Under the surface: Delving deep into CAW
June 11-17, 2018
By Becca Bona
From lawns and gardens to pets and even residents, “parched” can perfectly describe the effects of brutal Arkansas summers. Thankfully, turning a knob might be all it takes to get that much-needed water flowing.
Luckily, there’s no reason to fear drinking straight from the tap, as Central Arkansas Water (CAW) provides a quality product.
A tale of two lakes
CAW’s Director of Public Affairs and Communications Douglas Shackelford says it all starts with excellent raw water sources, adding – “We have the best drinking water in Arkansas, and I do not hesitate in any way shape or form to say that.”
Lake Winona and Lake Maumelle are CAW’s water sources, and a lot of work goes into their protection and regulation.
“We take so much time with this water before we even treat it. We refer to this as our green infrastructure […] our lakes are like storage tanks for raw water,” he explains.
Lake Winona is the older of the two, dating back to the ‘30s. In the height of the Depression, the City of Little Rock was able to secure a loan and grant from the federal Public Works Administration to develop a water supply more secure than the briny Arkansas River. In 1936 the city began construction of a dam at the Alum Fork of the Saline River. The work also included the construction of a 39-inch diameter, 35-mile raw water line which leads all the way to Ozark Point in Hillcrest – the site of the water purification system.
Shackelford is amazed at the feat of engineering built back then that still connects Lake Winona to Ozark Point, as he says, “It’s all gravity fed – gravity feeds that water straight from the lake to Ozark Point without any generation.”
Lake Maumelle was developed by the former Little Rock Municipal Water Works as a second raw water supply in 1954. Located in West Pulaski County the scenic 13.9-square-mile reservoir provides approximately 65 percent of system wide demand.
Both lakes were originally controlled by Little Rock Municipal Water Works, but on July 1, 2001, the water utility and its largest wholesale customer, the North Little Rock Water Department, merged into Central Arkansas Water.
“There were concerns about who was going to maintain those lakes and the infrastructure for all the years to come,” Shackelford explains. “UA Little Rock was asked to do a study on the feasibility of a merger. […] The findings were that it would be really beneficial to the citizens of Central Arkansas if those utilities merged to form one.”
Today, CAW serves a population of almost 450,000, which includes Little Rock, North Little Rock, Sherwood, and now Maumelle, which joined in 2017. CAW also provides wholesale water to communities such as Jacksonville and Bryant, among others.
Even so, the utility is roughly near 50 percent capacity, and still has room to grow in the future.
Much of the work involved in getting water to residents begins on and around the lakes. “We do ecological thinning, which is where we actually go in and pick out specific trees to take out. It’s not an invasive procedure, it’s really more to do with opening up the canopy,” says Shackelford.
This process helps with the undergrowth and prevents soil erosion, which is important for keeping unwanted sediment out of the water.
“The thing that is hardest for us to treat is what we call Total Organic Carbons (TOCs). That can be anything organic from tree branches to body contact,” Shackelford continues.
Keeping TOCs out of the water is the main reason why both lakes come with a list of strict regulations – i.e. – no swimming, no littering, no fire building, and so on.
Honing in on Lake Maumelle, the intake station includes a pier with seven pumps that are each capable of operating at 2500 horsepower.
“They don’t all always run – some kick on and some kick off. We can rev them all up when needed in high consumption periods” Shackelford says, which typically include hot, dry summers.
Through the intake, water is drawn to the Jack H. Wilson Treatment Plant, which is located on Pleasant Valley Drive in Little Rock.
“We can pull about 133 million gallons a day (MGD) out of Lake Maumelle, and we can pull pretty close to 30 MGD from Lake Winona,” says Shackelford. And, while the treatment plants aren’t capable of treating as much as they can pull in, they can process a huge portion.
To date, 2012 holds the record for consumption, as Shackelford says, “We had one day in August where we actually treated 126 million gallons, so we were pretty close to yield. That was the biggest day in CAW history so far.”
Inside the Jack H. Wilson Treatment plant
“My background is not in science, but I’m blown away by the amount of work that occurs at CAW on a daily basis,” says Shackelford. “That’s part of what makes CAW what it is. It’s not only that we do work in the watershed with our multi-barrier approach to protecting our water sources, but then once it gets to treatment we’re still not done.”
Before Lake Maumelle was built, all of Little Rock’s water was treated at Ozark Point. “Back then it wasn’t what you would call a treatment plant, it was just a collection of settling basins,” Shackelford explains. “They let the water settle and then, of course, they added chlorine – which was one of the greatest advancements in all of history to eliminate water born illness.”
These days, Ozark Point is more than simple settling basins. But, focusing on the Wilson Treatment Plant, basins are still an important part of the process. After traveling 13 miles to the plant, the Lake Maumelle water is pumped into the basins and treated with aluminum sulfate – alum – which starts a process called flocculation. The alum creates particles which then latch on to any TOCs that might be left in the water. Particulate forms, and as it gets heavier it separates out to the bottom of the basins.
“This water is still not ready to drink, but we’ve eliminated most of the particulate at this point,” Shackelford says. The maze of basins was engineered to utilize gravity to push the water to its next stop – filtration. After the particulate is filtered out of the water, chlorination occurs. A varying amount of sodium hypochlorite – chlorine – is added depending on the necessary levels with licensed water operators at the helm.
Utilizing sodium hypochlorite eliminates the need to keep chlorine gas on site, which makes the entire process much safer.
The treated water flows to one of three wells capable of holding 2 million gallons each or a combined total of 6 million gallons, which is nearly always full. The water then travels to 25 other tanks throughout the system for use.
Distribution and beyond
When it comes to distribution, infrastructure is top of the list of important elements to monitor. There are over 2500 miles of pipe under the CAW umbrella, and the utility is responsible for making sure that they have tabs on the pipes that are nearing the end of their useful life.
“We set aside money every year strictly for replacing aging pipes,” Shackelford explains. “As far as standard repairs – we handle those as they come.”
CAW has a good idea of what water consumption is going to be on any given year, but things like the weather –specifically droughts – can be game changers.
“We budget with some flexibility. We have an idea of how much to expect in any given year but we do have to estimate,” he says.
Although it seems counterintuitive, CAW is almost like a city within itself, offering varied employment opportunities. “We talk to people about that all the time – there are so many jobs in the water industry that people have no idea. Yes, we have chemists, biologists, and conservationists,” says Shackelford, “but we also have accountants, journalists, and the list goes on.”
In order to stay on top of their game, CAW keeps their eyes toward the future. The utility is constantly conducting studies to see if there are ways to better its operations. For instance, there’s an opportunity to utilize solar power at the Wilson Treatment Plant, which might help lessen their current operational carbon footprint. CAW is in the process of accessing the feasibility of making that solution become a reality.
Along with providing quality water to Central Arkansas, CAW also tries to keep a conversation open to the public via an educational avenue. The utility hosts tours with various educational institutions as well as offers days open to the public to better explain operations. Find more information about the next tour, water use tips, and annual reports on their website: http://www.carkw.com/.
Three of the pumps that power water from Lake Maumelle to the Wilson plant.