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Quik Stop Station No 39 September 23,2005 <br /> Stockton California Results of Additional Subsurface Invests atton <br /> SITE DESCRIPTION AND BACKGROUND �v <br /> The site is a convenience market and retail gasoline station located on the northwestern <br /> corner of the intersection of East Fremont Street and E Street in a commercial and residential <br /> area in San Joaquin County as shown on Figure I Structures and installations at the site <br /> include a station building, gasoline dispenser islands under a canopy, and two 12,000-gallon <br /> gasoline USTs as shown on Figure 2 <br /> The site elevation is approximately 22 feet above mean sea level (msl) and the surface is <br /> predominantly underlain by alternating beds of sandy silt, silty sand and clay with minor <br /> cemented sand and sand to approximately 100 feet below surface grade (bsg) The <br /> groundwater level in site monitoring wells over the past five years has generally dropped <br /> from approximately 44 feet bsg in 2000 to approximately 51 feet bsg in 2005 Groundwater <br /> flow directions have been variable with gentle gradients of less than 0 01 <br /> Results of third quarter 2005 groundwater monitoring indicate the groundwater flow <br /> direction beneath the site was northward under a gradient of 0 001 as shown on Figure 2 <br /> The distribution of total petroleum hydrocarbons as gasoline (TPHg), benzene and DCA are <br /> shown on Figure 3 Groundwater monitoring data are summarized in Table 1 <br /> In November 1998, two single-walled, steel, 10,000-gallons, gasoline underground storage <br /> tanks (USTs) T-1 and T-2, product piping and dispensers were excavated and removed from <br /> the site Removal of the former UST systems and analytical results of soil samples were <br /> ddcumented=by=Horizon=in Tank=C--losure=Report=dated=February=17;_1999 Tabulated_soil <br /> analytical results and soil sample location map for the UST removal are contained in <br /> Appendix B <br /> In November 1999, Horizon conducted a soil and groundwater investigation consisting of <br /> the drilling and installation of three 2-inch inside diameter (ID) groundwater monitoring <br /> wells MW-1, MW-2, and MW-3 Groundwater was encountered in the borings at depths of <br /> approximately 55 feet bsg The monitoring wells were screened across the interval from 40 <br /> 7039rpt9-05 <br /> Project No 7039 16 2 HORIZON ENVIRONMENTAL INC <br />