Characterization of Fish Passage Conditions through the Fish Weir and Turbine Unit 1 at Foster Dam, Oregon, Using Sensor Fish, 2012 [report]

Joanne P. Duncan
2013 unpublished
Fish passage conditions through a Kaplan turbine and spillway fish weir at Foster Dam, located on the South Santiam River in Linn County, Oregon, were evaluated by Pacific Northwest National Laboratory for the U.S. Army Corps of Engineers, Portland District, using Sensor Fish devices. The objective of the study was to describe and compare passage exposure conditions, identifying potential fish injury regions encountered during passage via specific routes. The investigation was performed in May
more » ... 012, concurrent with HI-Z balloon-tag studies by Normandeau Associates, Inc. Sensor Fish data were analyzed to characterize the passage exposure conditions through the spillway fish weir and turbine Unit 1 at Foster Dam at two forebay pool elevations (616 and 634 ft mean sea level [MSL]) and to estimate data relationships with live fish injury and mortality estimates. For the spillway fish weir evaluation, Sensor Fish and live fish were deployed through injection system piping mounted on the weir. The bottom of the injection pipe was at an elevation of approximately 614 ft during testing at the 616-ft MSL (low) forebay elevation and at 632 ft during the 634-ft MSL (high) forebay level tests. Two systems were used-a 4-in. pipe for juvenile fish releases and an 8-in. pipe for adult releases at each elevation. Low discharge flows over the fish weir at Foster Dam resulted in a shallow depth of flow and a poorly formed discharge jet. As a result, the Sensor Fish came into contact with the spillway surface multiple times during passage, from initial impact to the bottom of the spillway chute. In addition, the slope of the spillway chute, at approximately 25 degrees, and the discharge jet's angle of impact contributed to conditions that could be deleterious to fish passing via this route. All Sensor Fish passing over the spillway weir experienced significant events, as determined from acceleration magnitude data (n = 42). A significant event is defined as an impulse in acceleration magnitude greater than or equal to 95 g. Significant events are caused by strike, collision with dam structure, or exposure to shear. Shear events were observed during the high-forebay treatment (634 ft MSL), and all occurred at chute impact. All other significant events were collisions, regardless of treatment condition. Event severity was greatest for Sensor Fish passing over the weir at the low-forebay level through the juvenile fish pipe, with a mean value of 157.6 g. However, 23% of the Sensor Fish passing over the weir at the high-forebay level were damaged following passage through the juvenile fish pipe compared with 5% at the low-forebay level. The nearly vertical drop after exiting the injection pipe and the fact that some of the Sensor Fish and steelhead were not entrained in the flow prior to passage over the spillway weir likely contributed to injuries-especially at the high-forebay level, where the drop was over 40 ft. Sensor Fish weighing approximately 50 grams with their attached balloons and radio tag would have an impact force of 1,865 and 3,185 newtons (N) for the low-and high-forebay levels, respectively. Adult steelhead may experience forces of as much as 260,540 N, resulting in injury or mortality, depending on the surface area over which the force was distributed. For the turbine evaluation, Sensor Fish were injected into the turbine intake flow at an elevation of approximately 593 ft MSL, slightly higher than the penstock centerline elevation (590 ft MSL). Exit from the pipe terminus occurred into flows of approximately 5 fps, providing guidance into the penstock. Final Report iv Four turbine operation levels were tested at the low-forebay level, ranging from 2.8 to 7.0 MW, and three operation levels were tested at the high-forebay level, ranging from 4.9 to 9.0 MW. Sensor Fish experienced high damage/loss rates of more than 22% during turbine passage. Evidence of grinding or squeezing was evident in several Sensor Fish units, assumed to be from being compressed between the turbine blade and wall. Sixty-two percent of the Sensor Fish experienced at least one significant event during turbine passage (n = 50). For the low-forebay turbine operations, events were most frequent at the wicket gates; for the high-forebay operations, events were more prevalent during runner passage. Events observed at the wicket gates at high-forebay operations were generally of a lower magnitude than those detected at the low-forebay operations. The significant event magnitude values for the most severe event experienced by Sensor Fish during passage through turbine Unit 1 were greatest at the low-forebay 4.9/5.0-MW operation, averaging 152.8 g. Highest severe event magnitude at the high-forebay level was 142.8 g, at the 6.5-MW operation. Significant events of the greatest magnitudes were generally higher during the low-forebay treatment than during high-forebay treatment. The occurrence of more than one significant event during the passage of an individual Sensor Fish was more likely during high-forebay operations. Significant event occurrences as experienced by the Sensor Fish were two to three times more frequent for Foster Dam turbine passage than those observed during previously conducted studies of Kaplan turbine passage at Columbia River dams. Contributing factors to the higher number of events at Foster Dam may include the following: the turbine runners are smaller in diameter, have six blades, and rotate at 257 rpm, and the associated velocity at the periphery of the runner is approximately 224 fps. A simulation model was used to estimate the possibility of fish being injured by a strike with the runner blade. The strike probability estimates made using a blade strike model compared favorably with the frequency of occurrence of severe events observed using Sensor Fish. In addition, the blade strike model estimates of injury probability tracked the observed frequency of occurrence of injury to live balloontagged test fish. Lowest pressure nadirs observed during turbine passage were for the high-head (high-forebay) operations. The observed nadir values for the Foster Dam turbine are comparable to those observed for Kaplan turbines installed in the mainstem Columbia and Snake river dams, ranging from approximately 14 to 21 psia. Comparison of Sensor Fish results for the two passage routes tested at Foster Dam during spring 2012 indicate that Sensor Fish passing over the spillway weir experienced higher event magnitudes than those passing through the turbine because most experienced significant events upon impact with the spillway chute. Increasing the depth of flow would likely enhance passage conditions by providing an improved discharge jet as well as a cushioning effect for fish and Sensor Fish. Possible changes to the weir design should also be investigated to improve the route's safety at both pool levels. Final Report v
doi:10.2172/1067960 fatcat:ak324pjz5zfa5npearsku2jzai