NEW HANOVER — The local water authority is actively seeking advanced solutions to address the challenge of 1,4-dioxane contamination in the region’s drinking water.
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The Cape Fear Public Utility Authority’s (CFPUA) Long Range Planning Committee convened July 24 to discuss and evaluate potential strategies for improving the removal of the chemical from the region’s drinking water supply. It suggested three main options: advanced oxidation process upgrades, foam fractionation, and propane-based treatment, with some estimated capital costs tapping out at $17 million.
CFPUA’s current treatment method for 1,4-dioxane, ozone and biological filters, removes around 52% of the chemical from raw water. The water authority’s existing granular-activated charcoal (GAC) filtration system — installed in 2022 for $48 million to treat PFAS — is not intended to fight against 1,4-dioxane due to the chemical’s unique properties.
“I can tell you when it’s all said and done and all figured out, this place [CFPUA] will be the one that figured it out,” New Hanover County Chair Commissioner Bill Rivenbark stated to PCD. “They’re that good.”
1,4-dioxane is a synthetic chemical and serves as an industrial solvent — a byproduct from industrial PET resin production. It’s also an ingredient or contaminant in many household products, including shampoos, detergents, and paint.
Its primary source of entry into the Cape Fear River is the discharge from upstream municipal wastewater treatment plants, such as those in Asheboro and Greensboro, which process industrial waste containing the chemical.
As of today, the Environmental Protective Agency does not have a legally enforceable federal maximum containment level (MCL) for 1,4-dioxane. However, the agency considers 1,4-dioxane as a “likely human carcinogen” posing an “unreasonable risk to human health.”
Currently, the EPA provides risk guidelines, stating that a 1-in-10,000 lifetime cancer risk is associated with 35 parts per billion (ppb) of 1,4-dioxane. This risk drops to 1 in 100,000 at 3.5 ppb, and to 1 in 1 million at 0.35 ppb.
In 2023, the EPA proposed an MCL of 0.33 ppb for the chemical to be legally imposed on public drinking water treatment facilities, but it has not yet been adopted.
Similarly, the North Carolina Department of Environmental Quality also does not have legally enforceable water quality standards for 1,4-dioxane. While DEQ did adopt a standard of 0.35 ppb for drinking water sources in 2022, this rule was ultimately voided by the North Carolina Rules Review Commission due to legal and administrative challenges, including issues with the rulemaking process and rulings against DEQ’s authority to impose such limits.
The DEQ has since appealed the ruling that struck down its authority to enforce discharge limits, with a hearing held in Wake County Superior Court on July 11. A decision on this matter has not yet been made and the litigation remains pending.
North Carolina Department of Environmental Quality Secretary Reid Wilson visited Sweeney Water Treatment Plant Friday for a tour of the facility and to learn about how CFPUA is addressing PFAS and other contaminants in the water supply. Upon being questioned by Port City Daily regarding 1,4 dioxane, he said he could not comment much due to the pending litigation, but stated it remains a concern.
“1,4 dioxane is another serious health threat, a forever chemical, coming from various sources,” Wilson stated. “It’s an issue that particularly plagues downstream communities. We believe that emissions limits need to be set on those discharges as well.”
The DEQ continues to classify 1,4-dioxane as a likely human carcinogen and has established in-stream target values as guidance, and actively monitors and identifies sources of the contaminant, advocating for its reduction. However, the absence of enforceable statewide regulation leaves downstream water treatment facilities like CFPUA to bear the burden of removing the chemical from drinking water supplies.
From July 1, 2023 to July 1, 2025 the finished drinking water from the Sweeney Plant has had an average 1,4-dioxane concentration of 0.33 parts per billion (ppb). The maximum concentration observed during this period was 2.1 ppb. Notably, the finished water concentrations remained below 0.35 ppb more than 70% of the time, placing it below the EPA’s health advisory level of 35 ppb.
The closure of the Alpek Polyester plant in Fayetteville on July 31 is poised to significantly reduce 1,4-dioxane pollution in the Cape Fear River. The facility, which Alpek acquired in 2001, primarily manufactured PET resin, a key plastic used in products like beverage bottles, food containers, and polyester fibers for textiles. Alpek announced the closure as part of a strategic effort to optimize its global operations and achieve cost savings, anticipating approximately $20 million in annualized savings.
As a major upstream source, Alpek’s discharges were responsible for an estimated 37% of the 1,4-dioxane found in CFPUA’s raw river water. The plant’s shutdown is expected to lead to an improvement in water quality for downstream communities like Wilmington, according to CFPUA’s Environmental and Safety Management Director Beth Eckert.
“We’re looking forward to Alpek being gone,” she said. “I hate the fact that they’re closing and losing people, but I am excited about the fact that the 1,4-dioxane that comes from that plant that has the most impact on our raw water is going down.”
