Determination of barometric efficiency and effective porosity, boreholes UE-25 cNo.1, UE-25 cNo.3, Yucca Mountain, Nye County, Nevada
Simultaneous records of water-level altitudes in boreholes UE-25 cNo.1, UE-25 cNo.2, and UE-25 cNo.3 (the C-holes) and atmospheric pressure at and near the C-holes were obtained from July 15 to September 8, 1993, to determine the barometric efficiency of the entire uncased section of each of the C-holes, for the purpose of analyzing pumping tests. Each of the C-holes is 3,000 feet deep. About 1,600 feet of each borehole is open in Miocene tuffaceous rocks. Water-level altitudes in the C-holes fluctuate in response to Earth tides and changes in atmospheric pressure, which are characteristics of wells completed in an elastic, confined aquifer. The barometric efficiency of the C-holes in this study was analyzed by filtering simultaneously collected water-level-altitude and atmospheric-pressure data to remove the influences of Earth tides and semi-diurnal heating and cooling and then regressing filtered water-level-altitude changes as a function of filtered changes in atmospheric pressure. The average barometric efficiency of the uncased sections of boreholes UE-25 cNo.1 and UE-25 cNo.3 was determined to be 0.94. Malfunctioning equipment prevented determining the barometric efficiency of bore-hole UE-25 cNo.2. An average effective porosity of 0.36 was calculated from barometric efficiency values determined in this study and a specific storage value of 0.497 x 10{sup -6} per foot that was determined previously from geophysical logs of the C-holes. A porosity of 0.36 is consistent with values determined from geophysical logs and core analyses for the Calico Hills Formation.
- Research Organization:
- US Geological Survey, Denver, CO (United States)
- Sponsoring Organization:
- USDOE Office of Civilian Radioactive Waste Management, Washington, DC (United States); Geological Survey, Reston, VA (United States)
- DOE Contract Number:
- AI08-92NV10874
- OSTI ID:
- 573100
- Report Number(s):
- USGS/WRIR-97-4098; ON: DE98004095; TRN: 98:009248
- Resource Relation:
- Other Information: PBD: 1997
- Country of Publication:
- United States
- Language:
- English
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