EPA has been asked to investigate tetrachloroethylene (PERC) contamination in Hyattsville (Chillum), Maryland and Washington, District of Columbia. PERC contamination was discovered during an on-going investigation of a gasoline-products release from a service station located in Hyattsville near the Chillum Perc property. The site under investigation includes a dry cleaning facility and a residential community. The dry cleaning facility is located in Maryland and is immediately adjacent to the Washington, DC border. Groundwater flow flows from Maryland into Washington, DC, and one or more plumes of groundwater containing PERC may be present beneath the local residential community.
A. July 7 - July 20, 2003: EPA and START continued preparation for field activities scheduled for late July 2003. EPA and START mailed property access approval forms to individual property owners. START secured the services of a drilling subcontractor to install permanent soil vapor implants and pre-packed monitoring wells using direct-push (as opposed to rotary drilling) methods. Laboratory analytical services were requested for the analysis of indoor air, groundwater, tap water, and aqueous sump samples to be collected during the upcoming field event.
B. July 8 and 9, 2003: OSC Aquino met with EPA-ERT SSC Mickunas at the site to discuss the use of the mobile air laboratory in the upcoming sampling event scheduled for late July 2003.
A. Implementation of the sampling plan is scheduled to begin on July 21, 2003, with the installation of soil vapor implants. Using power hand-tools or manual methods, one implant will be installed no more than 5 vertical feet beneath the concrete basement slab of each selected residential duplex. The six monitoring wells will be installed in two groups of three: one set will be located in the vicinity of the southern end of Oglethorpe Street block between Riggs Road and 8th Street, and the other set will be located near the intersection of Oglethorpe Street and Riggs Road. The wells will be installed using direct-push methods.
EPA and START will begin the second phase of field activities during the week of July 21 by conducting resident interviews and coordinating temporary removal of any potential household vapor sources (e.g., gasoline, rubbing alcohol, spray paint, etc.) from indoor areas of individual residences. During the week of July 28, the Emergency Response Team's (ERT) Trace Atmospheric Gas Analyzer (TAGA), a mobile laboratory, will subsequently be utilized to conduct real-time screening of specific individual homes to determine if any hidden or undiscovered vapor sources remain in the home. By removing all vapor sources from indoor areas, EPA can more accurately assess potential intrusion of soil vapor into the home. If ERT determines that all vapor sources have been removed from indoor areas, START will place Summa canisters in basement and first-floor areas of the home. The Summa canisters will use a continuous-flow regulator to collect air samples for a period of 24 hours. START will return the following day to retrieve the Summa canisters.
In addition, START will also collect active soil vapor samples from the permanent soil vapor implants during the week of July 28, and groundwater, tap water, and up to six aqueous sump samples during the week of August 4. (Sump samples will only be collected if water is observed in the sumps of any homes scheduled to be sampled as part of this phase of the project.)
B. EPA intends to secure use of the Mobile Command Post (MCP) during the completion of this phase of the project. The MCP will be used as a temporary office staging area for EPA and START personnel.
C. Attend public meetings and prepare presentations of completed, on-going, and planned activities in response to the PERC release.
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