New Clarksville Water Plant, Wastewater Thermal Dryer progressing

The City of Clarksville, through the Gas & Water Department, is making significant progress on two key projects. One will dramatically improve water capacity for the rapidly-growing City, while the other will create greater efficiencies in wastewater treatment.

Clarksville is gaining a second water treatment plant, this time in north Clarksville, while at the City's wastewater treatment plant, advanced thermal dryer technology is being added.

"It is imperative for a City growing as fast as we are to have a second water treatment plant to take care of our needs for generations," said Clarksville Mayor Joe Pitts. "And the new thermal dryer system will reduce output from our wastewater treatment process, while saving space in our landfill.

"Both projects were carefully planned and executed by Mark Riggins, General Manager, and his highly-skilled team of professionals at Clarksville Gas & Water. These sorts of improvements are a hallmark of his leadership," Mayor Pitts said.

"We are ecstatic to be well into the construction phase of these two projects, which are integral in the management and operation of our water and wastewater systems," said Clarksville Gas & Water General Manager Mark Riggins.

"The North Clarksville Water Treatment Plant is vital in providing needed redundancy to our existing customers as well as additional capacity for our growing customer base. This project will also lay necessary groundwork for additional, future expansions as dictated by demand," Riggins said.

"The thermal dryer project at our Wastewater Treatment Plant is an innovative step within the progressive process of waste elimination that will significantly reduce the odor and volume of wastewater byproduct currently delivered to our local landfill," Riggins said.

North Clarksville Water Treatment Plant

The purpose of the North Clarksville Water Treatment Plant (NCWTP) project is to increase the potable water capacity of Clarksville Gas & Water with construction of a second water treatment plant.

The City of Clarksville and Montgomery County have experienced strong, sustained population growth for years. We have also been very successful in attracting new industry and business to the area.

This growth and associated increase in demand has reduced the City's available water capacity needed to allow for additional growth. The construction of the NCWTP will provide additional capacity for growth and the economic prosperity of our city and county for decades to come.

Having two water treatment plants also reduces risk and increases reliability by providing a backup source in the event of any issues requiring an emergency shutdown of one of the plants. It also provides greater flexibility in scheduling regular maintenance activities that require shutdowns.

The NCWTP is being constructed on about 30 acres situated on the Cumberland River off of Barge Point Road. It will have a service capacity of 36 million gallons of water per day (MGD).

The existing South Clarksville Water Treatment Plant has a capacity of 28 MGD, allowing for a future combined capacity of 64 MGD.

To put that into perspective, the current average daily water demand in Clarksville is about 19 MGD, with peak daily demand as high as about 25 MGD.

The NCWTP is being built in three 12 MGD phases. The two remaining future phases will be built in response to required demand, and will be considerably less expensive to build than this first phase, since far fewer structures will need to be built in future phases to achieve a 12 MGD increase in capacity.

The treatment plant includes several distinct structures with a combined footprint of about 110,000 square feet, as well as miles of underground pipe and conduit.

The Raw Water Pump Station (RWPS) includes a 65-feet-deep shaft into bedrock, as well as a tunnel and intake structure out into the Cumberland River.

Raw source water is drawn from the Cumberland River and pumped through the RWPS up to the treatment plant site. A PreTreatment Building houses chemical bulk tanks and chemical dosing pumps. The PreOxidation Basin provides residence time for chemical treatment processes.

The Flocculation/Sedimentation Basin provides a structure and specific equipment to promote the settling out of silt and other suspended particles in the raw river water. The settled solids are collected and conveyed to the solids handling facilities. Settled water is conveyed to the Membrane Building where the settled water is filtered through microfiltration modules to remove any remaining suspended solids larger than 0.1 microns.

The filtered water is then conveyed to a building where it is pushed through pressurized vessels that contain granulated, activated carbon, which removes other microconstituents that can affect taste and odor qualities of the finished water.

The finished water is then disinfected and stored in a clearwell. Then, water is pumped from the clearwell out into the distribution system for consumption. Settled solids are dewatered at the Solids Thickener Basins and further dewatered via centrifuge equipment in the Solids Handling Building. Dewatered solids are then loaded into trucks for disposal by land application or landfill.

On the new site, the Administration Building is connected to the Membrane Building. It houses offices, laboratories, and operation control rooms. A Maintenance Building is also included in the project.

The NCWTP project was competitively bid in accordance with the City purchasing policy and awarded to the lowest bidder. The successful bidder was Judy Construction Company with a current contract amount of $211,279,815.70, making it the single-largest capital project in Clarksville history. The project is funded with bonds.

Construction began in August 2021 and the estimated substantial completion date is May 2026.

Thermal Dryer In Wastewater Treatment

The purpose of the Thermal Dryer project is to build a facility to treat and stabilize biosolids generated in the treatment of wastewater at the Clarksville Wastewater Treatment Plant (WWTP).

The process will produce a stabilized, pelletized biosolid product that will be suitable for beneficial reuse in land application. Currently, unstabilized biosolids are hauled to Bi-County Landfill for disposal. Landfill operators have increasingly taken issue with the workability of these unstabilized biosolids, and odor complaints during hauling and disposal periodically occur. Disposal at the landfill will continue to be an option for the stabilized biosolids.

The thermal dryer will stabilize the material and significantly decrease the water content of the biosolids, which improves ease of handling at the landfill, reduces the volume and mass to be transported, and reduces landfill tipping fees. The stabilized product should also be less odorous, minimizing or eliminating complaints during hauling and disposal.

The project includes a thermal dryer facility housed in a new, 9,682-square-feet, 65-feet-tall building. The building houses the thermal drum dryer and associated natural gas-fired furnace as well as a complex, multi-story array of support equipment and associated process piping and ductwork.

The equipment is accessed by a series of stairways and platforms on four levels. In simple terms, the process conveys unstabilized biosolids from the adjacent dewatering building into the rotary drum dryer, where the biosolids are dried and processed into spherical pellets with heat generated from the natural gas-fired furnace.

The pellets are then screened, cooled and conveyed into silos for storage. The product can then be loaded directly from the silos into trucks for delivery to land application sites or disposal to the landfill. Much of the ancillary equipment is associated with conveyance and processing of product, and capture, conveyance, processing, and disposal of waste solids, liquids and gases.

A sludge-conditioning building and odor control facility to serve the biosolids processing area of the plant are also being constructed as part of this project. Sludge conditioning consists of screening of fibrous material from the sludge to increase the production efficiency and improve the quality of the final pelletized biosolids product. The odor control facility will pull air from the buildings and structures associated with solids handling processes through a biofiltration process to remove hydrogen sulfide and associated noxious odors from those airstreams.

The project was competitively bid in accordance with City purchasing policy and awarded to the lowest bidder. The successful bidder was Cumberland Valley Constructors with a current contract amount of $53,200,000.00. The project is partially funded with grant money in the amount of $15,388,496.73 through the American Rescue Plan. The remainder is funded with wastewater revenues.

Construction began in April 2023 and the estimated substantial completion date is April 2025.

Attached photos:

1. ) Shown above from L-R during a tour of new Clarksville Gas & Water (CG&W) facilities are: Pat Chesney (CG&W), City Chief of Staff James Halford, Chris Cherry (CG&W), Garth Branch (CG&W), Clarksville Mayor Joe Pitts, and CG&W General Manager Mark Riggins.

2. ) Below, a portion of the new water treatment plant under construction in north Clarksville

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