2019-08-06_REVISION - C1981019 (14)

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2019. See Figures 1 and 2 for the location of the SL-15 partial Phase I, II and III Bond Release areas. III. CRITERIA FOR BOND RELEASE Phase I Bond Release The Division evaluated Colowyo's request for partial Phase I Bond Release on 68.7 acres in the SL- 15 application, as shown on Figures 1 —5 of this document. The process of releasing the reclamation bond for a coal mine site in Colorado is explained in Rule 3.03 and further described in the Division's 1995 Guideline Regarding Selected Coal Mining Bond Release Issues. The bond release process involves three phases. At Phase I, Rule 3.03.1(2) (a) states, "Up to sixty percent of the applicable bond amount shall be released when the permittee successfully completes backfilling, regrading, and drainage control in accordance with the approved reclamation plan." Evaluation and inspection of the reclaimed areas was based on the specific requirements of the reclamation plan and the functional requirements of the post-mining land use. Criteria for bond release included the following. 1. Hillslope and drainage channel gradients and general design compliance; 2. Performance of the reconstructed topography. Symptoms of failure or instabilities such as slumping or exposed highwalls were examined; 3. Hillslope design/function with regard to erosion; 4. Swales and depressions with regard to numbers of features and effect on post-mining land use; 5. Blending of regraded land to undisturbed areas; 6. The functioning of drainages with regard to knickpoints,blending at disturbance boundaries and channel erosion; 7. Erosional features; and 8. Drainage control for the reclaimed area, including upslope diversions. Colowyo's approved reclamation plan was prepared in accordance with Rule 2.05.4. Colowyo was granted a variance for contemporaneous reclamation for the East Pit, West Pit and the South Taylor Pit due to the nature of multi-seam mining. Backfilling and rough grading commenced once a steady-state condition was reached in each of the pits. The approved backfilling and grading plan for the Colowyo Mine is found in Volume 1 (East and West Pit), Volume 12 (South Taylor), and Volume 15 (Collom) of the PAP. Maps 19, 19A and 19B show the approved post-mining topography, Maps 29 and 29A, and 29B show the backfilling and grading schedule. The pre-mining and post-mining cross-sections are shown on Maps 20, 20A and 20B, and the permanent drainage channel profiles are shown on Maps 33, 33A, 33B, and 33C. Map 2 of the SL-15 application show cross-sections of the SL-15 area for the East and West, including approved post-mining topography alongside the constructed topography. Proposed Decision and Findings of Compliance August 6,2019 Partial Phase I,II and III Bond Release SL-15 Page 5