2021-01-14_REVISION - M1977300 (3)

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r ,,COLORADo LEGACY LAND SCHWARTZWALDER MINE impacted soils will need to be excavated. The capacity of the CV Glory Hole was estimated in Technical Revision 14 to be approximately 56,000 CY. However,as of January 2020,the CV Glory Hole is approximately 50%full, with an estimated 28,000 CY of capacity remaining. In order to accommodate the additional volume of excavated materials,this amendment expands the affected permit area to include the former Black Forest Mine. The former Black Forest Mine is a dry underground aggregate mine wholly owned by Colorado Legacy Land, LLC (CLL) and within CLL's property boundary. It has an estimated capacity of 15,000 CY. The former Black Forest Mine permit(Permit No.M-2001-036)was formally closed in 2019. In accordance with Colorado Hard Rock Mining Rule 6.4.21.(19),CLL proposes disposing of excavated materials from the alluvial valley in either the former Black Forest Mine or the CV Glory Hole of the Schwartzwalder Mine. Technical Revision 14 documents the de minimums impact of alluvial soils disposed of in the CV Glory Hole. The former Black Forest Mine is a dry mine and is not connected to the adjacent Schwartzwalder mine workings. Dry mines do not have the opportunity to contact surface water or groundwater,therefore the impacts to water quality onsite are de minimis. Furthermore, as stated in Technical Revision 14, "...waste rock within the alluvial fill has demonstrated no propensity to acidify groundwater. This is based on sampling of several small seeps and the fact that pH of deep bedrock groundwater in the vicinity of the CV Glory Hole is approximately neutral or slightly basic." The Floor of the main entrance and escape portal for the Black Forest Mine are included in the current Schwartzwalder Mine affected area boundary. These entrances are currently closed with gates. Once alluvial valley excavation and disposal in the Black Forest is complete,the gates shall be removed,and the main entrance and escape portal gates shall be backfilled with rockfill for aesthetic purposes: • Adit Backfilling-Rockfill: Prior to backfilling adits,all wood,garbage,cribbing,or other vegetative materials shall be removed. Adits shall be backfilled to a minimum depth of fifteen feet(15')from the inner top of the fill to the outer top of the fill. There shall be no spaces between the top of the fill and the roof of the adit that exceed three inches(K)and there shall be no space between the top of the fill and the roof of the adit at the entrance of the adit. The innermost three feet(3') of the backfill shall consist entirely of large diameter rock (>V) sourced from onsite. The remainder of the fill with the exception of the outermost one foot(V)shall consist of Rockfill mixed with Common Fill to minimize visible void space between the rocks. The outermost one foot(1') of backfill shall consist of suitable plant-growth medium. All slopes greater than 2H:1V shall be covered with a layer of hydromulch with tackifier to keep the seed mix (Table E-1) in place. Figure E-1 illustrates a typical an adit closure for this project. The adit backfilling closure specification(above)is summarized from the Colorado Inactive Mine Reclamation Program's General Bid Specifications (Division of Reclamation,Mining&Safety,March 2009). This backfilling shall be completed consistent with the surrounding topography (approximately 15-30% slopes,as shown in Figure F-1) for a more"natural looking"closure. During the alluvial valley excavation project,clean materials for rockfill closure (soil,and rock) have been identified and set aside during excavation work. These native, clean materials shall be used to backfill the entrance and escape portal to the Black Forest Mine. Seed mix and hydromulch with tackifier shall be purchased from a third-party vendor and brought to the site. The specific volume of materials, haul distances, and equipment needed to complete the adit closures are presented in Exhibit L along with the associated costs. Backfilling shall be conducted along with the alluvial valley restoration and regrading once excavation work is complete. It is anticipated that this work will be completed in the 2021 calendar year. JANUARY 2021 15 AMENDMENT 5