Two of eight wells in a Perryman field that provides half of Harford County's piped drinking water have shown detectable levels of a suspected carcinogen intermittently for more than a year, county officials have confirmed.
Officials insisted yesterday that the county's drinking water is safe, but they will spend $650,000 to drill a new well to replace the one that has shown the most contamination, study other locations for new wells and investigate three ways of removing trichloroethylene from the county's drinking water.
"The water is safe," William T. Baker Jr., director of the county's Department of Public Works, said yesterday. "My children and my family drink that water. And, by God, I'm not going to put my family in jeopardy. Of course, my main job is to protect the public, and that's what we're trying to do now by monitoring the wells monthly."
Trichloroethylene is a toxic, non-flammable liquid that is used as a cleaning solvent for fats, oils and waxes.
While officials have known about the Perryman situation for 14 months, County Executive Eileen M. Rehrmann said yesterday that she didn't want to create panic by releasing information about the contamination until county administrators had a plan to deal with it. Ms. Rehrmann said she had planned to make a statement next month when she is to ask the County Council for permission to transfer $650,000 from other projects to pay for the new well at Perryman and related studies.
Harford has 24,000 water customers. Half its supply to these homes and businesses comes from the Perryman field. The rest comes from the Susquehanna River and a handful of wells in Joppatowne. Those portions of the supply have shown no trichloroethylene, or TCE.
Ms. Rehrmann said the county is trying to locate the source of the TCE. While the chemical could have come from one of several industries in the area, county officials and experts at nearby Aberdeen Proving Ground think the Army facility is a more likely source.
John Yaquiant, a Proving Ground spokesman, said TCE also has been detected in monitoring wells on the base, which is near the Perryman well field.
"We found TCE in our area monitoring wells in late 1990, but the readings we're getting don't indicate there's an immediate public health threat, and it's not in APG's drinking water either," he said.
Routine tests first detected trichloroethylene or TCE, at the Perryman well field in February 1991, when six parts per billion were found in the county's deepest well.
That well produces 800 gallons of water a minute, more than any of the other individual working wells, Mr. Baker said.
The federal Environmental Protection Agency has said the maximum amount of TCE allowed in drinking water is five parts per billion, Mr. Baker said.
No TCE was found in quarterly tests conducted on wells in 1991, but TCE was next detected in the same well in February 1992, also at a level of six parts per billion, Mr. Baker said.
TCE also was found twice in a second well -- in December 1991 and February 1992 -- in amounts less than five parts per billion, Mr. Baker said.
"There are no federal guidelines for raw water. We are well under the federal guidelines for finished, treated water," said Mr. Baker.
"By the time that water is mixed with water from the other wells and treated at the Perryman plant, the level is very low. TCE has shown up in four tests on finished water in the past 14 months. The maximum concentration we've found is 2.1 parts per billion. Last month's test showed none at all."
Dr. Boon Lim, program administrator for the state's Environmental Health Program, said the amounts of TCE in Harford's drinking water supply are so low "you would have to consume 12 liters of this water every day for 70 years to have a higher than one in 100,000 chance of developing cancer."
John Goheen, a spokesman for the state Department of the Environment, said the levels of TCE found in two of the eight Perryman wells "are cause for additional attention, but not alarm."