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S E C O R Second Quarter 2003, Quarterly Progress Report July 14, 2003 Page 3 3.2 Soil Vapor Extraction System The SVE system is comprised of four vapor wells (VE -1 through VE -4), connected by mechanical piping I. to a 5 horsepower (hp) positive -displacement blower, and a catalytic oxidizer. Vapors from the soil are removed under vacuum by the blower and petroleum hydrocarbons in these vapors are destroyed by a catalytic oxidizer, prior to discharging the air stream to the atmosphere. The San ,Joaquin Valley Air Pollution Control District (SJVAPCD) permits the operation of the SVE system under permit No. N-4343- 1-0. To assess the effectiveness of the SVE system, process samples were collected monthly from the vapor stream before (INFL) and after (EFFL) the catalytic oxidizer. Each sample was analyzed for TPHg, BTEX, and MtBE. Maximum constituent concentrations are presented below: SAMPLING Maximum Constituent Concentration (ppmV) LOCATION TPHgBenzene Toluene Ethyl -benzene Xylenes MtBE INFL 1.2 <0.5 <0.050 X0.050 0.18 X0.4 EFFL <5.0 <0.5 <0.050 X0.050 <0.050 X0.4 Explanations: ppmV = Parts per million by volume < Indicates the constituent was not present at or above the method reporting limit shown During the 2003 the SVE system was approximately 92% operable. System down time was attributed to a power outage. Tables 5 and 6 present operational measurements and calculated mass removal rates for TPHg, benzene, and MtBE, respectively. During 2003 the SVE system removed approximately 12.3 pounds of TPHg and 0.2 pounds of benzene. A concentration of one-half the laboratory detection limit was used to facilitate calculations when samples were reported as below detection limits. Since operation began, the SVE system has removed an estimated 4,129.1 pounds of TPHg, 85.8 pounds of benzene, and 443.8 pounds of MtBE. Mass removal trends and influent soil vapor TPHg, benzene, and MtBE concentrations versus time are shown on Figures 8 and 9, respectively. 3.3 Hydrocarbon Mass Estimate The hydrocarbon mass estimates presented below are an update of results presented within the Problem i Assessment Report / Final Remediation Plan (PAR/FRP) Addendum, dated June 5, 2001. Methodology for determining the mass of hydrocarbons adsorbed to soil and dissolved in groundwater can be found within the PAR/FRP Addendum. 3.3.1 Estimated Mass of Petroleum Hydrocarbons Dissolved in Groundwater The results presented below are based on the calculation presented within the PAR/FRP Addendum and cumulative 2Q03 GWE mass removal data. To conservatively estimate analyte mass remaining, historical groundwater analytical data was used. This information is summarized in the following table: lAChevron1957751Periodic Monitoring\Quartedy Progress Reports1200312nd Quarter -2003 oPR.doc E_J