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Page 9 of 18 <br />Gneiss and the Caribou Monzonite Stock geologic units. Within the subalpine and alpine <br />basins of the facility area ground water use is restricted to private wells (Flynn, 2003, <br />Bruce and O’Riley,1997). Other than the onsite wells there are no state-permitted wells <br />within one mile of the compliance boundary. The closest public water supplies <br />(Nederland, Boulder) rely on surface water sources (Weritz, 2015). <br />4.2 Generalized Conceptual Model <br />The hydrology of alpine and subalpine basins in the Colorado Front Range has been a <br />topic of research since the 1920’s.Recent research using naturally occurring chemical <br />tracers and groundwater dating has refined the conceptual model for recharge, <br />groundwater flow, and surface water groundwater interaction (Frisbee et al., 2011). <br />Hydrologic and climatic conditions cause the majority of precipitation to be released as <br />spring and summer snowmelt which drains rapidly from the mountain front and shallow <br />aquifers to streams and wetlands over the course of months. The sudden emergence <br />through old workings that intersect the current underground mines suggest a direct <br />pathway to some runoff being funneled into old shafts during run-off. Also, during runoff, <br />it has been observed that significant changes in Coon Tract Creek fill and perhaps overfill <br />a wetland that sits atop the Cross mine. Infiltration of significant volumes of water occur <br />also most as soon runoff occurs with fractures and leached out rock in low points close <br />to the surface. Obviously, these pathways have a very high transmissivity on the level <br />of course sand. Overland flow will occur if the infiltration capacity of the shallow regolith <br />is exceeded. <br />The sub-alpine hydrology conceptual model indicates that high elevation steep <br />catchments recharge to weather or leached near surface rock and overlying regalith and <br />that all ground water flow returns to the surface due, some in the form of springs and <br />artesian wells and the apparent gaining in surface waters to topographically-driven-flow. <br />This reemergence as surface water happens because of topography-driven- flow and <br />hydraulic conductivity contrasts with depth (Frisbee et al., 2013; Bukoski et al., 2021; <br />Foks et al., 2017; Tóth, 1963). <br />The time between snowmelt and discharge to streams can be highly variable depending <br />on path, but the steady-state mass balance is nearly complete within sub-alpine basins. <br />Because of the complete discharge to streams and springs, changes in groundwater <br />quality are detectable in surface water quality in sub-alpine basins such as Coon Track <br />Creek. <br />Groundwater flow at the facility is generally to the south-east, following topography and <br />the track of Coon Track Creek. Water table maps for late July 2021 and late March 2022 <br />are presented as Maps 3 and 4. The water table maps were created by hand-contouring <br />linear interpolations between water level measurements made at the three wells (Table <br />1) and the water level in the Cross Winze. Conceptual water table contour cross- <br />sections were drawn from these maps, where the surface projections of the cross- <br />section lines are presented in Map 5 and cross-section of the conceptual groundwater