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C' <br />• <br />Chevron Products Company Page 2 <br />Former Chevron Service Station #9-5775, 301 West Kettleman Lane, Lodi, California April 15, 2002 <br />Zone <br />Maximum Constituent Concentrations (µg/1) <br />January 16 through 17, 2002 <br />TPHg <br />Benzene <br />Toluene <br />Ethyl- <br />Xylenes <br />MtBE <br />TBA <br />EtBE <br />TAME <br />benzene <br />A -zone <br />1,500 <br />6 <br />0.71 <br /><0.50 <br /><1.5 <br />25,000 <br />190 <br />760 <br />250 <br />B -zone <br /><50 <br /><0.50 <br />1.3 <br />0.59 <br />2.o <br /><0.5 <br /><5.0 <br />0.6 <br /><0.5 <br />C -zone <br /><50 <br /><0.50 <br /><0.50 <br /><0.50 <br /><1.5 <br />4 <br /><5.0 <br /><0.5 <br /><0.5 <br />Explanations: <br />µg11= Micrograms per liter <br />< Indicates the constituent was not present at or above the method reporting limit shown <br />3.0 EVALUATION OF GROUNDWATER EXTRACTION AND SOIL VAPOR <br />EXTRACTION SYSTEMS <br />GWE and S VE systems were initiated on July 3, 2000. Certified analytical reports and <br />chain -of -custody documentation and remedial system operation and maintenance field data <br />sheets are included in Attachments E and F, respectively. A brief description and <br />performance evaluation of the remedial system during the I" quarter 2002 are presented <br />below. <br />3.1 Groundwater Extraction System <br />The groundwater extraction system consists of groundwater extraction wells EX -1, EX -2 and <br />EX -3 (Figure 5). These wells are equipped with submersible pumps connected through <br />mechanical piping to a series of granular activated carbon (GAC) vessels prior to an <br />industrial sewer discharge point. Chevron discharges treated groundwater at the subject site <br />under City of Lodi Wastewater Discharge Permit #310. Pumping through the wells from <br />areas affected by petroleum hydrocarbons prevents migration of these hydrocarbons off-site. <br />To assess effectiveness of the GWE system, process samples were collected weekly during <br />this reporting period. Sample locations include an influent port (INFL), prior to the first <br />GAC vessel, between the first and second GAC vessels (MID -1), between the second and <br />third GAC vessels (NM -2), and prior to discharge (EFFL) to the industrial sewer. During <br />these sampling events, influent (INFL), midpoint 1 (MID -1), midpoint 2 (MID -2), and <br />- effluent (EFFL) samples were analyzed for TPHg, benzene, BTEX compounds, MtBE, TBA, <br />DIPE, EtBE, TAME, ethanol, methanol, EDB, and 1,2 -DCA. Maximum concentrations of <br />detected constituents are presented below. Current and historical analytical information is <br />1AChevron1957751Periodic MonitoringlQuanerly Progress Reports1200211st Quarter -2002 Progress Report.doc <br />