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SECOR Fourth Quarter 2005, Quarterly Progress Report January 12, 2006 Page 1 1.0 INTRODUCTION SECOR International Incorporated (SECOR), on behalf of Chevron Environmental Management Company (Chevron), presents fourth quarter 2005 (4Q2005) groundwater monitoring and sampling results at 301 West Kettleman Lane, Lodi, California (Figure 1). This report covers the period from July 29 through October 21, 2005 and was prepared in accordance with Cleanup and Abatement Order (CAO) No. 5-00-704, dated April 20, 2000 (Appendix A). Groundwater extraction and treatment (GWET) and soil vapor extraction and treatment (SVET) systems were activated on July 3, 2000. On August 20, 2003, SVET was discontinued following approval by the Regional Water Quality Control Board (RWQCB) in their letter dated August 18, 2003. On April 18, 2005 groundwater extraction was discontinued to evaluate rebound of chemical constituents. Discontinuation of groundwater extraction was approved by the RWQCB in their letter dated April 15, 2005. Rebound of chemical constituents was not observed and the GWET system has remained offline. 2.0 GROUNDWATER MONITORING AND SAMPLING On October 21, 2005, Gettler-Ryan Incorporated (G -R), conducted 4Q2005 groundwater monitoring and sampling. Certified laboratory analytical reports, chain -of -custody documentation, and sampling field data sheets are attached as Appendix B. A brief summary of results is presented below. 1 2.1 Monitoring Well Gauge Data Monitoring well gauge data indicates the depth to groundwater, in A-, B-, and C -zones, ranged from 60.00 to 63.64 feet below ground surface (bgs). Groundwater gauging data are presented in Table 1. Groundwater in the A -zone flows radially inward towards a northwest to southeast trending trough, and the hydraulic gradient varies (Figure 2). Groundwater flow direction in the B -zone appears variable, with flow directions to the east at a hydraulic gradient of 0.009 foot per foot (ft/ft) and to the south-southwest at a hydraulic gradient of 0.01 fVft (Figure 3). There are F111an insufficient number of monitoring wells in the C -zone to evaluate groundwater flow direction. 2.2 Sample Analytical Results , During 402005, groundwater samples were analyzed for total petroleum hydrocarbons as gasoline (TPHg), benzene, toluene, ethylbenzene, total xylenes (BTEX), methyl tertiary butyl ether (MtBE), tertiary butyl alcohol (TBA), di -isopropyl ether (DIPE), ethyl tertiary butyl ether (EtBE), tertiary amyl methyl ether (TAME), ethanol, methanol, ethylene di -bromide (EDB), and 1,2-dichloroethane (1,2 -DCA). Sample analytical results are summarized in Table 2. An A -zone isoconcentration map for MtBE is presented as Figure 4. Maximum concentrations of constituents for A-, B-, and C -zones are presented in the table below. 4� L, Z:IChevron1957751Periodic MonitoringNO P 81200514th Quarter -2005 QPR.doc