Why Is Everyone Talking About Sub Slab Depressurization Systems (SSD Systems)?
Introduction – Why Sub Slab Depressurization is the “new big thing.”
Environmental contamination of soil and groundwater is an unfortunate but common fact. Releases of oil and hazardous materials from spills, tank leaks, past industrial disposal practices, or accidents have resulted in conditions that potentially can affect the health of residents and workers. Whether you are near a gasoline station, a dry cleaner, a Brownfield site, or even a residential site, these releases have the potential to impact your indoor environment.
Vapor intrusion occurs when vapors from volatile organic compounds (VOCs) in soil or groundwater enter a building through cracks, holes, or other penetrations in the foundation. Regulations typically require the removal of the contaminants from the soil or groundwater, but even then, a system may be needed to ensure short-term or long-term protection of the building occupants against breathing the vapors from the contamination.
A sub slab depressurization system (“SSD System” or “SSDS”) is used in these instances to protect against exposure by preventing contaminated vapors from entering a building. The public often refers to these systems as “radon systems” and they do operate in a similar manner; however, an SSDS is engineered to result in a higher level of protection compared to a typical radon system.
In the last few years, regulatory agencies have taken notice of the potential for vapor intrusion. The US Environmental Protection Agency (EPA) adopted new rules in December 2013 (ASTM E1527-13) for Phase I Environmental Site Assessments. Since these rules, to demonstrate compliance with EPA’s “all appropriate inquiry” requirements under CERCLA, Phase I Environmental Site Assessments now must evaluate the potential for vapor intrusion risk at a property.
Also, recognizing that vapor intrusion is the next frontier of environmental contamination concerns, in June 2014 the Massachusetts Department of Environmental Protection (DEP) enacted changes to the Massachusetts Contingency Plan (MCP) regulations, which now allow sites with active exposure pathway mitigation measures (AEPMMs) to achieve a Permanent Solutions with Conditions (PSC). In addition, in April 2016, DEP began reevaluating closed MCP sites for the existence of potential “Imminent Hazard” conditions, based on EPA’s changed position on the toxicity of certain volatile contaminants that pose a greater risk than previously believed. Given the new toxicity studies, DEP is encouraging property owners and/or Potentially Responsible Parties (PRPs) to take matters into their own hands by reviewing their site(s) and evaluating for the potential for ongoing exposure concerns.
In light of this increased regulatory scrutiny, more properties are being evaluated for vapor intrusion and are finding that vapor mitigation systems are required. These systems can be designed to operate as passive (with no mechanical assistance) or active (with mechanical assistance). When properly designed, installed, and operated, SSD systems are fully capable of rendering indoor air concentrations to below detectable levels – ensuring the safety of building occupants.
Cooperstown has expertise in evaluating sites for potential exposures, along with SSDS design, installation, and optimization. Cooperstown has also established itself as an industry leader in remote telemetry – which is required for site closure at AEPMM sites under MassDEP’s guidance and regulations.
Coming up: An introduction to telemetry …