Soil Vapor Poses New Challenges

Soil vapor has changed environmental and real estate due diligence practice. Minnesota follows the national trend in focusing on addressing concerns about potential vapor intrusion. The issue is with hazardous substances that are affecting structures where occupants may be exposed to potentially harmful vapors.

Minneapolis Como Case Triggers New Approach.

Vapor intrusion rose to prominence here after impacts were discovered in residences located near a former Superfund site in the Como neighborhood in Minneapolis. Thereafter, the Minnesota Pollution Control Agency (MPCA) required the responsible party to test and pay for mitigation in over 100 homes. A class action brought on by neighbors was initially certified by a federal court and then reversed on appeal.

Extensive testing was conducted in the area. As a result, evidence of additional vapor sources was found in a nearby upgradient area. The MPCA is investigating new potential sources in an adjacent multi-block industrial area named the SE Hennepin Area Groundwater and Vapor State Superfund Site. MPCA staff are reported to be preparing a referral of both the Como and SE Hennepin Area sites to the U.S. Environmental Protection Agency (EPA).

Therefore, concerns about vapor intrusion have had ripple effects in the Twin Cities and across Minnesota.

New Vapor Superfund Sites.

Last year the MPCA added ten sites to the State Superfund list. Most of the sites were in the Twin Cities metropolitan area. Vapor impacts often affect surrounding neighborhoods. The Superfund listing permits the State to use funds to conduct investigations and to pursue responsible parties for cost recovery.

Reopening Closed Files.

The MPCA is reviewing closed files and reopening sites to study vapor. Although groundwater contamination (with the contaminants trichloroethylene (TCE) and perchloroethylene (PCE)) was noted at these sites, tests for soil vapors were never completed. Therefore, regulators are now requiring owners and responsible parties to test for vapor releases on-site. If vapors are found, the MPCA requires tests on neighboring properties.

Vapor, Vapor, Vapor - Everywhere.

The two contaminants of concern - TCE and PCE - were used over time in the Twin Cities and across the state by many businesses. TCE was used widely to clean parts and in many manufacturing operations. PCE was used by dry cleaners. When the chemicals are used in normal operations there can be small spills and incidental releases. When PCE and TCE are spilled, soil and groundwater become contaminated. As a result vapors are released from impacted groundwater. For an example of how the MPCA addresses sites with releases of TCE or PCE see:

Minneapolis Former Waldorf Cleaners

Where is the source?

Finding the source of soil vapors can be challenging. In addition, in many cases multiple sources may contribute to a vapor plume. Releases of TCE and PCE in groundwater result in releases of soil vapor. Vapors migrate through porous soils and come to rest under building slabs. Small cracks and seams in structures create pathways for vapor to enter buildings. The Minnesota Department of Health (MDH) has found that exposure to low levels of vapors over time poses health risks.

Guidance Over Rules.

The MPCA has issued Guidance to address how sites are to be assessed for vapor impacts. The Guidance requires sampling in both heating and cooling seasons. The number of samples depends on the size of the building footprint. When elevated levels are found that are deemed to pose a risk to public health, building mitigation is now required. Mitigation systems need to be tailored to ensure proper removal of the vapors. Guidance provides regulators with flexibility. However, there is uncertainty and risk as to how the issues will be handled in the future. For more information see:

Understanding your vapor intrusion test results

Environmental Covenants.

The MPCA now requires that environmental covenants must be recorded that require building owners to notify future owners of the presence of vapors. The obligation to operate and maintain mitigation systems runs with the land into perpetuity. Mitigation systems typically are active systems so fans, blowers and other components will need replacement. Furthermore, an owner who fails to operate and maintain an active system may be subject to civil penalties. A copy of the recorded covenant needs to be provided to the MPCA, County and municipal authorities.

Fixes Can Be Costly.

When there is no responsible party and residences are affected by vapors, the MPCA or EPA generally will foot the bill to address the impacts. Responsible parties are tapped to pay for vapor mitigation on property they own and on off-site property until the end of the vapor plume is found. If a commercial or industrial business or building owner discovers it has a vapor issue but there is no known responsible party, the MPCA looks to the owner to investigate and mitigate its building at its cost.

Potential Claims.

With the vapor issue there are potential concerns and claims from many parties - homeowners, tenants and neighboring property owners. Once a vapor impact is found, there is arguably a duty to notify persons - employees, tenants and neighbors - who may be impacted. The cleanup standards are more protective for vulnerable individuals including the infants and young children, women who are pregnant or may become pregnant, elderly persons and those living with chronic disease or a compromised immune system.

Please see the disclaimer at the bottom of this page that relates to limitations on this blog and to legal advice. Thanks to associate Joseph Reutiman for his assistance in preparing this blog. Finally, for information on environmental covenants and how a covenant may affect property, please contact:

Joseph G. Maternowski

Hessian & McKasy, PA

T: (612) 746-5754

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