Environment |

Lake Mary water plant destroys ‘tricky’ 1,4-dioxane with high-tech solution unique to Florida

The appearance of machinery inside an industrial building in west Lake Mary suggests Frankenstein’s birthplace, or maybe a vintage supercomputer or even a hazardous waste incinerator – which is kind of what it is.

It’s not intuitive that the basic function of the machinery is so commonplace as purifying and providing 3 million gallons of drinking water daily to 17,000 residents of Lake Mary. It does so with extraordinary effect.

Angular, elongated and draped in dreadlocks of external wiring, the machinery is the heart of Lake Mary’s two-year-old water treatment plant. It combines high-strength hydrogen peroxide with high-wattage ultraviolet light to chemically incinerate a toxic substance into innocuous molecular shreds.

The city’s water – before treatment – contains small but concerning amounts of 1,4-dioxane, a chemical labeled by federal authorities as probably carcinogenic.

Lake Mary officials would not permit interior photos of the plant during a recent tour, and the city’s lawyer insisted that its components not be described in detail for security reasons.

Industrial chemical infiltrated Lake Mary, Sanford, Seminole water wells; few knew and there was no coordinated response

But Lake Mary’s chosen treatment methodology, more costly and complex than conventional means, is gaining visibility nationally as a utility solution for water contaminants of rising concern like 1,4-dioxane. Many experts also note multiple ways that such plants outperform home treatment systems such as reverse osmosis units.

In Seminole County, there may be few other realistic alternatives for ridding drinking water of 1,4-dioxane.

The chemical has infiltrated a large expanse of the underground Floridan Aquifer where Lake Mary, Sanford and northwest Seminole County pump up drinking water. As a synthetic chemical widely applied as a solvent, it dissolves completely in water.

1,4-dioxane stubbornly resists attempts to separate it from water and is difficult to remove from aquifers.

“It’s really tricky to deal with,” said Tony Sacco, co-founder of Spartan Environmental Technologies, an Ohio company focused on water solutions in North America like the one in Lake Mary.

Although water treatment that relies on hydrogen peroxide and ultraviolet light can have higher operation costs, Sacco said, “it’s a really nice approach for solving this problem of 1,4-dioxane.”

Hydroxyl radical

Combining hydrogen peroxide with ultraviolet light to clean water is a mature, settled technology, said Sacco and other experts, but its use so far has been more for recycling sewage into drinking water and for restoring polluted aquifers.

The process is called advanced oxidation, which creates and utilizes a ferociously destructive molecule called a hydroxyl radical.

NASA describes the hydroxyl radical as one of the most reactive elements in the atmosphere, where it occurs naturally and says it “acts like a detergent in the air” disposing of pollutants.

Manufactured and harnessed to treat water, advanced oxidation’s hydroxyl radical is able to destroy pesticides, pharmaceuticals and industrial solvents such as 1,4-dioxane.

Lake Mary’s plant finishes the treatment process by running water through enclosed tanks containing granulated carbon, which, by itself is a powerful cleaner, removing any unused hydrogen peroxide and trace organic substances.

“We are very proud of our plant,” said Lake Mary public works director Danielle Koury.

City officials understand that no other Florida utility treats water with the same technology.

“We are the guinea pigs,” said Scott Rankin, the city’s chief water plant operator, of the novelty of such treatment in Florida. He expects that the eyes of many utilities will be on the plant’s ongoing performance and durability.

Unregulated chemicals

For nearly two decades, the soil and groundwater surrounding a former telecommunications factory in west Lake Mary a little more than a half-mile from the city’s water plant has been documented as extensively polluted with 1,4-dioxane and other industrial chemicals.

In 2013, the U.S. Environmental Protection Agency for research purposes directed utilities nationwide to test for 1,4-dioxane and several other contaminants that are unregulated by the EPA for drinking water.

There is no requirement that utilities regularly test for unregulated contaminants. There is no legal limit for the amount of unregulated chemicals in drinking water and there is no ordinary requirement for telling consumers about unregulated contaminants in drinking water.

As a result of that 2013 EPA order, varying levels of 1,4-dioxane – collectively the highest in Florida – were found in tap water of Sanford, Lake Mary and northwest Seminole County.

By 2016, the two cities and the county reduced pumping from their Floridan Aquifer wells with the most 1,4-dioxane contamination.

By doing that, Sanford and Seminole County lowered 1,4-dioxane levels in drinking water to about half of the state and federal advisory level – 0.35 parts of the chemical in 1 billion parts of water.

Lake Mary reduced 1,4-dioxane in its drinking water to about two to three times the advisory level, which the Florida Department of Health deemed in writing as not a risk to consumers.

But Lake Mary’s public works director at the time, Bruce Paster, said the city worried that 1,4-dioxane levels in well water could increase and that health researchers might determine that the health advisory level should be far lower to protect consumers. And, he said, no utility wants any amount of a likely carcinogen in their water.

