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Technical Memorandum <br /> DATE: 3 May, 2021 PROJECT: Cross Mine <br /> ATTENTION: Richard Mittasch COMPANY: Grand Island Resources, LLC <br /> PREPARED BY: Dave Hallman, PE, PG REVIEWED BY: RM <br /> SUBJECT: Idaho Tunnel Portal—Slope Stability Analysis <br /> 1.0 INTRODUCTION <br /> This Technical Memorandum has been prepared to present geotechnical stability analyses for the slopes <br /> adjacent to the Idaho Tunnel Portal in response to a stipulation presented in the TR-7 authorization from <br /> DRMS dated December 3, 2020 in conjunction with the Cross Mine, DRMS Permit No. M-1977-410. The <br /> Idaho Tunnel (at the Caribou Mine) was in a collapsed condition creating potential slope stability issues <br /> near the northern permit boundary and the adjacent Caribou Road. This is a concern pursuant to Rule <br /> 3.1.5(3) and C.R.S. 34-32-116(7)(h)which require areas outside of the affected land to be protected from <br /> slides or damage occurring during the mining operation and reclamation. In order to address this concern <br /> the portal slope has been stabilized, reinforced and will be backfilled to a final slope of 3H:1V below the <br /> county road for reclamation using waste rock. <br /> As indicated in the authorization letter from DRMS, once the Idaho Tunnel was sufficiently stabilized to <br /> allow the necessary information to be collected and analyzed,the operator is required to submit updated <br /> engineering stability analysis which demonstrates the portal slope meets the stability requirements of the <br /> Mined Land Reclamation Board (as described in the Memorandum from Peter Hays, DRMS, dated May <br /> 27, 2020). This memorandum presents the required stability evaluation based on updated engineering <br /> data now that the tunnel has been adequately stabilized. The analyses were conducted by Mr. David <br /> Hallman,a geological engineer with 38 years of experience and licensed as Colorado Professional Engineer <br /> (Civil) 26076, as affirmed by the stamp and signature affixed at the end of this document. <br /> 1.1 BACKGROUND <br /> 1.1.1. Location <br /> The Cross Mine site is located approximately 3 miles west of Nederland, Colorado adjacent to the <br /> Roosevelt National Forest, at an elevation of 9700 feet above mean sea level (MSL).The general location <br /> is parcels of land in Section 9, Township 1 South, Range 73 West of the 6 Principal Meridian, County of <br /> Boulder, State of Colorado. This is an existing hard rock mining operation owned by Grand Island <br /> Resources Inc. (GIR), although at present, no active mining is being conducted. <br /> 1.1.2. Idaho Tunnel <br /> The Idaho Tunnel provides access to the Caribou Mine portion of the site. The timbered tunnel entrance <br /> and area around the opening were excavated in order to stabilize the historic tunnel portal. This effort <br /> involved excavating approximately 25 feet into the hillside, installing soil anchors, and applying a layer of <br /> fiber-reinforced shotcrete. The excavated slopes stood unsupported following excavation and were dry <br /> Applied GeoLogic LLC 5/3/2021 <br />