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DISCUSSION: TPHG and BTEX were not detected in the samples collected from monitoring wells MW-2 through MW-6, consistent with the previous quarter. Benzene, toluene and total xylenes were detected in the sample collected from monitoring well MW-1 at concentrations of 0.892 µg/l, 1.43 µg/I and 1.80 µg/I, respectively. MTBE was detected in the samples collected from monitoring wells MW-1 and MW-6 at concentrations of 19.0 µg11 and 2.12 pg/l, respectively. Delta conducted six site visits during the first quarter 2001 to measure and bail free-phase petroleum hydrocarbons in vapor extraction well VW-5D. Thickness of free product varied from a maximum of 2.7 feet(01/11/01) to 0.23 feet (03/15/01) (see Table 3). A total of approximately 4 gallons of free product was recovered during the quarter. The groundwater flow direction was calculated to be towards the east at an average gradient of 0.0021 ft/ft. An east groundwater flow direction is consistent with previous quarters. The groundwater elevation increased 1.29 feet (MW-2) to 1.49 feet (MW-6) in the monitoring wells since the previous sampling event (December 2000). A Delta technician conducted bimonthly site visits to optimize and maintain the SVE/AS system. The AS system was shut down during the first quarter (01/11/01) due to the presence of free product in well VW- 5D. Approximately 216 lbs of TPHG as gasoline was removed during the first quarter 2001, and a cumulative mass of 694.52 lbs since startup (09/28/00). Delta will optimize the operation of the SVE system by increasing flows, and therefore influent concentrations, by changing the vacuum and flows from the individual wells. The SVE system was in compliance with San Joaquin Valley Unitfied Air Pollution Control District permit to operate. • ATTACHMENTS: • Table 1 Groundwater Monitoring Data • Table 2 Groundwater Analytical Results for Oxygenates and Additional Compounds • Table 3 Floating Product Monitoring Summary, Well VW-5D • Table 4 Operational Uptime Information of the Soil Vapor Extraction System • Table 5 Flow Rates and Analytical Results of Air Sample Analyses • Table 6 Extraction and Emission Rates • Figure 1 Site Location Map • Figure 2 Groundwater Elevation Contours (First Quarter 2001) • Figure 3 Groundwater Analytical Summary(First Quarter 2001) • Appendix A Field Data Sheets • Appendix B Sampling and Analysis Procedures • Appendix C Certified Analytical Reports and Chain-of-Custody Records CAARC0105481QTRLY1200110548 QIGI.doc Delta 05/23/01