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Whetstone <br />Associates <br />Technical Memorandum <br />Table 2. Packer Locations for Three Stages of Corehole Grouting <br />Packer Location Depth from Steel Pipe Depth from PVC Pipe <br />(top of packer) (ft) (ft) <br />Top of bedrock, open hole 160 200 <br />10 ft above transition between open hole and steel pipe 150 190 <br />Near top of steel pipe 1 41 <br />3.1 Water Testing <br />Each stage will be water tested before grouting. A typical water test is performed by pumping water <br />into the section at a constant pressure for 15 minutes. Flows will be are recorded at 5 minute <br />intervals, and a lugeon values will be is calculated for each interval. A lugeon is defined as 1 liter of <br />water taken per meter of section at 10 kg/cm2 pressure (equivalent to a hydraulic conductivity of <br />approximately 1.5 x 10-3 cm/sec). Results from the water tests will be used to select the starting <br />grout mixture for the section. The standard test pressure will be 15 to 20 psi over the natural <br />hydraulic pressure at the corehole collar. The results of the water tests will be used to help <br />determine the starting W:C mixture. <br />3.2 Grout Placement and W:C Ratios <br />Starting W:C ratios will be determined based on the results of the water tests. To a large extent this <br />determination will rely on professional judgment because the same observed permeability can either <br />be a function of a few fractures with relatively large apertures, or many fractures with relatively <br />small apertures. A formation with many small fractures will have relatively lower permeability with <br />respect to grout than a formation with fewer larger fractures. The approach for grouting the corehole <br />will be to start with a relatively thin mixture (W:C = 2:1 or 1.5:1) and gradually thicken up to <br />achieve adequate penetration into the formation. The intent will be to thicken up the grout slowly <br />enough to prevent premature choking of the formation. The refusal criteria for the project will be <br />"no take" by the corehole or stage during a 15-minute period at the maximum allowable safe <br />pressure. No take will be verified by physical observation of the grout level in the agitator. <br />4. PROJECT PERSONNEL <br />Oversight and design would be provided by Whetstone Associates: <br />Scott Effner, Principal Hydrogeologist/Geochemist <br />Whetstone Associates, Inc. <br />243 N Main St. <br />Gunnison, CO 81230 <br />970-641-7471 (office) <br />970-964-8220 (mobile) <br />Grout installation would be provided by Hayward Baker: <br />Greg Boonstra, Rick Forsyth (Project Managers) <br />Hayward Baker / Denver Grouting <br />11575 Wadsworth Blvd. <br />Broomfield, CO 80020 <br />303-469-1136 <br />4109C.110106 4