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PRELIMINARY SUBSURFACE INVESTIGATION WORK PLAN INDUSTRIAL PROPERTY 248 INDUSTRIAL DRIVE STOCKTON, CALIFORNIA 95206 1.0 INTRODUCTION The subject property consists of an approximately 5-acre parcel of land, occupied by an approximately 50,000-square-foot single-story industrial building, and a 1,500-square-foot single-story office structure. The subject buildings were vacant during the site visit, but most recently were occupied by NICA Metals, a materials recycling business. The property is now in the hands of a Receiver, Mr. Stephen Donell, who is acting as owner of the property. The scope of the Work Plan for this preliminary subsurface investigation is based on information gathered during a July 23, 2010, Phase I ESA completed by Pinnacle Environmental, Inc. (PEI), and on the subsequent Limited Phase II ESA dated April 25, 2012, for the subject property. The scope of work for the latter report included the sampling and analyses of soil vapor from 26 locations, soil matrix from 50 (including 26 soil vapor, 20 soil, 4 groundwater) boring locations, and groundwater at four locations for VOCs and TPH-carbon chain analysis. In addition, eleven soil samples were analyzed by USEPA Methods 8270 (SVOCs), 8141A (organophosphorous pesticides), 8081 (organochlorine pesticides), 8151A(chlorinated herbicides), and CAM 17 metals. In PEI's April 25, 2012, report, PEI concluded the following areas at the subject property warranted additional subsurface assessment. Septic Tank Area- Concentrations of benzene and 1,2-dichloropropane were found to exist above drinking water MCLs in groundwater samples collected in the vicinity of the septic system. Two UST Graves - Two likely UST graves were detected on the southeast corner of the building during the geophysical survey. Observations made during PEI's March 2012 excavations of these two sites were (1) that USTs had been buried here and had been removed, and (2) that visual evidence of historical impact underlie these sites. No significant soil impact was noted in shallow soil samples collected from borings at these two locations (viz., S13-104, SB-106 & SB-108, and SV-5 and SV-7) within the building as well as adjacent to it. It is possible that higher concentrations of petroleum hydrocarbons exist at depths below the bases of the former USTs. Inside the Building; - Two anomalous large concrete patches were noted along the eastern warehouse floor space within the interior of the main building. They were located approximately at the northeastern and southeastern corners of the building. The results of laboratory analyses from soil samples in both of these locations indicate the presence of high concentrations (above regulatory standards)of both diesel range(C 11-22) and motor-oil range hydrocarbons (C23-C35). Specifically, soil sample SB-112 at 10 feet indicated diesel- and oil-range hydrocarbons at 20,600 and 48,200 mg/kg, respectively. As required by the city of Stockton and San Joaquin County Department of Environmental Health, PEI is pleased to present this workplan for limited subsurface assessment. Remediation Pilot Study Workplan Pinnacle Environmental,Inc. 248 Industrial Drive,Stockton,CA Page 3