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Battle Mountain Resources—San Luis SL-SOP-Groundwater Well Decommissioning <br /> STANDARD OPERATING PROCEDURES REVISION: 0-May 6,2019 <br /> In a complex situation, one or more decommissioning procedures may be used for <br /> different intervals of the same well. <br /> The remainder of Section 4 discusses the well decommissioning methods and the <br /> selection process. Refer to Attachment 13-2 for a flow chart diagram of the complete <br /> procedure selection process. The project manager has the discretion to deviate from the <br /> flow chart, (Attachment 13-2), based on site conditions and professional judgment. <br /> 4.1. Grouting In-Place <br /> Grouting in-place is the simplest and most frequently used well decommissioning <br /> method and grouting itself is the essential component of all the decommissioning <br /> methods. The grout seals the borehole and any portion of the monitoring well that may <br /> be left in the ground. Because dirt and foreign objects can fall into an open well, <br /> whenever possible a well should be sealed first with grout before attempting <br /> subsequent decommissioning steps. <br /> For the purpose of these decommissioning procedures, the well seal is defined as <br /> the bentonite seal above the sand pack. Aside from obvious channeling by in-flowing <br /> surface water around the well, an indication of the well seal integrity may be obtained <br /> through review of the boring logs and/or a comparison of groundwater elevations if <br /> the well is part of a cluster. Any problems noted on the boring logs pertaining to the <br /> well seal, such as bridging of bentonite pellets or running sands, or disparities <br /> between field notes (if available) and the well log would indicate the potential for a <br /> poor (compromised) well seal. <br /> If the well seal is not compromised and there is no confining layer present, a single- <br /> stem, <br /> 2-inch PVC, monitoring well can be satisfactorily decommissioned by grouting it in- <br /> place. If the seal is compromised, casing perforation may be called for as discussed <br /> in Section 4.2. <br /> As discussed in Section 4.4 and its sub-sections, this method is specified for the <br /> bedrock portion of a well, and is used for decommissioning small diameter cased <br /> wells. Grouting in-place involves filling the casing with grout to a level of five feet <br /> below the land surface, cutting the well casing at the five-foot depth, and removing <br /> the top portion of the casing and associated well materials from the ground. The <br /> casing must be grouted according to the procedures in Section 8. In addition, the <br /> upper five feet of the borehole is filled to land surface and restored according to the <br /> procedures described in Section 9. <br /> For open-hole bedrock wells, the procedure involves filling the opening with grout to <br /> the top of rock according to the procedures in Section 7. A thicker grout may be <br /> required to fill any bedrock voids. If excessive grout is being lost down-hole, consider <br /> grouting in stages to reduce the pressure caused by the height of the grout column. <br /> The standard mix with the maximum amount of allowable water will be required to <br /> penetrate the well screen and sand pack when a well assembly has been installed <br /> within a bedrock hole. For an assembly such as this, the grout should be mixed thinly <br /> SL-SOP Well Decommissioning EA, Inc.' <br /> Battle Mountain Resources, Inc. 711 Page 6 of 21 Ma 6, 2019 <br />