ALP 3

Contents
discharge curve) and to the discharge water passing through a second energy dissipating pipe.
The discharge pipe inside of the sump pit is designed to dissipate discharge energy further by
passing the water through large holes versus an open -ended pipe. This energy dissipating pipe
does not work like the sleeve valve but is in place to further dissipate discharge energy in the
sump pit and is not intended to kill fish or fish embryos. This second energy dissipating device
has 6 in diameter holes (compared to the 0.63 in. holes for the sleeve valve) and live fish are
likely to seek velocity shelters between the holes as well as near the bottom of the structure
where there are no holes. Observation of initial trials at lower reservoir elevations found that the
discharge water boiled up only in one -half of the pipe whereas, ramping the discharge up to 25
percent open created a 360 degree boil (figure 17). Therefore to flush out the remaining test
sample from the sump pit, we opened the sleeve valve to the 25 percent open position and held it
there for 5 minutes. And in effort to conserve water, we performed the outlet works flush at the
end of each testing period. However, few live test fish were found in tests at 6805 ft and 6828 ft
and none at the other sump pit flushing events.
Figure 16. Trash -rack grate over discharge sump well pit to prevent entry.
Figure 17. Sump well pit boil created by discharging water (notice the boil is occurring 360
degrees around the discharge pipe).
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