. At its peak the remediation project created 44 jobs.