Award-Winning Filter Plant Overcomes Raw Water Supply Challenges

Good was never good enough for the team at Birmingham’s Western Filter Plant. Aiming high has brought a string of awards.

Award-Winning Filter Plant Overcomes Raw Water Supply Challenges

Operator Scott Gormley and other team members rely on an in-house lab, supported by lab facilities at Auburn University.

Birmingham and its Alabama surroundings are home to more than half a million people. One of the plants supplying them with water has reached a high level of achievement, despite persistent challenges with part of its raw water supply. The others are not far behind.

The Western Filter Plant is one of four owned by Birmingham Water Works, which delivers about 100 mgd to its customers. The plant’s technology is familiar, but what the operations team has done with it is not. In 2013, the team won the Award of Excellence from the American Water Works Association. In 2018, the plant received a five-year Directors Award from the Partnership for Safe Water.

Conventional and not

The plant uses conventional filtration. What isn’t conventional is how water runs through the plant. The Mulberry Fork of the Black Warrior River is the plant’s main raw water source; also in the mix is Smith Lake Reservoir, about 35 miles away. Water comes by way of four pump stations.

Bromide is high in the river water. “Bromide creates bromoform,” says Jonathan Harris, water treatment manager for the utility. Chlorine is the main contributor to disinfection byproducts, but bromide adds to the problem because it reacts with bromoform to create trihalomethane.

To minimize DBPs, the Western plant team blends incoming raw water at about 60% river and about 40% lake water. Another step is to minimize chlorine contact time. A very small dose of chlorine is added just ahead of filtration to prevent microbial growth in the filters. The main chlorination is about 10 feet upstream of the clearwell. The water is tested as it leaves the clearwell; such tight timing requires operators to stay on top of the process.

Another step is to limit the water age in the storage system. Operators try to turn over 20% to 40% of the water per day. Part of the process includes thorough mixing. Instead of bringing water into a tank with a riser, water is introduced at the top and removed from the bottom. To do that, the utility replumbed all of its tanks, starting in 2005 and continuing during scheduled maintenance when tanks are drained, inspected, repainted and repaired.

“We researched this for quite a few years when the U.S. EPA changed the disinfection byproduct rules,” Harris says. The limits dropped from 120 ppb of trihalomethanes to 80 ppb. About three-fourths of the tanks have SolarBee solar-powered mixers (Medora): “It has been a tremendous help.”

Some groundwater receiving basins also use the mixers. Although expensive to install, they’re inexpensive to operate. Solar panels are installed on the outside of tanks, and batteries store energy to run the mixers at night. If a few cloudy days reduce the stored energy, the systems can draw from the power grid.

Maximum precipitation

Two Birmingham plants use ferric sulfate for coagulation, and two use aluminum sulfate (alum). Plants with the highest DBP ratings use ferric sulfate because it settles more material in a wider pH range. “The lower you get the pH, the more DBPs come out of solution,” Harris says. “Once you get the pH to 6.0, all the organics come out.” 

Plants using ferric sulfate typically have pH readings of 6.1 or 6.2, while the alum plants are at 6.7 or 6.8. Ferric is more expensive but more effective. The Western plant uses alum.

Raw water is sampled continuously with a total petroleum hydrocarbon analyzer (Hach) and a TOC analyzer (GE). Finished water is sampled at least three to four times a day for trihalomethanes and TOC. If raw water quality goes down, sampling frequency goes up.

“Over the years at Western, we’ve installed a lot of equipment,” Harris says. “We’ve got a lot of redundancy to make sure we can see what’s going on.” The petroleum hydrocarbon analyzer in particular was expensive. Utility computer specialists set up a special dashboard in the SCADA system so operators can see all the analyzer results all the time.

DBPs ceased to be a problem in about 2016 when water blending began. “Before that, the river water would average about 15-20 NTU and the lake water 1-2 NTU,” Harris says. With blending, raw water now is about 5 NTU on days without rain that swells the river.

Facing challenges

Birmingham, at the bottom end of the Appalachian Mountains, has a service area that includes hilly terrain. The Western plant lies at about 660 feet above sea level, and the service area extends to 1,100 feet elevation. “We probably have as many or more booster stations than most other places,” Harris says.

Running the filter plants is made easier by the city’s team of four water engineers. Jaquice Boyd runs a pilot plant that tests different chemicals and processes. April Nabors takes water samples and performs tests for the treatment plants. One position in special projects is vacant, and Jeff Cochran leads the team.

Algae can be a problem in the area’s hot climate; the waterworks handles the heat with its own lab and with help from Auburn University about 120 miles away. Alan Wilson, an associate professor in the School of Fisheries, Aquaculture and Aquatic Sciences, analyzes samples and provides advice on treatment, such as whether to use only carbon, or whether to use potassium if algae in a sample are sensitive to it.

There are plans to expand the Western plant but not for about 10 years. There is significant growth north of the city, and Western is one of the plants able to feed water to that area. What shape the expansion will take isn’t clear yet, but the team is currently considering a dissolved air flotation system.

If limits on DBPs become stricter, other technologies such as reverse osmosis may be on the table, but at the moment, operators have no trouble meeting regulatory limits. In the immediate future, the utility will upgrade one of its 20 mgd plants to about 40 mgd.

Sustaining the team

The Western plant has been part of the Partnership for Safe Water since 2005. The people who constantly uphold the high standards are:

Mike Walton, plant superintendent, and Lorenzo Clay, plant supervisor

Jeremy Hawkins, senior operator; William Abercrombie, plant crew leader; Jamie Urbanski, Scott Gormley, Justin Morrow, Johnathan Crawford and Brittney Reynolds, operators; Jonathan Foster and Wade Howard, operator helpers; and Aja Robinson, operator intern

Terry King, DeLandon Peebles, Sylvester “Sly” Thornton and Stephen Guyton, maintenance

Kenneth Moody and Rodney Woods, residuals staff

Finding operators and trainees is an ongoing challenge. To address that issue, the city provides in-house training at the plant, and Harris hires interns regularly. “Even though the interns work for us, they don’t necessarily have jobs at the water works,” Harris says. Two of the interns are college students; their hours are adjusted to avoid conflicts with their classes.

The intern program has been in place for two years, and half the interns have passed their licensing exams. “We probably have some of the highest-paid operators in Alabama, but when you’ve got 18-, 19- and 20-year-olds, pay isn’t always important,” Harris says. The utility also recruits with newspaper ads and through the Alabama Water and Pollution Control Association and the AWWA.

Harris continues to find creative ways to attract young people. Those he has on board are doing well, but he’s looking ahead a few years: “We’re being proactive as opposed to waiting until we’re seriously short before trying to do something about it.”

That’s one way to make sure things keep running smoothly and those awards keep coming.   


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