ATLANTA - Today, the E.P.A. (EPA) announced the status of its vapor intrusion sampling conducted at the Macon Naval Ordnance Plant Superfund location in Macon, Ga. Funded by EPA, the sampling focused on the Freudenberg Texbond facility, located down gradient of the Navy's former wastewater treatment plant. During the week of February 23, 2015, E.P.A. activities included:
· Fourteen indoor air samples at various locations were collected over a 24-hour period, with an emphasis on smaller enclosed areas where trichloroethylene (TCE) might accumulate (e.g., break rooms, laboratories, and offices). Outdoor air, sub-slab soil gas, and groundwater samples were also collected. · Thirteen of the fourteen indoor air samples did not indicate an unacceptable risk, with only trace detections of various volatile organic compounds found. · TCE was detected at a level of 230 µg/mthree (micrograms per cubic meter of air) in indoor air collected in the employee break room of the Line seven Building. This TCE level exceeds EPA's levels of concern of 9-27 µg/mthree for a commercial use, assuming an eight hour per day occupancy.
On April 7, E.P.A. informed Freudenberg Texbond of the sampling results. The company took immediate steps to increase the air exchange rate in the Line seven Building break room, thereby limiting worker exposures. Subsequently, on April 20
th/21
st, E.P.A. collected 2 additional 24-hour indoor air samples in the break room.
· TCE was found at levels of seven µg/mthree and 35 µg/mthree. These lower levels, along with the limited exposure durations actually experienced in the employee break room, represent an acceptable risk to location workers.
Next Steps
Additional air sampling will be conducted at the location using EPA's Trace Atmospheric Gas Analyzer (TAGA) mobile lab. The TAGA can analyze air samples in real time, without waiting on lab turnaround times. EPA's TAGA investigation is tentatively scheduled for the week of August 24, 2015.
Using the TAGA, E.P.A. will investigate where the vapors may be entering the Line seven Building break room. Using historical groundwater data, the TAGA will also sample indoor air in other buildings located on Bibb County's Allied Industrial Park, to ensure there are no other vapor intrusion issues.
Background
The US Navy and its contractors produced ordnance at the location Plant from before World War II until approximately 1973. The ordnance manufactured included flares, small primers, detonators, and other triggering mechanisms. The location is currently operated by Bibb Co. as Allied Industrial Park and was placed on Superfund's National Priorities List in May 2013. Groundwater at the location is contaminated with TCE from the Navy's former waste water treatment plant. TCE is one of the most common contaminants found on Superfund sites across the country. TCE is a volatile organic compound that can volatize from contaminated groundwater and seep through foundations to contaminate indoor air at levels of concern. This process is known as vapor intrusion. EPA's knowledge of and experience with assessment and mitigation of the vapor intrusion pathway has increased considerably in recent years. EPA's VI guidance was finalized in June 2015 and can be found at
http://www.epa.gov/oswer/vaporintrusion/.
For more information about the site, please visit:
http://www.epa.gov/region4/superfund/sites/fedfacs/maconnavalga.html
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