Part of the Brisbane River will be closed after contamination was found at the site of an old tar-processing facility, the Courier Mail reports.

The decision was made after an assessment auditor found contaminate in the groundwater of a West End block of land adjacent to the corner of Donkin and Buchanan Streets at Riverside Drive. The toxic substance is in the riverbed and stretches about 40 metres from the shore.

The site, earmarked for residential development, previously housed a coal tar processing facility in the 1980s and was listed on Queensland’s Environmental Management Register. Heavy metals, hydrocarbons and polycyclic aromatic hydrocarbons were all found at the site.

It’s understood the Brisbane City Council will erect signage in the coming days warning people not to come into contact with water and sediments in the area. The council is currently unable to say how long remediation would take or how much it would cost.

A spokesman for the Department of Environment and Science told the Courier it was still investigating the issue.

“DES is working with Brisbane City Council and other Queensland Government agencies to determine what further action is required to remediate the land and waterway,” he said.

A timeline for the remediation is currently unknown