Locating Sub-Slab VOCs in an Operating Manufacturing Plant


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Locating Sub-Slab VOCs in an Operating Manufacturing Plant

Locating the source of groundwater contamination often requires years of investigation, especially for a source beneath a large building. The process typically consists of coring and drilling through the floor with small drilling rigs, at locations based on waste management activities – to the extent known. Because of its cost and disruptiveness, the investigation progresses through numerous iterations until, if you’re lucky, the contaminant sources are found. Volatile Organic Compounds (VOCs) pose a particular problem because during the course of investigation, their vapors can enter the building through floor openings and cause a health threat known as “vapor intrusion”.

At an older, active manufacturing site in western Ohio, Cox-Colvin was asked to locate the source of VOCs in groundwater as a part of Source Control Interim Action Order. The source appeared to be beneath a large building, and the client needed to understand the scope of the problem in a matter of weeks without disrupting operations. Cox-Colvin investigated soil vapors beneath the floor by drilling 5/8-inch holes through the floor in a 20-foot grid configuration over the entire building and installing their patented Vapor Pins®. Two people, using hand-held equipment, thoroughly evaluated the building, after normal operating hours, in a single week. VOC contamination, which did not coincide with known history or waste management activity, was located, confirmed with limited drilling and soil sampling, and remediated within the year.