WSP04525 - Laserfiche WebLink

Home Browse Search

2. Natural discharges of water from regional aquifers commonly exceed 50 gal/min. Dis- charges of as much as 3,200 gal/min can occur from the Devonian and Mississippian carbonate rocks unit. The Yampa Spring at Glenwood Springs had an estimated discharge of 2,800 to 2,950 gal/min in November 1984. The nearby Redstone 21-9 well flowed water at rates of 1,740 to 2,300 gal/min in o November 1984. Discharges of several hundred gallons per minute are possible from the Pennsylva- ~ nian and Permian sandstone unit. Discharges from local aquifers and confining layers rarely exceed 50 00 nd clastic rocks, and Pennsylvanian and Permian red beds and carbonate rocks hydrostratigraphic units. Confining layers in the study area include the Cambrian shale, Devonian carbonate and clastic rocks, Mississippian and Pennsylvanian shale and carbonate rocks, Pennsylvanian carbonate rocks and evaporites, and Permian shale and carbonate rocks hydrostratigraphic units. 2. Natural discharges of water from regional aquifers commonly exceed 50 gal/min. Dis- charges of as much as 3,200 gal/min can occur from the Devonian and Mississippian carbonate rocks unit. The Yampa Spring at Glenwood Springs had an estimated discharge of 2,800 to 2,950 gal/min in November 1984. The nearby Redstone 21-9 well flowed water at rates of 1,740 to 2,300 gal/min in November 1984. Discharges of several hundred gallons per minute are possible from the Pennsylva- nian and Permian sandstone unit. Discharges from local aquifers and confining layers rarely exceed 50 gal/min, but flows of several hundred gallons per minute can occur from some intervals, particularly if they are extensively fractured. 3. Hydraulic conductivities generally increase from structural basins to uplifted areas. Hy- draulic-conductivity values for the Devonian and Mississippian carbonate rocks hydrostratigraphic unit range from less than 0.001 to more than 100 ft/d. Hydraulic conductivity values for the Pennsyl- vanian and Permian sandstone hydrostratigraphic unit range from less than 0.0001 to 20 ft/d. Hydrau- lic-conductivity values for local aquifers typically range from less than 0.0001 to 2 ft/d but can be as large as 10 ft/d for some sandstone layers. Hydraulic-conductivity values for confining layers typically range from less than 0.0001 to 0.25 ft/d but can be as large as 1 ft/d for some sandstone or limestone layers. 4. Transmissivity values in the Devonian and Mississippian carbonate rocks hydrostrat - igraphic unit increase from less than 0.1 ft2/d in structural basins to more than 1,000 sq ft/d in uplifted areas. In the Glenwood Springs area, this hydrostratigraphic unit consists of the Leadville Limestone and Dyer Dolomite. Aquifer tests of the Leadville Limestone at Glenwood Springs indicated a trans- missivity of47,000 sq ft/d. This relatively large value is believed to be a consequence of faulting and associated fracturing in the area. 5. The storage coefficient of the Leadville Limestone and Dyer Dolomite at Glenwood Springs determined from aquifer tests is 0.0005. Specific stor-age in these formations, based on their combined thickness and storage coefficient at Glenwood Springs, is .0000018 per foot. 6. Flow from artesian wells completed in the Leadville Limestone at Glenwood Springs can lower water levels in nearby alluvial and bedrock wells and decrease discharge from springs. In November 1984, a cumulative discharge of 10.5 million gallons from the Redstone 21-9 well at Glenwood Springs interfered with alluvial wells and springs as much as 1,100 ft away. The Wright no. 1 well, which is completed in bedrock 4,400 ft from the production well, was affected also. 7. Most of the water discharging from the Leadville Limestone and Dyer Dolomite at Glenwood Springs is estimated to come from the direction of Lookout Mountain and the Grand Hogback, south of the city. Some of the water discharging at Glenwood Springs is estimated to come from the White ~iver Plateau north of the city. In the Lookout Mountain and Grand Hogback areas, water from a gradually melting snowpack infiltrates the Leadville Limestone and Dyer Dolomite through fractures extending into overlying rocks. This water is heated to temperatures of 111 to 126 A-16