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Alum is working: Colfax lagoons only exceeded lower phosphorus discharge limit two times last year

By LeAnn R. Ralph

COLFAX  —  The Village of Colfax’s wastewater treatment lagoons only exceeded the lower phosphorus limit two times last year, according to the Compliance Maintenance Annual Report.

Exceeding the phosphorus limit twice is actually good news because it means the village’s wastewater treatment facility has reduced the phosphorus discharge by half.

The Colfax Village Board reviewed the CMAR at the August 24 meeting, and overall, the wastewater treatment facility received a grade of above a “B” (3.33 on a scale of 4.0), with a grade of “D” on the phosphorus section.

The higher phosphorus discharge amounts were caused by mechanical problems at the lagoons, said Rand Bates, director of public works.

The village’s new wastewater permit issued by the state Department of Natural Resources in 2014 set the phosphorus limit at 4 milligrams per liter.

The limit for phosphorus this year and next year will be 3 milligrams per liter.

By 2017, the phosphorus limit for Colfax will be 1.5 milligrams per liter.

Prior to the new phosphorus limit in the wastewater permit, Colfax was discharging between 8 and 10 milligrams of phosphorus per liter.

In 2013, the village began a pilot study of treating the wastewater lagoons with alum, which binds with the phosphorus and causes it to settle out.

The lower phosphorus limit for Colfax is part of the Total Maximum Daily Load (TMDL) for phosphorus that the DNR established for the 1900-square-mile Red Cedar Watershed.

Phosphorus run-off from the entire watershed drains into Tainter Lake and Lake Menomin, and the phosphorus from Colfax is only a small percentage of the overall phosphorus load.

The soil in this area is naturally high in phosphorus, and water coming out of the tap in Colfax is already high in phosphorus.

Phosphorus is the nutrient implicated in fueling the algae blooms that turn Tainter Lake and Lake Menomin a thick green color during the summer.

Effluent

According to the CMAR, the Colfax wastewater treatment facility began discharging in May of last year with an average of 4.9 milligrams per liter of phosphorus for the month — or a total of .9 milligrams above the permit limit.

Colfax discharges to the Red Cedar River, and the wastewater treatment lagoons discharge from May until November.

The wastewater facility exceeded the phosphorus limit again in November of last year with an average of 4.3 milligrams per liter for the month — or a total of .3 milligrams above the permit limit.

In June of 2014, the phosphorus discharge was 3.2 milligrams per liter. In July, the phosphorus discharge was 1.5 milligrams per liter. In August, the phosphorus discharge was .1, climbed to 2.3 in September, and dropped to 1.6 in October.

Solar Bees

The wastewater treatment lagoons were using devices called “Solar Bees,” floating solar-powered water circulators, to keep the water in circulation and to mix in the alum.

Prior to electricity being installed at the lagoons last year that allowed the use of a chemical feed pump with a meter, the alum was added to the water using a gravity feed system.

Lightning strikes caused problems at the lagoons last year and took out a motor and a circuit board, Bates told village board members at the August 24 meeting.

According to Bates’s explanation on the CMAR, “We are still in the experimental stage with the alum injection in the pond. We added power at the pond and changed the solar bee to a grid bee so we have 24 hour mixing. We also installed a VFD pump to inject alum to the flow of effluent to the river. We don’t have all of the bugs worked out quite yet, but I think we are getting close. We had difficulties with some lightning strikes.”

Leakage

The other section of the CMAR that reduced the overall grade for Colfax was related to pond and lagoon leakage.

According to the report, the leakage rate was estimated at 2,777 gallons per acre per day for 21 acres of lagoons.

Bates noted on the report, “We had battery problems with the solar power that powers the flow meter. The total flow did get measured properly. We have AC power that powers the flow meter now.”

As it turned out, the total amount of gallons coming into the lagoons was measured properly, but because of problems with the flow meter, the amount going out of the lagoons was not measured properly.

The inaccurate flow measures resulted in Colfax receiving a grade of “C” on the pond and lagoon leakage section of the report.

Resolution

Part of the rules for the Compliance Maintenance Annual Report on wastewater treatment facilities is that the Colfax Village Board must review the report and then pass a resolution informing the DNR that the board has reviewed the report.

The Colfax Village Board unanimously approved the CMAR resolution.

Village Trustee Susan Olson was absent from the meeting.