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Kerckhoff Lake, Powerhouse, and Dam


Kerckhoff Dam, Kerckhoff Powerhouse, and Kerckhoff No. 2 Powerhouse are all included in FERC Project Number 96, which was originally licensed in 1922. Kerckhoff Dam impounds Kerckhoff Lake, which serves as the forebay for both Kerckhoff and Kerckhoff No. 2 powerhouses. The dam is a concrete arch type, approximately 114 feet in height. The top of the dam is at elevation 994.50. The spillway crest is at elevation 971.34 and the normal maximum water surface is at elevation 985.00. The reservoir has a usable capacity of 4,252 acre-feet. Separate intakes and water conveyance systems are provided for the Kerckhoff and Kerckhoff No. 2 powerhouses. Both intakes are located on the south bank of Kerckhoff Lake near the dam. For Kerckhoff Powerhouse, the intake structure is constructed of concrete and is equipped with two steel, slide gates. The intake for Kerckhoff No. 2 Powerhouse is a concrete-lined box structure located upstream of the Kerckhoff Powerhouse intake. Kerckhoff Lake has limited storage capabilities, which allow the powerhouses to provide peak generating loads during periods of high electrical demand.
 

Kerckhoff Powerhouse

Kerckhoff Powerhouse, sometimes referred to as Kerckhoff No. 1 Powerhouse, is a reinforced concrete, tri-level building approximately 46 feet by 99 feet inside. It houses three vertical, Francis-type turbines directly coupled to generators with a total capacity of 38 MW. The normal maximum gross head is 350 feet and the turbine speed is 360 rpm; each turbine has a butterfly type shut-off valve generation voltage is 6,600 volts (v). The project was commissioned in 1920.  In the lower sections of the powerhouse, bedrock has been exposed in wall sections. These sections appeared very stable with little or no spalling, which attests to the high quality of the rock. Water supply to Kerckhoff Powerhouse is conveyed by an approximately 16,943-foot-long unlined tunnel leading to three penstocks, which range from 913 to 945 feet in length and allow for a normal maximum gross head of 350 feet. A surge chamber is located at the end of the tunnel but upstream from the penstock gate valve. Two adits used during construction are located along the tunnel. The adits were plugged on completion of tunnel construction and have not been opened or used since. Three 115 kilovolt (kV) transmission lines serve Kerckhoff and Kerckhoff No. 2 powerhouses.

 

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