CFPUA Board Member and Wilmington City Councilmember Charlie Rivenbark questioned whether another company would come into the facility after Alpek leaves, effectively making the positive impact on the water quality short-lived. There are currently no plans for another company to purchase the facility, but CFPUA Deputy Executive Director of Environment, Sustainability, and Linear Assets, Beth Eckert, said it is “very possible” another company moves in.
CFPUA Deputy Executive Director Kevin Morris presented three 1,4-dioxane treatment options to the Long Range Planning Committee for consideration.
The options
The first treatment strategy consists of an advanced oxidation process. CFPUA already uses a variation of this measure to treat raw water for 1,4-dioxane and other contaminants. It works by adding ozone gas (a powerful cleaning agent) to the water, which directly breaks down about 52% of the 1,4-dioxane it encounters.
Morris said an improvement to consider is adding a higher intensity UV light system along with chlorine. When it shines on the chlorine in the water, it creates even stronger chemical agents that are much more effective at destroying stubborn contaminants like 1,4-dioxane. 1,4 dioxane is tough to break down due to its high water solubility and resistance to conventional treatment methods.
CFPUA engineers estimated this process would remove about 90% of the chemical from the water.
To achieve these results, the upgrades come with a high cost: around $17 million. It would require installation of equipment and potential modifications to existing treatment plant facilities. Then the maintenance would be around $1 million annually.
Also explored was foam fractionation with photocatalytic destruction. The procedure pulls contaminants out of the water using foam and destroys them by shining UV light on a special material to further disband the chemical.
Invicta Water — a water technology company who designed the process — has shown it to be effective at reducing 1,4-dioxane and PFAS contaminants by roughly 90% each. Additionally, this strategy would put less strain on the current granular-activated charcoal filters, extending their lifeline before replacement is needed. GAC filters typically last about seven months and CFPUA budgets $5 million annually to replace the filters.
CFPUA recently sent raw water samples to Invicta Water for 1,4 dioxane testing through their foam fractionation method and are awaiting the results to see the effectiveness of the tech.
“No one has implemented this [foam fractionation] full scale yet, so this is experimental, but sometimes this is where great ideas come from, so it’s certainly something we want to continue to track,” Morris said.
Also uncertain are installation, maintenance, and recurring costs, but Morris expected they would be similar to the advanced oxidation process. The process would require large infrastructure changes, including the installation of new specialized equipment.
The final treatment option Morris presented included bioremediation using propane that is added to the water. The propane acts as food for certain helpful microbes, which eat the propane. The microbes then accidentally produce an enzyme (monooxygenase) that breaks down the 1,4-dioxane in the water, effectively “tricking” the microbes into cleaning it up.
Morris said it would be a simple way to go about treating 1,4-dioxane in the water supply because it adds on to the existing infrastructure of the Sweeney Water Treatment Plant.
“There may be a possibility that we could just add a small chemical dose in all the existing capital equipment we already have without making a huge investment in capital and see a significant improvement,” Morris said.
Using propane to treat water has been pilot-tested across the country, including in a landfill superfund site in Colorado. It resulted in successful biodegradation of 1,4-dioxane in contaminated groundwater.
Based on the pilots, Hampton Roads Sanitation District (HRSD) in Virginia has approved a $2.4-billion capital program through 2040. HRSD’s pilot test results show when propane was added at a 2-4 mg/L dose (milligrams per liter), it achieved between 40% and 80% removal of 1,4-dioxane on average.
CFPUA staff toured the Virginia facility in May to see the new water treatment process first-hand. The actual cost of installing this tech at the Sweeney Plant is unclear, but Morris said the propane treatment strategy is likely the cheapest option because of its at-ease integration.
However, pilot-testing would be needed and this process is less likely to be as effective at removing 1,4-dioxane from the water supply than the others. Though the costs to test it are not in this year’s budget, CFPUA staff is considering a plan for a test-study inclusion in the fiscal year 2026-2027 budget.
Looking ahead, CFPUA staff will continue to monitor and advocate for 1,4-dioxane treatment improvements, including pushing in Raleigh for state-level regulation and upstream enhancements. CFPUA formally petitioned state regulators in November 2024 for emergency rulemaking to require upstream dischargers to reduce 1,4-dioxane by a minimum of 80%. However, the petition was returned to CFPUA later that month by the Division of Water Resources Director Richard Rogers, who stated it lacked appropriate text for a proposed emergency rule.
CFPUA currently tests for 1,4 dioxane weekly and posts results on its website. The last test ran July 24 and came back at 0.11 ppb for finished water and 0.22 ppb for raw water, both under the EPA’s health advisory level of 35 ppb.
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