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i i Report—Monitor Well Installation and Sampling New Jerusalem School February 26,1999 Page-5 1 consisted of a driving reconnaissance of the site vicinity, review of information provided by the + PHS/EHD for a site located near the subject site, and inquiriesJto the California Department of Water Resources (DWR), Central District in Sacramento, California. No surface water bodies that could be impacted by groundwater`migration from the site were identified during the driving reconnaissance. Fifty six structures (businesses or residences) were observed within approximately 2,000 feet of the subject site during the driving reconnaissance. These structures are shown on Figure 3, Appendix A. Numerical addresses for nineteen of these structures were observed during the driving reconnaissance. The numerical addresses identified during the driving reconnaissance i Lare provided in Table A, in Appendix A. Information provided by the PHS/EHD for a site located at j 1600 Durham Ferry Road is included in Appendix D. Additional information pertaining to the wells in the study area is pending from the DWR. f j " 4. INVESTIGATION RESULTS P 4.1 FIELD OBSERVATIONS/SITE GEOLOGY ` Field observations include OVA screening results, detection of sample odors and visual observations of the site geology. Field observations are included on the drilling Iogs prepared for monitor wells MW-I, MW-2,and MW-3. The drilling logs are included in Appendix B of this report. The lithology encountered at the site generally consisted of reddish'brown to olive brown clay to approximately 17 feet below ground surface (bgs). Grayish brown to reddish brown sands underlie the C clay to at least 25 feet bgs. Groundwater was encountered at approximately ten feet bgs in each boring. Organic vapors were not detected with the OVA in any of the soil samples collected from the MW-1, MW-2, and MW-3 boreholes. i 4.2 GROUNDWATER GRADIENT On December 29, 1998, the depth to groundwater was measu ed in each monitor well prior to the collection of groundwater samples. The average depth to groundwater at the site was approximately 8.8 feet below the surveyed well collars (slightly below the ground surface). The estimated groundwater gradient on December 29, 1998 was 0.23 ft/100 ft to the northeast(Figure 4, Appendix A). 5. LABORATORY ANALYTICAL RESULTS 5.1 SOIL SAMPLES E • Monitor Well MW-1. � Total xylenes were detected in the soil sample collected at five feet bgs from MW-I at a concentration of 7.3 micrograms per kilogram (µg/kg). Benzene, toluene, ethyl benzene, TPH-G, and MTBE were not detected at or above the laboratory reported detection limits in this sample. BTEX, TPH-G, and MTBE were not detected at or above thellaboratory reported detection limits in the soil sample collected from ten feet bgs. - • Monitor Well MW-2: I BTEX, TPI--G, and MTBE were not detected at or above the llaboratory reported detection limits in the soil samples collected from 10,20, and 25 feet bgs. r j r i tJ CONDOR I �, 4