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. Week of July 21, 2003: EPA, START, DC-DOH and local residents onsite. EPA and START contractors utilized a subcontractor to install permanent soil vapor implants on 13 of the 17 targeted residential duplexes. The project goal was to install one permanent implant no more than 5 feet below the basement slab level of each duplex (not each individual property) by advancing the implant through the concrete basement slab or at an angle from an outdoor location. At each location, EPA proposed to install the soil vapor implant through the concrete basement slab before installing the implant from an outdoor location. At one location, the basement slab could not be breached due to the integrity of the concrete; at all other duplexes containing outdoor implants, property owners requested that the basement slab not be breached.
EPA continued to receive property access during this week both in person and via U.S. mail. Where individual residents had not responded, EPA and START contractors attempted to contact the residences though a door-to-door campaign and by telephone. EPA also conducted removal of household items (e.g., spot remover, gasoline) from indoor areas of individual residences in advance of indoor air sampling.
In addition, one of the six proposed small-diameter, direct-push monitoring wells was installed during this week. All wells are to be installed in public areas.
B. Week of July 28, 2003: EPA, ERT, START, DC-DOH, ATSDR and local residents on site. EPA secured the Mobile Command Post (MCP) during the indoor air sampling portion of this project as a temporary office staging area for EPA and START contractors.
EPA collected indoor air samples using summa canisters from 23 of the 34 targeted residences. Canisters fitted with 24-hour regulators were placed on the first floor and basement of each home. Prior to collection, the EPA Environmental Response Team's (ERT) Trace Atmospheric Gas Analyzer (TAGA) mobile laboratory conducted screening of first floor and basement areas to determine background conditions prior to placement of the summa canisters. In addition, ERT also collected and analyzed active soil vapor samples from the 13 permanent soil vapor implants (analytical results will not be reported for two of the 13 samples at the request of the respective property owners). Analysis of the soil vapor samples were conducted onsite in the ERT mobile laboratory.
ATSDR and DCDOH observed the onsite activities. ATSDR met with some of the residents on Wednesday while their properties were being sampled.
EPA continued to receive property access during this week both in person and via U.S. mail. Where individual residents had not responded, EPA and START contractors attempted to contact the residences though a door-to-door campaign and by telephone. EPA also conducted removal of household items (e.g., spot remover, gasoline) from indoor areas of individual residences in advance of indoor air sampling.
A. A START subcontractor will install and develop the five remaining proposed small-diameter, direct-push monitoring wells.
B. START contractors will collect groundwater samples from the six small-diameter wells and analyze the samples for volatile organic compounds.
C. START contractors will procure the services of a subcontractor to survey the monitoring wells in reference to a local fixed reference point of known elevation.
D. Two of the 13 permanent soil vapor implants will be removed in the near future at the request of the respective residents. At both locations, the permanent implants were installed from outdoor locations; subsequently, EPA and START contractors will attempt to install permanent implants through the concrete basement slab of the two residences using power hand-tools. As during installation of the implants during the week of July 21, one implant will be installed no more than 5 vertical feet beneath the concrete basement slab of each selected residential duplex.
E. START contractors will procure the services of analytical services and collect active soil vapor samples from the two implants.
F. START contractors will procure the services of analytical services and collect two tap water samples from two homes in the community.
G. Attend public meetings and prepare presentations of completed, on-going, and planned activities in response to the PERC investigation.
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