Fire and Rescue NSW crews were called to the proposed Central Park residential unit development in Graham Street, Nowra on Tuesday after a strong odour was smelt coming from site.

A ruptured underground fuel tank, containing some residual fuel, is being blamed for an unusual odour.

Fire crews closed part of Graham Street as a precaution.

Shoalhaven Fire and Rescue NSW station officer Mark Kroom said a contractor working on the proposed development became concerned about a strong odour coming from a underground fuel tank he was removing.

It was originally thought only one fuel tank was buried on the south eastern corner of the three properties which make up the proposed development.

The Register has been told fuel was taken from the tank but as it was was being removed from the ground it ruptured.

“Our crews took gas readings over the site which were exceeding explosive limits, so there was a risk so we sealed off the site,” Station Officer Kroom said.

“It became a possible fire hazard.”

Crews laid down foam to suppress the vapours and worked was stopped on the site until the remaining fuel could be decanted from the tank and investigations made into the discovery of the second tank.

“The company involved in the work had organised the decanting of the fuel but some was left,” Station Officer Kroom said.

“Perhaps there was problems in removing all the fuel or they couldn't get complete access to the tank.”

He said around 80 to 100 litres of an unknown substance was discovered.

“It may not have been all fuel, it could be water as well,” he said.

Work was stopped until the remaining fuel could be decanted and investigations made into the second fuel tank.

Staff from council’s compliance team have followed up the issue with the contractors.

A council spokesperson said the contractors had been reminded of the conditions of the development consent regarding the removal of the fuel tank.

“Staff sought their confirmation of the initial measures and actions taken upon the discovery of the second fuel tank,” the spokesperson said.

“They also requested confirmation on the safety of the site and when available they have been requested to provide a copy of the scope of works for removal of the second tank.

“Apparently the discovery of the second tank was a surprise to the contractors, they were on the understanding there was only one fuel tank on the site.

“The contractor contacted the developer’s contaminated land consultant and arranged for them to investigate and advise how to proceed.”

An environmental site assessment by Geo-Environmental Engineering for the development made mention of an underground storage tank, but did not indicate what the tank might have been used for.

It stated there had been existing commercial buildings on site, believed to be former military buildings, brought to the site between 1961 and 1974.

The site’s final use was for a pet store, a shop selling various homewares and a charity store, but prior to their construction the site was a vacant and undeveloped parcel of land covered by grass.

It is not known when or why the fuel tanks were installed on the site.