Computer model for chemical cleanup rapped

A computer model used to guide cleanup efforts at the former Grumman defense complex in Bethpage ignores factors that could improve predictions on how nearby drinking water wells will be affected, according to a new report from the U.S. Geological Survey.

Local water district officials and Sen. Charles Schumer (D-N.Y.) said the findings show that Northrop Grumman and the Navy -- which share responsibility for the pollution -- have consistently underestimated the risk to supply wells.

"We've been telling the state and the feds and the Navy that the model hasn't been accurate for 20 years now," said Anthony Sabino, attorney for the Bethpage Water District.

The USGS paper released last week was prepared for the federal Environmental Protection Agency as part of an ongoing review of the Bethpage cleanup that Schumer requested last fall after complaints from nearby water districts. The pollution, from industrial solvents used to build military planes decades earlier, includes multiple plumes moving south through groundwater toward Sunrise Highway.

Plumes have already hit five of Bethpage's eight wells, triggering expensive treatments to filter out chemicals. Wells that supply the South Farmingdale and Massapequa water districts also are threatened.

A spokeswoman for Northrop Grumman said company officials are reviewing the report.

She said the firm had been "a good corporate citizen" and has spent more than $100 million so far on the cleanup.

The USGS analysis found that the most recent computer model of the plumes used by Northrop Grumman's consultant ignored certain factors that affect groundwater flow. Incorporating such factors as variations in rainfall and seasonal water use might provide greater certainty on where the plumes are headed, the report said.

Officials with the EPA and the state Department of Environmental Conservation were still reviewing the report last week.

But an EPA memo responding to a draft version of the report in December said the model had "too much uncertainty" and should not be used to predict how groundwater contamination would affect water supply wells that lie in the path of the plumes.

"The fact that the Navy and Northrop Grumman continue to rely on this flawed model is simply unacceptable," he said in a letter last week to Navy Secretary Ray Mabus.