EPA has been asked to investigate tetrachloroethylene (PERC) contamination in Hyattsville (Chillum), Maryland and Washington, DC. PERC contamination was discovered in 2001 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 flows from Maryland into Washington, DC, and one or more plumes of groundwater containing PERC may be present beneath the local residential community.
During this reporting period, EPA conducted an additional round of indoor air, soil vapor, and groundwater sampling. All residences sampled in July 2003 were approached to request EPA access so that the previous round of sampling could be replicated. In addition, several residences outside of the July 2003 area of investigation were added to the April 2004 round of sampling. A total of 41 property owners were sent letters offering to have samples collected by EPA. Of the 41, 28 property owners provided access.
A. Week of April 12, 2004: EPA, Superfund Technical Assessment and Response Team (START), and District of Columbia Department of Health (DC-DOH) on site. EPA and START contractors installed permanent soil vapor implants beneath the basement slabs at eight properties located on Eastern Avenue, Riggs Road, 8th Street, Nicholson Street, and the portion of Oglethorpe Street near Riggs Road. The implants installed were similar to those installed in July 2003.
EPA continued to receive property access during this week both in person and at the EPA Region III offices in Philadelphia, Pennsylvania via U.S. mail. Where individual residents had not responded, EPA attempted to contact the residences through a door-to-door campaign and by telephone. EPA and START contractors also conducted or helped residents conduct removal of household items (e.g., spot remover, gasoline) from indoor areas of individual residences in advance of indoor air sampling.
B. Week of April 19, 2004: EPA, EPA ERT (Environmental Response Team), START, and DC-DOH on site. Three sub-slab soil vapor points were installed through the basement slab at one property where two soil vapor implants were also installed. Subsequently, ERT collected soil vapor samples from most of the soil vapor implants and points installed during the week of April 19, 2004 and from those installed in July 2003. Samples could not be collected from two soil vapor implants installed along Nicholson Street due to the presence of a shallow water table in that area. The samples that were collected were analyzed by ERT's Trace Atmospheric Gas Analyzer (TAGA) mobile laboratory for volatile organic compounds (VOCs), including PERC, by EPA Method TO-15 modified.
ERT conducted monitoring of the first floor and basement areas of each residence to determine background conditions and identify any potential household sources of VOCs. After TAGA monitoring was completed, EPA and START contractors collected 24-hour-duration indoor air samples using Summa canisters from 27 of the 28 properties from which access was received. The owner at one property was not available to meet EPA and collect the Summa canisters, and samples were therefore not collected from that particular property. All Summa canister samples were forwarded to a Delivery of Analytical Services (DAS) laboratory for VOC analysis by EPA Method TO-15.
C. Week of April 26, 2004: EPA, START, and DC-DOH on site. Groundwater samples were collected from the six small-diameter monitoring wells installed in July and August 2003. The samples were sent to a Contract Laboratory Program (CLP) laboratory for VOC analysis.
EPA and START contractors attempted to collect 8-hour-duration soil vapor samples in Summa canisters from the two soil vapor implants on Nicholson Street where samples could not be collected by ERT during the week of April 19 due to the shallow water table. One sample was collected; the other could not be collected due to the presence of the shallow water table at a level above the bottom of the basement slab. The sample was sent to a DAS laboratory for VOC analysis by EPA Method TO-15.
A. EPA anticipates receiving preliminary analytical results for the indoor air and groundwater samples collected in April 2004. Data validation for these samples should be completed shortly thereafter. Residents will be notified of PERC analytical results via letter upon receipt and review by EPA.
B. EPA may collect additional indoor air samples from residences where the final vacuum pressure of either Summa canister placed in the home was reported at the time of collection to be at an ambient air pressure. In all time-dependent air samples, the final canister pressure should be negative so that the duration of sample collection is known (in this case, 24 hours). Sample canisters which have reached an ambient pressure are considered less precise than those where a negative pressure was maintained, but not unrepresentative of true site conditions. START personnel recorded a final canister pressure equal to that of ambient air in six of the 69 Summa canisters, which may or may not be a precise representation of the actual final pressure due to the potential inaccuracy associated with the regulator. However, the laboratory can record canister pressures using a more precise instrument.
C. Coordinate with other EPA Programs, DC-DOH, elected officials and residents for the upcomming public meetings. Prepare presentations of completed, on-going, and planned activities in response to the PERC release.
|
