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OMEN ONE <br /> G - <br /> ' � ti W ' <br /> t r <br /> The other five water supply wells within 1 mile of the site are used for <br /> ornamental and irrigation purposes. The four private wells (19L1, 19P1, <br /> 19P2, and 30B1), located in the Lincoln Village 'nest area, 3/4-mile west <br /> of the site, are used to fill an artificial lake during the summer. The <br /> Lincoln Village wells are drawing from an aquifer 156 to 114 feet below <br /> the surface. The PG&E well (21M1) approximately 1 mile south of the <br /> site is tised for lawn irrigation. <br /> SITE INVESTIGATION <br /> In May 1984, EMCON Associates initiated a subsurface investigation at <br /> the site when the subsurface leak was discovered. Twelve exploratory <br /> borings (E-1 through E-12) were drilled at locations shown on Figure 2, <br /> using continuous-flight, hollow-stem auger drilling equipment and logged <br /> by an EMCON geologist. Soil samples were obtained from auger-return <br /> materials and by using a California split-spoon sampler advanced into <br /> undisturbed soil beyond the tip of the auger. Logs of exploratory <br /> borings along with the well construction details are presented in <br /> 1 Appendix A. All exploratory borings were converted to monitoring wells <br /> j+ with the installation of 3-inch-diameter PVC casing. well E-1 drilled <br /> in the tank area was removed during the tank replacement operations. <br /> The exploratory borings ranged in depth from 19-1/2 to 30 feet. The <br /> site is underlain by 8 to 24 feet of clayey deposits. This clay unit is <br /> underlain by a fairly continuous water-bearing clayey sand, which ranges <br /> from 4 to 18 feet thick. Most of the wells were terminated in this sand <br /> or in the underlying clay deposit. Two cross sections through the site <br /> show the stratigraphy of the water-bearing zone (Figures 3 and 4). <br /> Ground water generally occurs between 13 to lb feet below ground <br /> level. The liquid elevation (water and petroleum product) contour map <br /> constructed from measurements taken on June 21, 1984 (Figure 5) shows a <br /> liquid level high at Well E-3 in the southeast section of the site. <br /> This unusual configuration may be caused by the effects of mounding due <br /> to the lost product, and indicates that gasoline migrated radially from <br /> the tank complex prior to activation of the recovery system. <br /> PJD 438-22.04 5 <br /> "m(on Rssociates <br />