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w The other five water supply wells within 1 mile of the site are used for <br /> ornamental and irrigation purposes. The four private wells (191.1, 191, <br /> 19P2, and 30B1), located in the Lincoln Village West area, 3/4-mile west <br /> or the site, are used to fill an artificial lake during the summer. The <br /> Lincoln Village wells are drai;�Ing from an aquifer 156 to 174 feet below <br /> the surface. The PG&E well (21MI) approximately 1 mile south of the <br /> site is used for lawn irrigation. <br /> SITE INVESTIGATION <br /> subsurface investigation at <br /> _. In May 1984, EMCON Associates initiated a s • <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 frau auger-return <br /> materials and by using a California split-Spoon sampler advanced into <br /> undisturbed soil beyond the tip of the auger:' La;s of exploratory <br /> borings along with the Welt construction details are presented in <br /> Appendix A. All exploratory borings were converted to monitoring wells <br /> �- 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 /> T!ie exploratory borings ranged in depth from 19-1/2 to 30 feet, The <br /> - <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 IS 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 /> stow the stratigraphy of the water-bearing zone (Figures 3 and 4). <br /> Ground :+iter generally occurs between 13 to 16 feet below ground <br /> level. The liquid elevation (water and petroleum product) contour map <br /> constructed frc-.i measurements taken on June 23, 1984 (Figure 5) shows a <br /> I E-3 in the southeast section of the site. <br /> liquid level high at Wel <br /> This unusual configura•Liori may be caused by the effects of mounding due <br /> to the lost product, anf,, indicates that gasoline migrated radially from <br /> the tank complex,.prior to.actiration of the recovery system. . <br /> .. pJ0 438-22.04 5 1i <br /> �— Emcon Assr,ciotel <br />