GNA Water Management Optimization and Prioritization. The East Boulder Mine Water Management Prioritization and Optimization Plan (see Appendix A) was developed in 2005 by Xxxxxxx & Associates to meet GNA requirements (Appendix L, Section 11). The Optimization Plan was developed with objectives focused to support implementation of the water program and the TTLF. The East Boulder Mine Optimization Plan has been incorporated into the GNA as Appendix Q, and is an important tool to complement and support this Water Resources Adaptive Management Plan. The Optimization Plan describes the water management system at East Boulder Mine, and includes development of a mass balance for nitrogen from the underground workings to discharge. A series of mass balance calculations are used to examine existing conditions through conservative estimation of nitrogen loading to groundwater and surface water; and to evaluate the effect of proposed operational changes and potential treatment alternatives on water quality downgradient of mine facilities. The estimates of pollutant loading to groundwater and surface in the mass balance are conservative, and do not account for natural attenuation, in situ denitrification, or other chemical and physical processes that are known to further reduce pollutant loading in natural systems. The mass balance calculations have only focused on TIN because no other contaminants of concern were identified for the East Boulder Mine at the time the optimization plan was developed. Additional mass balance calculations will be developed if concerns about other contaminants arise. The mass balance and Optimization Plan for East Boulder Mine will be updated in 2020 as part of the GNA to support the development and implementation of the Water Resources Adaptive Management Plan. The mass balance will continue to be used as a tool to estimate water quality change resulting from discharge of mine influenced water, and to predict the effectiveness of water treatment improvements and proposed mitigations on returning downgradient groundwater and surface water to baseline conditions. Water quality change predicted by the mass balance will be compared to and supported with water quality sampling results. The 2005 Optimization Plan and mass balance are provided as Appendix A for reference.
