The Benbrook Water Authority (BWA) prides itself on staying one step ahead of the game. “We’re always looking ahead,” says David Wasson, general manager. “We try to do something every year to improve the system and maintain system peak demands.”

That includes treatment plant improvements, new storage facilities, new lines, and water quality better than required. That last effort has earned Benbrook the Texas Optimization Program (TOP) award from the state regulatory agency for six consecutive years.

The TOP recognition is for turbidity removal. While the requirement from the Texas Commission on Environmental Quality (TCEQ) is 0.3 NTU or less, TOP standards are tougher — 0.1 NTU or less. “Our operators work hard to keep our water within that limit,” Wasson says.

It’s hardly a slam dunk. Michael Langlois, water production superintendent, says his team monitors turbidity off each of 16 filter modules every minute of every day (turbidity meters by Hach). “That’s 1,440 readings for every filter every day,” he says. “Not one drop has exceeded 0.1 NTU. I think we may be one of just two or three plants in the state that have maintained TOP recognition for six consecutive years.”

Diverse supply

Benbrook is a bedroom community of 23,000 residents in the Fort Worth metropolitan area. The BWA, founded in 1955, draws its water from surface and underground sources. Through an agreement with the Tarrant Regional Water District, the authority purchases water from Benbrook Lake, a 75,000-acre impoundment on the Trinity River, created by a U.S. Army Corps of Engineers dam in 1947.

BWA also owns 12 wells, two drilled about 1,000 feet into the deep Trinity regional aquifer, and the rest into the shallower Paluxy aquifer (about 300 feet). Finally, if needed, the authority has access to the Tarrant District’s Eagle Mountain Lake pipeline.

The water from Benbrook Lake, up to 10 mgd, flows by gravity a mile and a half through a concrete-lined 30-inch pipeline to the treatment plant and comprises most of the supply.

The well water, up to 1.3 mgd, supplements the lake supply and effectively dilutes disinfection byproducts in the distribution system, helping the authority to stay in compliance with DBP regulations.

“The well water doesn’t really need to be treated, but we are required to chlorinate it,” Wasson says. It is pumped to above-ground storage tanks and injected with chlorine before release to the system. “THMs in the treated water coming out of the plant are borderline,” says Langlois. “In the areas of town that have a good blend of well and surface water, THMs are not an issue.”

Conventional treatment

The plant itself is a 12 mgd conventional rapid mix-flocculation operation, dating to 1987, when it replaced an old 3 mgd upflow clarifier process. It was last expanded by 6 mgd in 2004. As raw water enters treatment, a cupric sulfate mixture is added to reduce odors and ward off algae, which can be a problem in Texas summers. “It used to be an issue for us,” Langlois recalls. “We had to take the sedimentation basins down regularly to remove algae. But it’s not a problem anymore.”

A chlorine dioxide generator (Siemens Water Technologies) provides pre-treatment disinfectant. Then the water flows into a pair of pre-sedimentation basins. The basins are designed to collect heavy solids, which were a real issue when BWA took water directly from the Clear Fork River, before the pipeline to the lake was built. The overflow passes to the rapid-mix stage, where aluminum sulfate and polymers are added, and then to four dual-train sedimentation basins — eight trains in all.

Filtration is next. The plant uses four dual-media gravity filters (Siemens Water Technologies) packed with granular activated carbon over sand. Each filter has four cells for a total of 16 cells.

Final treatment consists of chlorination. Product water is stored in two circular tanks totaling 3 million gallons. Solids are removed automatically from the processes and sent to the city’s sanitary sewer system.

Langlois’ staff includes Mitchell Richard, chief water plant operator; Larry Dawson, plant operator; Michael Vecchio, water quality control specialist; and Tom Hoyt, water production maintenance technician. They staff the plant around the clock, making selective use of a SCADA monitoring and operations control system (Wonderware/Invensys Operations Management). “We have a fully automated system, but we like to have a hands-on procedure,” Langlois says. “Too much automation can cause operators to become less vigilant.”         

Forward thinking

Wasson and Langlois agree that if there were an operational mantra for Benbrook it would be: Stay ahead of everything. “The changes, especially with regulations, can add up,” Wasson says. “We’ve upgraded our treatment plant to keep pace with requirements. Right now, we’re looking at upgrading the older parts of the system.” That includes replacing a 100,000-gallon 1966 vintage storage tank with a new 500,000-gallon tank, and erecting it 11 feet higher than the old tank. The staff works continuously on upgrading pipes, using pipe bursting and other methods.

Wasson, who has spent his entire career with BWA and became general manager in 2001, says the authority has met peak demands continuously since 1976, the same year he signed on as a plant operator right out of high school. He attributes that record to being prepared and constantly monitoring the system’s condition and capacity. Although the recent drought has caused shortages in some Texas communities, Benbrook has had adequate water and has implemented water restrictions only once.

While customers have benefited from having high-quality water, they’ve also experienced reasonable and relatively constant water rates. “We have instituted modest rate increases year by year, usually in the 1/2 to 3 percent range,” Wasson says. “We think that’s better than avoiding rate hikes and then coming in with a big increase every 10 or 15 years.”

At the plant, Langlois and his staff make sure they monitor future regulatory requirements: “We stay on top of the regulations — anything we see coming down the line.” Monitoring for the upcoming Unregulated Contaminants Monitoring Rule 3 is a recent example.

“We anticipated the sampling protocol,” Langlois says. “And when the guidance came out, the sampling protocol and locations were pretty close to where we thought they would be. We were all set before it came time to do it. When we read about proposed regulations, we start preparing. We don’t like being behind.”

Staying on TOP

They also don’t plan to lose the TOP status. Langlois attributes the plant’s low-turbidity performance to raw water quality (influent NTUs are in the range of 5 to 6), good plant design, and a very diligent staff. “We have to really pay attention to the system, especially when backwashing the filters,” he says. “One high post-backwash spike and we are out of the program. It does create more work for each individual operator on shift. However, the record also creates more pride among the operations staff.”

All the dedication pays off: In 2005, BWA was honored by the state with an Outstanding Drinking Water System Award, recognizing the authority for meeting standards for production, storage and pressure; effective procedures for systems security; source water protection; conservation; vulnerability assessment and emergency response; no standards violations; and a consistent five-year history of coliform compliance.

“We knew we were pretty good but this award was a surprise,” says Dennis Lindgron, BWA board president said at the time. “We have consistently been classified as a superior drinking water system by the TCEQ. The award confirms that we are doing all the right things to make sure Benbrook has clean safe water, now and in the future.”