better results are emerging as full-scale test data becomes available to enhance understanding of the
turbine aeration problem.
TVA installed 2 auto-venting turbines at Norris Dam in 1995 and 1996. These units have been
successful at supplying DO uptake values of up to 5.5 mg/L to support TVA's goals of 6 mg/L for the
extremely popular cold water trout fishery downstream. Each turbine at Norris includes 4 air
passageway designs as shown in Figure 4.7.3.
Figure 4.7.3 Aerating Turbine for Norris Hydro Project
These turbines have been tested extensively to evaluate the performance of the various aeration
alternatives included in their design (Hopping et al., 1996, Hopping et al., 1997). A schedule of
operation has been developed that optimizes the effectiveness of each aeration alternative in providing
DO uptake with its effects on turbine efficiency at various operating conditions.
TVA is currently installing auto-venting turbines at Douglas Dam and has specified auto-venting
requirements for a total of twenty six replacement units.
Other hydropower utilities are also making use of auto-venting technology. Duke Energy has
installed new auto-venting turbines at their Wylie and Oxford Hydro Stations with preliminary results
that are promising (Jablonski and Kirejczyk, 1998). Duke has ordered an additional auto-venting unit
for Wateree. The Savannah and Mobile Districts are considering aeration requirements in specifications
for new turbines at sites with low dissolved oxygen.