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PHASE II ENVIRONMENTAL SITE ASSESSMENT REPORT MULTI-MODAL PROJECT AREA "SIX-BLOCK PROJECT" STOCKTON, SAN JOAQUIN COUNTY, CALIFORNIA BLOCK SPECIFIC EXECUTIVE SUMMARY January 6, 2003 Block 1 Tetrachloethene (PCE) was detected below the actionable level in the groundwater from a boring at 722 E Miner Avenue (see Figures A and B) 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 Low concentrations of toluene were also detected in groundwater samples from the block, but the concentrations do not appear to be of concern No other concerns for Block 1 were identified during this investigation Block 2 No areas of concern were identified during this investigation at the Block 2 properties (Figure A) It is possible that groundwater contamination from the southern blocks (Blocks 4 and 5) might have impacted groundwater at the southern Block 2 properties • Block 3 Toluene and tnchloroethene (TCE) were detected below actionable levels in the groundwater at 930 E Miner Avenue and the adjacent Union Pacific Railroad property The toluene detections may be related to an underground storage tank (UST) that was removed from 930 E Miner Avenue in November 1993 under San Joaquin County Environmental Health Department (EHD) supervision "No further action" was required by EHD for the tank removal The origin of the TCE, however, is unclear Block 4 An area of petroleum-impacted soil is present in the northern portion of 730 E Channel Street The vertical extent of petroleum-impacted soil in this area appears to extend to a depth of approximately 49 feet below ground surface (bgs) The lateral extent of the impacted soil appears to be constrained to the property (Figure A) 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 groundwater plume of various volatile organic compounds (VOCs) typically associated with solvents is present in the northern portion of 730 E Channel Street The VOCs detected in the groundwater are generally below actionable levels (for those with actionable levels) 1,1-Dichloroethene (1,1-DCE) was the only VOC at Block 4 detected above the actionable level The estimated extent of the intermingled plume is indicated on Figure A The 1,1-DCE groundwater plume also appears to extend to 701 E Weber Avenue, 729 E Weber Avenue, and possibly north to Block 1, northeast to Block 2, and east to Block 5 Groundwater contamination at 730 E Channel Street was also identified in a sample collected from 110 feet bgs, but detected values were below actionable levels The groundwater contamination should be further evaluated A UST was also found at 730 E Channel Street This UST should be properly removed according to San Joaquin County Environmental Health Department(EHD) requirements �t� iv CONDOR