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Packer Testing <br />October 2012 <br />Attorney Work Product, <br />Confidential and Privileged <br />8 <br />103- 81640A <br />natural weathering solutions. The chemical composition of the leachate is analyzed for the constituents of <br />interest. <br />Packer injection testing of the bedrock will be conducted as part of the drilling program, prior to the well <br />installation. The objective of the packer injection testing is to determine the in -situ hydraulic conductivity <br />of discrete rock intervals in the boreholes. It is anticipated that testing will be performed across 5- or <br />10 -foot test intervals which will be isolated from the rest of the borehole using pneumatic packers. <br />Testing is conducted by lowering the packer assembly to the desired depth interval, inflating the packers <br />to seal off the interval, and then injecting clean water from a known source into the interval at either a <br />constant rate or pressure. Within each depth interval to be tested, it is anticipated that several <br />consecutive tests will be performed at different pressures. If the test interval intake is very low, falling <br />head test may be conducted through the packer testing apparatus, where the water level in the injection <br />pipe is monitored over time. <br />Data will be recorded on a field data sheet or in a field book. These data will include all measurements <br />and flow and pressure readings. Using these data the hydraulic conductivity will be estimated using the <br />Thiem equation (Thiem 1906) or other analytical methods deemed appropriate. <br />Well Installation <br />Wells will be installed in the boreholes as drilling is completed. As shown on Figure 5, the wells will be <br />constructed with 2 -inch diameter, flush threaded, Schedule 40 PVC screen and riser pipe, such that they <br />can be sampled for water quality. The screen in each well will be perforated with 0.010 -inch slots and <br />may be up to 20 feet in length. Final screen lengths will be determined in the field based on geology and <br />actual groundwater conditions observed during drilling. PVC casing will be added to the top of the screen <br />as it is lowered in the borehole until the screen reaches the desired depth and the casing extends 2 to <br />3 feet above the ground surface. The annular space around the screen and end cap will be backfilled <br />with clean, washed, well- rounded silica sand ( #10 -20 or equivalent). The sand pack will be gravity fed or <br />tremied from the bottom of the borehole to approximately 2 feet above the top perforation. A minimum of <br />2 feet of medium bentonite chips will be gravity fed into the annular space above the screen and filter <br />pack to provide a seal. Grout will be placed in the annular space above the bentonite seal to within <br />approximately 3 feet of the ground surface. The grout will be mixed and placed in accordance with the <br />State of Colorado Division of Water Resources (DWR) Water Well Construction Rules 2 CCR 402 -2. <br />Once the grout has cured, a protective steel casing will be placed around the PVC riser such that the <br />bottom extends into the annual space to the top of the grout and the top rises above the PVC casing <br />several inches. The protective casing will be equipped with a locking cover to prevent unauthorized entry <br />\10 \81640\ 0400 \characterizat onpIn_ fn1- 23oct12 \charactenzationpin_fnl- 23octl2 docx <br />Golder <br />Associates <br />