1 - Alaska Energy Data Inventory

from these gauges will be converted to water surface elevation andmonitored continuously from the powerhouse. This system is similar to thatused for the Driva hydropower scheme in Norway (ref. 10).An additional system for monitoring water surface elevation would bedeveloped by WES for calibration and verification of the other dualsystem. This system will measure distance to the water surface based on asonic echo.Two additional pipes are shown on Plate 36. These are 2-inch diameterair pipes. One of the pipes is connected to a compressor in the powerhouseand is used for adding air to the chamber automatically or manually to keepthe water level between specified limits. The other pipe will terminateoutside the powerhouse at a valve which can be opened to release air fromthe chamber. The pipe must release air outside of the powerhouse becauseof the possiblity of carrying poisonous H 2S or other gases which may bepresent. (Laboratory studies for the Driva plant (ref. 10) found this tobe a possibility.)All monitoring and air pressure conduits will be contained in a metalconduit and will run from the air chamber, through the access adit plug,and to the powerhouse vicinity.J. Air Chamber Surge Tank Location Sensitivity Study - Due to thepresence of faults in the vicinity of the location selected for the airchamber surge tank, a sensitivity study was conducted to determine theeffects of moving the air chamber 200 ft upstream and 200 ft downstreamfrom the design location. Stability, rejection, and demand calculationswere done using "MSURGE".Preliminary IIMSURGE IIruns for stability, using an 11 ft tunnel and thecritical net head of 875 ft as predicted by the Svee Equations,demonstrated that the incipient stability condition occured at essentiallythe same air volume (between 25,000 and 26,000 ft 3 ) for both the upstreamand downstream locations. The demand condition was also run on IIMSURGE II84-17