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Battle Mountain Resources—San Luis SL-SOP-Groundwater Well Decommissioning STANDARD OPERATING PROCEDURES I REVISION: 0-May 6,2019 that may be present in the well. The tremie pipe or tube is withdrawn as (or after) the well is filled with grout. Using the tremie, grout is placed in the borehole filling from the bottom to the top. Two- inch and larger wells should use tremie tubing of not less than 1-inch diameter. Smaller diameter wells will call for a smaller tremie pipe. Grout will then be pumped in until the grout appears at the land surface (when grouting open holes in bedrock, the grout level only needs to reach above the bedrock surface). Any groundwater displaced during grout placement, if known to be contaminated, will be contained for proper disposal. At this time the rate of settling should be observed. If grouting the well in place, the well casing remains in the hole. But if the decommissioning method has involved down-hole tools such as hollow-stem augers or temporary casing for over-drilling, these will be removed from the hole. As each section is removed, grout will be added to keep the level between 0 and 5 feet below grade. If the grout level drops below the land surface to an excessive degree, an alternate grouting method must be used. One possibility is to grout in stages; i.e., the first batch of grout is allowed to partially cure before a second batch of grout is added. As previously described in Section 7.0, the outer protective casing "stick-up" should be removed only after a well has been properly filled with grout. This will ensure that the well is properly sealed regardless of any breakage which may occur when removing the stick-up. It is important to reiterate that when either casing pulling or over-drilling are required, due to the uncertainty of successfully pulling a well or over- boring a well, we insist that the driller tremie grout the well first. Then without allowing the grout to dry, the driller proceeds with pulling the casing or over-drilling the well. Upon completion of grouting, ensure that the final grout level is approximately five feet below land surface. A ferrous metal marker will be embedded in the top of the grout to indicate the location of the former monitoring well. Lastly, a fabric "utility" marking should be placed one foot above the grout so an excavator can see it clearly. 9. BACKFILLING AND SITE RESTORATION The uppermost five feet of the borehole at the land surface should be filled with material physically similar to the natural soils. The surface of the borehole should be restored to the condition of the area surrounding the borehole. For example, concrete or asphalt will be patched with concrete or asphalt of the same type and thickness, grassed areas will be seeded, and topsoil will be used in other areas. All solid waste materials generated during the decommissioning process must be disposed of properly. 10. DOCUMENTATION A form which may be used in the field to record the decommissioning construction is included as Attachment 13-3. Additional documentation and notifications may be required by a project manager and/or regulatory agencies which should be verified prior to initiating decommissioning. Programs that maintain geographic data on monitoring wells should strive to keep that data up to date. Owners of these data sets must be notified when a well is SL-SOP Well Decommissioning EA, Inc. Battle Mountain Resources, Inc. Page 14 of 21 May 6,2019