Lake Mary turned to former owners of the telecommunications plant – General Dynamics, MONI Holdings and Siemens – and negotiated for them to construct and pay for operations and maintenance of a treatment plant able to get rid of 1,4-dioxane in the city’s drinking water.

A pilot study was underway in 2016, Rankin said, and the plant was completed in 2021. It reduces the concentration of 1,4-dioxane to a trace amount.

The cost, according to city estimates, was upwards of $40 million, though that was never directly disclosed by the former owners to the city. A Siemens spokesperson declined to comment to the Orlando Sentinel on plant costs.

According to the city, ongoing operations and maintenance costs include $180,000 annually for hydrogen peroxide, which the plant consumes at a rate of about 80 gallons a day.

The plant uses 50-percent strength hydrogen peroxide, which is stored in double-line tanks and is more akin to rocket propellant than to the medicine cabinet variety of 3 percent hydrogen peroxide and 97 percent water.

Hydrogen peroxide at that water plant’s concentration poses a hazardous risk to workers, though water plants typically use challenging chemicals such as chlorine or liquid oxygen.

One morning last month, Rankin arrived at the Lake Mary plant to encounter what he feared was a hydrogen peroxide leak, which prompted a major fire department response.

During the recent plant tour, Rankin said an initial investigation determined that hydrogen peroxide in one of the tanks reacted to a foreign material of some sort and emitted what appeared to him in early morning sunlight to be mist or vapor venting from the tank.

What the material was and how it got there remains under investigation, Rankin said.

Equipped with big pumps, water plants typically are hungry for electricity. Lake Mary’s also utilizes nearly 200 ultraviolet light tubes. Each of those is a 1,000-watt light, but dimmable according to the amount of water flowing through.

Koury said the plant’s monthly power bills run at about $20,000, an amount equal to the bills of nearly 150 homes using an average amount of power.

Those components – hydrogen peroxide and electricity – along with other operations and maintenance costs and half the salaries of four plant operators are paid for by former owners of the telecommunications factory, Koury said.

With the telecommunications factory located in city limits, Lake Mary was able to secure a high-end water plant but not be saddled with its large financial burden.

“The technology, I think, has been great,” Rankin said.

Floridan Aquifer

For two decades, the Florida Department of Environmental Protection has monitored or directed investigation of the plume of toxic pollution spreading outward from the former telecommunications factory off Rinehart Road and adjacent to a hospital under construction.

Still today, the department has not publicly provided a timeline or overall strategy for comprehensively determining the responsibility and solution for 1,4-dioxane contaminating the Floridan Aquifer and tainting the drinking water of tens of thousands of residents.

That has left Sanford officials vexed and frustrated over how to address higher concentrations of 1,4-dioxane in some of the city’s Floridan Aquifer wells and lower concentrations – lower than the health advisory level of 0.35 parts per billion – in its tap water.

For many years, Sanford has urged the state’s environment department to come up with answers for 1,4-dioxane contamination.

The city also recently has explored options for building a water plant like that in Lake Mary.

How a toxic chemical infiltrated the Floridan Aquifer, tainting Seminole County tap water

“We need Lake Mary to be a partner,” said Jake Varn, a Tallahassee environmental and water lawyer employed by Sanford. “We need to learn from them.”

Seminole County leaders had lost track of 1,4-dioxane contamination until the Orlando Sentinel began to publish stories this summer about the chemical’s threat to drinking water.

The county hired a national firm, Carollo Engineers, to explore options for addressing 1,4-dioxane in tap water of northwest Seminole County.

In-home treatment

For residents of Sanford and northwest Seminole County who are concerned about 1,4-dioxane, in-home treatment systems can help to a degree.

Common, less costly treatment options don’t work, according to the Interstate Technology Regulatory Council, a state-led environmental coalition.

But a granulated, activated carbon filter can remove some of the chemical at home, as long as it is changed out regularly, with the most effective results occurring when it is installed under the kitchen sink according to a North Carolina state study.

Reverse osmosis systems under home sinks are also a potential solution: multiple studies estimate they can remove about 70 percent to 90 percent of the chemical.

Because 1,4-dioxane is so embedded in water, molecules inevitably slip through carbon filters and reverse osmosis. That has left some scientists hesitant to recommend these options, which can cost hundreds to thousands of dollars and not be available to many households.

Youneng Tang, associate professor in Environmental Engineering at the Florida A&M-Florida State University College of Engineering said reverse osmosis and carbon filters are “effective for removing a very wide range of contaminants. It just happens to not be very effective on 1,4-dioxane.”

Others think that the two treatment options are effective if there are low levels of 1,4-dioxane to begin with.

“If the concentration is already very low, then if you remove 50 percent that can bring it to a safe level. If the concentration is very high … those cases require a more complicated and much more thorough treatment process,” said Haizhou Liu, professor of chemical and environmental engineering at University of California, Riverside.

