Hydrogeology Of Rocks Penetrated By Test Well Jf 3 Jackass Flats Nye County Nevada

Author :
Publisher :
ISBN 13 :
Total Pages : 26 pages
Book Rating : 4.:/5 (684 download)

DOWNLOAD NOW!

Download or read book Hydrogeology of Rocks Penetrated by Test Well JF-3, Jackass Flats, Nye County, Nevada written by and published by . This book was released on 1996 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: The U.S. Department of Energy and U.S. Geological Survey are monitoring water levels in southern Nevada and adjacent parts of California in response to concern about the potential effects of pumping ground water to support the Yucca Mountain Site-Characterization Program. Well JF-3 was drilled in the western part of Jackass Flats for monitoring water levels, for determining the likelihood of a hydraulic connection between well JF-3 and production wells J-12 and J-13, and for measuring the hydraulic properties of the Topopah Spring Tuff. The borehole for JF-3 penetrated about 480 feet of alluvium and 818 feet of underlying volcanic rock. The well was finished at a depth of 1,138 feet below land surface near the base of the Topopah Spring Tuff, which is the principal volcanic-rock aquifer in the area. The Topopah Spring Tuff at well JF-3 extends from depths of 580 feet to 1,140 feet and consists of about 10 feet of partly to moderately welded ash-flow tuff; 10 feet of vitrophyre; 440 feet of devitrified, moderately to densely welded ash-flow tuff; 80 feet of densely welded ash-flow tuff; 10 feet of vitric, nonwelded to partly welded ash-flow tuff; and 10 feet of ashfall tuff. Fractures and lithophysae are most common in the devitrified tuff, especially between depths of 600 feet and 1,040 feet. Much of the water produced in well JF-3 probably comes from the sequence of these devitrified tuffs that is below the water table. The transmissivity of the aquifer is an estimated 140,000-160,000 feet squared per day and hydraulic conductivity is 330-370 feet per day. These values exceed estimates made at well J-13 by two orders of magnitude. Such large differences may be accounted for by differences in the development of fractures and lithophysae in the Topopah Spring Tuff at the two wells.