Soil Vapor Extraction removes potentially harmful molecules from below ground for treatment above ground. Vapors are the gaseous compounds released into the atmosphere when chemicals change phases. SVE applies a vacuum that extracts these carcinogenic substances from the soil above the water table. We sat down with EBI Consulting senior program director Richard George to learn more.
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Bisnow: What are the dangers associated with contaminated soil vapor? What are the health risks if they seep into concrete foundations?
Rich: Contaminated soil vapor can pose a cancer risk and non-cancer risks in either residential or commercial property exposure scenarios.
Bisnow: How does new regulation (revised E1527) impact the environmental due diligence process and protocols for those in the CRE industry?
Rich: I think we can no longer count on agency-issued No Further Actions as automatic signifiers to discount a regulatory site. It could still be a liability posing a health threat to those located at the subject property, and potential lawsuit.
The liability posed by vapor intrusion differs from contamination in other media in that it goes beyond simple Responsible Party and property valuation concerns. Even if there is an RP, there may be liability due to negligence if a property owner knowingly exposes occupants to hazardous levels of contaminants in indoor air. Circumstances may necessitate additional testing and remedial activities to mitigate exposure to tenants.
Bisnow: Could you give our readers a brief overview of the two approaches EBI recommends, SVE and SSDS, and circumstances where one might be recommended over another?
Rich: SVE is Soil Vapor Extraction and is a remediation technique with stronger fans. It is typically required at sites with higher levels of contamination, where source removal is required. SSDS is a Sub Slab Depressurization System, and it is a mitigation system typically used to address low to medium levels of contamination. SSDS is not intended to reduce the source, but rather serve as an ongoing protective barrier.
Bisnow: Why invest the extra money in SVE, which costs an estimated $250k to $500k when SSDS, at $30k to $60k, is so much cheaper?
Rich: SSDS is used as a mitigation measure to prevent vapor intrusion. SSDS is not necessarily intended to be a site cleanup method, only a mitigation measure. SVE is usually used when the intent is to remediate the site to reduce concentrations at the source area of contamination.
Bisnow: What site conditions can affect the cleanup time horizon of six to 18 months?
Rich: Four things:
The initial concentration of VOCs in soil vapor
Depth to groundwater
Soil types (permeable vs. low permeable)
Rigor of remedy selected (SSDS vs. SVE)
To learn more about EBI Consulting and SVE solutions, click here.
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