2006 Flood on the Hood River
PacifiCorp had planned to continue operating Powerdale until beginning the decommissioning process in April 2010. However, on Nov. 7, 2006, a flood and the resulting debris flow damaged the facility, including complete destruction of key sections of the flowline between the dam and the powerhouse. One section of the flowline collapsed into Hood River and another section collapsed in place. There also was flooding of the powerhouse and substation, and a significant amount of sediment ended up at the diversion dam intake and powerhouse tailrace.
Because of the potential that high levels of sediment in the flood flows would cause damage, PacifiCorp had shut down project operations before the flood occurred. Immediately after flood waters receded, PacifiCorp began stabilizing the project. This work, which was completed in February 2007, included measures to safeguard the public. The diversion dam, which previously had served as a recreational facility, became off limits. Public access to areas around collapsed sections of flowline and the powerhouse was also restricted. Hazardous materials were removed from the shop and chemical storage building. The section of steel flowline was removed from Hood River, as were sections in imminent danger of collapse. Both collapsed sections of wood-stave flowline and those in danger of collapse were removed. Security bulkheads were installed on all open flowline sections.
Given the extent of the November 2006 flood damage, PacifiCorp asked FERC early in 2007 for permission to immediately cease power generation. Decommissioning was to begin in only three years, the cost of returning the project to operation would be more than $4 million, and PacifiCorp’s other facilities could provide the 47,000 megawatt hours predicted to be lost at Powerdale, so FERC granted permission to cease generation on Feb. 8, 2007. PacifiCorp is still required to complete decommissioning by 2012, but no longer is required by FERC to generate power at the facility.
About the Project
The Powerdale Project is located on the Hood River in Hood River County, Ore. With an installed capacity of six megawatts, the project includes:
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a 10-foot-high, 206-foot-long concrete diversion dam
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an 80-foot by 60-foot concrete intake structure
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a reservoir with a storage capacity of approximately 5 acre-feet at the normal pool elevation of 292 feet National Geodetic Vertical Datum (NGVD)
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a 16,000-foot-long water conveyance system consisting of a concrete canal, steel flume, settling basin, penstock intake, wood stave and steel penstock, and surge tank
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an 86-foot-wide, 51-foot-long concrete powerhouse with a 6-MW turbine-generator unit
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a 15-foot-long rock-lined tailrace; and
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upstream and downstream fish passage facilities.
There are no federal lands within the project boundary, but the powerhouse and the lower half of the penstock are located in the Columbia River Gorge National Scenic Area, which is managed by the U.S. Forest Service. The project is operated in a run-of-river mode.
Powerdale Settlement Agreement
On June 6, 2003, a settlement agreement (Agreement) calling for decommissioning was signed by most of the intervenors. The Agreement provides for the interim operation of the project until decommissioning commences in 2010.
Powerdale Decommissioning
The Powerdale Hydroelectric Project is located near the mouth of the Hood River, near Hood River, Oregon. PacifiCorp has agreed to decommission and remove the project in accordance with the 2003 Powerdale Hydroelectric Project Settlement Agreement and the related Federal Energy Regulatory Commission (FERC) Surrender Order, issued in 2005.
The schedule for development and approval of the engineering, construction and permitting documents, and related management plans, is based on beginning the physical decommissioning activities by April 2010.
Steps involved in decommissioning the Powerdale Hydroelectric Project include removing the dam, adjacent Oregon Department of Fish and Wildlife fish facility, intake structure, power canal, steel flume, sand settling basin, transition structure and the concrete saddle supports for the previously removed wood stave flowline segments. The steel flowline segments and berm will remain in place. While the original powerhouse will remain in place, certain nearby structures will be removed and some equipment inside the powerhouse will be removed. Some existing facilities closer to the Hood River will also be removed.
These demolition activities will require permits from the U.S. Army Corps of Engineers, Oregon Department of State Lands and Hood River County.
The project has not been producing electricity since November 2006, when a flood on the Hood River caused severe project damage. The powerhouse has not been operable since then, and the main electrical transformers have already been removed from the switchyard adjacent to the powerhouse.
Annual Fish and Wildlife Meetings
The annual fish and wildlife meeting is scheduled to comply with Article 3.13.1 of the Powerdale Settlement Agreement which requires PacifiCorp to convene an annual meeting with NOAA Fisheries, US Fish and Wildlife Service (USFWS), Oregon Department of Fish and Wildlife (ODFW) and Confederated Tribes of the Warm Springs Reservation of Oregon (CTWS) to discuss any fish and wildlife mitigation and monitoring activities.
2007 Report to Federal Energy Regulatory Commissioning
History of the Project