What’s a vapor mitigation system look like?
Updated: Mar 17, 2021
Even when a source of environmental contamination is removed from soil or groundwater, dangerous amounts of contaminants may be left behind where removal isn’t feasible – under a building, for example. When the contamination left behind as a vapor or gas, installing an engineered control system prevents human exposure to contaminants. A vapor intrusion mitigation system is one important way of ensuring that people inside buildings are not exposed to hazardous vapors.
VI mitigation systems are site-specific, designed for the level and type of contamination, building size, new or existing building, and other factors. VI mitigation systems often include vapor barriers installed beneath the floor slab. One type of vapor barrier consists of high-tech vapor-retardant impregnated fabric layers that block vapors and is strong enough to stay intact under a concrete floor. The fabric is sprayed with a tar-like material that seals the edges of the fabric, including at the walls and around pipes. Venting system are installed beneath the barrier that allow trapped vapors to escape above the roofline, without entering the spaces where people could be exposed. Vents can be passive – just an open pipe where vapors can float out – or active, with a fan to pull the vapors from under the building. After a vapor barrier is installed, a smoke machine is used to test the system to ensure that every potential leak in the vapor mitigation system is sealed.
A vapor barrier can be installed in an existing building, or new construction. Installation in an existing building usually means removing the existing floor (whether at grade or in a basement), installing the vapor barrier, then pouring a new concrete floor.
Fishbeck staff are experienced in the design of these systems and are certified to inspect the vapor mitigation systems manufactured by Land Science Technologies and EPRO. Certification means our staff are experts in the design of both VI mitigation systems, and can choose the best solution for any application.