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Monitoring Well Installation Report 730 E Channel Street,Stockton,CA December 15,2064 Page 6 3.9 LABORATORY ANALYSES The soil samples collected from the monitoring well borings and the groundwater samples collected from _ L the monitoring wells were analyzed for TPH-G, TEPH-D, TEPH-MO, and total extractable petroleum hydrocarbons quantified as kerosene (TEPH-K) by EPA Method 801513, and for benzene, toluene, ethyl benzene, total xylenes (BTEX), and gasoline oxygenates/additives by EPA Method 8260B The gasoline oxygenates/additives include methanol, ethanol, tertiary-butanol (TBA), methyl tertiary-butyl ether ' (MTBE), di-isopropyl ether (DIPE), ethyl tertiary-butyl ether (ETBE), tertiary-amyl methyl ether s (TAME), 1,2-dichloroethane (1,2-DCA), and 1,2-dibromoethane (EDB) The soil samples were also analyzed for total lead by EPA Method 7420 4.0 FIELD OBSERVATIONS Field observations included monitoring well boring observations, PID screening results, detection of soil I sample odors, and visual observations of the Site geology Field observations are included on the geologic logs prepared for all of the monitoring well borings (Appendix B) Monitoring well borings MW-1, MW-2, MW-3, and MW-3R were all advanced to a depth of approximately 47 feet bgs Soils encountered by the borings were predominantly clay with interbedded silty sand and clayey sand Drill cuttings from the borings for MW-1, MW-2, and MW-3 were placed in polyethylene bags and checked with a PID for the presence of organic vapors PID measurements indicated the presence of organic vapors at concentrations up to 49 1 parts per million (ppm) in drill cuttings from MW-2 Organic vapors were not detected with the PID in the drill cuttings from the bonngs for MW-I and MW-3 Weak petroleum hydrocarbon odors were noted in the drill cuttings from below 36 feet bgs in the boring for MW-2 No petroleum odor was noted in the drill cuttings from MW-1, MW-3, and MW-3R Soil discoloration was not noted in the drill cuttings from the borings for any of the wells 5.0 GROUNDWATER GRADIENT On November 8, 2004, the depth to groundwater was measured in monitoring wells MW-1, MW-2, and T MW-3R Groundwater elevation data are presented in Table 3 The average depth to groundwater in the monitoring wells was approximately 37 19 feet below the`surveyed well collar measuring points (the measuring points are slightly below the ground surface) The estimated groundwater gradient for the Site on November 8, 2004, was 0 0054 ft/ft to the northeast and is shown on Figure 3, Appendix A Table 3 Groundwater Elevation Data Monitoring well TOC Elevation Depth to Groundwater Groundwater Elevation Y MW-1 1635 3723 -2088 I MW-2 1652 3749 -2097 MW-3R 1578 3685 -2107 All measurements are in feet TOC=Top of Casing TOC Elevation referenced to NAVD88 vertical datum 6.0 RESULTS OF LABORATORY ANALYSES ISoil samples from the monitonng well bonngs and groundwater samples from the monitonng wells were • submitted to Argon for analyses The laboratory analytical results of the soil samples are presented in 1 a� �st� CONDOR