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the remedial measure itself. <br />4. Minimize Environmental Impacts: Minimize impacts to the environment, including <br />preservation and restoration of local ecosystems and wildlife as appropriate with respect <br />to future land uses. <br />Several remedial options for short-term mitigation and long -term management of the mine pool <br />have been identified and extensively evaluated by Cotter, State regulatory agencies, and <br />scientific /engineering consultants. These options include mine dewatering with active water <br />treatment, in -situ treatment of the mine pool, temporary pipeline diversion of the creek past the <br />mine site, and grouting /sealing of any exploratory core holes or natural faults /fractures through <br />which mine pool water could potentially migrate into the alluvium and fill (hereafter termed <br />"alluvial fill "). Although the overall remedial objective of meeting water quality standards in <br />Ralston Creek is common to all stakeholders, the most appropriate combination and sequence of <br />mitigation strategies and measures to achieve this common objective remain in dispute. <br />This circumstance is similar to that recently encountered for the larger Clear Creek Watershed, <br />which includes many historic mines along its intersection with the Colorado Mineral Belt. To <br />address water quality issues related to historic mining within this district, stakeholders <br />recognized that in order to resolve highly complex water quality issues and achieve acceptable <br />remedial outcomes, a common ground between many stakeholders with varying perspectives had <br />to be found (CCWF, 2011). As a result, the Clear Creek Watershed Forum was established in <br />1990, involving a broad stakeholder constituency including regulatory agencies and local <br />communities, industries and organizations. The role of the Forum was to bring people together <br />to share knowledge, perspectives and values and to cooperatively develop water quality <br />improvement strategies and projects. A similar approach of cooperation and technical <br />collaboration would likely be beneficial to remedial outcomes at the Schwartzwalder Mine. <br />A systematic assessment of remedial strategies against fundamentally accepted selection criteria <br />such as those indicated above has not been formally conducted. Cotter respectfully provides the <br />following remedial alternatives assessment for consideration by DRMS, MLRB, WQCD, Denver <br />Water and all other stakeholders. Cotter hopes that this effort can lead to an acceptable <br />framework for further technical discussions and offer an alternate path forward. The goal is to <br />ultimately agree on an overall strategy that will meet the common remedial objective and will be <br />acceptable to all stakeholders. <br />REMEDIAL ALTERNATIVES ASSESSMENT FOR MINE POOL MANAGEMENT <br />This assessment was designed to systematically rate each remedial alternative for addressing the <br />mine pool under the remedial criteria listed above. The rating system is qualitative in nature yet <br />provides a systematic method for comparing the remedial alternatives in a quantitative manner. <br />Each remedial criterion was assigned a weighting factor based on relative importance as follows: <br />Criterion Weighting Factor Rationale <br />1. Effectiveness 8 Impacts other Criteria <br />2. Sustainability 6 Relates to cost - effectiveness issues <br />2 <br />