Holding tank base now in place

Wednesday, November 9, 2011
Tribune photo by Jim Ward Twenty-one concrete mixing trucks brought more than 1,000 cubic yards of concrete to this construction project on Friday.

City utility project costs $13 million

Approximately 1,000 cubic yards of concrete were poured Friday for the base of a cylindrical tank being built to hold 10 million gallons of wastewater at Lewisburg's treatment plant across Woodbine Avenue from the animal shelter.

"It's something that has to be done, or we'll be swimming in this stuff," said Dennis Bowman, the resident inspection representative and observer for J.R. Wauford & Co., the Nashville engineering firm that designed the tank and expansion of the treatment plant.

The plant's current capacity is three million gallons a day. It's being doubled.

When sewers are flowing full, the plant can't treat all the flow, so with permission from the state and the U.S. Environmental Protection Agency, great volumes of wastewater have passed through, partially treated by a swirl system to remove and treat solids only.

Discharge of partially treated wastewater is an overflow. It happens when rain-swollen groundwater seeps into broken sewers, thereby increasing the flow. It's diluted, but the plant hasn't been able to deal with the volume. The 10-million-gallon tank will allow treatment on a delayed schedule when flows are lower after rain stops.

Some 50,000 cubic yards of dirt and rock were excavated and removed from the site to create a place for the base of the holding tank, said Ryan Leisey, vice president and area manager at the Murfreesboro office of Crom, the company building the tank.

"Completion depends on the weather," Leisey said. "We could be done in February and come back in the spring to paint it."

Friday's work was just for the base. Work started at about 6 a.m. By mid-day, it was clear the job would continue after sunset, so lights were set up.

Twenty-one cement-mixing trucks hauled 10 cubic yards of concrete at a time during about 100 trips to the construction site from cement plants.

So, batch plant workers, truck drivers and about 25 concrete finishers were working on a major construction project in Lewisburg on Friday.

"It's got to be done today," Bowman said Friday. "Once you start, you can't stop."

Leisey agreed, noting there were clearly more than 50 people working on this phase of the project Friday.

Bowman said, "You bring in extra people for something like this...

"It's a perfect day for it," Bowman said that afternoon. "The cooler temperatures allow it to cure slow."

Marshall County Building Inspector Don Nelson agreed.

"If it was July, they'd have to pour at night," Nelson said. "It's an impressive pour."

The concrete construction contractor used a device to raise liquid concrete from the trucks so it could fall through a hose hanging from a crane to the proper place.

"They have to do that because if they didn't, they'd have to back the trucks up over the rebar," Nelson said.

The tank will have a diameter of about 250 feet.

Concrete poured for the slab was six inches thick at the center and 11 inches thick at the perimeter, Leisey said.

Bowman said, "The walls will be about 32 feet high." He spoke without a set of plans immediately at hand, but that was to provide relative sizes of the project. Height may not seem that great when finished, given the site and how much of the tank might be underground. "At the top, the wall will be about six inches thick and it will be 16-20 inches thick at the bottom," Bowman said.

"We feel like this particular contract is going well," he said.

Pepper Biggers, assistant superintendent for the water and wastewater department, said the contractors were on schedule Friday.