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Privileged and Confidential—Attorney Client Communication Geosyntee l> <br /> consultants <br /> 2. TREATMENT SYSTEM OVERVIEW AND TREATABILITY <br /> TESTING METHODS <br /> 2.1 Overview <br /> The water treatment system currently in place at the Mine is presented in Appendix A. <br /> Starting from the Mine portal, an existing set of dual pipelines that are each 8 inches in <br /> diameter receive water from the Mine portal by gravity flow and convey the water to <br /> the Mine Water Pond(MWP), a geomembrane lined pond. On the downgradient side of <br /> the MWP, Outfall OOIA discharges to Sneffels Creek when in operation. There is also a <br /> pipeline discharge option from MWP that feeds into Pond#2. Pond#2 is currently <br /> operated as an infiltration system with water pooling before seeping into the subsurface <br /> under Pond#2 and is monitored at groundwater water well 3R(GW-3R). This results in <br /> high water quality associated with GW-3R. Further east on the Mine site is Pond#3, <br /> which is currently serving as a stormwater detention pond. <br /> OSMI conducted a capacity analysis for the existing Mine ponds using survey data <br /> collected in October 2017 and the results are included in Table 4. The volumetric <br /> capacities of Ponds #2 and#3 assume the ponds will be completely full of <br /> water/materials and during detailed design that assumption will be refined according to <br /> the pond construction requirements and freeboard requirements for storm events. In <br /> order to estimate the pore volume and calculate hydraulic residence times, a porosity <br /> value of 0.34 (EPA, Sept. 2008)was applied to Ponds#2 and#3. <br /> Table 4: Approximate Volumetric Capacity of Water System <br /> Future Con e itions After Pond <br /> Current Conditions Expansion <br /> Estimated Estimated Pore Estimated Estimated Pore <br /> Pond Empty Bed Volume of Pond Empty Bed Volume of Pond <br /> Volume of Assuming 0.34 Volume of Assuming 0.34 <br /> nd(gal)*„,„ Porosity(gal) .',;.tTo.�, <br /> MWP 285,000 NA evaluated NA <br /> Pond#2 683,200 232,000 928,000 316,000 <br /> Pond#3 239,000 81.000 803.000 278.000 <br /> *Information provided to Geosyntec b )SMI Qtktrter 12018:MwP NI,as calculated using the <br /> approximate current surface area of the pond and an estimated depth of water—the reconfigured MWP <br /> will in the future have a different configuration and design basis that will be evaluated further as the <br /> design progresses <br /> Treatability Testing Report 6 December 11.2018 <br />