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Ouray Silver Mines Inc. <br /> Technical Revision 10 August 14, 2018 <br /> facility. The exact placement of new media is still being evaluated through an underground <br /> Treatability Study; however, Pond #2, is intended to be remove metals via sulfate reduction. The <br /> pond will be lined and maintained in a saturated state. Details can be seen in Figure 3. Pond #2 <br /> will retain 2 feet of free board, including bio-reactive material (Figure 5). The storm water <br /> spillway is retained under CDPS general permit# COR040289. <br /> Pond #3 is expected be a polishing pond (Map 1, Figure 3), transitioning the water back to more <br /> aerobic conditions and encouraging settling utilizing passive treatment wetlands. The exact <br /> media to be placed in the pond is under review as the underground pilot test moves into its stress <br /> testing phase. Pond #3 will retain 2 feet of freeboard, including bioreactive materials (Figure 6). <br /> The storm water spillway from Pond#3 is retained under CDPS general permit# COR040289 <br /> Outfa11002A is completed with a stand pipe (generalized detail in Figure 3), under the <br /> jurisdiction of the WQCD per Modification 4 of CDPS permit number CO0000003. <br /> 4.2 Groundwater Monitoring Well Installation <br /> A new monitoring well (GW-4)will be installed between Pond #3 and Sneffels Creek for <br /> monitoring purposes. The approximate location of GW-4 can be seen on Map 1 and Figure 2. <br /> The well, expected to be approximately 10 feet deep will be drilled with perforated pipe, a <br /> completion packer or bentonite plug will be placed a few feet below the groundwater <br /> intersection. Final coordinates and well construction details will be submitted to DRMS and the <br /> State Engineer's Office upon completion. <br /> 4.3 Diesel Tank Relocation <br /> The diesel tank is unchanged with respect to physiochemical properties. The C-1, 10,000-gallon <br /> diesel tank is double walled for spill prevention. The new location of the diesel tank eases <br /> congestion and removes the diesel tank from the proximity of the Reagent Building (Map 1). <br /> 5 Construction and Implementation <br /> Construction and implementation information for each change is provide in this section. All <br /> construction activities will utilize best practices. Erosion control structures, such as straw <br /> waddles, hay bales and silt fence will be utilized and maintained during construction and <br /> installation to reduce erosion. <br /> 5.1 Five Stage Passive Treatment System <br /> Construction of the Five-Stage Treatment System is expected to occur over several steps, to <br /> facilitate water management during construction. Final as-built designs will be submitted when <br /> construction is complete. Construction is expected to begin in September of 2018 and be <br /> complete in the fall of 2019. Anticipated staging of construction activities follows. <br /> 1. Expand Ponds#2 and #3 —expected in 2018 as allowed by weather <br /> 2. Divert water to Pond #2 and #3 <br /> 3. Reconstruction of Pond #1 (Mine Water Pond)—earthmoving and liner placement <br /> 4. Divert water around Pond#2, and reconstruct <br /> 4 <br />