Over the years, the east Tennessee city of Crossville has faced challenges in keeping the water flowing to customers. With each challenge came a solution. 

Today the city enjoys three surface water sources and operates two water treatment plants, providing significant flexibility in serving a population of about 42,000. City officials are looking at alternatives that will help secure a reliable supply for many years to come.

In recognition of strong performance, the Crossville team picked up the 2017 Award of Excellence in Water Plant Operations in the medium-sized plant category from the Kentucky/Tennessee Section American Water Works Association.

Citizen with a vision

A gift from a farsighted citizen provided Crossville with a source of good-quality raw water. In the 1930s, the city received about 2,200 acres crossed by the Meadow Creek. A dam then created the 275-acre Meadow Park Lake, and legal protections restrict development on the rest of the land so that water running into the lake remains clean.

The land around the lake is used for recreation: There are walking paths, a boat dock and a small RV park. “The only way anyone could develop the property for other uses would be to go through the state Legislature,” says Jerry Kerley, director of the city’s Water Resources Department. In 1968, the city built a water plant on 225-acre Lake Holiday. A third water source is 405-acre Lake Tansi, about 6 miles southwest.

“A few years back we had a pretty severe drought here, and we got down to about 45 days of storage in Meadow Park Lake,” Kerley says. After that, city officials, knowing Tansi could be a water source, approached the lake property owners association to ask about drawing from it. Now a pipe runs from there to Meadow Park Lake, and the city can draw Tansi water from October to April if Meadow Park Lake is low. Valves are set up so Tansi water can be fed to Meadow Park Lake to raise its level, fed directly to the water plant or both.

Simultaneous pumping to Meadow Park Lake and into the plant has a cost advantage because then only the Lake Tansi pump station is running. The electric supply to Meadow Park is billed based on peak demand. “When our big pumps start, that’s the electric bill we pay for the month,” Kerley says. “If we start up a pump station, it costs us about $3,500 for that month. If we work it so we’re harvesting water from Tansi and using it at the same time, it saves us that money.” 

Fall challenge

A continuing challenge is manganese, naturally present in the soil and rock around Crossville and in the lakes. “In the fall, the lakes turn over,” Kerley says. “If there’s a severe weather change, and up here on the mountains we have that every fall, we’ll have 50- or 60-degree F days and all of a sudden 20-degree F days. The water on top of the lake gets colder and sinks very quickly. Warmer water is pushed up and pulls the minerals off the bottom.” To counter the manganese, the Crossville team feeds sodium permanganate.

Unlike many small cities, Crossville has those two drinking water plants. That means more management, but also certain benefits. Meadow Park operates around the clock. Holiday runs seven days a week on a day shift only. The SCADA system allows Kerley or operators to keep an eye on everything in both plants. When no one is on duty at Holiday, operators at Meadow Park can still see the levels in tanks in that part of the system. The south side of the system, fed by Meadow Park, is about 60 feet higher than the north side.

Although they can’t completely control the plants remotely, operators can turn on any of the high-service pumps. “I can actually log in from anywhere and turn those pumps on or the pumps here at Meadow Park,” says Kerley, certified as Grade 4 for operations and Grade 2 for distribution.

The Meadow Park team includes Kerley’s son Joe, Grade 4 operations, Grade 2 distribution, also certified for laboratory; Grade 3 operators Brian Lowe, Gary Barnes, Jan Nix, Pat Horst, Dusty Norrod, Travis Hall, Mike Brown and Mike Hillis (also Grade 2 distribution); and Matt Jones, trainee.

Plants interconnected

The city’s two plants are tied together in a limited way. Holiday can be turned off for a few days, and a single valve then diverts the Meadow Park output into the pipes fed by Holiday. Because of the elevation difference, supplying the whole system from Holiday is more complicated and requires more valve changes.

“The dual system costs us more money in the long run to operate,” Kerley says. “But if we go through periods when something happens, then we can operate off one plant for four or five days. If we just had one system, we’d be out of luck.”

