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ARCADIS <br />4.4 Monitoring Well Abandonment Activities <br />On April 7, 2009, three groundwater monitoring wells (MW-6, MW-8 and MW-10) were <br />abandoned via pressure-grouting techniques. Water was measured in wells MW-8 and <br />MW-10. Therefore, per State well abandonment guidelines, the wells were filled to <br />static water level with clean sand (#16/30 silica sand), prior to emplacing the cement- <br />bentonite grout. Approximately three 98-pound bags of silica sand were used <br />downhole at MW-8 to bring the sand up to static water level. Approximately two 98- <br />pound bags of silica sand were used downhole at MW-10. The grout mixture was <br />pumped downhole through 1-inch PVC tremie pipe. Approximately 60 gallons of <br />cement-bentonite grout was used to abandon MW-6, approximately 60 gallons to <br />abandon MW-8 and approximately 40 gallons to abandon MWA 0. <br />After abandoning the wells by pressure-grouting methods, a loader was used to <br />remove the surface completions at the three wells. Abovegrade well surface <br />completions (i.e., steel casing) and protective posts were removed from each of the <br />three wells. The surface completion debris was disposed at a local private landfill. <br />Following the abandonment activities, monitoring well abandonment reports were <br />submitted on May 15, 2009 to the State Colorado, Office of the State Engineer. Copies <br />of the well abandonment reports are included in Appendix E. <br />Final April 2009 <br />Groundwater <br />Monitoring Report <br />Florence, California <br />cAdocuments and settings\stobgy\my documents\holcim\025911978_holcimreg version_final.dou 12