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Red Gap Ranch LLC retained the services of HSI to conduct a groundwater resource evaluation for the Red Gap Ranch. The ranch property encompasses slightly more than 25,000 acres located approximately 40 miles east of Flagstaff, Arizona. Since June 2001, several hydrogeologic investigations have been conducted on Red Gap Ranch along with limited data collection activities conducted off of the ranch property. Results from completing various field investigations indicate that a significant quantity of good quality groundwater is potentially available from beneath Red Gap Ranch. Because of the undeveloped nature of the area, groundwater resources have remained relatively unrecognized as a potential resource in this part of northern Arizona. The research conducted on the ranch consisted of 3 phases of investigations. Phase 1 activities on Red Gap Ranch included drilling of three large diameter productions wells (one well is not completed); two monitor wells and one slim exploration well; two 24-hour aquifer tests; water quality sampling and analysis; water level measurements and water quality testing of several area wells; and a surface geophysical survey. Phase 2 consisted of drilling three new livestock wells, additional groundwater sampling and testing, and an extended 7-day aquifer test at one of the ranch production wells. Phase 3 was an evaluation of the potential impacts related to the development of groundwater resources from the ranch using numerical groundwater modeling. |
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Well testing and site reconnaissance at Red Gap Ranch |
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Water Supply |
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HSI aided Utility Source, LLC in applying to the Arizona Department of Water Resources (ADWR) for a Physical Availability Demonstration (PAD) and later an expanded PAD to prove that groundwater resources are available to serve its Certificate of Convenience and Necessity (CCN). In 2004, ADWR approved a PAD of approximately 110 acre-feet per year. The CCN extension to 446 acre-feet per year currently under review by the Arizona Corporation Commission is based on the successful outcome of the recent drilling and testing of a fourth deep well near the current CCN for Utility Source, LLC. This demand is expected to increase based on the requests for water supplies from potential users. A surface geophysical survey using the controlled source audio-frequency magnetotellurics (CSAMT) method was used to determine the subsurface geologic structure beneath the property. The CSAMT method has been an extremely useful tool to locate faults and fractures, which may not be seen on the ground surface or because the faults usually dip at an angle to the ground surface. This methodology allows the wells to be sited to intersect the fault beneath the regional aquifer, which is over 1,500 feet deep in this part of northern Arizona. Using the geophysical information, HSI located Deep Well 3 to intersect the Bellemont Fault and Deep Well 4 to intersect an unnamed fault trending northwest that also intersects the Bellemont Fault on 20-acres of land owned by Greenfield Land Development. HSI provided oversight of the drilling of Deep Wells 3 and 4, as well as aquifer testing and analysis, and water quality sampling. Both wells successfully produced excellent quality water. Deep Well 3 was drilled to 2,825 feet below land surface and produced about 73 gpm, whereas Deep Well 4 was drilled to a depth of 2,908 feet and was pumped continuously at 371 gpm (or approximately 600 acre-feet per year) for seven days as part of the testing. This is in vast contrast to Deep Wells 1 and 2, also located in the regional aquifer but outside of a fault zone. These wells only produce approximately 11 and 23 gpm, respectively. The total combined capacity of the four deep wells drilled in the regional aquifer is sufficient to serve the current and committed demand for the next 100 years. |
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Groundwater produced from Deep Well 4 when making a pipe connection during drilling. |
