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r July 27,2001 Project No 2005-2050-01 page 2 wells (MW-1 through MW-7), two vapor extraction wells (VEW-1 and VEW-2), and two manometers (MP-1 and MP-2) Well locations are shown on Figure 2 Petroleum hydrocarbons were detected in soil samples collected from bonngs B-1, VEW-1, MP-1, and MP-2 Dissolved petroleum hydrocarbons were detected in samples collected from monitoring wells MW-1 and MW-5, and to vapor extraction well VEW-1 In June 1994, a soil vapor extraction (SVE) remediation system was installed The system is comprised of an internal combustion engine with catalytic converter and associated filters, controls, and piping Vapor extraction wells VEW-1 and VEW-2 are mantfolded to the SVE system The system operated continuously from July 1994 to December 1996 The system operated intermittently dunng the first quarter 1997 due to mechanical problems EMCON submitted a Case Closure Report (July 17, 1997) that included estimates of remaining petroleum hydrocarbon mass in soil and groundwater, and recommended case closure under the low risk criteria After reviewing the report, San Joaquin County PHS/EHD requested additional vertical assessment of soil and groundwater In February 1999, EMCON directed the installation of onsite monitoring wells MW-8 and MW-9 to a depth of approximately 105 feet bgs Dissolved petroleum hydrocarbons were detected in groundwater samples collected from monitoring wells MW-8 and MW-9 . First encountered groundwater beneath the site has ranged from 68 to 44 feet bgs Previous consultants have calculated groundwater flow directions to be south and east, with the predominate flow direction toward the southeast It is our understanding, based on conversations with San Joaquin County PHS/EHD, that first encountered groundwater in the area of the site was recorded as low as 110 feet bgs in 1979 A work plan to conduct additional soil and groundwater investigation activities was submitted to San Joaquin County PHS/EHD on December 3, 1999 The work plan was subsequently approved Stratus obtained one onsite and two offsite access agreements and a revocable encroachment permit from the City of Stockton prior to initiating field work This report presents the results of the field work proposed in the December, 1999 work plan SITE INVESTIGATION ACTIVITIES The purpose of this investigation was to further evaluate the lateral and vertical extent of petroleum hydrocarbons beneath the site To accomplish this objective, Stratus initiated the following activities • Advanced thirteen (13) Cone Penetration Test (CPT) soil bonngs (CPT-1 through CPT-13) to depths of 140 to 160 feet bgs, • Advanced twenty six (26) direct push soil borings, two directly adjacent to each CPT boring, to collect soil and groundwater samples, C 1Proaect Files\Apache Plasticsllteports\Apache Sot]&GW 072001A doc