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CONDOR EARTH TECHNOLOGIES INC 188 Frank West Circle Suite I Stockton CA 95206 Phone 209.234.0518 FAX 209.234.0538 CONDOR www.condorearth.com March 24, 2008 Ms. Ava Langston-Kenney Program Manager City of Stockton Redevelopment Department 425 N. El Dorado Street,Room 317 Stockton, CA 95202-1997 Re: Subsurface Investigation,216 N. California St., Stockton, San Joaquin County, California Condor Project No. 5401 Dear Ms. Langston-Kenney: This is a report of findings for the fieldwork conducted at 216 N. California Street, Stockton, California on February 19, 2008. The property is referred to as Parking Lot B and is designated by Assessor Parcel Number(APN) 139-250-26 (Site) (Figures 1 and 2, Attachment A). This report includes Site background information, a description of field activities, laboratory analyses, and conclusions. This report presents results of subsurface soil and groundwater sampling adjacent to the northwestern corner of the Site,where a former underground storage tank (UST) was located. The Site is owned by the City of Stockton, and managed by the Redevelopment Department (Client). Due to unexpected subsurface conditions, only one boring was completed to 50 feet below ground surface (bgs)in the central former tank pit area. SITE BACKGROUND INFORMATION On December 3, 2004, Thorpe Oil removed one UST at the Site. Soil staining and petroleum odors were noted in the excavation and excavated soil. Soil samples were collected from locations directed by the SJCEHD, following removal of the UST. Based on our review of the project's background information, and the correspondence provided to us by the Client, Condor understands that a UST was located and removed from the western portion of the Site. The UST had the following characteristics: 1,500 gallon capacity; single-wall steel construction; formerly contained heating oil; and was located beneath the sidewalk on California Street. Upon removal, the UST was noted to have corrosion and adjacent dark, stained soil, with indications of long-term leakage. The laboratory analytical results provided to Condor along with the correspondence indicated that diesel-range hydrocarbons were detected in soil samples collected from the excavation during the UST removal activities. Samples were collected from the north and south ends of the UST excavation near the bottom of the excavation. The laboratory analytical results indicated that the total petroleum hydrocarbons quantified as diesel (TEPH-D) were detected at a concentration of 3,300 milligrams per kilogram(mg/kg) on the north end, and 6,300 mg/kg on the south end of the UST excavation. The UST removal activities were described by the San Joaquin County Environmental Health Department(SJCEHD) and Thorpe Oil in the notes made during the UST removal.