By John Novaria
AJWC typically treats 800,000 to 1.2 million gallons a day, but with the new tank and aeration system, it now has the ability to reach 2 million gallons.
There’s iron in your well water, you’re sitting on a fault line and your soil is silty. Three strikes and you’re out, right? Not if you’re the Anna-Jonesboro Water Commission (AJWC).
AJWC is a wholesale water supplier to several municipalities and rural water districts in southern Illinois. How it overcame everything nature threw its way is an epic tale of partnership and persistence.
Iron Contamination
“The Illinois EPA put us under review due to restraints we had on aeration capacity, which stems from the high iron content in our water source,” said Casey Johnson, superintendent of the Anna-Jonesboro Water Commission. “At 24 parts per million, it’s the highest concentration in the region.”
Even though AJWC has the filtration capacity, the EPA advised that the high iron levels put stress on its aeration capacity, which could hamper supply. For example, the district might not be able to meet increased demand in the event a neighboring district had a failure or if a new manufacturing facility were to locate in the area.
“The plant had been derated to about 1.4 million gallons a day from its original capacity of 2 million,” said Ted Beggs, president of J.T. Blankinship Engineering. “So we worked with Aquastore to develop a system that would improve the aeration of the incoming water and increase filtration capacity.”
Beggs and his firm have worked for years with Cady Aquastore, the authorized CST dealer in DeKalb, Ill. The company has extensive experience with aeration systems, having designed and installed about two dozen for water districts over the last 25 years, according to Dave Hemauer, Cady Aquastore project manager.
“Our aeration system is a big value-added feature because it’s fully integrated with the storage tank and complements the treatment process,” said Hemauer. “Forced aeration is superior to gravity tray systems because the forced air speeds up oxidation, while gravity systems rely on the water percolating over trays that require frequent maintenance and backwashing.”
Armed with their expertise and intimate knowledge of AJWC’s requirements, the intrepid crew from J.T. Blankinship and Cady Aquastore built an aeration system to attach to the top of a new Aquastore tank. The system features two powerful fans that force air on the water and promote rapid oxidization. The iron settles at the bottom of the tank and the oxidized water is pumped into a clarifier.
“It has greatly improved our overall treatment capability,” said Johnson. “Using air pressure to force water to oxidize makes it easier to treat. If you have iron or manganese underground, it’s definitely worth the investment.”
Johnson noted that iron content in the water reaching the clarifier has gone from between 0.30 and 0.40 mg/L to almost zero. “So I’d say we’ve tripled the amount of oxidation,” he said.
AJWC typically treats 800,000 to 1.2 million gallons a day, but with the new tank and aeration system, it now has the ability to reach 2 million gallons.
Shake and Soil
AJWC’s treatment facility is located in the New Madrid seismic zone and sits on weak soils, so Cady Aquastore engaged the services of a structural engineer that specializes in designing platforms for problematic foundations. Together, they evaluated a range of possible earthquake-and-soil scenarios. One involved the outlet pipe from the aerator to the tank becoming obstructed or compromised, causing the aerator to fill with water and become top-heavy.
“When you face these risks you have to calculate the conditions under which a structure could fail and design against it,” said Hemauer. “Our goal was to get the foundation and tank to perform as a single unit and withstand the stress of shaking and shifting soil.”
An aeration system atop the tank addresses the high iron content in AJWC’s source water.
The Aquastore tank is engineered for durability and construction is simpler than that of welded or concrete tanks. The roof is assembled first and then lifted with a jacking system so the individual steel panels can be bolted underneath. Crews work at ground level and require only a few feet of space around the foundation. A tank like this goes up in about a third of the time of a welded tank and if an owner anticipates needing increased capacity, the entire tank can be designed to add panel courses for future installation at the bottom of the tank shell.
It also stands up to the harsh Midwest weather. The glass coating applied in the factory makes the tank resistant to extreme cold and heat — more so than welded steel tanks. Its seamless surface prevents cracking which can attract rust, and the absence of corrosion or leakage greatly mitigates the chance of hazardous runoff or leaching. There’s no need to repaint and maintenance costs are lower than other tank types.
Johnson can testify to Aquastore’s reliability and quality. He has a 1.2-million-gallon ground storage tank manufactured by CST that was installed in 1994 and he says he’s never had a single issue or problem with it. But if one should arise?
“If there should be a problem, they’re easy to reach and responsive,” said Johnson. “The less we have to worry about storage or aeration, the easier it is to do our job.” WW
About the Author: John Novaria is principal of Novaria Communication, based in Los Angeles. He has more than 30 years of experience in PR consulting, corporate communications and television news, where he was a two-time Emmy winner. Since 2012, Novaria has maintained his own practice counseling clients in engineering, financial services, manufacturing and technology. Before that he worked as a TV news producer, as a PR account manager and as a corporate communications executive at GE, Raytheon and Swiss Re.
