FREDERICK -- Army officials say they have pinpointed a source of contamination of well water near Fort Detrick but have not determined the extent of pollution.
Water and soil tests persuaded Army officials that a 20-foot-long pit in which acids, chemicals and solvents were likely buried decades ago is a source of well pollution, said Norman M. Covert, the post's chief of public affairs.
But more tests are needed, state and Army officials agree, to establish the extent of contamination. Since toxic contaminants were first discovered last year, however, no additional contamination has been found in residential drinking wells.
"No families are at risk at the moment," said Mr. Covert. "They are either on city water or will be hooked up to city water."
The Army's findings and plans to clean up the pit, known as Trench 11, will be discussed at a public meeting at 7 p.m. today at Frederick City Hall. State environmental officials will be on hand.
Mr. Covert said Army officials plan to clean up Trench 11 during the federal fiscal year that ends next September.
The cleanup, officials have said, could mean excavating the acid pit and trucking the debris to a disposal site off the base. The cost of the cleanup was unknown yesterday.
"The good news is that we know more than we did a year ago, but we still need to do more tests," said Arlene Weiner, division chief of state and federal facilities of the Maryland Department of the Environment. "They haven't found anything that will alarm us."
Ms. Weiner said preliminary data support the Army's contention that the pit is a source of contamination. But other tests are needed, she added, "before we can say Trench 11 is the sole source."
About a year ago, traces of trichloroethylene, or TCE, were found in the well water of homes on Montevue Lane, southeast of Area B, a 400-acre tract in which biological, chemical and radioactive waste were buried more than 20 years ago. Widely used as a degreasing agent, TCE is known to cause cancer in humans. The amounts found were double to triple the levels considered safe by the U.S. Environmental Protection Agency.
The Army began a $500,000 study earlier this year to target the source of chemicals polluting the wells. The study has focused on Area B, which contains Trench 11.
A 1977 Army environmental report concluded that Area B was likely to be contaminated with chemical wastes and that a "high potential" existed for the pollution to spread beyond the base because of underlying porous rock and a high water table.
The Army is expected to provide a draft of its investigation by mid-November.
In recent months, the Army has conducted soil, water and other tests that have shown traces of TCE and other contaminants at "barely detectable levels," Ms. Weiner said.
Michael E. Burns, a private environmental contractor who lives near Fort Detrick, criticized the Army for not undertaking in the past year a study to determine the full extent of contamination.
"They're going to try and color this like they have accomplished something over the past year," he said, "but what they have is a lot of loose information that adds very little to the picture."