Resolution No. 4814 - Laserfiche WebLink

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13.0 DISRUPTION OF UTILITY AND TRANSPORTATION SYSTEMS The previous chapters dealt with each of the major natura~ hazards affecting the Eugene/Springfield Metro Area including floods, winter storms, landslides, wildland/ urban interface fires, earthquakes and volcanic hazards. These chapters evaluated each of the hazards and the risk arising from the hazards as they affect the buildings, infrastructure and people of the Eugene/Springfield Metro Area. Each of these hazards may result in not only damage to buildings but also damage to and disruption of utility and transportation systems. Mitigation projects may be formulated to reduce or avoid such damage and disruptions and a few examples were discussed in the previous chapters. In this sense, evaluating the potential damage and disruption of utility and transportation systems from each hazard is part of the risk assessment for each locality affected by a hazard. However, disruption of utility and transportation systems may have consequences for the affected communities which are far broader than the direct damage and corresponding direct loss of service. In this sense, disruption of utility and transportation systems may be viewed almost as a hazard. As for other hazards, the probability, duration, and extent of such outages can be assessed and the impacts (risk) associated with such outages can be quantified. Among the major utilities, loss of electric power generally has the most widespread effect on other utilities and on the community as a whole. Therefore, this chapter dea~s with electric power outages in more detail than for the other utility and transportation systems. 13,1 Transportation Systems Streets, roads, and highways are subject to closure during flood events because of high water levels on road surfaces. This type of closure may occur either during a major flood event on the larger rivers and streams in the Eugene/Springfield Metro Area and surrounding areas or during winter storms as a result of localized flooding on smaller drainage systems. ~n major floods or major winter storms, such road closures may be widespread, if flow velocities are Iow, then such closures are usually due primarily to water depth and there is generally little damage to the road system; reopening the road simply requires waiting for the water level to drop and then cleaning up mud and debris on the road surface. However, if flow velocities are higher then erosion of the road surface or undermining of the road may occur. This type of damage is most common in hilly areas with relatively steep slopes and occurs most often on smaller roads rather than on major highways. Reopening such roads requires repair of the damaged road surface. The flood of February 1996 provided ample evidence of the effects of flooding on roads. For example, in Lane County, there were dozens of flood-caused road closures. These closures included major routes such as US 101 North and South of Florence, Highway 36 in three ~ocations, Highway 126 at Noti, the Marcola Road in the Mohawk Valley, and the McKenzie Highway at Milepost 24. Even ~nterstate 5 had water flowing across it just north of Eugene near the Boston Mil~ Road overpass. In addition numerous smaller roads also had closures. Public Review Draft: August 6, 2004 13-1