Two years after a 50,000-gallon fuel spill was discovered in the Ferry Reach area, less than five percent of the spill has been cleaned up, according to an environmental impact report obtained by The Royal Gazette, yesterday.

While area residents are frustrated with the pace of the clean-up - particularly as they are bombarded by a foul smell every low tide which they believe is linked to the spill - a Ministry of Environment officer said yesterday the time frame is not unusual for a spill of this magnitude and Shell has been working on the problem continuously.

The fuel leaked from one of Shell's underground pipelines which carry jet fuel from the Ferry Reach depot to the airport and was discovered only after a discrepancy between depot and airport records was investigated in August, 2000.

While the leak was reported to the Environment Ministry and repaired, the massive volume of jet fuel has been sitting underground as the company examined clean up options and last year area residents began to complain of a bitter, rotten eggs odour in the area.

The leak occurred under Ferry Road at the point the road crosses Esso's bulk fuel storage terminal and much of the fuel is under neighbouring fuel rival Esso's property.

When The Royal Gazette broke the story of the fuel spill last Spring, residents dubbed the odour `the Shell smell', although Shell claims there is no proof it developed as a result of the fuel spill.

"There is no scientific evidence of that," general manager John Vickerman said last night. "No one is aware precisely what the problem is. I am not a scientist but I've been told it's very complicated."

However, Government Environmental Engineer Dr. Tom Sleeter told The Royal Gazette the odour is created from the interaction of the fuel and bacteria in the bay.

"Richardson's Bay is a low-energy environment," he said. "It already has a resident population of bacteria in black mud which has anoxic conditions. With the addition of the extra organic matter - a combination of the jet fuel and organic matter from the cess pits - that anaerobic situation is exacerbated. When that combo hits the bacteria in the bay it releases hydrogen sulphide."

Efforts taken by Esso last year to abate the smell were unsuccessful and Shell has hired a consultant to develop both short and long-term plans to solve the problem, Mr. Vickerman said.

"It is a horrible smell," he said. "It is back this year with a vengeance. At the moment, our consultant wants to install a spray. It will spray oxygen into the bay at low tide."

He said the spray would be automated to coincide with the tides.

Dr. Sleeter explained the hope is the extra oxygen will reverse the reaction between the organic matter and the bacteria and prevent the release of hydrogen sulphide.

While it may seem like much time has passed without progress, he said the Ministry of Environment is happy with the pace of the clean-up efforts.

"They are working on it but these things take time," Dr. Sleeter said. "The fact that it's creating this hydrogen sulphide smell is really unfortunate.

"The Ministry is not minimising that situation in any way. It is a real nuisance to the people affected."

To remove the fuel from the soil and water, Shell hired an American company called EnviroTrac which developed a plan following a comprehensive site assessment in November 2001.

According their May 2002 report on their results, EnviroTrac recovered 1,514 gallons of fuel by the end of March using two recovery methods.

They also looked at how tides affected the fuel's movement and assessed human health and ecological risks.

There appear to be no health risks associated with the spill.

"The analyses performed utilised conservative assumptions of exposure, and conservative ground water and soil concentration values," the report said.

"Results indicated that although there are risks associated with the jet fuel release, these appear to be low and remedial measures will be implemented to eliminate current and future risks."

The fuel is sitting underground near Richardson's Bay - in pools up to a third of a metre thick at points - and has also penetrated the ground-water in certain sections, according to the report.

Shell estimates that 50,000 gallons of jet fuel were lost, so there is considerably more work to be done, but EnviroTrac have stepped up vacuum evacuation efforts in the past few months.

They will never recover all of the fuel however. "Typically you get about 50 percent recovery," Dr. Sleeter said.