In March, Motors Liquidation Co., under U.S. Environmental Protection Agency supervision, will begin collecting indoor air samples from about 60 homes and buildings in Moraine, Ohio’s, Riverview Plat neighborhood. The neighborhood is southwest of the former GM manufacturing complex, now known as MLC Moraine.

The air samples are being collected to determine whether hazardous vapors are seeping into homes and buildings. Historical chemical releases from the facility have contaminated underground water supplies 2,000 feet to the southwest, toward the Great Miami River. These releases involve a class of chemicals called volatile organic compounds. When VOCs are spilled on the ground, they can soak into ground water. Vapors from the ground water can then rise through the soil and seep through cracks in basements and building foundations.

Soil sampling along city streets last fall revealed some hot spots with high levels of VOCs. While there is no evidence of actual vapor intrusion problems in area homes, the indoor air sampling effort aims to confirm residents are safe. The municipal drinking water system has been and remains safe from VOC contamination.

EPA is now seeking signed access agreements from property owners allowing contractors to install air sampling equipment. (Access forms will be available at the Feb. 17 public meeting.) There is no cost to residents. Results will be available about four weeks after samples are collected. In the event hazardous VOC levels are found, MLC will pay for any vapor venting systems required.

The MLC Moraine site covers 465 acres along Dryden, Stroop and Springboro roads and includes former manufacturing sites for Delphi Harrison Thermal Systems, the GM Truck Group Assembly Plant and the GM Powertrain Group Engine Plant. Delphi ceased operations in 2003, and GM stopped all manufacturing in late 2009. Though many of the buildings have been torn down, a 4.5 million-square-foot assembly complex remains, as well as the DMAX Engine plant built in 2001 at 3100 Dryden Road. MLC was formed out of the 2009 GM bankruptcy and took over most of GM’s nonproductive assets. EPA and state partner Ohio EPA have been involved with the site since 1991.

See information including a fact sheet on the MLC Moraine investigation at

Bottom line…..Vapor Encroachment is a serious issue that can certainly impact surrounding properties and pose significant environmental and legal liabilities.

Contact us when you know of a site that could potentially have vapor encroachment concerns.