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First Quarter 2006 Groundwater Monitoring Report Boyett Petroleum,419 S.Main,Manteca,CA Page 2 included on the Groundwater Monitoring Field Forms, attached. Groundwater monitoring field measured parameters are presented in Table 1. Table 1: Groundwater Field Measured Parameters March 27 200 Monitoring pH Specific Dissolved Oxygen Oxidation-Reduction Well Conductance S (mg/L) Potential(relative mV) MW-2 7.06 772 4.32 385.1 MW-3 7.03 809 5.73 373.4 MW-4R 6.99 872 2.48 370.4 MW-6 7.29 658 6.02 415.8 MW-7 7.36 1,594 4.82 357.1 MW-8 7.19 1,064 5.73 358.0 MW-9 7.52 802 2.32 340.9 MW-10 7.03 1,195 3.76 348.5 MW-11 7.29 799 2.11 319.2 EW-1 7.27 770 1.69 319.2 GROUNDWATER ELEVATIONS AND GRADIENT Groundwater elevation data collected during the first quarter 2006 monitoring event indicate an average groundwater elevation at the site of 20.55 feet, an increase of 2.36 feet since the previous monitoring event (December 2005). Shallow groundwater elevation contours based on the depth to water measurements collected on March 27, 2006, indicate the groundwater gradient at the site is very flat and that there may be a small groundwater mound near the northeast corner of the site. Groundwater elevation data are presented in Table 2, and historical groundwater elevation data are attached. • Table 2: Groundwater Elevation Data Darch 27 2006 Monitoring Well TOC Elevation Screened Depth to Groundwater Interval b s Groundwater Elevation MW-2 35.97 15-25 15.33 20.64 MW-3 36.18 15-25 15.60 20.58 MW-4R 35.21 10-25 14.57 20.64 MW-6 36.07 10-25 15.56 20.51 MW-7 36.42 10-25 15.88 20.54 MW-8 36.43 10-25 15.90 20.53 MW-9 35.95 40-50 15.42 20.53 MW-10 36.09 10-25 15.56 20.53 MW-11 36.15 29-39 15.65 20.50 EW-1 36.23 29-39 15.76 20.47 'TOC Elevation:Elevations are referenced to NAVD88 datum,NGS Benchmark HS 4486. =Groundwater Elevation:Elevations are measured from the top of the well casings and are referenced to the benchmark indicated above. All measurements are in feet. LABORATORY ANALYTICAL RESULTS The groundwater samples collected from the monitoring wells were analyzed for benzene, toluene, ethyl benzene, total xylenes (BTEX), and selected gasoline oxygenates/additives by EPA Method 8260B, and for total petroleum hydrocarbons quantified as gasoline (TPH-G) by EPA Method 8015M by Argon Laboratories of Ceres, California. The selected oxygenates/additives included MTBE, ethanol (EtOH), ---___.L..a.,«.-1 /TD A 1 A. ..1 „tit.,,.. /nTr)C\ -4.1 ,1 ♦....E:..-„ L,,F..l -+I.-- /L"TDM �e.-t:.,,..> .. ..1 __+1-1 teivaiy-vu .O' L•ap�j, ui-iavpropya �ui�. ��... �, .�..), waV. y-vu.y. v.i. ',.. J, -J. ....r ..�. ether(TAME), 1,2-dichloroethane (1,2-DCA), and 1,2-dibromoethane(EDB). M �/� CONDOR