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Tuesday, May 19 10:30 - 11:45 AM Track I - CRS Planning - Moderator: Tim Ramsaur .:'~, THE FORT COLLINS FLOOD OF 1997: PU1TING A SYSTEM TO THE TEST Marsha Hilmes On July 28, 1997, Fort Collins, Colorildo experienced record amounts of rainfall that resulted in extreme flooding on Spring Creek and several other smaller streams, Fort Collins is nationally recognized for its proactive floodplain management program, but there was still loss of life and severe property damage, Rainfall amOlmts during the most intense 5.5 hour period of the storm exceeded 10 inches in some areas, almost three times the 100-yellr, 6-hour rainfall for Ft Collins, Rainfall amounts as high as 14,5 inches in southwest Fort Collins accumulated over 30 hours; the aver,lge annual precipitation is 14.5 inches, Satellite and radar images show that a monsoonal moisture pattern from the south got trapped against the foothills on the west side of Ft. Collins and remained stationary for several hours, Precipitation from these types of monsoonal storms is difficult to estimate, In the case of the Ft. Collins flood, National Weather Service radar llllderestimated the precipitation by approximately 50 percent. Discharge estimates of streamflow show that the July 28, 1997 flood was larger than the 500-year flood at "lllocations along Spring Creek At one site, the estimated discharge is more than twice as large as the 500-year flood, Estimates on several of the smaller streams are also greater than the 500-year discharge. The events that occurred during the flood were severe: five people died, numerous homes and businesses were damaged, a trailer park that was not in the floodplain was destroyed, a train derailed, trailers caught on fire, and a building exploded due to a gas leak, Fort Collins had been working hard for a number of years to mitigate for flocding. On Spring Creek alone, $5 million dollars had been spent on improvements and acquisition, Other mitigation that is continually being done includes outreach projects, preservation of open space, higher regulatory standards, land-use planning, and advanced planning. The lesson to be learned from the Ft. Collins flood is that no matter how much planning and mitigation a community does, the system will be p,"t to the test, and there is no way to prepare for all situations, We don't know when, where, or how big the next disaster will be, But we do know that every community faces the potential for disaster no matter how well prepared, and the key is to try to mitigate for as many situations as possible. THE COMMUNITY RATING SYSTEM (CRS) - THE 1999 CHANGES Brett Gates Four years after implementation of the program. the FEMA 's Community Rating Task Force formed an Evaluation Committee to determine whether CRS is meeting its original ,expectations, The Committee utilized numerous evaluation techniques such as; Local Official & Floodplain Resident Surveys; focus gronps with experts from the fields of insurance, outreach, flood warning, stormwater & drainage systems; as well as, developing various technical and statistical studies, The Committee validated the CRS program in general, but. made specifically recommendations based on this evaluation taking into account community suggestions and 8 years of experience, The proposed changes fall into three general areas. First, certain activities deserve more credit based on their proven effectiveness in reducing flood losses, such as: Additional Flood Data; Open Space Preservation; Higher Regulatory Standards; Stonnwater Management; Acquisition and Relocation; and Retrofitting, Second, communities should be encouraged to design their own programs, This will be especially recognized in Outreach Projects; Stcrmwater Management; and Drainage System Maintenance. Finally, the CRS should be simplified, While there will always be a need to difli:rentiate levels of a program through documentation, the CRS will support a simplified approach, ISO/CRS Specialists will now be providing more assistance to communities in scoring and documenting their programs. This session will provide a brief overview of the evaluation process, and focus on the major revisions to the 1999 CRS Program, PLANNING COASTAL SUCCESS: FLOOD MmGATION PROJECTS ON IDLTON HEAD ISLAND Trudie A. Johnson Hilton Head Island is a 42 square mil,: barrier island located off the coast of South Carolina With its low elevation and flat topography, storm drainage is critical to flood mitigation strategies, In October 1994, two weeks of rain produced island-wide flooding which damaged over 300 structures, closed roads and disrupted business activity. As a result. the Town ofRilton Head Island completed an assessment in 1995 titled the Island Wide Drainage Study, This study mapped drainage systems in all major watersheds using GIS teclmology, Drainage deficiencies were detennio,:d by modeling measurable watershed characteristics and estimating peak flow rates of stormwater runoff. Sixteen necessary drainage improvements were identified and prioritized. Cost estimates and sources of funding were documented, Stakeholders were identified and meetings were held to gain agreement on the roles of each of the dependent partners. Public meetings were held with effected neighborhoods, Construction began in 1996 cn the first of the projects, The Study identified the Jarvis Creek Drainage Project as a critical priority. Initial calculations indicated that the cleaning and widening of an existing drainage ditch would destroy wetlands, trees and wildlife habitat. In 1996, as design proceeded, the Town of Hilton Head Island began negotiations to purchase fifty acres of adjacent pasture land. This paper will chronicle the Island Wide Drainage Study and the synergistic public/private partnerships that resulted in a unique solution for one drainage project in an environmenta\ly sensitive watershed, A team of engineers, hydrologists, biologists, land planners and landscape architects contributed to the finaI plan. A thirteen acre lake capable of storing and conveying the necessary stormwater was designed within a new fifty acre public park. A FEMA Flood Mitigation Assistance Grant recognized the project in 1997.