Deep Casper Aquifer Groundwater Development along the Laramie Range, Cheyenne, Wyoming

The City of Cheyenne, Wyoming, is considering expansion of its municipal groundwater resources through development of the Casper Aquifer along the Laramie Range front on the city-owned Belvoir Ranch. Hydrogeologic data suggest the Paleozoic Casper Aquifer has not been severed along a bounding range front fault, and therefore may allow significant aquifer storage and downgradient transmission of groundwater. Two 2006 test wells suggest that the Casper Aquifer has significant development potential that is only partially defined.  

Aquifer testing of the Lone Tree No. 1 test well indicated that significant groundwater could be obtained from the Casper Aquifer within the northern Lone Tree hydrostructural compartment. This well was drilled to a depth of 1,348 feet with casing set into the top of the Casper, and was completed as an open borehole through 961 feet of the Casper Formation. This well yielded excellent quality groundwater at rates of up to 782 gpm during air rotary drilling and testing.  The static water elevation was measured to be 6,996 feet AMSL (108 feet below ground surface).

Immediately to the south, the Duck Creek hydrostructural compartment appears to be hydraulically isolated from the Lone Tree compartment. The Duck Creek No. 1 test well was drilled to a depth of 1,130 feet. Approximately 24 gpm was discharged from the open borehole portion of this well during drilling. The static water elevation was measured to be 6,859 feet AMSL (340 feet below ground surface).

Differences in well yield across the ranch and bedrock geology that is obscured by overlying Tertiary sediments dictated the use of 2D geophysical techniques to further identify potential drilling sites. Seismic reflection and CSAMT resistivity surveys were recently completed to identify subsurface structural features indicating enhanced permeability and to direct future test well drilling at the highest ranked sites.