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1 <br /> i <br />' 3. SUBSURFACE INVESTIGATION <br /> ETIC observed the drilling of four soil borings (EBI and IPI-IP3) between 20 and 22 September <br /> 2004 The soil borings were drilled using hollow-stem auger drilling methods <br /> Three of the soil bonngs (IPI-IP3) were completed as injection point pairs (IPIA, IP113, 22A, <br />' IP213, and IP3A, IP313) The injection point pairs were installed as two nested stainless steel <br /> injection points (one point for the potential injection of ozone [IP113, IP2B, and IP3B] and one <br /> point for the potential injection of hydrogen peroxide [IP1A, IP2A, and IP3A]) The injection <br />' point boreholes were advanced to a depth of approximately 40 feet Three-foot ozone points <br /> were installed at depths between approximately 33 and 39 feet, and one-foot hydrogen peroxide <br /> points were installed at depths between approximately 29 and 315 feet The injection points <br />' were installed in the suspected source area, the location of the former tanks If 1n situ chemical <br /> oxidation using a combination of ozone and hydrogen peroxide is a viable option as a remedial <br /> technology, the suspected source area would be targeted first <br />' The exploratory boring (EB 1) was drilled to a depth of approximately 60 feet The exploratory <br /> boring was installed to further define the vertical extent of hydrocarbon impacted soil <br />' A permit to install the injection points and exploratory boring was obtained from the SJCEHD <br /> prior to drilling and is included in Appendix C The locations of the injection points and <br />'. exploratory boring are shown on Figure 2 <br /> 3.1 DRILLING OF SOIL BORINGS <br />' The borings were cleared on 17 September 2004 by Cascade Drilling, Inc of Rancho Cordova, <br /> California (C-57 license #717510) with an air knife and vacuum ng to ensure that there were no <br />' obstructions near the potential path of the augers Each boring was cleared to a depth of 8 feet <br /> bgs <br />' The borings were drilled between 20 and 22 September 2004 by Cascade Drilling, Inc using a <br /> CME 75 drill ng equipped with 8 25-inch-diameter hollow-stem augers The borings were <br /> logged every 5 feet and then continuously from 20 feet bgs to the total depth, and selected soil <br />' samples were collected from each boring for laboratory analysis <br /> IPI was drilled to a total depth of 41 feet bgs, and IP2 and IP3 were each dulled to a total depth <br />' of 40 feet bgs Exploratory boring EBI was drilled to a total depth of 62 feet bgs, and upon <br /> completion of soil sampling EB I was abandoned with a cement grout <br />' The hollow-stem augers and downhole equipment were pressure washed before drilling began <br /> and upon completion of each borehole Equipment rinsate was collected in 55-gallon drums and <br /> temporarily stored on the site Field methods and procedures are descnbed in the protocols, <br />' presented in Appendix D <br />' G\Pro,sects\73942\7A5TERIWP11PR1204UPRtm doc 6 <br />