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Battle Mountain Resources—San Luis SL-SOP-Groundwater Well Decommissioning <br /> STANDARD OPERATING PROCEDURES REVISION: 0 -May 6,2019 <br /> 8.1. Standard Grout Mixture <br /> For most boreholes, the following standard mixture will be used: <br /> • One 94-pound bag Type I Portland cement; <br /> • 3.9 pounds powdered bentonite; and <br /> • 7.8 gallons potable water. <br /> Slightly more water may be used in order to penetrate a sand pack when a well <br /> screen transects multiple flow zones. This mixture results in a grout with a bentonite <br /> content of four percent by weight and will be used in all cases except in boreholes <br /> where excessive use of grout is anticipated. In these cases, a special thicker <br /> mixture will be used. <br /> 8.2. Special Mixture <br /> In cases where excessive use of grout is anticipated, such as high permeability <br /> formations and highly fractured or cavernous bedrock formations, the following <br /> special mixture will be used: <br /> • one 94-pound bag type I Portland cement; <br /> • 3.9 pounds powdered bentonite; <br /> • 1 pound calcium chloride; and <br /> • 6.0-7.8 gallons potable water (depending on desired thickness). <br /> The special mixture results in a grout with a bentonite content of four percent by <br /> dry weight. It is thicker than the standard mixture because it contains less water. <br /> This grout is expected to set faster than the Standard Grout Mixture due to the <br /> added calcium chloride. The least amount of water that can be added for the <br /> mixture to be readily pumpable is 6 gallons per 94-pound bag of cement. <br /> 8.3. Grout Mixing Procedure <br /> To begin the grout-mixing procedure, calculate the volume of grout required to fill the <br /> borehole. If possible, the mixing basin should be large enough to hold all of the grout <br /> necessary for the borehole. <br /> Mix grout until a smooth, homogeneous mixture is achieved. Grout can be <br /> mixed manually or with a mechanized mixer. Colloidal mixers should not <br /> be used as they tend to excessively decrease the thickness of the grout for <br /> the above recipes. <br /> 8.4. Grout Placement <br /> This guidance requires that grout be placed in the well from the bottom to the top <br /> by means of a "tremie." A tremie is a pipe, a hose or a tube extending from the <br /> grout supply to the bottom of the well. The tremie delivers the grout all the way <br /> down through the water column without its being diluted and mixed with the water <br /> SL-SOP Well Decommissioning EA, Inc. <br /> Battle Mountain Resources, Inc. Page 13 of 21 Ma 6, 2019 <br />