Resolution No. 4814 - Laserfiche WebLink

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The 2002 windstorm event had significant effects on the Eugene/Springfield Metro Area Area, primarily from tree fails. Widespread tree fal~s resulted in significant damages to utility lines and poles as well as damages to vehicles and buildings. The most widespread impact on the Eugene/Springfield Metro Area was numerous areas with localized ~oss of electric power from downed electric lines and poles. 7.3 Winter Storm Risk Assessment Winter storm flooding and wind damage may affect both infrastructure and buildings. Localized flooding from winter storms very commonly affects the transportation system, especially roads. Severe winter storms will result in numerous road closures due either to washouts or due to depth of water on road surfaces. Such localized flooding also affects buildings located in the flooded areas. Additional road closures are likely in some events from landslides/mudslides as well as from snow/ice storms. Wind impacts from winter storms arise primarily from tree fails, which may affect vehicles and buildings, to some extent, but whose primary effect is often on utility lines, especially eiectdc power lines. Wind damages may result in widespread downing of trees or tree limbs with resulting widespread downage of utility lines. Such tree-fall induced power outages affect primarily the local electric distribution system. Transmission system cables are generally less prone to tree fall damage because of design and better tree-trimming maintenance. In severe wind storms, direct wind forces and wind driven debris may cause building damages, especially for more vulnerable types of construction such as mobile homes. As discussed above in Section 7.1, both winter storm flood hazards and winter storm wind hazards have highly localized impacts. The location and severity of such impacts depend very strongly on specific local conditions~ Therefore, it is difficult to make regional risk assessment or loss estimates from mapping the hazards and overlaying the inventory: such a risk assessment simply requires too much detailed data which are not available. An alternative approach is to document the severity and locations of winter storm flood and wind damage from historical events. A good example of this approach is the excellent summary of damages and losses experienced in the February 1996 floods: The Cascades West Region of Oregon and the February Flood of 1996: A Regional Flood Recovery P~an for Benton, Lane, Lincoln, and Linn Counties, Oregon Cascades West Council of Governments, November 1996. For more quantitative risk assessment of localized flooding and wind damages arising from winter storms, the best approach is to systematically gather data on sites of repetitive damages due to localized flooding or wind damages. By documenting (and mapping using GIS) the sites of repetitive damage events, along with documentation of the type and cost of damages and losses, the most seriously affected sites can be clearly identified. Clearly, such repetitive loss sites with significant damages are likely candidates for mitigation actions. The potential impacts of winter storms on the Eugene/Springfield Metro Area are summarized below in Table 7.4. Public Review Draft: August 6, 2004 7-9