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Scientists dispute chemical plant studies

They say the "mound and cap" cleanup plan will not work because the area has a lot of sinkhole activity.

TARPON SPRINGS - Scientific experts have told the U.S. Environmental Protection Agency they have doubts about the conclusions of two recent studies on the defunct Stauffer Chemical plant.

Prepared by Stauffer Management Co. consultants and released in late June, the studies concluded that most of the land at the Superfund toxic waste site is geologically stable and there is little chance of contaminants leaching into area groundwater supplies. That finding led to the endorsement of a plan to pile up contaminated dirt at the plant and cover the piles with watertight caps.

But this week, two experts familiar with the reports said they have serious questions about the proposed "mound and cap" cleanup plan. They say geophysical and groundwater studies conducted by Stauffer consultants are full of holes.

"Their data clearly shows sinkhole activity and a lot of it," said Tarpon Springs hydrogeologist Sandy Nettles. "To try to do a mound and cap on a sinkhole area is just bad science and bad engineering."

Stauffer's consultants, O'Brien & Gere Engineers, concluded that 120 acres, or about 92 percent of the site, show no signs of past sinkholes.

The remaining 10 acres show signs of sinkholes that took place more than 40,000 years ago. Engineers used carbon dating to determine the age of the sinkholes and concluded those areas "appear to be very stable with an extremely low risk" of further collapse.

But Nettles said data included in the report do not fully support those conclusions and consultants left out important information. Though Stauffer consultants used a technique called electro-resistivity to measure anomalies such as sinkholes and other geological features of the site, they did not publish those test results, he said.

Nettles estimates that electro-resistivity tests could reveal an additional 15 to 20 smaller potential sinkholes on the site. More detailed study would also likely reveal that sandy sediment at the former phosphate plant provides little in the way of stability and protection from contaminants leaching into groundwater, he said.

A former Pinellas County geological consultant, Nettles has spent close to two decades studying the Tampa Bay area's sediments and groundwater. He submitted a written review of the Stauffer studies to the EPA in July, pointing to several inconsistencies in Stauffer's methodology and data.

"Their investigation was not complete," Nettles said. "Everybody knows that there's a huge incidence of sinkholes in that area," Nettles said. "There is no confining layer. It's just sand on top of limestone."

Stauffer president Brian Spiller disagrees. He said the criticism was premature because only draft versions of the geophysical and groundwater studies were submitted, and the EPA has yet to evaluate all the comments received about the reports.

"We think our experts have done a fine and thorough job and we're going to let them review all of the comments," Spiller said, adding that further comment was unwarranted until review by the EPA and his company's consultants later this year.

Some of those comments will come from toxicologist and environmental scientist Kevin Pegg. He is a technical consultant hired by the Pinellas-Pasco Technical Advisory Grant, also known as Pi-Pa-TAG, the citizens group charged with monitoring site cleanup.

Pegg said he was impressed by the thoroughness of the Stauffer studies. But he worries that the findings are incomplete.

Echoing Nettles' concerns about Stauffer's geophysical data, Pegg also questioned whether the groundwater study was properly conducted.

"I would be a lot more comfortable if those studies were repeated because I thought perhaps they were relying too much on past studies when they were supposed to be creating new studies," Pegg said Wednesday.

He said consultants had not shown enough convincing evidence that the contaminants from the site are not leaching into the Floridan Aquifer, the water-filled underground layer of porous limestone that supplies most of the state's drinking water. Pegg said he is leery of the findings, because of technical problems that could have affected the consultants' ability to gather accurate data.

"I don't know why the data looks the way it does, but there's a lot of unsupported conclusions," Pegg said. "We cannot recommend that the Pi-Pa-TAG board can support the findings of the (geophysical) study. There were pump breakdowns and electrical shortages. Yet they concluded everything was okay."

Those problems could have affected measuring and monitoring equipment used for the studies, Pegg said.

EPA project manager Nestor Young said he had received Pegg and Nettles' written comments. But his agency was still awaiting reviews of the Stauffer studies from the United States Geological Survey, or USGS.

Young expects to field plenty of questions about the findings of both Stauffer studies during a public information session Wednesday in Tarpon Springs. He and USGS experts will meet with community members for an invitation-only technical review of the reports the next day.

"We have received a lot of comments from different people - these are not the only ones we're looking at," Young said.

The U.S. Environmental Protection Agency will hold a public information session about recent reports on the Stauffer Chemical plant on Aug. 13 from 5 p.m. to 8 p.m. at the Tarpon Springs Public Library at 138 E. Lemon St.