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Mr Ronald Rowe Project 22640-100 001 May 21, 1999 Page 2 Based on laboratory analysis, residual hydrocarbons were detected in soil samples collected from borings B-1, VEW-1, MP-1, and MP-2 Dissolved hydrocarbons were detected in monitoring wells MW-1 and MW-5, and in 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 manitolded to the SVE system The system was put into operation on July 1, 1994 The system operated continuously from July 1994 to December 1996 Due to mechanical problems, the system operated intermittently during the first quarter 1997 The unit was repaired in early March 1997 and was returned to operation in mid-March 1997 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, the San Joaquin County PHS/EHD requested additional delineation of soil and groundwater impacts SCOPE OF WORK Prior to implementing field activities, EMCON obtained drilling permits from the PHS/EHD and conducted utility clearance EMCON supervised the drilling and installation of exploratory borings (B-1/MW-9 and B-2/MW-8) to 105 and 108 feet bgs, respectively Drilling was performed on February 22 through 24, 1999, by Woodward Drilling, a California licensed drilling contractor Soil borings were drilled using 8-inch diameter hollow stem auger drilling equipment An EMCON geologist prepared exploratory boring logs consistent with the Unified Soil Classification System Soil samples were field screened for petroleum hydrocarbon impacts by conducting head space analysis with a portable photolonization detector (PID) and flame ionization detector (FID) PIDIFID readings are listed on the boring logs Drilling and sampling methods are discussed in detail in Appendix A Exploratory boring logs and well details are presented in Appendix B Soil samples were continuously collected from 60 to 105 feet in boring B-1 and 60 to 108 feet in boring B-2 using a modified California Split Spoon Sampler fitted with brass sample tubes HydroPunch groundwater samples were collected at approximate changes in lithology Soil samples were preserved for laboratory analysis by sealing the tubes with Teflon tape ' and plastic end caps and placed in an ice chest pending laboratory analysis CP\E 1APACHE\REPORTS\APACP102 DOC-98%1sg 1 emton