Claiborne County Wastewater Facility First of its Kind in Tennessee
The Utility District went online with its new HEXA-DITCH treatment plant in February, the first such plant of this kind in Tennessee. The patented HEXA-DITCH plants use a common-wall design, which allows for a less expensive expansion when needed. The average daily flow is 4.0 million gallons per day, but the plant has a capacity of 1.300 million gallons per day. In addition to its efficiency when it comes to expansion, the treatment plant saved the Utility District 30-to-40 percent on initial construction of the structure, 75-to-90 percent on process piping, and will help save the District up to 70 percent on energy costs.
"To expand our old plant, the prices on a single facility were estimated at $3 million to $4.5 million," said Carl Doane, general manager of Claiborne County Utility District. "This plant cost us $1.8 million. The plant really has its advantages. Typically the tanks are round, but this one isn't, so when you need to expand, it's a lot easier and a lot more cost-effective."
The HEXA-DITCH design, which is six-sided rather than round, is the brainchild of W. B. (Sonny) McNeill Jr., who founded the McNeill Company in Tallahassee, Fla. in 1964. The company used to operate treatment plants, up to as many as 200, but got out of that business in 1981. In 1970, the company began manufacturing secondary and tertiary treatment plants with its original design. The built-in-place plants, the QUAD and HEXA-DITCH designs that were first built in the 1990s, are constructed of poured-in-place concrete.
"You have a 650,000 gallon tank producing 8.33 pounds per gallon, so you are looking at over five million pounds of water and getting it moving," McNeill said. "In addition to saving by using the common walls, you are going to see energy savings."
The plant was installed using the Design/Build approach, and Claiborne County Utility District used SKH Construction as the contractor.
McNeill Co. has built more than 600 of the HEXA-DITCH and QUAD plants around the Southeast, and one each in the Bahamas and Haiti.
"Another uniqueness in this project is that usually you will use an engineer to custom design a plant," McNeill said. "An engineer will go to school to design treatment plants. The plants will go out to bid and most often it is one of a kind. It's like building a car. You might take the body from Pontiac and the bumpers from Buick and the windows from Oldsmobile. You would have a one-of-a kind car, but you would also have a very expensive car.
"This is a design we have worked with constantly," he said. "We have built 600 treatment plants and have the benefit of having learned from our mistakes."
The new treatment plant in Claiborne County is the first HEXA-DITCH design that uses a mono-directional aerator. The mono-directional aerator features a unique C-shaped radial beam that stiffens the unit and distributes the operating loads while providing hydraulic channeling of the pumped liquid. The liquid straightens as it exits the deflector, changing the course of the liquid to a flatter dispersion pattern. This course reduces aerosols and misting. The construction also has no potential leaking points caused by bolt or other penetrations.
The McNeill-designed plants are not only cost efficient when it comes to expansion, but longevity of the structure itself is also a plus. The structure is made of concrete and features aluminum handrails and walkways, and all parts of the mono-directional aerator are stainless steel.
"We were awarded the first publicly financed job along the Suwanee River in 1975," McNeill said. "We weren't the lowest bid, but were the most cost-effective. We went back to that location two years ago to expand and we didn't have to replace one piece of equipment."
The construction of a new wastewater treatment facility allows the Utility District to provide expanded service in Claiborne County. When City of Harrogate officials tried to get a wastewater permit from the State of Tennessee, they were unable to because there was no discharge point. The facility that they could get a permit to build would have been very expensive. So the Claiborne County Utility District stepped in and offered to help with their needs.
"We installed an eight-inch force main along Highway 25E," Doane said. "The outside cost to provide wastewater service was going to be about $1.6 million. We looked at the abilities of our own people to see if we could do it. That kind of money for Harrogate is too much, so we looked at it and estimated it would cost about $400,000 for us to install a force main that would carry the wastewater to our treatment facility."
CCUD installed about 42,000 feet of pipe and three large pump stations along the force main. During the same time the work was going on to run the main from Harrogate, two new high schools were being constructed in the county, with one being in Harrogate. Outside contractors estimated a cost of between $300,000 and $400,000 to run wastewater service from the high school. However, CCUD added to its force main project, by running a four-inch line from the high school and building two pump stations to the newly installed eight-inch line for less than $200,000.
"This gives service to Harrogate and also opens up commercial property along Highway 25E," Doane said. "It's good for the community and good for Claiborne County as a whole."
CCUD is also in the process of installing a collection system force main for Harrogate, which will be able to supply about 98 customers with service. The outside estimate was $1 million-plus, and the Utility District is doing the job for about $600,000.
With more growth in Claiborne County on the horizon, the Utility District is doing everything it can to have an excellent, yet cost-effective, infrastructure in place to handle it.
Source: Claiborne County Utility District (CCUD)