Manager, Water Quality Support | Knoxville, Tenn.
Let’s get one thing clear up front: Jeff Ogden isn’t a fisherman. He chuckles when you ask him, because you—along with everybody else—are likely to assume that he would be. He gets the question a lot. But his answer is this: “I never did get into fishing, but I support the anglers wholeheartedly.”
He means that both metaphorically and literally—it’s his job at TVA to help create the kind of healthy, oxygen-rich waters in which sport fish and other aquatic life can thrive, in particular those below TVA’s dams.
“I coordinate with TVA staff and personnel in the preparation and safe operation of all the assets in the Reservoir Release Improvements program to ensure that TVA maintains a desirable dissolved-oxygen level in the tailwaters of our hydro plants,” he says.
That’s an issue, he explains, because of thermal stratification, a phenomenon that happens in many reservoirs, especially in the South. A layer of water heated by the sun stays on top and layers cooled by early spring runoff stay on the bottom—the layers don’t mingle until the air temperature cools the layers in the fall and the lake water “turns over,” or mixes again.
Organic material washes into the reservoir during the year and settles to the bottom. The dissolved oxygen in the bottom layers of water reacts with the organic material and often gets used up. Because the lower depths of water are not exposed to the air, this dissolved oxygen is not replenished.
“With thermal stratification the water with the higher dissolved oxygen level stays near the surface, and then in the deep areas of the reservoir the dissolved oxygen can be near zero,” Ogden says.
“Unfortunately, turbine intakes for dams are usually located near the bottom of these reservoirs, and when the turbines are operated water low in dissolved oxygen is discharged into the downstream river.”
You’ll rarely hear the words “fish kill” associated with TVA dams, and that’s a testament to Ogden’s work, and to the systems he keeps running to make sure oxygen levels in the tailwaters stay high.
TVA has developed and now uses several techniques for increasing the dissolved oxygen in these turbine releases.
“We have turbine venting, and that is where the air is drawn into the turbine in the plant through a vacuum and aerates the water as the turbine is generating,” Ogden explains.
Compressors and blowers act in much the same way by injecting air into the water passing through the turbine runner, thereby aerating the discharge.
Then, he says, there are the surface water mixers. “Those look like the ceiling fans in our houses, only huge,” he says. “They’re mounted on the upstream face of the dam and push the higher dissolved oxygen water downward toward the turbine intakes.”
His favorites, he says, are the weirs—essentially mini dams—below South Holston, Norris and Chatuge dams. “As the water tumbles over the top of the weirs, it acts like a natural waterfall, and it’s just as effective at adding natural oxygen into the water,” he says. “The weirs are beautiful.”
And finally there are the oxygen diffuser systems, made of HDPE pipe, “like pipe you’d see in your neighborhood for natural gas supply,” Ogden explains. “Interconnected to the pipe is soaker hose, asimilar to what you might use in your garden to water—only we’re putting oxygen through it.”
The oxygen diffuser systems are installed upstream of a dam and are suspended just above the reservoir bottom. Liquid oxygen is converted to a gaseous form and injected into the soaker hose via the HDPE pipe—offering aquatic life a direct hit of the good stuff.
Managing the Air Down There
As with so many other managers at TVA, fiscal responsibility is top of mind for Ogden as he ticks off his day-to-day: “I spend my time securing funding, forecasting, looking ahead and deciding where to spend on maintenance and where to spend on upgrades and new initiatives,” he explains. “It’s all a matter of setting priorities.” Project support staff from the Inspection, Testing, Monitoring, & Analysis (ITMA) organization are instrumental in identifying maintenance needs to ensure systems are operational when needed.
A big project this year is a replacement of the oxygen diffuser system at Cherokee Dam. “The former design was more difficult to maintain in that the soaker hose was at the bottom of the system and couldn’t be easily replaced,” he explains. “With the new generation design, the soaker hose will be on top so that component can be easily replaced.”
The year-long project will come together like a puzzle, as ITMA field staff weld the pipe sections together and strategically sink them into place.
Even though the air is cooling, it’s still prime time for oxygenation, Ogden explains. “You think of aeration season as a summer need, and it is, but really it’s much longer. That might not be the case for every site at every time, but with overlap the season can last from April through December.”
And throughout, Ogden is a busy bee, not only managing the upkeep and performance of his systems, but keeping an eye on oxygen levels, too. “I interact with the River Forecast Center on a daily basis,” he says. “There is an aeration engineer on staff 24/7—another set of eyes watching our oxygen tanks and oxygen levels and I’ll get called to step in and resolve an issue whenever needed.”
He loves that interaction. “It’s exciting knowing that the environment TVA has made in their tailwaters by implementing our oxygen improvements and scheduled minimum flow requirements has had such a positive impact,” he says.
TVA for Life
Ogden, a graduate of the University of Kentucky, was recruited to TVA right out of college, and has worked here for all of the 24 years since. He started off as an environmental engineer, working his way up the ranks in that capacity, serving as manager for the Environmental Engineering Field Services group, then as program manager for Environmental Support. He served as environmental NEPA liaison for the Boone Dam project, among other high-profile positions, before accepting his current position in 2016.
In this role, he likes the freedom and the people. “With this job I really enjoy that I have the opportunity to get out in the field and see the Valley, and that I have the flexibility to work with different groups who support us,” he says. “I’m a bit of a rolling stone.”
At the same time, he appreciates that he doesn’t have to roll too far, too often. “TVA has provided the opportunity to work on some challenging projects so I’ve had the chance to grow while maintaining a work-life balance,” he says. “That’s one of the advantages. I don’t have to be on the road so much that it interferes with family and activities after work.”
Wife Angel and he have three children: Elizabeth, 15; Annalise, 12; and Elijah, 9. With them come a full roster of school and sports activities. The family is also very active in their church, where Ogden volunteers as a small group leader to eighth grade boys and in other areas of ministry.
No, he doesn’t fish, but he’s very fulfilled on that front anyway. “I know my work in improving water quality helps the fish population, which helps attract anglers to our area, which helps the Valley from an economic development aspect. I’m proud to do what I do—I’d be crazy to do anything else.”
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