Vapor Mitigation Strategies Completes Install of Vapor Barrier for Bank

Vapor-Mitigation-Roll-out-300x336Vapor Mitigation Strategies, a local installer of vapor intrusion barrier solutions, recently completed a single-day install of a 4,600-square-foot chemical vapor barrier system in St. Louis.

“The previous building was a car service center and when the property was purchased by a bank, the bank decided to tear down and build a new structure on the existing lot,” said Wes Robb, director of technical strategies and applications at Vapor Mitigation Strategies. “Before completing construction of the new facility, a chemical vapor barrier was installed because many former car service centers used vehicle fluids and cleaning chemicals that may have emitted toxic gasses into the subsurface soil vapor over many years.”

Improper handling, previously unregulated disposal or accidental spills and leaks of these car service chemicals may have introduced themselves into the subsurface where they emit toxic gasses into the soil vapor. These chemical vapors can cause air quality and health concerns for occupants of buildings directly over and adjacent to the source contamination.

“To reduce the risk of exposure to vapor emanating from subsurface contamination through the concrete floor and utilities openings of the building (known as vapor intrusion), we installed a chemical vapor barrier system,” Robb added.

Vapor Mitigation Strategies installed Geo-Seal® Spray-on Membrane Gas Vapor Barrier, which includes three layers: 5 mil Geo-Seal® FILM 5 (High-density polyethylene layer), 30 mil Geo-Seal® CORE (Spray-applied copolymer modified asphaltic membrane), and an 18 mil Geo-Seal® BASE (High-density polyethylene layer).

To install this system, Vapor Mitigation Strategies’ crew prepared the surface by removing potential penetrating materials. Next, they rolled out the lowest layer of tarp, the 18 mil Geo-Seal® BASE (high-density polyethylene layer), and made cut-ins around the uprights. This step was followed by the application of the 30 mil Geo-Seal® CORE (spray- applied copolymer modified asphaltic membrane) on the first layer of closure to all seams and uprights of the tarp. Next, they rolled out the final tarp, the 5 mil Geo-Seal® FILM 5 (high-density polyethylene layer) and applied a second seal to all the seams and uprights. Lastly, they measured thicknesses and conducted a smoke test to ensure the chemical vapor barrier system was installed properly.

This solution, which has been accepted by state environmental agencies, branches of the military and environmental consulting firms around the world, takes the advantages of chemically resistant, high-density polyethylene and combines it with the benefits of spray-applied membranes. With this new chemical vapor barrier system in place, the bank mitigated any potential vapor intrusion issue and reduced the risk to human health.

Published in Construction Forum St. Louis Magazine