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Page 3 3.0 SOIL BORINGS AND HYDROGEOLOGY The soil borings(B1 through B-7)were drilled into native soils. Soil borings B-1 through B-3 were located at the northern-most,down-gradient positions available on the property. Soil boring - B-4 was located in an estimated down-gradient direction from the three underground storage tanks. Boring B-4 was also near the 2-inch vapor lines. Borings B-5 and B-6 were located in the estimated down-gradient direction of the two pump islands and boring B-7 was Iocated in the estimated down-gradient to cross gradient direction of the waste oil tank. Borings B-4 through B- "" 7 were drilled with 8 and 1/4-inch diameter hollow-stem augers using a Mobile B-61 drill rig. Soil R borings B-1 through B-3 were drilled with 10 and 1/4-inch diameter hollow-stens augers using a Mobile B-53 drill rig. Both drill rigs used a 140 pound drop-hammer with a 30 inch drop. The drilling was performed by a state-licensed driller(C-57#519428),B&F Drilling of Rancho Cordova, California. Soil samples were collected frosts the borings at approximate intervals of 5.0 feet,for lithologic and hydrologic characterization,and for chemical analysis. The samples were screened in the field with a photoionization detector(PID)to qualitatively evaluate the concentration of volatile hydrocarbons that were present. The Standard Operating Procedures for collecting organic vapor data are described in Appendix A. All soil cuttings were stored on-site in 55-gallon Department of Transportation(DOT) approved 17 H drums pending laboratory analysis for appropriate disposal. Each borehole was sampled and logged by state-registered geologist(R.G,#4815),James A. Jacobs. Soil samples were logged in accordance with the Unified Soil Classification System (USCS). Boring logs are included as Appendix B. Twenty-one soil samples were collected, sealed,refrigerated and sent under chain-of-custody to Chromalab, Inc. of San Ramon,California. The seven soil borings penetrated similar soils consisting of clays,sandy clays,clayey sands and sands to a maximum depth of 28 ft, below ground surface. Monitor wells MW-1 through MW-3 were terminated in the highly plastic "Stockton Blue Clay"which was encountered between 22 and 23 feet below ground surface. Groundwater was encountered during drilling of borings B-1, B-2, and B-4 through B-7 between 14.4 ft, and 16.5 ft. below ground surface. Flowing sands were observed while removing the augers from boring B-3 at total depth. The depth to the flowing sands in B-3 was estimated to be about 20 ft, below ground surface.