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ARCADIS <br />The boring was completed to a total depth of 32 feet below ground surface (bgs). <br />Groundwater was encountered at approximately 17 feet bgs within a sandstone unit <br />(the Codell Sandstone). At approximately 18.5 feet bgs, the lithology changed to a <br />nonsaturated limestone; however, drilling continued to 32 feet bgs to provide a <br />reservoir for the groundwater encountered in this saturated section of the sandstone <br />unit in which to set the well screen. <br />On April 3, 2009, the groundwater monitoring well was installed. The well was <br />constructed of 2-inch schedule 40 polyvinyl chloride (PVC) casing with a screen <br />consisting of 0.010-inch slot size schedule 40 PVC, set from 15 to 30 feet bgs. The <br />boring was backfilled from 30 to 32 feet bgs with #10/20 silica sand. The monitoring <br />well was constructed in accordance with the State of Colorado well construction <br />guidelines using #10/20 silica sand for the filter pack from 13 to 30 feet bgs, 1/8-inch- <br />diameter bentonite pellets from 11 to 13 feet bgs and Type 1/11 Portland cement with <br />approximately 5 percent bentonite powder (i.e., cement-bentonite grout) from 2 to 11 <br />feet bgs (State of Colorado, Office of the State Engineer 2005). <br />Following the installation activities, a monitoring well permit application was submitted <br />to the Colorado DWR to finalize the permitting process. Holcim surveyed MW-13 using <br />a hand-held Global Positioning System (GPS) unit to obtain longitude, latitude and <br />elevation, and verified its location against a U.S. Geological Survey (USGS) map. A <br />well construction and test report was created using the boring log and survey <br />information, and the report was submitted on May 15, 2009 to the State of Colorado, <br />Office of the State Engineer to incorporate the well into the State's database. Copies of <br />the well permit application, well permit and well construction and test report are <br />included in Appendix E. <br />4.3 Monitoring Well Development Activities <br />The well screen was swabbed with a surge block for approximately 30 minutes to <br />develop the filter pack (by allowing the fines to settle and set up in the sand pack). The <br />groundwater level was later measured while surging the well, and the level was <br />approximately 15 feet bgs. Additional well development activities (i.e., purging the <br />groundwater and stabilizing the water quality parameters) occurred during groundwater <br />sampling on April 21, 2009 and were discussed in Section 2.2. <br />Final April 2009 <br />Groundwater <br />Monitoring Report <br />Florence, California <br />cAdocuments and setfingslstobgytrny documentslholciml025911978_holcimreg version_final.docx 11