Energy saving measure could save city millions in water treatment plant upgrades | The Hawk Eye - Burlington, Iowa | mississippivalleypublishing.com

The City of Burlington wastewater treatment plant sits along the Mississippi River and Main Street.

The Iowa Department of Natural Resources studies and determines how much contamination is allowable for water that is treated and then returned to surrounding surface water.

Discharge permits are issued by the Iowa Department of Natural Resources under delegation of a federal permit program known as the National Pollutant Discharge Elimination System (NPDES).

The NPDES program regulates the direct discharge of wastewater to surface waters.

For communities, this means changes, upgrades and costs to continue to comply with the designated permit limits.

The staff at the City of Burlington wastewater treatment plant made some adjustments to the plant’s blower system as an energy saving measure and, coincidentally, these changes could prevent the need to make a $6.9 million upgrade to the facility to meet the permit requirements.

Don Fitting, Wastewater Treatment Facility Superintendent for the City of Burlington, told the city council Monday that the tweaks made to the blower system have had a collateral effect of reducing the level of nutrients in the water going out of the plant after treatment.

The IDNR accepted a report in October that will give the city another five years to study the effects of the system tweaks, combined with efforts to incent local farmers to consider edge-of-field solutions, bioreactors, to prevent run-off from ag land into surface waters.

The cost to make the required upgrades to the treatment plant to meet the permit limits is an unfunded mandate according to Burlington City Manager Chad Bird. “This will directly affect resident’s sewer rates,” Bird said.

The $6.9 million upgrade will add $400,000 per year in operational costs at the wastewater treatment plant.

Hypoxia is a condition of low oxygen in the water that occurs in the Gulf of Mexico due to the Mississippi River’s discharge of nitrogen and phosphorus into the Gulf.

The Burlington Wastewater Treatment Plant plays a role in mitigating the threat of hypoxia.

The Mississippi and Atchafalaya Rivers discharge nutrient-rich freshwater into the Gulf of Mexico, which mixes with the denser saline seawater. This creates layers that prevent oxygen-rich surface water from mixing with oxygen-poor bottom water. The nutrients also promote algal growth, which consumes oxygen as the algae decomposes.

The low-oxygen area, also known as the Dead Zone, can trap and kill weaker swimming organisms, leaving behind a barren area.

Seasonal hypoxia began in the 1950s and has worsened in severity since the 1970s.

The Mississippi River/Gulf of Mexico Watershed Nutrient Task Force was established in 1997 to coordinate activities to reduce the size, severity and duration of hypoxia in the Gulf.

In its 2008 Action Plan, the task force called upon each of the 12 states along the Mississippi River to develop its own nutrient reduction strategy. Nutrients that lead to algae growth are the main culprit.

Fitting told the council that the changes to operations by the plant’s staff could result in putting off a $7 million plant upgrade to meet National Pollution Discharge Elimination System limits.

Fitting said the city recently installed a redundant line, which has increased the amount of water flowing into the facility by 36%. The plant processes 28.3 million gallons of wastewater per day. Before the redundant line was installed, that amount was 20.8 million gallons per day.

The benefits include the ability to complete major repairs to the system, maintenance activities, and inspection in headwaters. Fitting said it will also help with the total residual chlorine permitted in the water.

The city adds chlorine to the water going out of the plant to provide disinfection. Fitting said the DNR cut chlorine limits in 2022 by 32% in concentrate and 60% in mass.

“There was no way we could meet the limits that go into effect in 2026,” Fitting added.

The results of a 12-month site specific study showed the permit limits for chlorine were more restrictive than necessary. Fitting said the DNR removed the restriction in the permit and increased the amount allowable 20-fold.

The other means of water disinfection is an ultraviolet system, which could cost around $1.6 million.

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