Multi-Hazard Mitigation Plan: Executive Summary

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Executive Summafv • Tsunami. New mapping is being developed for tsunami inundation areas (delineation of historical and modeled run-up used to control development) and tsunami evacuation areas (more conservative delineation than inundation areas based on identifiable landmarks such as roads and used to facilitate field evacuation logistics). Historically in Hawaii Flood Insurance Rate Maps (FIRM) also accounted for the tsunami inundation risk areas and limits of historical inundations (VE zone). • Flooding. FEMA and the County are working on making the FIRMS available in digitized format, which will improve the GTS. The County is also working on improving the accuracy of the FTRMs based on updated topographic information. Additionally, the GIS includes revisions to the FIRM (called Letter of Map Revisions or LOMRs). Improvements are needed to the rainfall and stream-flow gauging system to improve forecasting and real-time monitoring. In December 2008 and February 2009, FEMA submitted to the the County Preliminary Digital Flood Insurance Rate Maps (Pre-DFTRMs). The County is currently doing flood studies (map updates) in the following areas: Puna, Hilo, North and South Kona. There are several privately funded flood studies ongoing in the Kona, Hilo and Waimea. As part of FEMA's mapping process, the County is also pursuing, with the help of the U.S. Army Corps of Engineers, levee certifications for Alenaio, Paauau and Wailoa Flood Damage Reduction Control Projects. All of these studies will be completed within the next year to year and one half. • Dam Failures.Dam break studies have been conducted to map areas were flooding may result due to dam failure. • High Surf. The entire coastline of Hawaii Island is susceptible to the effects of high surf, areas were the potential for coastal flooding exists are defined as the VE zones on the current FIRM maps as described in the Hurricane and Flood chapters. • Coastal Erosion.No studies or GIS data exist to establish safe setback limits to address sea cliff erosion risks. Beach erosion in Hawaii County is not a significant enough problem to presently warrant detailed mapping. • Droughts and Wildfire. As part of the Hawaii Drought Plan areas where the water supply sector, agriculture and commerce, and/or environment, public health, and safety are vulnerable to the effects of drought were mapped in GTS. This mapping also identifies areas where historic wildfires have occurred and where this risk is present. • HAZMAT. The Department of Health Hawaii State Response Program List of Priority Sites identifies all Hawaii sites for potential or known non-emergency response actions managed by the HEER Office Site Discovery, Assessment, and Remediation Section Remedial Project Managers (RPMs). Sites are categorized as a potential hazard when sampling data indicate that contaminant concentrations exceed Hawaii Environmental Action Levels. The DOH Hawaii SRP Priority List of Sites shows 83 sites on the Big Island with potential or known hazardous substance or petroleum contamination. Three sites were determined to require No Further Action (NFA). HEER Office Remedial Project Managers (RPMs) continue active oversight on 70 assessment and response actions. X Hawaii Countv Multi-Hazard Mitigation Plan