Anton's Cleaners has operated a dry-cleaning facility at the Wilmington Plaza property since the 1960s. One DEP wellpoint was installed behind the main building, approximately 50' from Anton's back door where refusal was encountered 19' below the ground surface. One groundwater sample was collected from the 14-19' interval and was found to contain 3.5 ug/l PCE. Refusal was encountered at several other locations in the area of Anton's and also in the facility's leach field, centrally located behind the Plaza. No additional groundwater samples were collected.

A limited subsurface investigation was also completed in the area of West Junior High School to determine if groundwater contamination was present in shallow groundwater. Groundwater samples were collected and analyzed for VOCs at two locations (please refer to attached " Wilmington, DEP Subsurface Investigations" map). Attempts to collect a third groundwater sample east of the new school building presently being constructed were unsuccessful as refusal was encountered above the water table at several locations in the area. Groundwater samples were collected from the 10-15' and 17-22' intervals at DEP-1, with refusal (likely bedrock) being encountered at 22' below the ground surface. Refusal was encountered at 16' at DEP-2 with one groundwater sample collected from the 10-15' interval. Results of the laboratory analyses found that trace levels of MtBE (12 ug/l), toluene (1 ug/l), ethylbenzene (1 ug/l) and total xylenes (2 ug/l), were found in each of the two samples collected from DEP-1. The sample from DEP-2 was found to have no detection of VOCs.

A DEP subsurface investigation was completed at the property located at 287 Main Street (please refer to attached "DEP Subsurface Investigations" map). Several commercial businesses are located within this building including a machine shop, an auto body shop and an automobile service facility. The property was formerly a home heating fuel depot and gasoline station from the 1940s through the early 1970s. In 1988, a total of thirteen underground storage tanks were excavated and removed from the property. No reports of leaking underground storage tanks were associated with the tank removal activities at the property. Two DEP wellpoints were installed in the rear of the property near the property boundary with the Boston & Main railroad. Groundwater samples were collected from the 10-15' and 19-24' intervals at DEP-1, where refusal was encountered at 24' below the ground surface. Groundwater samples were collected from the 10-15' and 25-30' intervals at DEP-2, with refusal encountered at 31' below the ground surface. Results of laboratory analyses found that multiple heavy end petroleum compounds, consistent with mineral spirits oil, were present in each sample from this property. A trace level of PCE, 3.5 ug/l, was found in the 10-15' sample of DEP-2 but was absent in the deeper sample collected from the 25-30' interval.

DEP also completed a groundwater investigation of the Middlesex Avenue and Clark Street area to determine whether high concentrations of chlorinated VOC contamination from the JJT/BP sites had migrated towards the residential neighborhood. Five wellpoints were installed at locations depicted on the attached map labeled "Wilmington, DEP Subsurface Investigations". Groundwater samples were collected from shallow and deep intervals at each DEP wellpoint to determine the extent of contaminant migration within the overburden aquifer. Refusal was encountered at what was likely the basal till/ bedrock interface in four of five locations between 30 and 54' below the ground surface. Results of the study found that levels of TCE and other VOCs were highest in the vicinity of 10 Middlesex Avenue where TCE was found at 64 ug/l in the shallow sample collected from the 10-15' interval and 300 ug/l in the 25-30' interval. PCE was also found in the shallow and deep samples at 6 and 11 ug/l respectively. Trace levels of MtBE were identified in the shallow and deep samples. The VOC levels detected in shallow groundwater samples were all below the DEP standards for protection from the migration of VOC vapors into residences. Results of the groundwater investigation for this area indicate that although groundwater contamination has migrated to this location, the residences in the Middlesex Avenue and Clark Street area do not appear to be at risk.

Test wells installed by DEP consist of 1-inch diameter steel pipe. Each wellpoint is completed with a five-foot section of 0.020 slot wellscreen on the leading end, followed by successive 5-foot lengths of riser pipe. Each wellpoint is advanced by a direct push method using a hand-held electric vibratory hammer drill. Groundwater samples were collected in each well using 1/4-inch polyethylene tubing with an attached inertial bailer of the same diameter. Each groundwater sample was analyzed by a headspace screening technique in accordance with the standard operating procedures developed by DEP/NERO using an SRI portable gas chromatograph equipped with a photoionization detector and halogen specific, dry-electron capture detector, in series. All samples were compared to laboratory standards.

DEP also collected several dewatering samples from utility-related construction activities along Main Street. One sample was collected and analyzed for VOCs from a sewer-line trench located in front of the former Wilmington Ford facility, 275 Main Street. The depth to groundwater was approximately 5.5' below the ground surface. No VOCs were detected. A second groundwater sample was collected from the excavation of the sewer lift station in the Wilmington Plaza parking lot across from the Hess station. Elevated levels of gasoline related compounds were detected although no chlorinated VOCs were present. All groundwater from construction work at this location was treated through carbon adsorption before being discharged to Mill Brook.

Subsurface soil samples were also collected and analyzed from an excavation related to the replacement of a private septic system at a home on Newbern Avenue, where PCE levels exceeded the safe drinking water standard in the private well. Two soil samples were collected from the sidewall of the excavation where soil appeared to be slightly discolored. Results of the laboratory analysis found no detection of VOCs.

DEP also required the collection of groundwater samples from a 220' deep private well located on Hillcrest Street immediately adjacent to the former Sweetheart Cup site. The depth to bedrock is unknown (see attached map "Wilmington, Private Well Sampling, Kelly Hill" for location). Due to the proximity of the well to the Sweetheart industrial property, groundwater samples were analyzed for VOCs by EPA Method 524.2, extractable ("semi-volatile") organic compounds by EPA Method 525.2, and 13 priority pollutant metals by EPA Method 200. On the basis of these tests, no contamination was identified in the well water samples above the analytical detection and reporting limits.