Downtown redevelopment officials reported Friday that they have identified a 460,000-gallon lake of gasoline and diesel fuel 19 feet below the ground in the Marina area.
And, like an underground blob spreading silently beneath the city's streets, it is headed--or more precisely, being sucked--toward the $125-million bayfront convention center now under construction.
That's because the center's dewatering system, which pumps about 1 million gallons of water a day from the site, is acting like a giant vacuum, pulling the potentially hazardous motor fuel closer to the facility.
If nothing is done, the toxic plume would reach the center in about six months. But the Centre City Development Corp., or CCDC, the city agency in charge of downtown redevelopment, approved a $228,000 plan Friday that consultants say will stop and reverse the plume's movement and lead to its removal in about a year.
Total cleanup, including disposal of dirt saturated with gasoline and removal of the gasoline itself to a refinery, could ultimately cost more than $1 million.
Officials have not yet determined the source of the gasoline and diesel fuel. It could have come from decades-old leaks in underground tanks operated by businesses that, in most cases, are no longer there.
Possibility of Explosion
Redevelopment officials said the primary danger from the contaminants is the possibility of explosion and fire during excavation. Since there is no current construction, there is no immediate danger to businesses or nearby residents.
Who will pay for the cleanup, both now and in the future, is a question that so far has no answer.
CCDC, concerned that the toxic lake will hinder its redevelopment plans in the area, wants to start cleaning up the plume now. The agency hopes that it can recoup its costs with the help of both the county Department of Health Services and the Regional Water Quality Control Board.
The water board has the authority to force private property owners to pay for all or part of the cleanup, and the agency is now studying the contaminated area in an effort to identify the sources of the fuel.
The plume was discovered almost by accident. A year ago, redevelopment officials were concerned about the alleged illegal dumping and storing of hazardous wastes at Super Plating Works, at Martin Luther King Way and 1st Avenue. Soils tests confirmed the presence of heavy metals, acid, cyanide and other corrosive materials. But these toxic wastes were mainly confined to the site.
What came as a surprise was the discovery of gasoline contamination in the groundwater. How it got there, where it was coming from and how much there was, nobody knew. What officials knew, however, was that it didn't originate at the Super Plating location.
Another round of tests carried out last May showed that the contamination extended much farther than anyone thought. Those tests also turned up what appeared to be a second plume at Martin Luther King Way and 3rd Avenue, at a site owned by CCDC where a 30-unit apartment building is planned.
More tests, though, carried out through Aug. 7, showed that the two plumes were really one and, more ominously, that the plume was spreading rapidly southward, in some areas as much as 40 feet a month.
The reason for the relatively fast movement was the massive pumping out of water being done as part of the construction of the convention center, about 2 1/2 blocks away. The design of the convention center includes underground parking, which, because of its waterfront location off Harbor Drive, requires the use of a dewatering system that removes about 1 million gallons of water a day.
The underground lake of fuel spreads roughly about three blocks, from 1st Avenue on the west to just past 3rd Avenue on the east, and Martin Luther King Way on the north and the middle of Island Avenue on the south.
Greatest Risk from Plume
Bernard J. Luther, a principal in the firm of Applied Hydrogeologic Consultants--the company that conducted the soils tests for CCDC--said the greatest risk from the plume is the threat of explosion during an excavation for a building because vapors from the plume have been detected as close as six feet from the surface.
Luther says the gasoline is as old as 40 years, and he and others point out that the area, over the years, has been the location of many gasoline stations and that a large truck stop once stood on Martin Luther King Way between 2nd and 3rd avenues.
The densest concentration of fuel is in a block bounded by Martin Luther King Way and Island, 1st and 2nd avenues. On that block are three businesses: Ray Dobson Welding, Don's Automotive Center and a repair and storage facility for Greyhound Lines Inc.
Luther said there could be as many as seven or eight sources of the contamination. He noted that there is 100% gasoline under the auto repair shop and 100% diesel under Greyhound's underground diesel fuel tank.
"We have reason to believe that's the source," Luther said.