by Duane Craig
Chlorinated solvents such as tetrachlorethylene (PCE) are thought to have contributed to the vapor intrusion of homes in Madison, Wisconsin. The Wisconsin Department of Natural Resources sampled soil from below the homes’ foundation slabs and found concentrations of PCE ranging from 305 parts per billion to 1,080 parts pre billion. If there are just six parts per billion in indoor air the department considers that a problem.
So far, only one home has had vapor intrusion at the threshold level but a filtration system is still recommended for the involved homes as a precautionary measure. The contamination is thought to originate with PCE storage tanks and external vents at the Madison-Kipp Corporation’s nearby Waubesa plant. The company used PCE to clean products.
There are five homes that will get filtration systems and two other homes will be tested for the contaminant to see if the contamination has migrated. A Department of Natural Resources spokesperson said the vapor problems usually only persist for 100 feet before they “peter out.” The depressurization systems installed below the slabs of the homes will vent the air from beneath. Once the vapors enter the atmosphere they will break down and harmlessly disperse, officials say.
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