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LFR an 0 ARCADIS company Soil-Gas Investigations Scope of Work. Soil-gas samples were collected during two sampling events at the locations shown on Figures 2 and 3. The initial sampling event occurred on December 6, 2007 and included collecting soil-gas samples from a depth of approximately 5 feet bgs from three temporary borings inside and near the dry-cleaning facility (SV-1 through SV-3; Figure 3), and the second sampling event was performed on April 9 and 10, 2008 and included collecting soil-gas samples from two temporary borings located outside the building (SV4 and SV-5; Figure 2) and 10 soil-gas monitoring wells constructed inside the dry-cleaning facility (SVP-lA through SVP-513; Figure 3). Results. A summary of soil-gas sample results is presented in Table 1. Analysis of the soil-gas samples revealed the presence of relatively low concentrations of PCE (maximum of 8,700 micrograms per cubic meter [µg/m'1) in shallow soil gas in 12 of the 15 samples collected from the Site. The concentrations of PCE detected beneath the dry-cleaning facility exceeded the California Human Health Screening Level (CHHSL) of 603 µg/m'for the potential vapor intrusion pathway set forth by the California Environmental Protection Agency (Cal-EPA). According to Cal-EPA, the presence of a chemical at concentrations in excess of a CHHSL does not indicate adverse impacts to human health are occurring or will occur, but suggests that further evaluation of potential human health concerns is warranted. PCE was not detected in the soil-gas sample collected near the back door entrance to the facility (SV-2) and was detected at only a very low concentration at the exterior location adjacent to the sewer line cleanout (SV-1, 460 µg/m'). These data indicate that the extent of PCE impacts to soil vapor associated with the Site is limited to the area below the interior of the facility. PCE was detected in the soil-gas sample collected downgradient from the dry-cleaning facility and near the vicinity of the sewer line that serves that facility (SV-5, Figure 2). This result indicates the potential for off-site migration of PCE, although the magnitude of the concentration of PCE detected in this exterior sample (2,000 µg/m') was too low to suggest a likely threat to groundwater. Soil and Groundwater Investigation LFR conducted a focused soil and groundwater investigation at the facility to confirm the finding from the soil-gas investigation that the concentrations of PCE detected in soil gas were below levels that represented a threat to underlying groundwater. This investigation was performed in accordance with the "Proposed Sampling and Analysis Plan, C&S One Hour Martinizing, Robinhood Plaza Shopping Center, Stockton, California," dated September 8, 2008 and conditionally approved by the RWQCB on September 9, 2008. The methodology and results of that investigation are presented in the report titled "Subsurface Investigation Report, C&S One Hour Martinizing Site, Robinhood Plaza Shopping Center, Stockton, California," dated May 15, 2009 wp-CS-SV E-M ay09-09366.doc:deh 3