Geohydrology Of The Eastern Part Of Pahute Mesa Nevada Test Site Nye County Nevada

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ISBN 13 :
Total Pages : 46 pages
Book Rating : 4.:/5 (684 download)

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Download or read book Geohydrology of Pahute Mesa-3 Test Well, Nye County, Nevada written by and published by . This book was released on 1997 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Pahute Mesa-3 test well is on Pahute Mesa about 3 miles west of the Nevada Test Site and 20 miles northeast of Oasis Valley near Beatty, Nevada. The well was drilled for the U.S. Department of Energy Radionuclide Migration Program to monitor conditions near the western edge of the Nevada Test Site. The well was drilled with conventional rotary methods and an air-foam drilling fluid to a depth of 3,019 feet. A 10.75-inch diameter steel casing was installed to a depth of 1,473 feet. The test well penetrates thick units of non-welded to partly welded ash-flow and air-fall tuff of Tertiary age with several thin layers of densely welded tuff, rhyolite and basalt flows, and breccia. Geophysical logs indicate that fractures are significant in the Tiva Canyon Tuff of the Paintbrush Group and this was confirmed by high flow in this unit during a borehole-flow survey. The geophysical logs also show that the effective porosity in tuffaceous units ranges from 19 to 38 percent and averages 30 percent, and the total porosity ranges from 33 to 55 percent and averages 42 percent. The measured temperature gradient of 1.00 degree Celsius per 100 feet is steep, but is similar to that of other nearby wells, one of which penetrates a buried granite intrusion. Injection tests for six intervals of the well yielded transmissivities that ranged from 3.1 x 10−3 to 25 feet squared per day and hydraulic conductivities that ranged from 6 x 10−5 to 0.12 foot per day. The sum of the transmissivities is 28 feet squared per day and the geometric mean of hydraulic conductivity is 1.7 x 10−3 foot per day. Estimates of storage coefficient range from 2.1 x 10−5 to 3.8 x 10−3, indicating that the aquifer responded to the injection tests in a confined manner. An aquifer test produced a drawdown of 78 feet during 31 hours of testing at 169 gallons per minute.