Deep Groundwater Exploration in the Flagstaff, Arizona Area Using CSAMT
Zonge, 2009. Presented at the Annual Meeting of the Arizona Hydological Society and the American Institute of Hydrology, 2009.
Norman R. Carlson, Zonge Engineering & Research Organization, Inc., Tucson, Arizona;
Phillip M. Paski, HydroSystems, Inc., Phoenix, Arizona;
Randy Pellatz, Director, Utilities Department, City of Flagstaff, Arizona.
Paper — [pdf] GRW_AHS2009CarlsonPaskiPellatzPaper
Based on background geology, hydrology, and land restrictions, 14 different sites in and around Flagstaff, Arizona were selected for geophysical controlled source audio-frequency magneto-tellurics (CSAMT) surveys for the purpose of siting deep ground-water wells. This is a difficult exploration environment, since the presence or absence of faults and fracture zones, below the deep ground water table, has a significant impact on the well production. Given that well costs in this area can be on the order of 1.5 million dollars, and that good production and very poor production locations can be separated by very short distances, well site selection is extremely important.
The CSAMT surveys utilized very distant transmitters in order to acquire low frequency, deep data. At some sites, lines were added and re-oriented in order to aid in differentiating between the effects of cultural features (such as power lines, pipelines, fences, etc.) and the effects of valid subsurface changes. On the basis of all information, sites were prioritized, and the highest priority site, in the middle of a racetrack at the county fairgrounds, was drilled and completed early in 2008. The well has been successfully tested at over 1340 gpm, one of the highest production wells in the Flagstaff area.