Work to remove the 12 fuel storage tanks at the Phillip Business Park and ACTION depot was severely delayed when it became clear there was no information regarding layout of electrics, previous work done or even how many tanks there were on the site.

now

In addition, while the original cost of the project was $1 million, it has blown out to $2.01 million.

The site had originally been used as an ACTION sub-depot in the 70s and 80s, according to the directorate,

ACT Property Group director Daniel Dailey said following initial investigations the project had turned out to be significantly more complex than originally thought.

"[This was] due to the number of fuel tanks identified, 12 in all across the site, and the lack of documentation that detailed the location of services, water and electricity," he said.

"These services, both active and redundant, ran over and around a number of the tanks."

Mr Dailey said the site had been established more than 40 years ago and installation plans were not available for the depot.

"Most of the site was constructed in the early 1970s, with some further construction in the early 1980s, all well before self government... An exhaustive search was undertaken in an attempt to locate the original plans however this proved unsuccessful," he said.

"As the plans were not available, significantly more time was invested in investigating the location of these services. Records were also not clear on what remedial action, if any, had been taken once the tanks were decommissioned."

He said the northern end of the site, including space in the main building, was being used as an ACTION bus depot, while the southern end was leased to a private company.

The Office of the Commissioner for Sustainability and the Environment said there were 110 potentially contaminated service station sites in the ACT, of which 74 were operational, 30 had been closed and six were historic sites for redevelopment.

There were also five potentially contaminated fuel depots in Canberra, four of which were operational and one had been closed.

Fuel remediation works have become increasingly common across the ACT as the number of service stations closing continues to grow.

In 2013, Environmental Protection Authority head Daniel Walters said well-managed sites could take as little as 12 months to remediate, but others could take longer if fuel had leaked into the groundwater.

Mr Dailey said the work at the Dundas Court site had been completed, as of June 2014, with the tanks removed, although the contaminated soil taken from the area still needed to be properly disposed of.

"The only remaining work is the remediation of the soil. This is expected to be completed by December 2014," he said.