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Red Gap Ranch Water Resource Investigation Red Gap Ranch encompasses over 25,000 acres of land located approximately 40 miles east of Flagstaff, Arizona. Groundwater beneath the ranch is found in the Coconino Sandstone which is a major component of the regional Coconino aquifer. The Coconino Sandstone is composed of fine-grained sand and in the absence of fractures or structural features this formation will only produce limited quantities of groundwater. Surface geophysical methods were employed to identify the thickness of the Coconino Sandstone across the ranch in addition to locating potential well sites in fractured portions of the aquifer. Drilling of three wells after the geophysical survey, confirmed the thickness of the Coconino Sandstone and helped to identify target areas for drilling of additional water production wells. |
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The Search for Water……
Many areas within the State of Arizona rely on groundwater for domestic, municipal, industrial, and agricultural needs. The two major types of aquifers where groundwater can be developed are alluvium and hard rock. Developing water supplies from hard rock aquifers generally incurs the most risk and cost and is the most difficult to accomplish. Presently, the common technique used to locate new well sites in the hard rock aquifers is a combination of a fracture trace analysis utilizing aerial photographs followed by a site visit for field verification. This technique to site the well directly over the fracture can be successful if the fracture extends in a near vertical direction. Often that is not the circumstance. Fractures may be offset or angled, thus moving the point at which the fracture intercepts the groundwater several feet from the surface expression of the fracture. The result of drilling a well on top of the surface expression in this type of situation can be a well with poor performance. Regardless of the performance of the well, the construction costs remain the same.
Technology now exists whereby a relatively inexpensive, non-intrusive, surface geophysical method can be utilized to develop subsurface profiles to depths exceeding 2,000 feet. Together, experienced geophysists and geologists collect, model, and interpret the resistivity data with a high level of accuracy and create subsurface geologic structural profiles. Assemblage of several of these profiles allows the hydrologist to determine favorable sites for drilling. Validation of this process has been successfully completed in the Tule Desert of southern Nevada as well as in the Winslow and Flagstaff areas of northern Arizona. |
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Evidence of success….. Tule Desert Water Resources and Water Rights |
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Town of Payson Water Resource and Well Site Study Like other Arizona cities, the Town of Payson has continued to experience increased growth over the last several years. The Town relies on groundwater resources to meet their water demands. Groundwater for this community is obtained primarily from fractures in the Payson Granite. Over the past few years the Town has taken a leading role of developing groundwater from fractured rock. Several surface geologic mapping activities have been performed in addition to confirmatory drilling at potential well sites. The Town has pursued potential groundwater resources that are believed accessible from various locations on land under the jurisdiction of the U.S. Forest Service (USFS). Developing of groundwater resources on USFS land is complicated by site access and other environmentally sensitive issues. Because of this, a surface geophysical program has been initiated to provide definition of structural features for development of groundwater. The selected geophysical method has been approved for use by the USFS mostly due to its low impact on forest lands. Once the geophysical survey has been completed, this information, with the hydrogeologic data will be used to select target sites for exploratory and confirmatory drilling. It is expected that results from the survey will greatly reduce the number of wells expected to be drilled for this project. |
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Prior to the a basin-wide groundwater hydrogeologic investigation and surface geophysical survey in Tule Desert, Nevada, the 192 square mile Tule Desert Groundwater Basin contained virtually no subsurface information, other than a few remote sensing studies. The complex geology of the area is characterized by a shallow alluvial-fill basin underlain by a highly fractured carbonate rock aquifer. Initial well site evaluation consisted of conventional techniques including limited surface geologic mapping and fracture trace analysis. Subsequent drilling of two exploratory test wells confirmed the need to define the subsurface structural conditions by use of surface geophysical methods. The combination of hydrogeologic testing and geophysical structural definition permitted preliminary characterization of this groundwater basin to locate additional water production well sites. |
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City of Flagstaff Well Site Study The City of Flagstaff is known for its mountain beauty, green forests, and many outdoor attractions. Over the last several years Flagstaff has experienced considerable growth with a commensurate need for developing water resources to meet the increased water demand. In the past, the City has relied on assistance from the U.S. Geological Survey to map surface fractures and perform various geophysical surveys in hopes of locating suitable well sites within the City limits. From these initial studies the City identified potential areas for locating water production wells, but the investigative methods did not provide the resolution necessary to select actual well sites. Well drilling and development of water resources in the Flagstaff area is complicated by deep groundwater levels and subsurface structural features that control accessibility and availability of the supply. After performing a geophysical test line between two well sites, the hydrogeologic conditions were evaluated and provided an explanation for the water production difference between the well sites. Subsequent drilling at two of the proposed well sites has indicated that the geophysical methods employed could be used to locate fractures and structures at depth, which could be correlated with the drill cuttings and water production potential of the well sites. Extension of the investigation allowed potential well sites to be identified.
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Estrella Mountain Ranch Water Resource Studies The SunChase Estrella Limited Partnership property encompasses approximately 18,600 acres located in Rainbow Valley within the city limits of Goodyear, Arizona. Groundwater in Rainbow Valley is found in a deep alluvial-fill basin. In portions of the basin, however, a buried pediment complicates drilling. Previous land use practices and fracturing of the host rock has allowed groundwater quality to deteriorate. Drilling of two deep exploration test wells helped to define the geologic structure and groundwater quality at two basin locations. Geophysical techniques provided further definition of the geometry of the basin and potential sites for drilling of additional water production wells. |