Laserfiche WebLink
<br />Proposed Decision and Findings of Compliance October 2018 <br />Partial Phase II and III Bond Release SL-14 Page 8 <br />WP015 as a whole. All three of the reclamation parcels met the requirements for their requested <br />Phased Bond release as summarized in this document below. <br /> <br />All reclamation parcels contained in SL-14 being requested for Phase II bond release were sampled <br />in 2016 or 2017 in accordance with the vegetation monitoring plan, detailed in Volume 1, Section <br />4.15 in the Colowyo PAP. Sample adequacy was determined using the Cochran formula. Both the <br />sampling plan and the sample adequacy determination are acceptable to the Division. <br /> <br />Sedimentology <br /> <br />The Division reviewed the sedimentology evaluation provided in the SL-14 application. As per <br />Rule 4.15.1(2)(b), vegetation cover shall be capable of stabilizing the soil surface to achieve erosion <br />control equal to pre-mining levels. In addition, Rule 3.03.1(3)(b) states that lands which to which <br />the release would be applicable are contributing suspended solids to streamflow or runoff outside <br />the permit area in excess of pre-mining levels as determined by baseline data. To demonstrate this, <br />Colowyo provided estimation on soil loss based upon post-mining site specific data using the <br />Revised Universal Soil Loss Equation (RUSLE). Results from the RUSLE were then compared to <br />baseline data from each of the reclamation blocks being requested for Phase II bond release. Results <br />of this demonstration as well as vegetative cover results are summarized below. <br /> <br />Phase II Bond Release Parcel Results – WP015, WP017, WP018, WP019 and WP020 <br /> <br />2017 Cover: Herbaceous cover: 29.88% <br /> Herbaceous cover standard (90%): 20.88% <br />The 2017 sample data successfully exceeds 90% of the herbaceous cover <br />standard. <br /> <br />2017 Sedimentology: Post-Mining: 0.176 tons/acre/year <br /> Pre-Mining: 0.302 tons/acre/year <br />The 2017 sedimentology evaluation data shows post-mining condition <br />sediment loss to be less than pre-mining conditions. <br /> <br />Phase II Bond Release Parcel Results – WP014 and WP016 <br /> <br />2016 Cover: Herbaceous cover: 31.93% <br /> Herbaceous cover standard (90%): 18.29% <br />The 2016 sample data successfully exceeds 90% of the herbaceous cover <br />standard. <br /> <br />2016 Sedimentology: Post-Mining: 0.099 tons/acre/year <br /> Pre-Mining: 0.378 tons/acre/year <br />The 2016 sedimentology evaluation data shows post-mining condition <br />sediment loss to be less than pre-mining conditions. <br />