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. PHASE II ENVIRONMENTAL SITE ASSESSMENT REPORT MULTI-MODAL STATION "SIX-BLOCK PROJECT" STOCKTON, SAN JOAQUIN COUNTY, CALIFORNIA EXECUTIVE SUMMARY i January 13,2003 A Phase 11 Environmental Site Assessment (ESA) was performed by Condor Earth Technologies, Inc (Condor) at the request of the City of Stockton, Department of Housing and Redevelopment (DHR) The primary purpose of this investigation was to identify large- and medium-sized soil and groundwater contamination issues The assessment was performed for the properties (site) comprising the six-block area bounded by E Miner Avenue to the north, N Stanislaus Street to the west, E Weber Avenue to the south, and the Union Pacific Railroad tracks to the east In the city of Stockton, California, with the exception of 132 N Stanislaus Street (see Figure A) Fieldwork commenced in May and June of 2002, and a second phase of fieldwork was completed in September of 2002 Field and Iaboratory work is summarized as follows • One hundred and fifty-one (15 1) soil borings were completed • Prior to the installation of the borings, a total of 936 ground penetrating radar (GPR) data lines were collected • hour hundred and nine (409) soil samples were collected • Seventy-two(72) groundwater samples were collected • Two hundred and sixteen(216) laboratory and analytical tests were performed Subsurface data indicates that the first unconfined water-bearing zone (groundwater) is approximately 30 to 35 feet below ground surface (bgs) Based on the data collected and documented in the full report, the following paragraphs summarize many of the important features of the six-block area The site perimeter borings indicated that no off-site sources of contamination are moving into the six- block area, and no sources of contamination from within the six-block area are moving out of the area Significant contamination was not encountered in the groundwater of the northern part of the six blocks (Blocks 1, 2, and 3, see Figure B) Due to the spacing of the field explorations, small-sized areas of contamination may be present in Blocks 1 through 3 Several groundwater contaminant plumes were discovered in the southern three blocks (Blocks 4, 5, and 6) At Block 4, a large plume of chlorinated solvents consisting of tetrachloroethene (PCE), trichloroethene (TCE) and breakdown products was observed centered on the property at 730 E Channel Street The plume extends to the east and west in an oblong shape (see Figure A) At Block 5, a chlorinated solvent (TCE) groundwater contaminant plume was discovered centered on the property at 805 E Weber Avenue A larger plume of chlorinated solvent(PCE) was discovered that extended across properties at 815, 829, and 843 E Weber Avenue, with possible extensions north to the properties at 836 E Channel Street and 147 N Aurora Street, and east onto Block 6 properties All three of these plumes had contaminants detected above the respective maximum contaminant levels (MCLS) for each contaminant The three groundwater plumes are fairly well defined, but additional borings will be needed to further delineate their character Other small-sized contamination may also be present in Blocks 4 through 6 4 i �� CONDOR