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comprehensive and effective grouting /sealing is important to all stakeholders. As previously <br />indicated, the success of any grouting /sealing program is contingent upon dewatering of the <br />alluvial fill area (with pipeline diversion of the creek) and maintaining the mine pool in a flooded <br />state in order to facilitate identification and sealing any such seepage related to the mine pool. <br />In terms of quantitative effectiveness (Criterion 1), grouting /sealing could improve short-term <br />realization of beneficial effects on water quality in the creek relative to mine dewatering /active <br />treatment or in -situ treatment of the mine pool. It is also expected to be an effective long -term <br />measure for mitigating any such impacts related to potential migration pathways from the mine <br />pool to the alluvial fill and Ralston Creek. <br />At face value, the sustainability (Criterion 2) of grouting /sealing rates fairly high because costs <br />would be very low relative to other remedial alternatives and its potential short- and long -term <br />effectiveness is expected to rival or exceed that of mine dewatering /active treatment or in -situ <br />treatment of the mine pool. However, the possibility of a rise in the mine pool to the Steve Level <br />workings means that a long -term component of the grouting /sealing strategy may be necessary. <br />With respect to minimization of potential health risks (Criterion 3), the grouting /sealing <br />alternative rates the same as all other alternatives in terms of potential water quality <br />improvements in Ralston Creek because potential health risks due to uranium levels in the creek <br />are already minimized by incidental factors as previously discussed. Potential health risks <br />associated with the remedial alternative itself are negligible and thus, grouting /sealing rates <br />better overall versus in -situ treatment and pipeline diversion, and significantly better versus mine <br />dewatering /active treatment. <br />The strategy of grouting /sealing would have minimal impacts on the environment (Criterion 4) <br />due to its spatially targeted and passive subsurface nature. The presence of grout in subsurface <br />void spaces will not affect overlying terrestrial or aquatic ecosystems and elimination of any <br />small seeps that may be hydraulically connected to the mine pool through core holes or <br />faults /fractures in bedrock will not significantly change the overall water balance between <br />groundwater and surface water regimes. A grouting /sealing strategy rates highly with respect to <br />Criterion 4. <br />Considering the preceding conceptual assessments of grouting /sealing with respect to the four <br />remedial Criteria, individual Criterion ratings for this remedial alternative have been <br />conservatively estimated as follows: <br />Criterion <br />5. Effectiveness = <br />6. Sustainability = <br />7. Health Risks = <br />8. Environmental Impacts = <br />RATINGS SUMMARY FOR REMEDIAL ALTERNATIVES <br />Rating (and summary rationale) <br />6 (only partial mitigation, any beneficial effects sooner) <br />6 (reasonable cost effectiveness, possible future grouting) <br />5 (negligible health risks due to the method itself) <br />9 (negligible impacts expected) <br />Individual ratings and overall scores for each remedial alternative for short-term mitigation and <br />10 <br />