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Varra - Coulson Stability Analysis <br />2/14/14 <br />Page 2 of 2 <br />4. Please include an additional stability analysis for the proposed clay liner and keyway in the <br />final reclamation model. <br />5. The Applicant's cross section analysis dated January 13, 2014 represents the final <br />reclamation grade at 2.45H:1V, not the required 3H:1V slope. Please revise the stability <br />analysis with the correct reclamation slope. <br />6. Please include residual soil strength parameters (124 unit weight, 0 effective cohesion and <br />14 effective friction angle) for the upper 2.5 feet of weather bedrock, at minimum. <br />7. Please provide the Division with the slope stability monitoring plan to be used during mining <br />and reclamation activities at the site. <br />8. The stability analysis was based on generalized conditions and produced a factor of safety <br />less than 1.3. Since the factor of safety was less than 1.3, the Division will require the <br />Applicant to obtain structure agreements for all property, including easement holders, and <br />structure owners within two hundred feet of the affected land. <br />9. The soil properties used by AWES, LLC for the Varra - Coulson stability analysis were taken <br />from the Western Sugar and Durham sites. Therefore, the Division will require the <br />Applicant to use the most conservative soil parameters for the analysis at the Varra - Coulson <br />site. <br />The Division will verify the Applicant's stability analysis models using Clover Technology's <br />Galena v6.0 slope stability software following the Applicant's response to this letter. <br />If you have any questions, please contact me at 303 - 866 -3567 Ext. 8124. <br />Sincerely, <br />Peter S. Hays <br />Environmental Protection Specialist <br />Cc: Tom Kaldenbach - Division of Reclamation, Mining & Safety <br />Joby Adams - AWES, LLC (by email) <br />