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Revisions to Restoration Reclamation Plan <br /> TR02 allows for the restoration of approximately one mile of stream corridor within the Swan River Resource <br /> permit boundary. Implementation of this restoration reclamation plan commenced in early June 2016. <br /> During the process of excavating the new channel for the Swan River Restoration Project, unexpected areas of <br /> mine waste were encountered in an approximately 1,000 linear foot segment (approximately 25,000 CY) of the <br /> proposed new channel alignment (Refer to the attached River Realignment and Mine Waste Mitigation Plan for <br /> additional detail). The restoration contractor immediately segregated this portion of the project area to avoid <br /> discharge of water that contacted exposed mine waste. Summit County staff reviewed the mine waste area with <br /> the restoration contractor on June 29, 2016 to ascertain conditions and identify solutions to avoid onsite and <br /> offsite impacts. Initial actions included: <br /> • Termination of excavation at a level above the groundwater level <br /> • Removal and consolidation of mine waste from a portion of the channel section <br /> • Construction of cofferdams at the upstream and downstream ends of the mine waste to isolate these <br /> areas from the rest of the planned channel work <br /> • Design modifications to sections of the new channel to minimize sections where the channel intersects <br /> mine waste <br /> Summit County's stream restoration contractor also excavated test pits in several areas, both within and <br /> outside the channel alignment, to further visually identify the extent of mine waste and retrieve soil and water <br /> samples for analytical characterization. Soil analyte concentrations (Toxicity Characteristic Leachate Procedure <br /> (TCLP) plus zinc) are below the CDPHE reference concentrations, with the exception of one analyte in one <br /> sample taken from TP-3. The soil sample taken from TP-3 contains an elevated inorganic lead concentration of <br /> 3.6 mg/1 (compared to the CDPHE lead leachate reference concentration of 1.1 mg/I1). Despite the reported <br /> elevated concentration, this concentration is several orders of magnitude lower than the reported lead <br /> concentrations in tailings piles capped onsite under the VCUP (23 mg/I). Future land uses on the subject site are <br /> also restricted through the attached Environmental Covenant. <br /> Following initial response actions and soil/water testing, Summit County notified the Division of Reclamation, <br /> Mining, and Safety (DRMS) Minerals Regulatory Program, which administers the Swan River Resource mine <br /> permit. Following notification, DRMS Inactive Mines Reclamation Program staff visited the Swan River <br /> Restoration site on July 8, 2016 to review site conditions and potential remediation approaches. Summit County <br /> also held a site visit with the White River National Forest (WRNF) Forest Hydrologist to discuss implications <br /> for the overall river restoration approach. Following this initial interagency coordination, Summit County staff <br /> reviewed proposed solutions with Colorado Department of Public Health and Environment (CDPHE) <br /> Superfund, Voluntary Cleanup, and Remedial Program staff to seek feedback and confirmation of a proposed <br /> design solution to address onsite mine waste. The appropriate Agency representatives have concurred with the <br /> revised restoration/reclamation design approach that maintains the overarching goals and objectives for the <br /> reclamation project and addresses the existing onsite mine waste. <br /> Based on the current understanding of the nature and extent of known onsite mine waste, and subsequent <br /> interagency coordination, Summit County intends to implement the following design and construction <br /> modifications to avoid surface exposure of mine waste. <br /> 1. The channel excavation where mine waste was encountered will terminate above the groundwater level. <br /> 2. All mine waste that has been excavated will be consolidated in a stockpile area located in uplands. <br /> 3. All stockpiled mine waste will be consolidated and capped with a minimum two-foot-thick cap. <br /> 4. The cap will include a minimum three (3) inch thick soil layer. The capped mine waste will then be <br /> `Groundwater Protection Values Soil Cleanup Table, Colorado Department of Public Health and Environment,Hazardous <br /> Materials Management Division(March 2014): https://www.colorado.gov/pacific/sites/default/tiles/IIM iZroundwater- <br /> protecti on-val ues-soi l-c lean up-tab le.pdf <br />