Olympic National Park Road Hazards and Solutions Report

ENTRIX

From the Introduction: Most roads in ONP are located within floodplains and channel migration zones in a highly unstable mountain region. Numerous natural hazards pose ongoing threats to the park's ingrastructure, including landslides, avalanches, debris flows, and flooding from heavy rainfall and rain-on-snow events. Poorly situated roads and facilities in valley bottoms are frequently damaged by relatively small storm events. Damaging events are linked to the inherent park landscape, including steep mountainous topography, geologic materials, and the high rainfall characteristic of the western and southern flanks of the Olympic Peninsula. Determining the natural processes that pose a risk to infrastructure is at the root of designing appropriate solutions of determining whether and where a road segment or facility should be moved. Recurring road washouts and flooding cause chronic environmental impacts and economic hardship for the park. The current road maintenance program is largely based on reacting to emergency situations, which precluded a balanced long-term approach to ensuring safe transportation routes, protecting natural and historic resources, and preventing ecologic impacts that degrade riparian and aquatic ecosystems and the visitor experiences. Due to the perceived "crisis" nature of the situation, the traditional design approach (engineers not familiar with fluvial geomorphology and local ecology), and funding constraints, emergency repair to park infrastructure not only recreates the pre-storm situation but is mandated to exactly that. This traditional approach essentially insures future problems with further degradation of aquatic resources, including habitats of federally listed endangered fish. We believe this process can be greatly improved by incorporating geomorphic hazard assessments and providing better flood and erosion protection alternatives such as those described in this report. Emergency situations can be viewed as opportunities to recognize natural processes that shape the landscape (floods and debris flows) and utilize funding resources to provide long-term flood protection. This report describes some of the locations identified by ONP with recurring damage. A brief introduction to fluvial geomorphic processes and associated hazards that threatened road infrastructure are discussed. The report also presents a series of design solutions that include both typical measures to address road problems and designs that provide an innovative, sustainable, natural systems engineering approach. The latter have been developed and used more recently, and can serve the park maintenance efforts by providing viable alternaitves to more conventional approaches that may not be as friendly to aquatic life. Furthermore, these approaches incorporate a strategy for floodplain restoration as a whole, rather than simply site-level repairs. The preferred approach should always be sustainable natural systems engineering based on thorough understanding of geomorphological processes, ecology, and context-sensitive engineering. When properly designed and constructed, the alternatives presented here all present viable solutions that will not require recurring maintenance -- a key goal of flood response funding programs.