Beneath the Slab: Vapor Intrusion and the Grenada, Mississippi TCE Superfund Site
By Paul E. Rosenfeld, M.S., Ph.D., Principal Environmental Chemist, RoseyFields LLC, Santa Monica, California
When groundwater contamination becomes an indoor air problem
Vapor intrusion occurs when volatile chemicals dissolved in groundwater or soil evaporate and migrate upward through soil and foundation cracks into the indoor air of overlying buildings, converting a subsurface contamination problem into an occupant exposure problem. Dr. Paul E. Rosenfeld, M.S., Ph.D. of RoseyFields LLC addressed this exact pathway in litigation arising from a former wheel-cover and automotive-parts manufacturing facility in Grenada, Mississippi (Cooper, 2016).
The Rockwell International Wheel & Trim site
The Grenada facility, successively operated by Rockwell International, Textron, and Grenada Manufacturing from 1966 onward, used trichloroethylene (TCE) as a degreasing solvent for decades. EPA subsequently found TCE inside the manufacturing building, in groundwater beneath the site, and in the surrounding Eastern Heights residential neighborhood, leading to the site’s listing on the federal Superfund National Priorities List (US EPA, Rockwell International Wheel & Trim Site Profile).
Property owners’ claims against the successor company
Homeowners near the facility sued Meritor, Inc., the corporate successor bearing legal responsibility for Rockwell’s historic operations, along with related corporate entities, alleging that TCE releases and discharges damaged their properties and created ongoing exposure risk (Cooper, 2016).
The physical mechanism: vapor migration through soil and foundations
TCE readily volatilizes from contaminated groundwater and soil, and EPA’s own site documentation confirms the compound can vaporize and move into buildings located above the contamination, a mechanism that previously caused unacceptable TCE levels inside the manufacturing facility itself before EPA required corrective action (US EPA/MDEQ, Rockwell Grenada Fact Sheet).
The engineering remedy: sub-slab depressurization
In 2017, EPA required the responsible party to install a sub-slab depressurization system, an engineering control that creates negative pressure beneath a building’s foundation to intercept vapor before it enters indoor air, at the manufacturing facility, and has continued periodic indoor air testing of nearby homes since that time (US EPA/MDEQ, Rockwell Grenada Fact Sheet).
Why residential vapor intrusion assessment differs from occupational assessment
Unlike an industrial worker with defined shift hours, a resident is potentially exposed to indoor air continuously, including overnight, requiring a 24-hour exposure duration assumption rather than an 8-hour occupational exposure assumption, along with different default body-weight and inhalation-rate parameters for a household that may include children, older adults, or other especially sensitive individuals.
The toxicological and regulatory basis for TCE
TCE is currently regulated under the Safe Drinking Water Act with a Maximum Contaminant Level of 5 parts per billion, and EPA’s IRIS assessment has concluded that TCE is carcinogenic to humans by all routes of exposure, in addition to non-cancer effects on the kidney, liver, immune system, and fetal heart development (US EPA, IRIS: Trichloroethylene).
The groundwater-to-surface-water pathway as an additional exposure route
At the Grenada site, TCE has also been detected in Riverdale Creek, prompting a state contact advisory, illustrating that groundwater contamination plumes can generate multiple simultaneous exposure pathways, vapor intrusion, groundwater ingestion where relevant, and surface water contact, that a complete exposure reconstruction must address together rather than in isolation (MDEQ, Rockwell Grenada Fact Sheet).
Long-term monitoring as ongoing evidence
Because EPA and the Mississippi Department of Environmental Quality have continued indoor air and groundwater monitoring at Grenada for nearly a decade following the initial vapor intrusion discovery, the site provides an unusually well-documented, ongoing public record of how a vapor intrusion exposure pathway evolves over time in response to engineering controls, a resource directly useful for exposure reconstruction in comparable matters.
Why vapor intrusion litigation is likely to increase
As EPA and state agencies apply increasingly sensitive vapor intrusion screening guidance to a growing inventory of historical dry-cleaning, metal-degreasing, and manufacturing sites nationwide, the number of residential communities newly identified as sitting above a chlorinated-solvent plume is likely to continue growing, along with the associated litigation. Further reading on Dr. Rosenfeld’s vapor intrusion and chlorinated-solvent exposure work is posted at RoseyFields.com.
References
1. Cooper BJ, et al. v Meritor, Inc., et al. No. 4:16-cv-52-DMB-JMV, US District Court for the Northern District of Mississippi, Greenville Division.
2. US Environmental Protection Agency. Rockwell International Wheel & Trim Superfund Site Profile. Washington, DC: US EPA.
3. US Environmental Protection Agency; Mississippi Department of Environmental Quality. Rockwell International, Grenada, Mississippi: Community Fact Sheet. Jackson, MS: MDEQ.
4. US Environmental Protection Agency. Toxicological Review of Trichloroethylene. Integrated Risk Information System (IRIS). Washington, DC: US EPA.
5. US Environmental Protection Agency. National Primary Drinking Water Regulations: Volatile Organic Chemicals. 40 CFR § 141.61.
6. US Environmental Protection Agency. OSWER Technical Guide for Assessing and Mitigating the Vapor Intrusion Pathway from Subsurface Vapor Sources to Indoor Air. Washington, DC: US EPA; 2015.
7. Mississippi Department of Environmental Quality. Grenada Stamping / Rockwell International Wheel & Trim: Groundwater and Vapor Intrusion Sampling Work Plans. Jackson, MS: MDEQ.
8. IARC Working Group on the Evaluation of Carcinogenic Risks to Humans. Trichloroethylene, Tetrachloroethylene, and Some Other Chlorinated Agents. IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Vol 106. Lyon, France: International Agency for Research on Cancer; 2014.
9. Agency for Toxic Substances and Disease Registry. Toxicological Profile for Trichloroethylene. Atlanta, GA: US Department of Health and Human Services; 2019.
10. US Environmental Protection Agency. Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) Overview. Washington, DC: US EPA.
11. Rosenfeld PE. RoseyFields LLC: Vapor Intrusion and Chlorinated Solvent Assessment. Santa Monica, CA: RoseyFields LLC; 2026.
12. US Environmental Protection Agency. Toxicological Review of Tetrachloroethylene (Perchloroethylene). Integrated Risk Information System (IRIS). Washington, DC: US EPA.
13. Rosenfeld PE, Spaeth KR, McCarthy SJ, et al. Camp Lejeune Marine cancer risk assessment for exposure to contaminated drinking water from 1955 to 1987. Water Air Soil Pollut. 2024;235:124.
14. US Environmental Protection Agency. Revisions to the Guideline on Air Quality Models. 40 CFR Part 51, Appendix W. Fed Regist. 2017;82(10):5182-5235.