Resolution No. 4814 - Laserfiche WebLink

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Facilities," (J. M, Eidinger, editor, 1999; chapter by K. A. Goettel "Seismic Upgrades of Water Transmission Systems: When Is It Worth It?"). Very similar principles appty to evaluating hazard mitigation projects for other utility systems for any type of hazard. The following sections briefly review utility systems with emphasis on identifying the system components which are most vulnerable to damage and loss of service from hazards covered in this Mitigation Plan: flooding, winter storms, landslides and earthquakes. Such components are thus logical targets for high priority mitigation projects whenever important components are subject to the hazards. 13.3 Potable Water Systems Water treatment plants, including those in the Eugene/Springfield Metro Area, are often located in flood prone areas and are subject to inundation when raw water enters the filters, sedimentation or floccu~ation basins, resulting in loss of capability to treat incoming raw water properly. Water system control buildings and pump stations may also be subject to flood damages. Public or private water systems with wells as the water source are subject to outages when flood waters contaminate well heads; this is a common problem for smaller water systems. Water transmission or distribution pipes are rarely damaged by flood waters, unless there are soil settlements or major erosion, because the ~ines are sufficiently pressurized (for water quality) to prevent intrusion of flood waters. Water transmission or distribution pipes are, however, subject to breakage when they cross landslide areas or in earthquakes~ Water treatment plants are also subject to earthquake damages to the building and to process and control equipment. Water systems, including the Eugene/Springfield Metro Area's water systems, are also highly vulnerable to electric power outages. Many water systems include pumped storage systems where water is pumped to storage tanks which are typically located 60 to 200 feet above the elevation of water system customers. Such tanks generally contain no more than 1 or 2 days of storage beyond typical dai~y usage (for reasons of water quality). Thus, electric power outages of more than 1 or 2 days may result in loss of potable water due to the inability of pumping plants to pump water. The most logical mitigation projects to minimize such outages are to provide back-up generators at key pumping plants or to provide quick connects so that portable generators (if available) can be quickly installed. Water treatment plants are also subject to outages due to loss of e~ectric power. Common mitigation projects for water systems include flood protection for treatment plants, providing back-up power, moving pipes from active landslide areas, and seismic upgrades for treatment plants. 13.4 Wastewater Systems Wastewater systems are often highly vulnerable to flood impacts. Rising water may cause collection pipes to backup and overflow. Intrusion of storm water into collection systems may result in flows that exceed treatment plant capacities, resulting in Public Review Draft: August 6, 2004 13-5