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400 feet east of the project site. This well is screened from 144 to 176 feet below grade and <br /> is not expected to be affected by activities associated with this tank closure. <br /> 3.0 METHODS AND PROCEDURES <br /> ' To further assess the vertical extent of contamination, two additional angle soil borings were <br /> advanced beneath the existing tank utilizing 6-inch hollow stem augers These borings were <br /> ' advanced at 450 from vertical and terminated beneath the longitudinal center-lune of the tank <br /> ' approximately 22.5 feet, 37 feet respectively, beneath the tank bottom, (Figure 4). One vertical <br /> soil boring was also advanced to determine lateral extent of the contamination. To determine <br /> ' if groundwater has been impacted, one 85 foot monitoring well was installed. The location and <br /> orientations of the soil borings and monitoring well are depicted on Figure 5. Work commenced <br /> on January 15, 1991 and was completed on January 16, 1991. Drilling was conducted by <br /> Spectrum Exploration, Inc , under C57 License 512289, using a hollow stem auger drill rig. <br /> ' The well is constructed of 2-inch diameter F480 threaded PVC screen and casing No glues or <br /> solvents were used Screen slot size is 0.010 inch. Sand pack material is No. 2112 pre-washed <br /> silica sand A 2 foot bentonite seal was placed, prior to grouting, with neat cement grout All <br /> monitoring well construction details are shown on the Well/Bonng Log included in Appendix <br /> 1 III <br /> Drill cuttings were logged continuously for characterization of soil contamination and soil type <br /> ' by an experienced staff geologist using the Unified Soil Classification System Descriptions of <br /> soils encountered are as recorded on Well/Bonng Logs presented in Appendix III. Soil samples <br /> were collected from each boring at 5 foot intervals beginning at a depth of 5 feet below the <br /> surface. The samples were collected using a two-inch diameter by 18-inch long split spoon <br /> ' sampler lined with three, 6-inch long thin-walled brass soil tubes The sampler was driven its <br /> entire length using a 140-pound drop hammer. <br /> Select soil samples were submitted to Applied Analytical (DHS Certification no 1211) for <br /> laboratory analysis. Analyzed sample intervals are noted on the Boring Logs (Appendix III). <br /> ' erlsx122 me 4 <br />