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I. PHASE 1.1 ENVIRONMENTAL SITE ASSESSMENT WORK PLAN L. Heritage Square Lo 640 North San Joaquin Street Stockton, Stanislaus County L. 1.0 INTRODUCTION This Work Plan for a Phase 11 Environmental Site Assessment for the property designated by Assessor's Lff Parcel Numbers (APNs) 139-161-10 and 139-161-11, located at 640 North San Joaquin Street, Stockton, California, has been prepared at the request of David and Marianne Warwick, the property owners, and the Stockton Unified School District (Stockton Unified), the prospective property buyer, by Condor �., Earth Technologies, Inc. (Condor). The site is located at the southeast corner of the intersection of North San Joaquin Street and East Park Avenue in Stockton, as shown on Figure 1. The purpose of the site work is to investigate if a release of hydrocarbons from a previously unidentified underground storage tank (UST) on the north side of APN 139-161-10 has occurred and to investigate potential hydrocarbon contamination on APN 139-161-11 due to migration of contaminants from a previously unidentified UST to the west of the parcel boundary. All work conducted by Condor will be under the supervision of a California registered geologist or engineer. This Work Plan includes project background information; a description of the field, laboratory, and reporting procedures proposed to conduct the work; and a project schedule. 2.0 PROJECT BACKGROUND The site is located in a commercial area in downtown Stockton and is currently known as Heritage L' Square. The existing structure at the site is an unreinforced concrete and masonry building that was constructed on APN 139-161-10 in 1916 (Parcel 2, Figure 3). Stockton Unified is proposing to purchase the building for use as a charter school. Based on the age of the structure and proposed use, Stockton �+ Unified requested that Condor perform an investigation at the site to evaluate subsurface conditions. A borehole (B-1) was drilled in February 2002 in the parking lot (APN 139-161-11)jointly owned by the + Warwicks and the Women's Center of San Joaquin County (Women's Center) on the east side of the building, at the location shown in Figure 2. The borehole pierced a metal pipe not identified by the Underground Service Alert (USA). A viscous black fluid seeped from the pipe onto the soil. One sample of the fluid and underlying soil was collected for laboratory analyses. The sample was analyzed for +r gasoline, kerosene, diesel, and motor oil by EPA Method 8015M; for volatile organic compounds (VOCs) by EPA Method 8260B; and for California Administrative Manual (CAM) metals by EPA Methods 7471A/ 6010B. The hydrocarbons detected in the extractable range are primarily diesel and a. motor oil. Gasoline was also detected; however, the chromatogram did not match a typical gasoline pattern. The detection of gasoline may result from the weathering of kerosene and motor oil. No CAM metals were detected at or above the Preliminary Remediation Goals (PRG) for residential sites or Total �. Threshold Limit Concentrations (TTLC). The laboratory results of hydrocarbon constituents are summarized in Table 1 on the next page. t. �i CONDOR