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2, Field Activities <br />2.1 Installation of New Monitoring Wells <br />In accordance with applicable Colorado state regulations for mining operations (DMG, 2001), <br />and to satisfy the requirements for approval of TR-06 set forth by the DMG in its second <br />adequacy review letter dated October 22, 2002, two new monitoring wells were installed within <br />the permit boundary from June 23 through 25, 2003. The first well, MW-12, was installed <br />adjacent to existing monitoring well MW-6 and was completed to the base of the Codell <br />sandstone (Figure 2). The purpose of MW-12 is to characterize the quality of groundwater in the <br />Codell Sandstone upgradient of the mining and CKD disposal areas. The second well, MW-] 1, <br />was installed neaz the quarry office (Figure 2). The purpose of MW-11 is to chazacterize the <br />quality of groundwater downgradient from all CICD disposal areas. Monitoring well MW-11 has <br />been designated as the compliance well for the permitted area. <br />Monitoring wells MW-11 and MW-12 were installed by Layne Western, Inc. using air rotary <br />drilling techniques. Well casings were constructed using two-inch diameter, Schedule 40 PVC, <br />threaded blank pipe and well screen (0.010-inch slot size). Colorado Silica 10-20 was used as <br />filter pack material and cement/bentonite grout seals were placed in each of the wells (Table 1). <br />The wells were developed by bailing approximately 3 casing volumes from each well. Well logs <br />are included in Appendix A. <br />A survey of the new wells was performed by a qualified land surveying company. Elevations <br />were established for the top of each casing with an accuracy of 0.01 fr. A referenced survey point <br />was demarcated with a black mark on the north side of each well casing from which the depth to <br />groundwater will be measured. <br />2.2 Groundwater Sampling <br />Field sampling methods and procedures described below include sample collection methods, <br />sample handling procedures, sample chain of custody procedures, and collection of quality <br />control samples. <br />Groundwater sampling activities were conducted at the site on August 7 through 9, 2003. <br />Groundwater sampling activities included measurement of the depth to groundwater at each of <br />the five pre-existing and two new monitoring wells (MW-6, MW-7, MW-8, MW-9, MW-]0, <br />MW-11, and MW-12), and piezometers PZ-2 and PZ-3, as well as purging and sampling of all <br />seven monitoring wells. <br />The depth to groundwater was measured using an electronic water level indicator prior to the <br />initiation of monitoring well purging and sampling activities. Prior to the collection of <br />groundwater samples, three well casing volumes of water were purged, or wells were purged dry. <br />Two different purging methods were used depending upon the total cased depth of the monitoring <br />well. If the total cased depth of the monitoring well was greater than 60 ft, the well was purged <br />using a dedicated Teflon bailer. If the total cased depth of the monitoring well was less than 60 <br />fr, the monitoring well was purged using a direct current pump with dedicated tubing. <br />Monitoring wells MW-6, MW-7, MW-9, and MW-]0 were bailed and monitoring wells MW-8, <br />MW-11, and MW-12 were pumped. <br />1:U-lolcim\GW Monitoring Report\9A332186.doc 2_ 1 <br />