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<br />Cripple Creek & Victor Gold Mining Company Exhibit G Cresson Project Amendment 13 5 <br />modify the hydro-geologic regime. The average regional groundwater flow from the District has not increased due to current mining and no increase is anticipated to occur due to proposed Amendment 13 activities. <br />As shown on Figure G-1, no significant groundwater usage occurs in the area of the diatreme. The wells located within the diatreme as shown on Figure G-1 are exclusively Cresson Project groundwater monitoring wells. Shallow groundwater in the Cresson Project occurs at some locations in alluvial aquifers associated with the surficial drainages or in shallow, fractured bedrock. Deeper groundwater in the District occurs in two distinct hydrologic zones that are strongly controlled by the geologic setting: i.e., the volcanic diatreme and the surrounding granitic rocks. A description of the general geology of the region, and specifically the geology beneath project areas has been provided in prior submittals. <br />The volcanic diatreme that was emplaced into the Pikes Peak granite formed an inverted cone of highly fractured volcanic rocks. The surrounding granite and gneiss are relatively impervious, except in the immediate vicinity of the diatreme, where it was fractured during the volcanic episodes. As a result, the brecciated rock within the diatreme filled with water, receiving recharge from the regional groundwater system, precipitation at the surface and storing it as groundwater in the faults, fractures, veins and joint structures. The relatively impermeable Pikes Peak granite acted to hold this water in place within the diatreme, with local overflow to the west via springs in valleys that intersect at the boundary. A series of tunnels were created from the 1890’s to 1941 as historical underground mining encountered water at depth. These tunnels lowered the regional groundwater elevation from the original elevation of approximately 9,500 feet above mean sea level (amsl) to a level between approximately 7,000 feet and 8,000 feet amsl. The regional groundwater system was intersected in 1941-42 at an elevation of approximately 7,000 feet amsl by the Carlton Tunnel, the portal of which is 7 miles southwest of the diatreme near the confluence of Four Mile Creek and Cripple Creek. Flow from the diatreme to this tunnel has controlled the water table in the diatreme ever since. <br />Recharge to the diatreme groundwater system occurs by regional inflow from the surrounding granite and infiltration of precipitation in the spring, summer, and fall months. Infiltrating water moves vertically downward through the unsaturated portion of the system either through the brecciated diatreme country rock, through sub-vertical fractures, through mined voids created during historical underground mining, or a combination of these pathways. <br />Surface manifestation of the natural groundwater flow system and the overlay of the flow removed from the diatreme by the historical flow to the tunnels intersecting the diatreme is apparent throughout the District. Streams in the central and southern portions of the diatreme tend to be ephemeral in nature, as most of the precipitation and snowmelt infiltrates into the porous rock and