Laserfiche WebLink
1 <br /> WEISS ASSOCIATES M64 <br /> 2 PHASE II SUBSURFACE INVESTIGATION <br /> P C Exploration of Roseville,California drilled three angle borings and three vertical <br /> borings and installed three ground water monitoring wells between January 15 and 25, 1991 <br /> Eric Anderson, WA Staff Geologist, directed the drilling and well installation under the <br /> supervision of Joseph P Theisen, California Registered Geologist No 4981 <br /> i <br /> Soil samples were collected beneath Vaults 1,6 and 8 and analyzed for the compounds <br /> formerly stored in each vault The angle borings were drilled at angles to profile soil conditions <br /> directly below and adjacent to each vault The vertical borings were drilled to further define <br /> soil conditions and to install ground water monitoring wells Where possible, the borings for <br /> the wells were drilled in the anticipated downgradient direction from the vaults, which was <br /> presumed to be west northwest, parallel to the regional topographic gradient <br /> R <br /> 21 SOIL BORINGS <br /> WA drilled one angle boring and one vertical boring adjacent to each vault All borings <br /> were initially drilled with 6-inch outside diameter(O D )hollow stem augers The angle borings <br /> were drilled adjacent to each vault at angles of between 60 to 69 degrees from horizontal to <br /> penetrate sediments directly below and across the width of the vault After sampling,the angle <br /> borings were filled with cement grout containing 3-5%bentonite powder The vertical borings <br /> were drilled immediately adjacent to each vault as close to the presumed downgradient <br />' direction from the vault as drill rig access would allow After reaming the vertical borings <br /> with 10-inch OD hollow stem augers, the monitoring wells were installed as described in <br /> Section 2 3 The locations of all borings are shown in Figures 3 through 5 and the boring logs <br /> for the vertical borings are presented in Appendix A <br /> Soil samples were collected below the vaults beginning at about 13 ft depth and then <br /> at 5-foot intervals The vertical borings were 40 to 55 ft deeper than the angle borings and soil <br /> s <br /> samples were collected to a maximum depth of approximately 96 ft, which was about 25 ft <br /> below the water table The samples collected below the water table were used for lithologic <br /> i <br /> D IALL1331DWG1331R1MA1 WP Page 6 <br />