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Coors Energy Company Keenesburg Mine—Phase III Bond Release Application <br /> Revegetation Success Demonstration <br /> Table 4: 2021 and 2022 Bond Release Standards <br /> Sept-July Vegetation Herbaceous <br /> Precipitation Cover Production <br /> Year (inches) (%) (g/m2) Species Composition <br /> 2021 9.8 27.2 21.0 4 perennial grass species, <br /> 2022 6.6 19.9 11.0 3%-40%relative cover <br /> 5 Revegetation Success Evaluation Results <br /> A summary of each parameter evaluated for Phase III bond release is presented below. <br /> Vegetation cover and species composition data from 2021 for each Reclamation Area is <br /> presented in Attachment 2. Herbaceous production data from 2021 for each Reclamation Area is <br /> presented in Attachment 3. Vegetation cover and species composition data from 2022 for each <br /> Reclamation Area is presented in Attachment 4. Herbaceous production data from 2022 for each <br /> Reclamation Area is presented in Attachment 5. <br /> 5.1 Vegetation Cover <br /> The average allowable vegetation cover for Reclamation Area 31 was greater than 90% of the <br /> calculated standard and a statistically adequate sample was collected,thus no hypothesis testing <br /> was required in 2021 or 2022 (Table 5 and Table 6,respectively). Reclamation Areas 29/23 and <br /> 30 were both subjected to hypothesis testing with a reverse null hypothesis in both 2021 and <br /> 2022 (Table 5 and Table 6, respectively). Both areas passed the standard in both years. <br /> Table 5: Vegetation Cover Success Standard Comparison for 2021 <br /> 2021 <br /> Vegetation Cover Area 29/23 Area 30 Area 31 <br /> Average Allowable Cover(%) 29.1 27.5 37.7 <br /> Technical Standard(%) 27.2 <br /> 90% of Standard(%) 24.5 <br /> T-Test T-Test Direct <br /> Statistical Testing Reverse Null Reverse Null <br /> Hypothesis Hypothesis Comparison <br /> T-Value 4.84 4.37 n/a <br /> T Critical Value -0.863 -0.868 n/a <br /> Standard Passed? Yes Yes Yes <br /> SL-12 9 May 2024 <br />