Project: Bonneville Post-Deflector Total Dissolved Gas Exchange Study
PI: Mike Schneider
Project Description/Activities/Capabilities:
The proposed TDG exchange evaluation provides information regarding the impacts of added flow
deflectors and associated spill management strategy on TDG exchange below the Bonneville Spillway.
This information can be used to quantify the water quality benefits associated with the modified structure,
provide operation direction for the spillway, and help identify the relative TDG exchange properties
associated with the new and old spillway flow deflector design.
Sponsor: Portland District, POC Laurie Ebner
CHL Personnel: Mike Schneider and Calvin Buie
Project Location and Description:
Bonneville Dam is about 6400 feet long and includes two powerhouses, a spillway, two
navigation locks, multiple fish ladders, and four islands. A total of six 59-megawatt units
and eight 77-megawatt turbines reside in Powerhouse No. 1 and No. 2, respectfully. The
18-bay spillway is approximately 1100 feet long, and has twelve 50.75-ft-high vertical lift
gates and six 60-ft-high wheel gates. The spillway crest is located at elevation 24 with a
normal pool elevation ranging from 71.5 to 76.5. Spillway bays 4 through 15 and 18 have
deflectors that are 12 ft long and are located at el 14. The stilling basin is a horizontal
apron-type with a double row of sloping baffle blocks. The stilling basin is 147 ft long with
an invert elevation of -16 for the first 71 ft and drops to el -24 for the remaining length. An
irregular concrete apron is at the end of the stilling basin and usually slopes downward to
the tailrace topography. The old lock is76 ft wide by 500 ft long. It discharges into a
navigation channel that joins the releases from Powerhouse No. 1 approximately 1200 ft
downstream of the lock. The new lock is 86 feet by 675 feet and discharges into a channel
that joins the discharge from the remainder of the project about 2600 ft downstream of the
lock.
Facilities: Field Study
Related Topic Areas: Hydrualic Structures, Environmental Studies, Spillway Flow Deflectors, Total
Dissolved Gas, Hydropower, reservoir
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