The Yukon government has expanded its search for an underground fuel leak that's contaminating a section of the downtown core.

Brian Levia of the Department of the Environment said Tuesday that heating fuel records for businesses and homes from Main Street to Rogers Street, and from the Yukon River to Third Avenue, are now being examined.

Records for every customer of North 60 Petro Ltd. and Summit Fuels in the downtown from Robert Service Way to the bottom of Two Mile Hill have been requested, the manager of monitoring and inspections told reporters during a briefing.

A laboratory test indicates both North 60 and Summit Fuels sell the same product that continues to leak into the sump of the Optometrists Building at the corner of Second Avenue and Lambert Street, he explained. The lab results also indicate the fuel leaking into the sump is no more than a year old.

Levia said Yukoners are being encouraged to call the department if they have any information. He noted they're welcome to use the anonymous TIPS line if they don't want to reveal their identity.

Individuals, he said, may be apprehensive about providing information, fearing they may cause themselves or the responsible party undue financial hardship.

But the longer the mystery continues, the larger the contaminated area and the greater the cost of clean up, he said.

'So the sooner we are able to find the source, the cheaper the cleanup will be.'

The government has so far spent $105,000 looking for the source.

It was the initial opinion of the territorial Department of Justice that the cost of investigating a spill could not be retrieved from the responsible party; that only the cost of the cleanup could be recovered under the law, Levia explained.

He said there have been some second thoughts, however, and it's likely any effort to recoup the cost of the cleanup will include an attempt to recover the cost of searching for the source.

In late March, a local resident reported a sheen on the Yukon River. Federal authorities traced the slick of diesel fuel back to the Lambert Street storm drain, and eventually the sump at the Optometrists Building.

The two underground fuel tanks supplying the building were tested, eventually dug up and cleared of any problems.

But when crews dug down below the tanks, they encountered a gush of fuel that amounted to 800 litres in two hours, before the hole had to be filled back to protected the integrity of the building's footings.

To date, a total of 3,500 litres equivalent to about 3 1/2 home heating fuel tanks have been recovered by a recovery and treatment system installed at the building to ensure no more fuel gets into the storm drain and the Yukon River.

Attempts to find the source have proved fruitless to date. A specialized drill imported from B.C. drilled a series of 12 holes around the Optometrists Building in May but failed to locate any trace of fuel.

One of the holes was within three metres of where the two tanks were buried.

'Everybody involved was surprised,' Levia said of the unsuccessful drill results. 'This is very unusual for us that we do not find anything.'

He said fuel records of buildings in the immediate vicinity have been checked for anything suspicious. The examination of fuel records will now involve all buildings on both sides of Main Street from the river to Third Avenue, and down to Rogers Street.

While records for homes will be looked at, the source is probably a commercial building because of the volumes involved.

'Some residences don't even use 3,500 litres per year,' he said.

The local consulting firm of Gartner Lee Ltd., initially retained to provide advice on the initial search for the source, has now been hired on as project manager in the effort to find the source of the leak.

Levia said discussions are ongoing to develop a new plan of action, though he was unable to detail the nature of those discussions.

There is talk, however, of re-excavating the hole where the tanks were that supplied the Optometrists Building, he said. Levia said the exact spot was not drilled by the special unit from B.C. because the shed containing the treatment system was placed over the hole, though they are now thinking of relocating it.

Officials had also thought the source may have been the result of fuel accidentally poured down an abandoned filler pipe, but there's no evidence of any such pipe in the neighbourhood, Levia said.

There was a loss of up to 2,000 litres from the government's youth probation office on Lambert Street between Third and Fourth Avenues, but it was a Great Northern Oil product, Levia explained.

Officials suspect that thieves stealing heating oil from the probation building had poked a hole through the bottom of the old tank, causing the leak to occur. The government has so far spent $30,000 on that cleanup, and is awaiting a recommendation from a local consulting firm regarding a plan of action to complete the remediation.

Similarly, during the initial investigation, it was noticed that there was a discrepancy of 10,000 litres in the fuel records for the territorial visitor reception centre.

But again, the product is Great Northern Oil, and the tanks have been tested and cleared of any problems, Levia said.

Further examination of the records, he noted, reduced the discrepancy to 5,000 litres, and the matter is now in the hands of the government's property management branch.

Government spokesman Darren Butt said this morning he was not in a position to discuss the 5,000-litre discrepancy.

'We are looking into this issue, and we will have further comment forthcoming,' Butt said.