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SubTerra, Inc. Peabody Twentymile Coal, LLC 03/16/2015 <br />Foidel Creek Mine <br />Permit Revision for Longwall Mining in the Wolf Creek Seam - Subsidence Evaluation <br />6.5. Field Monitoring Program <br />Subsidence data will continue to be collected as part of Twentymile Coal, LLC's monitoring of the <br />railroad that runs over the Wolf Creek Seam in the Northern Mining District. These data will continue <br />to be used to verify the predictions at the locations of the power line structures. <br />It is recommended that Twentymile implements the field monitoring protocol previously applied during <br />the previous undermining of these power lines. In this case, a power line contractor was on stand-by <br />during power line undermining but was not mobilized. We understand that the wooden "H" frame <br />structures on the Foidel Creek — Steamboat line have previously been subject to more than 6 -ft of <br />subsidence without damage and the lattice structures on the Archer -Hayden and Craig -Hayden - <br />Steamboat Transmission Lines were subjected to up to 6 -feet of subsidence with only minor damage <br />(Hansen, 2002). <br />For this project we recommend that a detailed field -monitoring program be developed in consultation <br />with the power line Owners. <br />16 PN: 2013-26 <br />