LaGrande dam
| LaGrande dam | ||
|---|---|---|
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| location | ||
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| Coordinates | 46 ° 49 '22 " N , 122 ° 18' 15" W | |
| country |
 United States
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| place | Pierce County , Washington | |
| Waters | Nisqually River | |
| Height upstream | 285 m | |
| power plant | ||
| owner | Tacoma Power | |
| operator | Tacoma Power | |
| Start of operation | 1912 | |
| technology | ||
| Bottleneck performance | 64 megawatts | |
| Expansion flow | 39.6 m³ / s | |
| Standard work capacity | 345 million kWh / year | |
| Turbines | 4 × 6 MW; 1 × 40 MW | |
| Others | ||
The LaGrande dam ( English LaGrande Dam or La Grande Dam ) is a dam in the state of Washington , USA . It dams the Nisqually River to a small reservoir. The Nisqually forms the boundary between Pierce County and Thurston County at this point . The dam's power plant is located approximately 58 km (36 miles ) southeast of Tacoma ; the Alder dam is about 3 km upstream of the dam.
history
The Tacoma City Council decided in 1909 to build a hydroelectric power station on Nisqually in order to become independent of private electricity producers. A proposal by the city council to issue bonds in the amount of US $ 2.3 million was approved by citizens. The construction of the power station and the associated barrier structure began in February 1910. The power plant went into operation on schedule in November 1912.
This first dam was 10.7 m (35 ft ) and 13.7 m (45 ft) high ; its length was 68.5 m (225 ft). It was a little upriver from where the Alder Dam is today. A tunnel with a length of approx. 3 km (2 miles ) led from the barrier structure to the power plant. The electricity generated was carried over a 58 km (36 miles) 69 kV line to Tacoma and sold there for 6 cents per kWh .
Due to the increasing demand for electricity in the city of Tacoma, the original barrier structure was replaced by the two Alder and LaGrande dams in the 1940s, increasing the installed capacity from 24 MW to 114 MW (Alder 50 MW; LaGrande 64 MW).
The construction costs for the Alder and LaGrande dams were USD 23.6 million, more than double the originally estimated USD 11 million.
Barrier structure
The barrier is a concrete gravity dam with a height of 66 m (217 ft ) above the foundation level or 58.5 m (192 ft) above the river bed. The length of the top of the wall is 216 m (710 ft). The volume of the structure is 65,000 m³ (85,000 cubic yards ). The thickness of the dam is 26 m (85 ft) at the bottom and 3.65 m (12 ft) at the top.
Reservoir
At the normal storage target of 285 m (935 ft) above sea level , the reservoir extends over an area of around 0.182 km² (45 acres ). The minimum congestion destination is 277 m (910 ft).
power plant
The power plant is located about 3 km downstream from the dam. The installed capacity is 64 MW . The average annual production is 345 million kWh . The power plant is owned by Tacoma Power and operated by Tacoma Power.
The first 4 machines of the power plant were installed in 1912. They each provide a maximum of 6 MW. Another machine with 40 MW was put into operation in 1945. The normal flow is 39.6 m³ / s (1400 ft³ / s).
The power plant's machine hall was flooded in 1995 when the water level of the Nisqually reached the highest level ever recorded. Only in the following year could the power plant go back into operation after the necessary repair work.
See also
Web links
Individual evidence
- ↑ a b c d e f g h Hall of Fame: Facility Begins Legacy of Public Power in Tacoma. www.hydroworld.com, December 1, 2012, accessed on August 18, 2017 (English).
- ↑ a b Tacoma City Light's Alder Dam on the Nisqually River generates electricity in September 1945. www.historylink.org, January 25, 2003, accessed on August 18, 2017 (English).
- ↑ a b c d e LaGrande Dam. Tacoma Power , accessed August 18, 2017 .