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` Phase l Environmental Site Assessment East Main Street,Stockton,California December 10,2004 Page 9 L CRWQCB. Both irrigation wells located on the Site properties are included in the facility's monitoring system. The most recent report available in the SJCEHD files was the Semi-Annual Groundwater Monitoring Report—October 2003/January 2004, by Dudek and Associates, which indicated that the irrigation wells located on the Site properties had laboratory analyzed groundwater concentrations of TDC at 7 ug/L and 10 ug/L in July 2002. The most recent off-Site well analytical results were 9.3 ug/L TDC and 3.0 ug/L hexavalent chromium in the Columbini irrigation well immediately east of the Site. The direction of groundwater flow indicated in this report for the'MCT location is to the south, towards the Site. The Semi-Annual Groundwater Monitoring Report — April 2001, had indicated the Site wells were previously being monitored �. for hexavalent chromium (chromium VI) as well as total dissolved chromium. The 2001 report indicated analyzed groundwater samples from the Site irrigation wells at up to 7 ug/L of chromium VI. Marley's location is approximately 4,500 feet north of the Site and the risk v posed to the project Site is documented by the indicated groundwater flow direction and C continued presence of chromium and chromium VI found in on-Site wells. ` A past file review, dated April 23, 2002, for the Site vicinity included information regarding the following database sites. • 4010 E. Main Street is the current location of Stockton Fire Station #12 and is located approximately 1,500 feet northwest of the Site. The file review revealed two USTs had been removed in 1994 with some remedial action taken.The SJCEHD issued a Case Closure Summary C in November 1995; thus the property does not appear to pose a risk to the Site. • 4075 E. Main Street is the current location of JAMAR Service and is approximately 1,300 feet northwest of the Site. The file review revealed that at least five USTs have been removed since 1995. The property is registered with the California State UST Clean-Up Fund and has at least 16 monitor wells. The groundwater flow direction at this location was indicated to be to the south- southwest. In a Third Ouarter, 2001 Groundwater Monitoring Report by GHH Engineering, Inc. and dated January 2002, the monitor wells were being sampled for groundwater contamination concentrations of TPH quantified as gasoline (up to 100,000 ug/L); benzene (up to 35,000 ug/L), ` toluene (320 ug/L), ethyl benzene (390 ug/L), and total xylenes (BTEX); and 1,2-dichloroethane (1,2-DCA, up to 370 ug/L), tertiary butyl alcohol (TBA, up too 77 ug/L), and other fuel oxygenates. The most recent report in the SJCEHD files concerning this property is entitled Monitoring Report, Second Quarter 2004, by ATC Associates, dated August 10, 2004. The inferred groundwater flow direction is to the east, toward the Site. However, due to distance and /. indicated extent of contamination,this location does not appear to pose a risk to the Site. (� • 4125 E. Main Street is the past location of Hershel Vance Auto Repair and is approximately 1,300 feet northwest of the Site.The file review revealed the removal of two USTs in May 1990. 3 A workplan was submitted to SJCEHD in November of 1997 indicating remedial progress. The SJCEHD issued a "no further action" letter for this location on January 27, 1998; thus this r 1) location does not appear to pose a risk to the Site. • 1030 S. Olive Avenue is the current location of Quik Stop #76 and is approximately 1,800 feet northwest of the Site. The file review revealed that a UST was removed from this location in October 1998. Laboratory analyzed soil results indicated that ethyl benzene (0.0052 parts per million, ppm), total xylene (0.056 ppm), and MTBE (0.0073 ppm) were present in the soil at approximately 14 to 16 feet below ground surface. Due to distance, this location does not appear ` to pose a risk to the Site. o +.4) CONDOR