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Phase Q Environmental Site Assessment Multi-Modal Station Stockton,San Joaquin County,California Page 27 6.3 2 Block 1 Laboratory analytical results of the soil and groundwater samples collected from the Block 1 properties indicate that no VOCs were detected in the soil samples However, toluene was detected in two groundwater samples (DBKI-701-1-6/5/02 and DBKI-750-1-6/5/02) and PCE was detected in one groundwater sample (DBKI-722-1-615/02) The toluene and PCE concentrations are below the MCLS for these constituents There was no clear source of the PCE identified during this investigation In order to evaluate the extent and potential source of the PCE, additional borings and a soil vapor gas survey are recommended No other concerns for Block 1 were identified during this investigation 6.3.3 Block 2 Laboratory analytical results of the soil and groundwater samples collected from the Block 2 properties indicate that no VOCs were detected in the soil or groundwater samples, with the exception of chloroform Chloroform was detected in the groundwater sample collected from boring DBK2-830-1 As indicated above, the presence of chloroform may be the result of laboratory contamination It is possible that groundwater contamination from the southern blocks (Blocks 4 and 5) might have impacted groundwater at the southern Block 2 properties (Figure 19, Appendix A) 6.3 4 Block 3 i Laboratory analytical results of the soil and groundwater samples collected from the Block 3 properties indicate that no VOCs were detected in the soil samples However, chloroform, TCE, and toluene were detected in groundwater samples collected from 930 E Miner Avenue The concentrations of toluene and TCE detected in DBK3-930-2-5123102 are generally similar to those of DR4-5/22/02, a sample collected . immediately east of DBK3-930-2-5/23102 Low concentrations of toluene were also detected in DBK3- 930-1-5/23102 and DR5-5122102 These toluene detections may be related to a UST that was removed from 930 E Miner Avenue in November 1993 The origin of the TCE, however, is unclear The detected concentrations of these constituents are below applicable MCLS 6.3 5 Block 4 Based on field observations and laboratory analytical data, an area of petroleum impacted soil is present in the northern portion of 730 E Channel Street Volatile organic compounds and semi-volatile organic compounds including TPH-D were detected in sample DBK4-730-5-15 collected at a depth of 15 feet bgs in the northern portion of 730 E Channel Street at Block 4 Laboratory analyses of a sample collected from the same boring at a depth of 36 5 feet bgs (DBK4-730-5-36 5) indicate none of the requested analytes were detected at or above the laboratory reported detection limits with the exception of TPH-D, which was detected at a low concentration Volatile organic compounds and/or semi-volatile organic compounds including TPH-D were detected in soil samples collected at depths of 6, 15, 25, and 30 5 feet bgs from nearby boring DBK4-730-10 None of the requested analytes were detected at or above the laboratory reported detection limits in a deeper sample (DBK4-730-10-49) collected from this boring at a depth of 49 feet bgs Therefore, the vertical extent of petroleum impacted soil in this area appears to extend to a depth of approximately 49 feet bgs The lateral extent of the impacted soil appears to be limited by DBK4-730-3 to the west, DBK4-730-2 to the south, and DBK4-730-4 to the north The lateral extent of the impacted soil has not been evaluated east of DBK4-730-10 due to the presence of the building Figures 15 through 17 (Appendix A) present iso-concentration contours and the assumed extent of impacted soil The lateral extent of the impacted soil appears to be constrained to the property This soil contamination appears to have also impacted groundwater in the same portion of the property The impacted soil should be removed and further evaluated �a t CONDOR