August 13, 2014

Riverbank’s wastewater plant will become more energy-efficient

Energy-guzzling aerators used in the city of Riverbank’s wastewater treatment lagoons will be replaced by technology using 75 percent less electricity for an estimated savings of $240,000 per year.

The floating aerators that churn the liquids in Riverbank’s wastewater treatment lagoons are energy guzzlers. So the city will start replacing them next week with a new system that uses 75 percent less energy.

“The aerators we have now are very inefficient and use lots of electricity,” explained Michael Riddell, Riverbank’s superintendent of public works. “What we’re replacing them with will give us better coverage for a lot less money.”

Those energy savings, estimated at $240,000 per year, are expected to cover about $3.6 million of the $3.9 million cost for the new diffused air bubble system.

Because the wastewater project is being financed with a 15-year loan, however, the system ultimately will cost nearly $5.4 million to pay off.

The public is invited to a ceremony kicking off construction at 9 a.m. Aug. 22 at the treatment plant, 23865 S. Santa Fe Road, Escalon.

Yes, Riverbank’s wastewater treatment facility has an Escalon address. That’s because it is north of the Stanislaus River in San Joaquin County, not far from Jacob Meyers Park.

The 146-acre facility processes about 1.7 million gallons of wastewater per day, using a series of lagoons. After treatment, the water stays on-site and is absorbed into the soil.

“We’re doing groundwater recharge,” Riddell explained.

That won’t change. What will change is the way air gets mixed into the wastewater during the treatment process.

Riverbank has contracted with Schneider Electric, an energy management company, to retrofit the lagoons with diffused air bubble lines using Parkson Corp.’s Biolac technology.

By installing that newer technology, the plant is expected to save more than 2.5 million kilowatt-hours of electricity each year. That’s enough to power about 224 houses.

The plant buys its electricity from the Modesto Irrigation District.

Schneider Electric guarantees that Riverbank will save at least $204,000 per year in electricity costs, or it will pay the difference. But the city will be responsible for maintaining the system.

“The project … will provide the city a cost-effective means to reduce energy consumption, to make improvements that would otherwise not be feasible and to help move the city into a more sustainable future,” Riverbank Mayor Richard O’Brien said.

O’Brien said the retrofit also may “put the city in a better position to respond to any new requirements” from the Central Valley Regional Water Quality Control Board.

The new equipment is expected to be installed and operating by February.

Oakdale’s wastewater treatment plant uses Biolac technology, and so do the Lake Don Pedro Community Services District and the Tuolumne Utilities District.

Schneider Electric is negotiating with the city of Gustine to upgrade its wastewater treatment plant, too.

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