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31 <br /> 06 January 2010 <br /> AGE-NC Project No. 98-0440 F <br /> Page 2 of 3 <br /> G <br /> any obstruction found in the well will be removed. Well boxes 'and caps will be removed to expose <br /> ` the casing. P <br /> Wells MW-1 through MW-12 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, <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 rade with a - <br /> g grout mixture (A <br /> ratio of six gallons water for every 94-pound sack of Portland cement will be utilized in preparation <br /> of the grout mixture) and covered with concrete or asphalt. k <br /> Well MW-13 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 <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 fo}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 surfacegrade (bsg)using 8.25-inch hollow stem au'` <br /> ers. A borehole one foot 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 All the boring to approximately 0.5 <br /> feet above the to of the well casing.The remain' <br /> P g mg borehole willj 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 /> :r <br /> Soil cuttings generated during over-drilling activities and rinseate will be containerized in properly <br /> labeled Department of Transportation (D.Q•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 /> .i <br /> Sincerely, <br /> �SNONAL GAO <br /> Advanced GeoEnvironmental, I ��W M1��<o� <br /> CO <br /> Z <br /> ` No.8574 <br /> P <br /> Brian W. Millman OF CAVE°� �• <br /> Project Geologist ° <br /> California Professional Geologist No. 8574 <br /> l <br />