Laserfiche WebLink
Coors Energy Company Keenesburg Mine—Phase III Bond Release Application <br /> Revegetation Success Demonstration <br /> 4 Bond Release Standards <br /> The Keenesburg Mine Reclamation Permit includes a species composition standard and <br /> predictive equations to determine the success standards for vegetation cover and herbaceous <br /> production. The equations for both cover and production were revised in 2012 with a Technical <br /> Revision to the permit(TR43) and the cover standard was revised again in 2014 with a Minor <br /> Revision(MR46)to the permit. Both the vegetation cover and herbaceous production equations <br /> use the previous year's precipitation(September—July)to predict the success standard for any <br /> given year. These equations are as follows, where x is equal to the cumulative September—July <br /> precipitation: <br /> Vegetation Cover Standard=-0.0127x3+0.2115x2+2.1772x <br /> Herbaceous Production Standard= 0.4666x2.'405 <br /> To meet the reclamation standard specified in the permit, data are subjected to statistical testing <br /> as described in the DRMS Regulations of the Colorado Mined Land Reclamation Board for Coal <br /> Mining (DRMS 2020). Per this guideline, <br /> 1. If the sample mean for the Reclamation Area is equal to or greater than 90% of the <br /> approved technical standard, and a statistically adequate sample size was collected, <br /> revegetation is considered successful. <br /> 2. If the sample mean for the Reclamation Area is less than 90% of the approved <br /> technical standard, and a statistically adequate sample size was collected,the dataset <br /> is subjected to hypothesis testing using a one-sample T-test with a one-tailed <br /> confidence interval of 90%. <br /> 3. If the sample mean for the Reclamation Area is equal to or greater than 90% of the <br /> approved technical standard, and a statistically adequate sample size was not <br /> collected, the dataset is subjected to hypothesis testing using a one-sample T-test with <br /> a reverse null hypothesis and a one-tailed confidence interval of 80%. <br /> Noxious species cover or production is removed as well as annual vegetation cover or production <br /> in excess of 10% of the overall average for each Reclamation Area to derive the allowable <br /> vegetation cover or production value used for hypothesis testing per the DRMS Guideline <br /> Regarding Selected Coal Mine Bond Release Issues (DRMS 1995). <br /> Species composition is considered an indicator of successful vegetation establishment and a <br /> diverse vegetation community. The species composition standard for the Keenesburg Mine was <br /> modified in 2020 with a Technical Revision to the permit(TR47). The revised standard requires <br /> that there be at least four perennial grass species, each of which comprise between 3% and 40% <br /> relative cover. Any perennial grass species, native or introduced,that is not defined as a noxious <br /> species may be used in the calculation of species composition. <br /> The Phase III bond release guidelines require that vegetation cover,herbaceous production, and <br /> species composition meet the standards for two years. Table 4 presents the Phase III bond release <br /> standards for 2021 and 2022. Monthly precipitation data used to calculate these standards is <br /> presented in Attachment 1. <br /> SL-12 8 May 2024 <br />