Air Systems Used to Lower Exposure Risk
Bert Davis is CRREL’s director. (Valley News - Sarah Priestap) Purchase photo reprints »
Hanover — After potentially cancer-causing vapor was found in the indoor air of the Army’s Cold Regions Research and Engineering Laboratory, officials used air purification systems in a way they say eliminates a health threat to adult workers at the lab and their children at an on-site day care center.
Depressurization systems are designed to extract potentially harmful vapor from the soil beneath buildings, and one has been installed under the Cradle and Crayon child care center and another underneath the main laboratory. Darrell Moore, project manager with the Army Corps of Engineers, called the system at the main laboratory a “pilot” and said more underground ventilation systems will be installed throughout the Army lab complex soon.
The Army lab also put air purifiers in more than 100 locations. If an Army lab employee is working in an area with high levels of trichloroethylene, known as TCE, and an air cleaner isn’t readily available, the employee and his or her supervisor can discuss moving to another location or working from home, said Bert Davis, director of CRREL.
While news of TCE vapor contamination is alarming, officials agree that the ventilation and air purification systems are generally effective enough to allow people to continue living, working and going to school in affected structures.
Dartmouth College also agreed to place the underground ventilation systems in all 32 of the Fletcher-Cedar homes south of the Army lab.
“We were taking the measures that need to be taken in order to remediate the TCE that may be present and also to demonstrate that we are going to do what is necessary to make residents feel cared for,” Dartmouth spokesman Justin Anderson said.
The systems are installed in buildings with concrete floors. Pipes are placed into the slab, then connected to a fan that acts as a vacuum, pulling harmful gases from the soil and venting them into the air outside. Such systems are commonly used beneath homes with radon contamination.
Researchers have found that women of childbearing age can be at risk for fetal cardiac malformation during the first trimester of pregnancy if they are exposed to certain amounts of TCE. Davis said the Army lab has closely monitored the rooms in which young women work.
Davis said many of the fixes are short-term solutions until the Army lab can definitively pin down the pattern of the soil vapor contamination and work to remove it. Moore said the contamination clearly began in areas where the solvent spilled during the late 1970s, but it’s unclear exactly where and how far the TCE vapor has traveled through the soil.
The vapor contamination has been fooling officials, Davis said. During one set of testing at a particular location the levels of TCE can be very high, and during the next round it can show up much lower.
“It’s like trying to grab smoke in a way,” Davis said. “We know where it spilled, but we don’t know where the main underground places are where it’s hanging out now.”
The latest round of TCE vapor testing has shown spotty results, Davis said, with TCE popping up in areas of the Army lab where the chemical has never been detected. In other areas where TCE has been detected in the past, the levels have dropped.
Davis is also making it mandatory that every employee meet with his or her supervisor and have conversations about where TCE has been found in the Army lab and if they would like an air purifier in their office. In the past, conversations about TCE have been voluntary.
In August, there will be at least one more round of vapor intrusion testing at Richmond Middle School and neighboring residences, Moore said. He added that he doesn’t anticipate needing to conduct additional testing at neighboring properties. So far, the levels of TCE have been so low that they don’t prove that there is a pathway from the soil to indoor air beyond the Army lab campus.
“The low measures off-site does not tell us that the problem has gone away,” Davis said. “It tells us we have time to find out what the true sources are in the ground and what are the pathways of how it gets around.”
The Army lab has made efforts over the years to rid the soil at its site of TCE contamination, with limited success.
One of the efforts involved an “extraction” method, in which a powerful suction pump pulls vapor and water through a well and filters out the contaminant. But the method wasn’t very effective at the lab because the soil consists of fine silt and clay and is very dense, said Daniel Groher, senior engineer with the Army Corps of Engineers.
Another method was also attempted in which air is bubbled out of the groundwater to try to strip out TCE. But that didn’t work “terribly well,” Groher said.
Dr. Robert McLellan, chief of occupational and environmental medicine at Dartmouth-Hitchcock, has been working with Dartmouth College during the last several months on how to protect the health of Fletcher-Cedar residents.
McLellan stressed that there are harmful substances everywhere, but the key is took at the concentration of contamination and the duration of exposure.
“There is no such thing as zero risk,” McLellan said. “That’s an uncomfortable feeling. In fact, it’s not happy to think about, but we are surrounded by carcinogens all the time, everywhere.”
Even consumer products contain small traces of potentially harmful substances. It’s the dose that makes the poison, McLellan said.
But Anthony Roisman, a lawyer who has had extensive involvement with TCE lawsuits, said when it comes to TCE, any risk is unnecessary.
Roisman, of Lebanon, said school officials have a right to insist that the Army lab remove any TCE found on the school’s property. Roisman said the school or neighbors could file for a mandatory injunction, which if granted would require the Army to completely remediate sites if TCE is found in the soil on school property or other non-Army properties. Roisman said he couldn’t guarantee that neighbors would win the case, but they would have a good claim.
“Their statement that there’s not a health issue is false,” said Roisman, a managing partner with the National Legal Scholars Law Firm who has worked on a Woburn, Mass., case that was turned into a book and a movie, A Civil Action . “Trichloroethylene is a known — not a suspected, but a known — carcinogen. It causes cancer in human beings. … It looks like everybody’s just sort of laying back and letting CRREL take the lead, and the lead that they’re taking is to say, ‘Be happy, don’t worry.’ And I think that’s wrong. I don’t think that’s responsible.”
Sarah Brubeck can be reached at email@example.com or 603-727-3223.