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