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  <br />   <br />   <br />  <br />  <br /> <br /> <br />DISCLAIMER: This report contains professional opinions based on information provided by the Owner. AAI makes <br />no warranties, either expressed or implied, as to the accuracy or completeness of the information herein. Opinions <br />are based on subjective interpretations of geologic data; other equally valid interpretations may exist. Identification <br />and control of hazardous conditions are the responsibilities of the Owner. <br />  <br /> 1536 Cole Blvd., Suite 310, Bldg. 4 715 Horizon Drive, Suite 340  <br /> Lakewood, CO 80401 Grand Junction, CO 81506 USA  <br /> +1 303.271.3750 +1 970.242.4220  <br />www.agapito.com  <br />December 7, 2021 227-43 <br />Mr. Lee Sampson, P.E. <br />Senior Mining Engineer <br />Colowyo Coal Company <br />5731 Highway 13 <br />Meeker, CO 81641-9124 <br />Re: Additional/Expanded Highwall Mining Areas, Collom Box Cut and South Taylor Pit, <br />Colowyo Coal Mine, Meeker, Colorado <br />Dear Lee: <br />As you requested on behalf of Colowyo Coal Company (Colowyo), Agapito Associates, Inc. (AAI) <br />has reviewed additional target areas for potential highwall mining (HWM) near the Collom box <br />cut (Collom) and from the South Taylor Pit (South Taylor). AAI previously studied HWM areas <br />for Collom and South Taylor and developed detailed reports for each.1,2 The additional/expanded <br />targets relative to the previously studied areas are shown in Figure 1. <br />AAI’s previous South Taylor study1 included mining of the G7 Seam, and where the G7 and G8 <br />Seams come together, their combined thickness (referred to as the G78 Seam). This mining was <br />planned from the low wall (southeast portion) and endwalls (southwest and northeast portions) of <br />the pit. Colowyo is currently considering an additional area not specifically addressed in our <br />previous report, in the northwest and southwest portions of the pit. The original study area and the <br />expanded area for South Taylor are shown in Figure 1. <br />AAI’s previous Collom study2 included mining of several seams from the low wall and endwalls <br />of the Collom Box Cut. Most of the targets are seam splits that occur close to one another, with <br />little or no parting thickness. For example, the B2/B3 Seam consists of the combined B2 and B3 <br />splits. Mining from the low wall generally included HWM panels mined downdip to the north. <br />This previously studied HWM area in Collom is also shown in Figure 1. Colowyo is currently <br />considering mining in an expanded area not specifically addressed in our previous report, as shown <br />in Figure 1. <br /> <br />AAI reviewed the relevant South Taylor1 and Collom2 HWM reports and the updated seam models <br />supplied by Colowyo for the target seams in the additional/expanded areas shown on Figure 1. The <br /> <br />1 Agapito Associates, Inc. (2014), “Geotechnical Design and Operational Considerations for Highwall Mining, South <br />Taylor Pit G78 and E/D2 Seams, and West Pit F, E, D2, and C Seams,” report to Colowyo Coal Company, <br />April 21, 78 pp. <br />2 Agapito Associates, Inc (2019a), “Geotechnical Design and Operational Considerations for Highwall Mining, <br />Collom Box Cut,” report to Colowyo Coal Company, November 20, 143 pp.