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Northwest Colorado Consultants, Inc. <br /> Geotechnical/Environmental Engineering•Materials Testing <br /> January 9,2020 <br /> Twentymile Coal Company <br /> 29515 RCR 427 <br /> Oak Creek,CO 80467 <br /> Attn: Miranda Kawcak <br /> Job Number: 99-3983 <br /> Subject: Quarterly Observation Report,Refuse <br /> Pile,Foidel Creek Mine,Routt County,Colorado. <br /> Miranda, <br /> As requested, NWCC, Inc. (NWCC) has prepared this report outlining our observations made during the <br /> fourth quarter of 2019 at the Refuse Pile located at Twentymile Coal Company's(TCC)IA oidel Creek Mine <br /> in Routt County, Colorado. During this quarter, Timothy Travis of NWCC visited the project site on <br /> December 31,2019 to provide the quarterly inspection/observations of the Refuse Pile. <br /> At the time of our site visit on December 31, 2019, NWCC completed a site inspection of the existing <br /> refuse pile. Based on our observations made during this visit, it appeared that the contractor was presently <br /> stockpiling and compacting refuse coal in the new Expansion Area. At the time of our site visit,the refuse <br /> coal had been placed and compacted to an elevation near the third bench situated along the east side of the <br /> stockpile. <br /> In addition, compaction testing in the new Expansion Area of the refuse pile was also completed on this <br /> date. Four compaction tests (#583 to #586) were taken in Expansion Area during this quarter. All of the <br /> tests taken during this quarter met the minimum compaction requirement of 90% of the maximum standard <br /> Proctor density. Copies of the compaction test results and the daily field reports are attached. It should be <br /> noted that the abbreviations given in the Nuclear Density Test Results (Proctor Data) are as follows: <br /> Maximum DD = Maximum Dry Density and OMC = Optimum Moisture Content. Both of these values <br /> have been determined in accordance with ASTM D698. <br /> The internal roadways in the new expansion area of the pile are in good condition; however, our <br /> observations were limited by snow cover. The upper haul road to Areas 2, 3 and 4 of the refuse pile was <br /> not accessible at the time of our site visit due to snow. <br /> A seepage area at the toe of the northeast end of the refuse pile expansion area, approximately 30 feet <br /> northwest of the outlet of the underdrain, developed in fall 2014. At the time of our observations, the <br /> seepage was surfacing at the toe of the slope and flowing into the drainage from the undrain outlet then into <br /> the existing pond east of the Refuse Pile Expansion Area. The discharge was clear, with no evidence of <br /> sediment. No signs of washout, slumps or slope instability were observed at this time. The seepage area <br /> (970) 879-7888 • Fax (970) 879-7891 <br /> 2580 Copper Ridge Drive • Steamboat Springs,CO 80487 <br />