ST. PETERSBURG — Cleaning up the underground toxic waste plume near the Raytheon facility in northwest St. Petersburg likely will take years and cost millions of dollars, experts say.
The plume, migrating west toward Boca Ciega Bay, consists of several chemicals considered a risk to human health.
The prospect of a long-term cleanup has further unsettled homeowners in neighborhoods west of the Tyrone area, where health effects and property values already are provoking deep concerns.
While Raytheon and the Florida Department of Environmental Protection insist no immediate health threat exists, other environmental experts disagree.
"If it's above a health level, there's a risk," said Jim Gore, a professor of environmental science at the University of South Florida St. Petersburg.
Two lawsuits on behalf of residents were filed in April.
Cleaning up underground toxins involve a number of expensive and time-consuming processes ranging from removing affected soil to filtering groundwater.
Engineers discovered toxic chemicals at the site in 1991 during construction of the Pinellas Trail. In 1994, additional chemicals were found leaking from an underground tank, which was removed.
At the time, E-Systems owned the site, and the Florida Department of Environmental Protection designated them the responsible party in March 1995. Raytheon inherited the responsibility when they purchased the facility in April of that same year.
A 1999 feasibility study by Arcadis, Geraghty and Miller, the engineering firm Raytheon hired to handle their environmental issues, determined that the plume was stable or shrinking, "posing no imminent human health or ecological risk."
But a DEP document shows that wells tested in March 2007 at Azalea Park, 72nd Street N, the Brandywine Apartments, 70th Street N and Stone's Throw Condominiums show levels of trichloroethylene (TCE), vinyl chloride, 1,4-dioxane and other toxic chemicals well above levels considered potentially hazardous to human health.
It will likely be several years before cleanup begins because state regulations require determination of the plume's size and makeup first, said Gabrielle Enos, vice president of Solana Environmental Associates, a Tampa based company.
"It creates a situation where I can almost bet they will spend a lot of time chasing the plume."
And while regulatory compliance has its place, Enos said it may not be the best way to get things cleaned up.
"It's like asking an ambulance to go the speed limit," she said. "You don't want that if you're in the back."
Gore said the geological makeup of the area, including the shallow and fast moving Floridan Aquifer, makes the plume's actual extent hard to determine. Gore said he wouldn't be surprised if the cleanup takes more than 10 years — once it begins.
Cleanup can involve several processes used individually or in combination, depending on the chemicals identified and the extent of the contamination.
Workers can physically remove soil and dispose of it off-site as toxic waste.
A common method of on-site remediation involves pumping the groundwater out, running it through filters and then re-injecting it back into the ground, a process akin to kidney dialysis. Engineers can also inject various chemical compounds or microbes into the soil and groundwater, which will neutralize or consume the contaminants.
Gore said the DEP or EPA determine the methods, making costs nearly impossible to estimate.
"I don't think I can even give you a ballpark," he said. "The EPA can pick the most expensive method if they want."
A similar site near the small Manatee County community of Tallevast exemplifies the time and cost involved in cleaning up toxic plumes.
Lockheed Martin discovered chemical contamination at the site in 2000. Initially thought to encompass only five acres, the affected area had grown to nearly 200 acres by 2006.
It took Lockheed six years to define the plume and the cleanup began last year. The company has spent $20-million so far, said Lockheed spokeswoman Gail Rymer.
Wilma Subra, a chemist and consultant who worked with Tallevast resident groups, estimates the actual cleanup cost will run an additional $20-million and said it will take about 20 years to completely remediate the area.
"Once the chemicals get in the water and start moving, you're looking at a big expense to address the source areas and a big expense to keep it from migrating," she said.
Michael Maharrey can be reached at 727-893-8779 or firstname.lastname@example.org.