Centerton, Decatur to unite wastewater treatment systems

A crew from K.B. Structural based in Rogers works on a new pump system Thursday at Allen Road Lift Station in Centerton. The new pump system is part of a project to pipe sewage from Centerton to a facility in Decatur for treatment.
A crew from K.B. Structural based in Rogers works on a new pump system Thursday at Allen Road Lift Station in Centerton. The new pump system is part of a project to pipe sewage from Centerton to a facility in Decatur for treatment.

CENTERTON -- A 13-mile sewer line project snaking its way across the countryside from Decatur to Centerton holds the promise of stable wastewater bills, according to those involved with the project.

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Seth Wolf (right) and another construction worker who identified himself only as Kamell set forms for concrete Thursday as a crew from K. B. Structural in Rogers works on a new pump system at Allen Road Lift Station in Centerton. The new pump system is part of a project to pipe sewage from Centerton to a facility in Decatur for treatment.

Centerton's wastewater will be treated in Decatur by late fall, and the Decatur and Centerton utilities will share the cost of running the treatment plant.

Savings

How much does Centerton save?

The average sewer customer in Centerton is billed for 6,500 gallons of wastewater a month, according to the utility. The current average bill, including a $16.76 base rate, is $68.70. A switch to the regional treatment facility, if the base rate remained unchanged, would have upped the cost to the customer to about $98. No rate increase has been planned with the Decatur connection, although an increase will be studied once the project is complete. The two utilities will share treatment costs based on usage under the new agreement.

Source: Staff report

The partnership is a good thing, said Decatur Mayor Bob Tharp, who voted for the project while still a City Council member.

"We had the capacity. They had the need," Tharp said. The scale of the operation will create financial stability for Decatur's wastewater department, he said.

"We'll have a new customer, and they're big," Tharp said.

Centerton Mayor Bill Edwards also lauded the project as keeping costs down for a city that's had a growth boom since 2011.

The sewer line project will cost about $10 million, far less than Centerton building its own wastewater plant, said Frank Holzkamper, director of Centerton's Water and Sewer Department.

Wastewater from Centerton is currently pumped to Bentonville, which treats some of the waste, but passes most of it through to the Northwest Arkansas Conservation Authority's regional treatment facility. Centerton has seen a 125 percent increase through five rate hikes over four years through its Bentonville arrangement, Holzkamper said.

A spokesman for the authority said Friday the utility supervisor wouldn't be available until Monday to comment.

Right now the Centerton utility charges customers $7.99 per thousand gallons, 12 cents more than what Bentonville charges the utility.

"We're not even breaking even," Holzkamper said.

Centerton's Water and Sewer Department applied for permission from the state to build its own wastewater treatment facility in the mid-2000s, Holzkamper said. Centerton got its final rejection in about 2012. The state wanted the city to look at a regional concept, such as the one operated by the Northwest Arkansas Conservation Authority opened in 2010.

"The cost was just prohibitive," Holzkamper said.

Centerton would have brought in about 25 percent of the flow at the regional treatment center and would have been responsible for 25 percent of the cost, he said. The city would have had to purchase part of the line used by Bentonville that leads to the facility. And, like the city is doing now, it would have had to build miles of line to connect.

Decatur officials proposed that the two smaller cities join forces, and plans started a couple of years ago to get the project rolling. Centerton will pay for the project with $10 million in municipal bonds sold last year. Costs will include a $7.5 million bid for construction of the pipeline by Rosetta Construction of Springfield, Mo., plus project engineering, easement preparation and acquisition, permits and other costs.

WATER QUALITY

Keeping costs down also helps industry, one of the primary water and wastewater customers in Decatur, said James Boston, public works director.

The quality of water released by the Decatur Water Treatment Plant is about to improve, Boston said. Water treated by the plant is released into Columbia Hollow Creek and flows downstream to Spavinaw Creek and Lake Eucha in Oklahoma.

Phosphorus levels are an issue for wastewater treatment. The limit for Decatur is 1.0 milligrams per liter, but if regulations change, the limit will probably drop, Boston said.

The utility decided to be proactive in its approach to phosphorus, he said, and is installing what is referred to in wastewater terminology as a "polisher." The $1.8 million system will add a coagulant to treated wastewater to facilitate filtering phosphorus and other materials out with a sand ballast.

When water comes into the Decatur plant, it might have 8 to 15 milligrams per liter of phosphorus -- it depends on how much rainwater has diluted it, Boston said. Sources of phosphorus include fertilizer runoff, animal manure, soil and the runoff from wastewater treatment plants, according to the U.S. Environmental Protection Agency.

He hopes the new system puts the phosphorus level below 0.1 milligrams per liter, the standard for the regional treatment facility.

Marketing materials for the polisher claim a 0.05 level of phosphorus is possible.

"You never know until you turn the switch," Boston said.

NO RATE INCREASE

There is no planned rate increase for customers of either utility.

Holzkamper said rates for Centerton will be reviewed once the two start sharing costs.

Because the Centerton utility is a nonprofit and not a government entity, everything it buys is paid for by rates, Holzkamper said. He expects to see savings in treatment cost.

Centerton's sewer line project will be 13 miles of 18-inch pipe buried 4 feet. The pipe is plastic where it crosses fields and epoxy-coated steel pipe in subdivisions and under roads, Holzkamper said. Construction was scheduled to wrap up this month, but weather delays have pushed it into September, he said.

There are four pump stations where water will be delivered in an even flow to Decatur from Centerton's tanks. Decatur's wastewater flow is consistent 24 hours a day because industries are its biggest customers, and the plants are always running, Boston said.

Centerton's wastewater flow peaks about midmorning and again from 6 to 10 p.m., Holzkamper said. Keeping the flow consistent to the treatment plant will slow the need for expansion.

The Decatur Wastewater Treatment Plant opened in 2009. It can treat 2.2 million gallons of wastewater per day, Boston said. Right now the Decatur facility treats and average of 1.2 to 1.3 million gallons of wastewater a day, Boston said.

Holzkamper estimated Centerton's average daily flow at 600,000 thousand gallons a day.

Soon it will need to expand, the men said. Centerton will see the opening of a Walmart Supercenter and Bentonville West High School in the next year, Edwards said.

Decatur welcomed a Neighborhood Market and will open a Farmer's Coop next month, Tharp said.

Boston estimates it will be five to 10 years before the treatment facility needs to add capacity.

"We're growing too," Boston said.

NW News on 07/26/2015

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