One example of what can happen was in 2012 when the dam at Meadow Park Lake was repaired and at the same time the pipe from Lake Tansi was laid for additional water supply. Meadow Park Lake was drawn down about 15 feet, and the lake is only about 30 feet deep. That limited how much the Meadow Park plant could draw, but Holiday picked up the load. Each plant can meet the 3.5 mgd demand and sustain it for about a week.

Treating the flow

Both plants use gravity filter systems. Polymer is fed to create floc, and water flows through sand/anthracite filters. Raw water is dosed with sodium permanganate, and sodium hypochlorite generated on site in a MIOX unit is fed just before water enters the filters.

At the Holiday plant, water flows by gravity into a 1-million-gallon tank below the filters and is pumped into the system as needed. Meadow Park has a 1-million-gallon tank above ground on its site, and water is pumped to that from the filters. This is in addition to the 5 million gallons of system storage.

At some times in the year, the team feeds activated carbon to remove disinfection byproducts. A side benefit is removal of the earthy taste the water can acquire during hot summers. Carbon is fed in the sedimentation basins as the floc has begun settling. 

Weather impacts

Another challenge to the plant involved adding resiliency for natural events, such as storms. “We had a tornado here several years ago,” Kerley says. “The land around our plant was woods until the tornado came through and cleared every bit of it. Power lines to our old plant were down for about 48 hours.” That was another time the Holiday plant took up the slack.

After that, Meadow Park water plant was equipped with 400 kW emergency generators (Caterpillar Inc., Electric Power Division). The Holiday water plant is on a main power line that can be easily repaired, but it has never lost power. “In an ice storm about three years ago, we had 2 inches of ice,” Kerley says. “It tore down a bunch of power lines. We had to run our generators for three days to keep Meadow Park plant going.”

“The biggest problem we had was getting diesel fuel to the generators. You don’t think about that ahead of time. You have generators that will run for 24 hours, but then you have to put fuel in them. We had to go out to the main highway and break ice off service lines so a fuel tanker could pass underneath.”

New vision

For the near future, various plant improvement projects are in the works. One almost complete is a new chemical building. Old tanks for polymer and caustic soda in 2002 in the north end of the Meadow Park main building will be removed, and the space will be converted to parts storage.

Another plan calls for installing a pipe and pump station to add Meadow Park plant sludge to the city wastewater system. At present, the material is dried outside and spread on land near the plant.

As for water supply, the Crossville system did a study to look at future needs. One option was to draw water from the Tennessee River about 20 miles east, but that would require significant cost for lifting and pumping. Instead, the city has settled on raising the Meadow Park Lake dam by 20 feet, expanding the lake to 500 acres, enough to meet projected demand for the next 75 to 100 years.

With all the attention on restoring rivers to their natural flows, raising the dam is no slam-dunk. “We’ve been working it for probably 10 years, and we’re still getting the permits for it,” Kerley says. “It’s a huge undertaking.” Or maybe just another challenge for which there will be a solution.

Fighting winter myths

Repeat misinformation often enough and it takes on a life of its own. That’s what the water utility in Crossville, Tennessee, is fighting.

“Some of our highest usage days are in January when it’s cold,” says Jerry Kerley, director of the city’s Water Resources Department. “The radio stations keep telling people to keep their water running so their pipes don’t freeze.”

At one time that would have been good advice, but home construction has improved since those times. Insulation is better, and pipes are better placed. “There are still a few places where, if we have a really cold winter, it might freeze the meter or they didn’t put the waterline in deep enough,” Kerley says. Any pipe buried deeper than 18 inches is typically safe, although builders can create risk if they lay a pipe too shallow as it approaches a house.

Although Crossville lies in a southern location, the city is high, at 2,000 feet above sea level. “We’ll normally have at least some zero temperatures here every winter,” Kerley says. “If we get four or five days when it goes down to zero, there will be people whose pipes are not able to withstand it. I’ve lived here my whole life. When we were kids, we had much more severe winters than we’ve been having here lately.”