DNR sets new deadlines for Clarence wastewater improvements

State regulators want the city of Clarence to evaluate the water flowing through its wastewater system and potentially upgrade its treatment process within six years.

The town of 1,000 that lies 35 miles east of Cedar Rapids in Cedar County has aging wastewater collection pipes made of clay that have cracked and allowed water to infiltrate it for decades.

That — combined with water that illegally enters the system from basement sumps and roof gutter drains — has led to flows that are too high for the city's wastewater lagoons to sufficiently hold.

It's possible that the city will have to spend an unspecified, substantial amount of money to update its treatment process.

"It's like having an old car — eventually you have to do maintenance on it," said Terry Jones, a senior environmental specialist for the Iowa Department of Natural Resources. "It's a problem that a lot of cities have."

The city's wastewater is supposed to be contained in a series of four lagoons that — after reducing contaminants over many months — release the water into Mill Creek, a tributary of the Wapsipinicon River.

Those releases must be limited to twice each year, yet because of the amount of wastewater and rainfall flowing into those lagoons, they have at times discharged into the creek eight times in a year, DNR documents show.

The additional releases have not resulted in an obvious environmental impact to the creek or river, in part because the level of contaminants are significantly diluted by excessive rainwater infiltration, Jones said.

The department's efforts to get the system into compliance date back more than 20 years, according to DNR documents. In that time, the department has extended deadlines for the work at least twice.

"These things take time," Jones said. "The city has done an exceptional job, especially when it comes to investigating the sewer lines."

He said the city has used special equipment to view the insides of those lines and then attempted to seal the cracks. It has inspected homes and other places for illegal connections to sump pumps and roof drains.

A recent DNR order gave the city a deadline of April 2026 to finish a flow study of the system. That will evaluate flow data over a long period of time to determine whether the city's work to cut system infiltration has been adequate.

If it hasn't, the department wants the city to submit plans for treatment system upgrades by April 2028 and to complete the work by October 2030.

It's unclear what upgrade the city might choose, but Jones said it could add aeration equipment to the lagoons to speed the treatment process and allow releases into the creek throughout the year.

Several city officials did not immediately respond to requests to comment for this article.

Comments: (319) 368-8541; jared.strong@thegazette.com