In addition, a drawback with home filtration is that filtered-out 1,4-dioxane is sent down sewage lines to sewage plants. “​​It can find a way back into our water resources,” Liu said.

Liu concluded that reverse osmosis may be an answer for people relying on water from private, household wells. But for those connected to a public water supply, complete destruction of the chemical makes the most sense.

“I think the most effective approach would be a centralized treatment,” said Liu, which describes Lake Mary’s plant.

New threats

Old-school drinking water in Florida happens this way: drill a deep hole into the ground, insert a pump, withdraw what is generally very clean water from the Floridan Aquifer, slosh it around to vent off sulfur odors, dose it with disinfecting chlorine and pipe it to homes.

Orlando Utilities Commission and others have improved the process over recent decades. OUC delivers liquid oxygen to its many water plants, where it is converted to ozone, which is injected into raw water as an energetic cleaning and polishing agent to remove odor, color and trace organic compounds.

But the old-school way is futile for dealing with new threats of unregulated contaminants: 1,4-dioxane and, of rapidly growing concern, the cancer-causing PFAS chemicals seemingly infiltrating whatever people eat, wear and drink.

An early adopter of technology to fight 1,4-dioxane and PFAS is the Cape Fear Public Utility Authority in Wilmington, N.C.,. For  a quarter of a century, the utility has been treating its drinking water from the Cape Fear River with a complex array of ozonation, carbon filtration and ultraviolet light.

The river — lapping up pollution from farms, factories and sewage plants — meanders for nearly 200 miles from near Raleigh to the Atlantic Ocean.

In the mid-1990s, the utility learned of elevated concentrations of various chemicals in the river, including 1,4-dioxane at as high as 4.6 parts per billion.

According to a recent sample data point, the plant on March 6 treated river water with 1.2 parts per billion of 1,4-dioxane, reducing it to 0.32 parts per billion.

The utility’s “multi-barrier treatment strategy” includes a version of advanced oxidation, though does not employ the hydroxyl radical.

“While the process is highly automated, the plant is staffed 24/7 by licensed operators,” said Ben Kearns of the Cape Fear Public Utility Authority in an email.

Very competitive

In 2018, Paster, Lake Mary’s director of public works, reached out to the city of Tucson, Arizona, about its water-treatment plant utilizing hydrogen peroxide and ultraviolet light.

Aquifer waters in the Tucson area have been affected by 1,4-dioxane and other solvent contamination from a Superfund site known as the Tucson International Airport Area.

The city’s plant, about the size of Lake Mary’s plant today, had gone online in 2014.

Lake Mary hired Carollo Engineers, which has designed treatment plants with hydrogen peroxide and ultraviolet light in several states, including Arizona and California.

Carollo’s George Maseeh became Lake Mary’s technical advisor for the construction of its water plant.

“The technology has been mature for some time,” said Maseeh, a Carollo senior vice president. “Probably 20 to 30 years ago, the technology was around but manufacturers hadn’t quite perfected their systems and they weren’t particularly energy efficient. It became very competitive about 15 years ago and has had a lot of applications since then.”

Construction of Lake Mary’s water plant was directed by consultant Brown and Caldwell, working for the former owners of the telecommunications factory.

At the same time, Carollo and Maseeh were working for the town of Marana near Tucson, assisting in its construction of two plants that are smaller versions of Lake Mary’s plant.

Some of Marana’s well water is contaminated with 1,4-dioxane levels similar to those in Seminole County.

Paul Martinez, water operations manager for the town of Marana, said there was a lot of learning “on the fly” and he wasn’t aware of that many other communities utilizing water treatment with hydrogen peroxide and ultraviolet light.

But he learned about Lake Mary’s plant and thought it was a useful comparison.

At Sentinel forum, government officials, public discuss Seminole County’s tribulations with 1,4-dioxane

“Temperatures here go up to 115 during the day, and you’ve got to make sure that you have everything cold enough because you’re dealing with all these UV lamps and all these electronics,” Martinez said. “But I figured in Florida it was kind of warm there too.”

Learn it

At Lake Mary’s plant, Rankin said that an old-school water utility unaccustomed to a hydroxyl radical may initially find the process overwhelming. “But they will learn it,” he said.

An upside to advanced oxidation is that it disinfects water, Rankin said, lessening the need for chlorine, the use of which can trigger a host of contamination trouble. The Lake Mary plant still adds a minimal amount of chlorine as required by state law to keep water sanitized as it flows through pipelines.

After nearly two years of operation, there is little Rankin would change about its design, other than to upgrade some components to reduce the frequency of maintenance.

Water conservation proponents likely would want to encourage a big change in habits and practices.

The highest usage of Lake Mary’s water occurs from 2 a.m. to 6 a.m.

That’s when home and business landscape sprinklers automatically switch on, raining some of the most intensively pampered, high-quality water in the region on grass.