Bull Run Hydroelectric Project
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The Bull Run Hydroelectric Project is a Portland General Electric development in the Sandy River basin in U.S. state of Oregon. Originally built between 1908 and 1912 near the town of Bull Run, it supplies hydroelectric power for the Portland area. The project uses a system of canals, tunnels, wood box flumes and diversion dams to feed a remote storage reservoir and power house. The entire project is slated for decommissioning, starting in the summer of 2007, due to rising environmental costs.
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[edit] History and Overview
The Mount Hood Company began the project in 1906, building the Little Sandy Dam to divert water through a 3 mile (5 km) long wood box flume to Roslyn Lake. The last few miles of the Little Sandy river were effectively eliminated since the entire river was diverted, and all salmon and steelhead habitat above the dam was lost. Roslyn Lake, completed in 1911, was built on a plateau, about 320 feet (100 m) above the Bull Run River and Powerhouse. The 160 acre (650,000 m²) lake acts as a forebay for the powerhouse and has long been used by the community for recreation. The powerhouse was completed and put into operation in 1912, the same year that the Mount Hood Company was bought by Portland Railway Light and Power Company, which would later become Portland General Electric.
In 1913 a second dam was built on the (Big) Sandy River. The 47 ft (14 m) high Marmot Dam would supply the majority of the project's water, about 600 ft³/s (17 m³/s), but use only a fraction of the Sandy's normal flow. The Sandy River, however, is on the other side of the Devil's Backbone ridge from the Little Sandy River. A series of canals and tunnels were required to reach the Little Sandy Dam, where their flows are combined and diverted to the flume and Roslyn Lake.
The Marmot Dam has always had fish ladders to allow migration of Salmon and Steelhead, however they performed poorly at first and have required frequent upgrades and maintenance, which continued into the 1990s. Fish screens were added in 1951 to prevent downstream migrating fish from entering the diversion and being killed by the water turbines.
In 1989 the original timber crib Marmot dam was replaced with a concrete structure.
[edit] Current operations
The powerhouse has a nameplate generating capacity of 21 MW and produces an average 13 MW, or about $6,600,000 worth of electricity annually (at local customer rates). PGE did not renew its license, which expired in 2004, and instead filed a notice stating, ... the likely cost of providing the necessary level of protection, mitigation, and enhancement for the resources affected by the Project would outweigh the economic benefit of generation at the Project over the life of a new license...2 The project continues to operate with a license extensions while decommissioning awaits approval.
[edit] Facts
| Nameplate Generating capacity | 21 MW |
| FERC license | No. 477 |
| Average power generation | 13 MW |
| Average annual power generation | 110,000 MW·h (400 TJ) |
| Electrical power value at $0.06/kW·h | $6,600,000 |
| Sandy River water supply | 600 ft³/s (17 m³/s) (max) |
| Little Sandy River water supply | 100% |
| Flume capacity | 900 ft³/s (25 m³/s) (in any combination of Sandy or Little Sandy water) |
| Lake surface area | 160 acres (650,000 m²) |
| Usable storage capacity | 928 acre feet (1,145,000 m³) |
| Penstocks | 2 x 1200 ft (370 m), 9 ft (2.7 m) diameter |
| Hydraulic head | 320 ft (98 m or 960 kPa) |
| Turbines | 4 |
[edit] Decommissioning
The decommissioning plan is currently under review by government agencies and presents special problems for PGE, since there isn't a large body of knowledge of similar dam/lake removals; the Marmot Dam will be the largest concrete dam ever removed in the United States. The area is a pristine wildlife habitat (for salmonids in particular) requiring special care to protect the environment during dam removal, and decommissioning will affect many people's livelihood (whitewater rafting companies, vendors at Roslyn lake, etc). One of the largest issues will be control of the estimated 1 million cubic yards (800,000 m³) of silt and gravel that has settled behind the dams and which can harm the rivers' health. PGE employed RESOLVE to develop a plan among the interested parties and an agreement was reached in 2002 (see reference section).
The plan's main points;
- Removal of the Marmot Dam during summer of 2007, create a temporary structure to hold the silt until the spring runoff flushes it.
- Removal of the Little Sandy dam in 2008, after which Roslyn lake will cease to exist. This will restore the Little Sandy river habitat and salmon and steelhead migrations.
- PGE will donate about 1500 acres (6 km²) to a wildlife conservancy and public recreation area, and transfer its hydroelectric water rights to the Oregon Water Resources Department.
- PGE will assist in fisheries, monitoring and site restoration until 2017
[edit] References
- Taylor, Barbara (1998), Salmon and Steelhead Runs and Related events of the Sandy River Basin - A Historical Perspective, (prepared for PGE, 340Kb pdf).
- Decommissioning Plan for the Bull Run Hydroelectric Project, FERC Project No. 447, Filed by PGE with the Federal Energy Regulatory Commission Office of Hydropower Licensing, Washington DC, November 2002. ( 602 kB pdf)
- Settlement Agreement Concerning the Removal of the Bull Run Hydroelectric Project..., PGE and interested parties, Oct. 24 2002. ( 1.2MB pdf)
- Clean Water Act § 401 Certification Evaluation and Finding Report For the Decommissioning of the Bull Run Hydroelectric Project (FERC No. 477), Sandy River Basin, Clackamas County, Oregon 1.2MB pdf.
