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' h <br /> ti <br /> 06 January 2010 <br /> AGE-NC Project No. 00-0697 F r <br /> Page 2 of 3 <br /> the casing. <br /> Wells MW-1 through MW-5 will be drilled-out to their total depth utilizing 8-inch diameter hollow <br /> stem augers.All original well construction materials will be removed(including well casing,screen, t <br /> filter pack,and annular seal)to ensure that no residual contamination is sealed within the abandoned <br /> borehole. The remaining borehole will then be backfilled to surface grade with a grout mixture (A <br /> ratio of six gallons water for every 94-pound sack of portland cement will be utilized in preparation i <br /> of the grout mixture) and covered with concrete or asphalt. <br /> Well MW-6 will be destroyed by pressure grout techniques. The well head will be fitted with a <br /> pressure tight adapter connected to a hose extending from a grout mixer.A ratio of six gallons water I <br /> for every 94-pound sack of portland cement (grout) will be utilized in preparation of the grout <br /> mixture.The grout mixture will be pumped into the well casing for 3-5 minutes under approximately <br /> 10-15 pounds per square inch(psi)of pressure.The well will then be over-drilled to approximately <br /> 3 feet below surface grade(bsg)using 8.25-inch hollow stern augers. A borehole one foot larger in <br /> diameter then the original boring will be excavated down to 3 feet bsg. The top 2.5 feet of the well <br /> casing will then be cut and removed and grout will be used to fill the boring to approximately 0.5 <br /> feet above the top of the well casing.The remaining borehole will then be backfilled to surface grade <br /> with the soil cuttings removed from the top 3 feet of the boring and covered with concrete or asphalt. <br /> Soil cuttings generated during over-drilling activities and rinseate will be containerized in properly <br /> labeled Department of Transportation(D.O.T.)-approved 55-gallon drums or a landfill disposal <br /> container, and stored on-site for disposal, in an area lacking public. <br /> If you have any questions or require further information,please contact our office at.(209)467-1006. <br /> F <br /> Sincerely, <br /> S\ONAL.GAO <br /> Advanced GeoEnvironmental,I <br /> No.8574 <br /> Brian W. Millman r� aF <br /> Project Geologist <br /> California Professional Geologist No. 8574 <br /> F <br /> i <br />