Water samples from monitoring wells at a closed Abingdon rubble fill show increasing levels of two chemical compounds, including one suspected of causing cancer, state environmental officials say.
"They are higher than the numbers we've seen before, but we can't pinpoint whether it's a change in the amount of chemical in the well, a change in sampling technique or a change in the analysis process," said John Goheen, a spokesman for the Maryland Department of the Environment.
"But our level of concern remains the same," he said. "The point is it's there and it needs to be addressed."
He said June tests showed a monitoring well on the east side of the rubble fill operated by Spencer Sand and Gravel Inc. contained 214 parts per billion (ppb) of trichloroethylene, or TCE. Another compound also found in a test well on the east side of the site, dichloroethene, was present in amounts of 119 ppb.
Trichloroethylene, thought to cause cancer, is used in pesticides, paints and degreasers.
Dichloroethene is a solvent that can harm the liver, nervous and circulatory systems, the federal Environmental Protection Agency says.
In September, a test showed levels of trichloroethylene at 88 ppb; the maximum allowable level under state and federal law is 5 ppb. Dichloroethene also was found at a level of 79 ppb, more than 11 times greater than the allowable level of 7 ppb.
Tests conducted in March measured levels of TCE at 99 ppb in one of the monitoring wells, and dichloroethene at 107 ppb on the same test site.
Spencer Sand and Gravel was shut down by the MDE in August because a current topographic map, which would show where rubble was deposited, had not been filed with the state agency.
State environmental officials, reviewing a map filed after the closing, found the company had filled about 7.5 acres outside the area for which it had a permit.
Two previous tests revealed lower levels of the two compounds.
To be harmed by the compounds, a person would have to ingest them over a long period, said Mr. Goheen.
"One of our primary concerns is finding the source," he said. "Is it coming from maintenance activities or landfilling activities? That's a vital piece of information. We have to know what the source is to remove it."