Vapor Intrusion Assessment at an Abandoned Manufacturing Facility Slated for Redevelopment
The process of vapors entering a building from underground sources is known as “vapor intrusion”, and has been one of EPA’s top priorities since 2002. Vapor intrusion has become in many ways a more sensitive issue than groundwater because it’s easier to avoid drinking contaminated drinking water than to avoid breathing contaminated air. Unfortunately, the use of volatile chemicals for manufacturing, maintenance, and transportation has resulted in their ubiquitous presence in soil and groundwater, especially in metropolitan areas, making vapor intrusion a constant concern.
An abandoned manufacturing facility in a major city in the Upper Midwest was to be converted into an apartment suite, but the presence of chlorinated solvents in soil and groundwater, especially trichloroethene (TCE) and tetrachloroethene (perchloroethene, PCE) made vapor intrusion a serious concern. Cox-Colvin thoroughly evaluated the vapor intrusion risk by installing Vapor Pins® into the floor in a 30-foot grid configuration to collect soil gas from beneath the floor. A team of two people, using hand-held tools, installed 90 points in a single day, and sampled, removed, and plugged them the following day. The results showed that TCE vapors came from a part of the building that was missed with earlier soil-gas, soil, and groundwater sample locations collected over the course of years. Awareness of the previously unknown source area enabled the remediation and vapor mitigation contractors to focus their resources on the actual problem area and bring indoor air contaminants to acceptable levels.