Effects of rock riprap design parameters on flood protection costs for uranium tailings impoundments
The Pacific Northwest Laboratory (PNL) is studying the problem of long-term protection of earthen covers on decommissioned uranium tailings impoundments. The major erosive forces acting on these covers will be river flooding and overland flow from rainfall-runoff. For impoundments adjacent to rivers, overbank flooding presents the greater potential for significant erosion. To protect the earthen covers against flood erosion, rock riprap armoring will be placed over the cover surface. Because of the large size rock usually required for riprap, the quarrying, transport, and placement of the rock could be a significant part of the decommissioning cost. This report examines the sensitivity of riprap protection costs to certain design parameters at tailings impoundments. The parameters include flood discharge, riprap materials, impoundment side slopes, and an added safety factor. Two decommissioned tailings impoundments are used as case studies for the evaluation. These are the Grand Junction, Colorado, impoundment located adjacent to the Colorado River and the Slickrock, Colorado, impoundment located adjacent to the Dolores River. The evaluation considers only the cost of riprap protection against flood erosion. The study results show that embankment side slope and rock specific gravity can have optimum values or ranges at a specific site. For both case study sites the optimum side slope is about 5H:1V. Of the rock sources considered at Grand Junction, the optimum specific gravity would be about 2.50; however, an optimum rock specific gravity for the Slickrock site could not be determined. Other results indicate that the arbitrary safety factor usually added in riprap design can lead to large increases in protection costs. 22 references, 19 figures, 15 tables.
- Research Organization:
- Pacific Northwest Lab., Richland, WA (USA)
- DOE Contract Number:
- AC06-76RL01830
- OSTI ID:
- 6632128
- Report Number(s):
- NUREG/CR-3751; PNL-5068; ON: TI84015951
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
MILL TAILINGS
COVERINGS
EROSION
COLORADO
COST
DESIGN
FLOODS
ROCKS
DISASTERS
FEDERAL REGION VIII
NORTH AMERICA
SOLID WASTES
TAILINGS
USA
WASTES
052002* - Nuclear Fuels- Waste Disposal & Storage
053000 - Nuclear Fuels- Environmental Aspects