Growing demand

Lafayette treatment plant expanded by more than 50 percent

By Karla Wall

An upgrade at the Ambassador Caffery Wastewater Treatment Plant in Lafayette will increase the facility's capacity by more than 50 percent from 6 million gal. per day to 9.25 mgd to accommodate increased demand from a growing population.

The $22.3 million project, begun in June, should be complete by October 2007, said project manager Kirby Stumpf of M.R. Pittman Group of Harahan, primary contractor for the project.

About 25,000 cu. yds. of dirt were removed for the installation of a three-cell equalization basin, or overflow buffer, with a 7-million-gallon capacity, Stumpf said. Judice Sand & Gravel of Lafayette performed dirt removal.

The 25-ft.-tall concrete basin, with 2-ft., 3-in.-thick walls, required 9,500 cu. yds. of 4,000-psi concrete, poured by Angelle Concrete's Lafayette facility. Total concrete needed for the entire plant renovation will be about 15,000 cu. yds., said M. R. Pittman project superintendent Patrick Daugherty.

advertisement

The lift station is being modified with the addition of two 2,700-gpm pumps and two 3,000-gpm pumps. About 80 ft. of 36-in. ductile pipe will transport the water underground from the primary treatment unit to the flow distribution box, which directs the flow to three locations in the primary clarifier and to the sequencing batch reactor, said Link Mixon of R.L. Mixon, mechanical subcontractor for the project.

Daugherty said piping for the project ranges in size from 4 to 36 in.

The new four-celled SBR unit measures 240 by 80 ft. and is 19 ft. deep, with walls 2 ft., 4 in. thick. It will require 3,400 cu. yds. of 4,000-psi concrete.

Stumpf said each cell is 80 ft. by 56 ft. To make room for the new unit, a rotating biological contactor was demolished and roughly 1,200 cu. yds. of concrete and 1,500 cu. yds. of dirt were removed.

The SBR unit includes a 12-in. discharge blower that draws off odor.

The wastewater goes through 240 ft. of 24-in. ductile pipe to the existing chlorine contact chamber, which introduces chlorine into the effluent to sanitize it as a final treatment.

The water will then go through a new, secondary chlorine contact chamber. Formed with 4,000-psi concrete, the new chamber will be 74 ft. by 45 ft. by 14.5 ft. deep. From the chamber, the treated water is directed into Vermillion Bayou.

Power will be supplied to the systems through a new control center located on site, said Tommy Breaux of Breaux Electrical in Lake Charles, electrical subcontractor for the project. Two distribution centers will feed the control building and will allow remote control of power and communication throughout the plant.

Breaux said wiring is routed mainly underground through about 500 ft. of duct bank. About 200 ft. of cable near the oxidation ditch is routed with cable tray.

Stumpf said one of the major challenges to the job has been a lack of laydown and storage space.

"It's a tight jobsite," Stumpf said. Dirt excavated for the equalization basin is being stored offsite at a location about a mile away from the project site, Mixon said. Deliveries are on an as-needed basis with no materials accepted more than two weeks prior to use.

Another concern is the heavy traffic flow along Ambassador Caffery. Given the jobsite's small size concrete pours often block traffic flow. Most pours are being done at night when traffic is lighter.

"The traffic is just horrendous and in order to pour 90-100 cu. yds. at time, we have to pour at night," Stumpf said.

Another problem on the project is a lack of workforce.

"Our labor force was pretty much depleted by the hurricanes," Mixon said. "It's been extremely difficult manning the job." Mixon says he hasn't had to go outside the state for workers as yet.