FLOOD RISK ANALYSIS OF COLD CREEK NEAR THE HANFORD SITE
As required by the proposed rule of 10 CFR 60, "Disposal of High-Level Radioactive Wastes in Geologic Repositories," the Pacific Northwest Laboratory has analyzed the flood potential at the 18-mi{sup 2} reference repository location located on the Hanford Site near Richland, Washington. This work was requested and funded by Rockwell Hanford Operations in conjunction with the Basalt Waste Isolation Project (U.S. Department of Energy Prime Contract No. DE-AC06-77RL01030). It is emphasized that this work is not intended as a basis for engineering design, but rather as an initial, regional appraisal of whether detailed engineering design analysis will be required. In order to achieve the detail required for engineering design specifications, the study results should be refined using more detailed channel geometry data, and the topography of the western portion of the reference repository location should be mapped using a contour interval of not less than 2 ft. Potential flooding at the reference repository location, located along the western boundary of the Pasco Basin, was analyzed both on a local and regional basis. Review of historical and theoretical flooding of the Columbia and Yakima Rivers indicates that there is no direct danger to the reference repository location due to flooding from these water courses. A detailed evaluation of local flooding in Cold Creek, an ephemeral channel adjacent to the reference repository location, was performed using empirically derived methodologies. The evaluation included development of maximum annual flood frequency curves, probable maximum flood peak discharges, and computation of water surface profiles. These results indicate a potential for limited flooding within the western portion of the reference repository location. These results indicate that about 3.5 mi{sup 2} of the reference repository location would be inundated by the probable maximum flood. The maximum depth of inundation along the widest point of the floodplain within the reference repository location is about 7.7 ft {based on minimal topographic resolution). Results also show that, under probable maximum flood conditions, access to the reference repository location from the east and north would, most likely, be unimpaired, although Route 240 would be flooded and unusable. These results are considered to be conservative based on several conservative factors assumed in computing the flood magnitudes. Also, based on the evaluation of study results, it is recommended that a more detailed study be performed if design of flood protection measures is necessary in the future.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- DE-AC06-77RL01030
- OSTI ID:
- 1127229
- Report Number(s):
- PNL-4219; RHO-BWI-C-120
- Country of Publication:
- United States
- Language:
- English
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