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August 2013 4 103- 81640A <br />3.0 GROUNDWATER CHARACTERIZATION FIELD PROGRAM <br />Golder conducted a drilling, well installation and hydraulic testing field program at the Site between <br />November 28, 2012 and March 5, 2013 in general accordance with the approved Groundwater <br />Characterization Plan (Golder 2012) and modifications (Pottorff 2012). <br />The field program consisted of the following components: <br />• Drilling; <br />• Packer Testing; <br />■ Well Installation and Development; AND <br />■ Well Hydraulic Testing. <br />Three monitoring wells, MW -5, MW -6, and MW -7, were installed at the site as shown on Figure 1. <br />Monitoring well MW -5 was installed north of the CKD area in lieu of a true geographic upgradient location, <br />which would have required screening the well to the west where older and stratigraphically lower <br />formations than the Codell sandstone occur due to the easterly dip. Monitoring wells MW -6 and MW -7 <br />were installed to the top of the Codell sandstone at geologically down -dip and hydrogeologically <br />downgradient locations from the CKD disposal area and monitoring wells MW -1 through MW -4. These <br />two monitoring wells are screened across the same zone as monitoring wells MW -1 through MW -4, which <br />is the CKD disposal in the A -band mining cut. Each location was cleared for utilities prior to drilling. <br />3.1 Drilling <br />Drilling was performed by a Precision Sampling, Inc. (Precision) using a CME -55 truck - mounted rotary <br />drilling rig capable of hollow stem auger (HSA) and rock coring. Drilling was supervised by Golder <br />personnel. The drilling program involved advancing hollow stem augers through the fill to collect samples <br />using either split spoons or a CME style dry core sampler. Upon contact with bedrock, rock coring was <br />conducted to collect continuous samples of bedrock. To the extent practical, air was used as the drilling <br />fluid until first groundwater was encountered. The borings were advanced to a minimum of 20 feet below <br />first encountered groundwater. However, as work progressed, it was found that groundwater was <br />encountered a shallower depths than expected. Consequently, Holcim contacted the DRMS to adjust the <br />Plan to drill and set the downgradient monitoring wells (MW -6 and MW -7) to the top of the Codell <br />sandstone in order to monitor the same stratigraphic zone as monitoring wells MW -1 through MW-4. In <br />addition, rock coring was not conducted at monitoring well MW -6 to compensate for the increase in time <br />and cost due to the greater drilling depths. The DRMS approved Holcim's plan (Pottorff 2012). <br />A field hydrogeologist or technician was on site during drilling to prepare a lithologic log of each borehole <br />as drilling progresses. Soil descriptions include some or all of the following: <br />i \10 \81640a\ 0400\ gwcharwelhnstallfeldrep_ 09aug13\ gwcharwellinstallfieldrep _09aug13 docx <br />( I <br />30i Golder <br />Associates <br />