Introduction to the Conduct and Organization of the Hawaii Dam Break Studies

Beginning around February 20, 2006, the Hawaiian Islands experienced unusually severe rain showers that caused severe flooding throughout the State. On March 14, 2006, the privately-owned Kaloko Dam on the island of Kauai failed sending a wall of water downstream that overtopped the Morita Dam, damaged Kuhio Highway, and swept away homes. At the request of the State of Hawaii, the Corps of Engineers' Honolulu District conducted emergency visual condition surveys of dams on the islands of Kauai, Maui, Oahu, Hawaii, and Molokai to determine if there were any immediate threats to public safety. These visual surveys resulted in point in time information on 143 dams. After touring the storm damaged areas on Kauai, particularly the damage caused by the Kaloko Dam failure, U.S. Senator Daniel K. Inouye requested emergency relief funds for Hawaii in the FY06 Emergency Supplemental Appropriation Bill that was being developed in the Senate at the time. The FY 06 Emergency Supplemental Appropriation Act (Public Law 109-234) contained $2M for the Hawaii Water System Technical Studies program for the conduct of dam break analyses. The dam break analyses evaluated the downstream inundation area in the case of a dam failure below selected dams. The analyses did not establish when or the likelihood of a dam failure. The selected dams were identified by the State of Hawaii, Department of Land and Natural Resources Dam Safety Program Office. These analyses were conducted in coordination with other Federal agencies, emergency management agencies, and counties. The 11 dams studied are: Kauai (7) — Twin Reservoir, Waita Reservoir, Elua Reservoir, Aepo Reservoir, Puu Lua Reservoir, Halamanu Field 21 Reservoir, and Upper Kapahi Reservoir; Maui (1) — Reservoir 24; Oahu (2) — Nuuanu Dam and Wahiawa Dam; and Molokai (1) — Kualapuu Reservoir. The studies were conducted by staff from the Corps' Honolulu District, Corps' Hydrologic Engineer Center (HEC), and the A-E firms of Parsons-Brinkerhoff/Northwest Hydraulic Consultants, SSFM/WEST Consultants, Tetra Tech, and Oceanit Laboratories. This paper discusses the coordination by the Corps with the State of Hawaii Dam Safety Program Office, conduct of a model workshop, creation and function of the Technical Advisory Group, the production and review of multiple study products, and final transmittal of products for use by the State of Hawaii in coordination with dam owners and emergency management agencies.