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Cone Penetrometer Testing Report - November 2002 Former HESS-DuBOIS CLEANERS 348 West Harding Way, Stockton, California 1.0. INTRODUCTION At the request of Mr. Peter Wallace Jr. for the estate of Mr. Peter Wallace Sr., Advanced GeoEnvironmental, Inc. (AGE), has prepared the enclosed report for 348 West Harding Way, Stockton, California. The report documents procedures and results for a cone penetrometer testing (CPT)investigation conducted at the site during November 2002;the objective of the investigation was to model the geologic and hydrogeologic frameworks and to assess potential dissolved petroleum-migration pathways beneath the site. The site setting is illustrated on Figure l; site structures, boring, monitoring well and CPT locations are depicted on Figure 2. This report is prepared in accordance with guidelines issued by the Central Valley Regional Water Quality Control Board (CVRWQCB) for investigation of underground storage tank (UST) sites. Included in this report are ground water analytical data from the latest site quarterly monitoring event as well as additional ground water data from the subsurface site investigation at 244 West Harding Way (Figure 2). A summary of site background information and previous investigations was included in the AGE-prepared Additional Site Assessment Work Plan, dated 12 February 2002. 2.0. PROCEDURES On 14, 15 and 26 and 27 November 2002, seven paired soil borings (CPT-1 through CPT-7)were advanced on and adjacent to the site(Figure 2) utilizing CPT technology. At each boring location, lithologic data was collected from the initial CPT boring; an immediately adjacent twin boring was then advanced to collect grab ground water samples from selected depths. 2.1. CPT LITHOLOGIC INVESTIGATION The CPT investigation utilized a 25-ton truck-mounted CPT drill rig equipped with 1.50-inch diameter hollow-stem rods. A hydraulic ram was utilized to advance a cone penetrometer tip attached to the hollow-stem rod assembly to total depth of each soil boring. Soil borings were advanced vertically to the following total depths at the specified locations: • CPT-1 was advanced to 148 feet below surface grade (bsg) at the former UST excavation; • CPT-2 was advanced to 138 feet bsg directly east of monitoring well MW-6; • CPT-3 was advanced to 152 feet bsg north of monitoring well MW-6, on the northern sidewalk landscape strip of Harding Way; . • CPT-4 was advanced to 110 feet bsg at monitoring well MW-10,on the sidewalk landscape strip of Harding Way; Advanced GeoEnvironmental,Inc.