Evidence of prehistoric flooding and the potential for future extreme flooding at Coyote Wash, Yucca Mountain, Nye County, Nevada

Technical Report · Thu Sep 01 04:00:00 EDT 1994

DOI:https://doi.org/10.2172/60735· OSTI ID:60735

Glancy, P A

Coyote Wash, an approximately 0.3-square-mile drainage on the eastern flank of Yucca Mountain, is the potential location for an exploratory shaft to evaluate the suitability of Yucca Mountain for construction of an underground repository for the storage of high-level radioactive wastes. An ongoing investigation is addressing the potential for hazards to the site and surrounding areas from flooding and related fluvial-debris movement. Unconsolidated sediments in and adjacent to the channel of North Fork Coyote Wash were examined for evidence of past floods. Trenches excavated across and along the valley bottom exposed multiple flood deposits, including debris-flow deposits containing boulders as large as 2 to 3 feet in diameter. Most of the alluvial deposition probably occurred during the late Quaternary. Deposits at the base of the deepest trench overlie bedrock and underlie stream terraces adjacent to the channel; these sediments are moderately indurated and probably were deposited during the late Pleistocene. Overlying nonindurated deposits clearly are younger and may be of Holocene age. This evidence of intense flooding during the past indicates that severe flooding and debris movement are possible in the future. Empirical estimates of large floods of the past range from 900 to 2,600 cubic feet per second from the 0.094-square-mile drainage area of North Fork Coyote Wash drainage at two proposed shaft sites. Current knowledge indicates that mixtures of water and debris are likely to flow from North Fork Coyote Wash at rates up to 2,500 cubic feet per second. South Fork Coyote Wash, which has similar basin area and hydraulic characteristics, probably will have concurrent floods of similar magnitudes. The peak flow of the two tributaries probably would combine near the potential sites for the exploratory shaft to produce future flow of water and accompanying debris potentially as large as 5,000 cubic feet per second.

• Research Organization: USDOE Nevada Operations Office, Las Vegas, NV (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: AI08-92NV10874
• OSTI ID: 60735
• Report Number(s): USGS-OFR--92-458; ON: DE94018347
• Country of Publication: United States
• Language: English

Related Subjects

05 NUCLEAR FUELS
54 ENVIRONMENTAL SCIENCES
ALLUVIAL DEPOSITS
ENVIRONMENTAL TRANSPORT
EXPERIMENTAL DATA
FLOODS
GEOLOGIC HISTORY
GEOMORPHOLOGY
IMAGES
MAPS
RADIOACTIVE WASTE DISPOSAL
RADIOACTIVE WASTE FACILITIES
RISK ASSESSMENT
RIVERS
SITE CHARACTERIZATION
SIZE
STRATIGRAPHY
YUCCA MOUNTAIN
Yucca Mountain Project