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Approximate Depth to Groundwater 25 66 to 27 75 feet bgs Direction of Groundwater Flow East Groundwater Gradient 0 0028 ft/ft DISCUSSION Results of the fourth quarter 2000 groundwater monitoring event indicate that the concentrations of dissolved hydrocarbons are generally consistent with the results of previous sampling events TPHG and BTEX constituents were not detected in the samples collected from monitoring wells MW-2 through MW- 6 Benzene and total xylenes at concentrations of 0 559 gg/L and 0 562 �igIL, respectively, were detected in the sample collected from monitoring well MW-1 MTBE (Method 8260) was detected at a concentration of 11 6 µglL in the sample collected from monitoring well MW-1 MTBE was below laboratory detection limits in the samples collected from monitoring wells MW-2 through MW-6 Delta detected free phase petroleum hydrocarbons in vapor extraction well VW-5d at a measured thickness of approximately 1 25 feet on December 18, 2000 Free product was bailed and stored in a U S DOT rated double lined 55-gallon drum Delta will initiate weekly monitoring, bailing and removal of free product from well VW-5d The direction of groundwater flow was to the east with a gradient of 0 0028 ft/ft This is generally consistent with previous groundwater monitoring events The groundwater elevation increased approximately 1 32 feet in the monitoring wells from the previous sampling event (September 2000) Startup and source testing was conducted for the SVE and AS system on September 28, 2000 Delta subsequently prepared and submitted a startup and source test report to San Joaquin Valley Air Pollution Control District (SJVUAPCD) on November 13, 2000 Delta conducted 10 site visits in the fourth quarter to optimize, monitor and maintain the systems On December 18, 2000, free phase petroleum hydrocarbons were detected in vapor extraction well VW-5d The AS system was shut down on December 27, 2000 ------------- System operated continuously during the fourth quarter extracting and abating soil vapors Soil vapor samples were collected from the influent and effluent of the system on October 19, November 28 and December 7, 2000 Vapor samples were forwarded to Sequoia Analytical for chemical analysis The system was in compliance with the SJVUAPCD Permit to operate The concentration of TPHG in the influent soil vapors decreased from 9,870 mg/nn3 to 6,050 mg1m3 since startup The system extracted approximately 465 91 pounds of TPHG during the fourth quarter 2000 and 478 62 pounds since startup ATTACHMENTS • Table 1 Groundwater Monitoring Data • Table 2 Groundwater Analytical Results for Oxygenates and Additional Compounds • Table 3 Operational Uptime Information of the Soil Vapor Extraction System • Table 4 Flow Rates and Analytical Results of Air Sample Analyses • Table 5 Extraction and Emission Rates • Figure 1 Site Location Map • Figure 2 Groundwater Elevation Contours (Fourth Quarter 2000) • Figure 3 Groundwater Analytical Summary(Fourth Quarter 2000) • Appendix A Field Data Sheets Appendix B Sampling and Analysis Procedures • Appendix C Certified Analytical Reports and Chain-of-Custody Records C 1ARCOW5481QTRLY1200010548Q400 DOC Delta 01/31/01