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The closest surface water to the site is the Mokelumne River, approximately one-half mile to the <br /> northeast The river in this location flows generally to the northwest and 1s subject to periodic <br /> flooding. The regional groundwater flow is generally towards the Mokelumne River to the <br /> north Groundwater beneath the site occurs at a depth of approximately 12 feet below grade and <br /> flows southwest. <br /> I2.3 Proximity of private, municipal, and irrigation wells <br /> A survey of all water wells within a one-half mile radius of the site was conducted based on <br /> information received from the California Department of Water Resources. The closest well to <br /> ' the site is a municipal supply well approximately 90 feet north of the site This well has <br /> screened intervals from 135-150 feet, 160-185 feet, and 225-235 feet below grade It is sealed <br /> to a depth of 70 feet and is not expected to be impacted by groundwater contamination <br /> Numerous monitoring and industrial wells of various depths exist at several local canneries along <br /> 1 the Southern Pacific Railroad tracks, approximately 1,000 feet east of the site The approximate <br /> locations of known water wells are plotted on Figure 3 <br /> 2.4 Locations of nearby septic tanks and underground utilities <br /> The locations of all underground utilities, septic tanks, and leach lines in the vicinity of the <br /> underground tanks and product lines are plotted on Figure 2 The location of the septic tank and <br /> leach line are approximate, based on verbal communication from Bruno Maury of the Thornton <br /> Fire Department <br /> 3.0 FIELD INVESTIGATION <br /> 3.1 Phase 1 Activities <br /> On November 1, 1990, RESNA Industnes/WaterWork Corp (RESNA) personnel advanced <br /> three soil bonngs (MW1, MW2, MM3) to depths ranging from 27 to 28 feet below grade at the <br /> project site to accomplish the following 1) define the lateral and vertical extent of petroleum <br /> hydrocarbon soil contamination, 2) determine soil stratigraphy, and 3) install groundwater <br /> monitoring wells within the uppermost aquifer in order to assess groundwater quality. The <br /> boring/well locations are plotted in Figure 2 <br /> GPR1227 7PL 2 <br />