Grimes fined $9K for wastewater pollution in creek

The city of Grimes has agreed to pay $9,000 for the elevated levels of pollutants that have been discharged from its aging wastewater treatment plant, according to the Iowa Department of Natural Resources.

The pollution culminated most visibly last year with smelly, murky water in Little Beaver Creek, gray or black deposits along the stream and pockets of fly larvae, the DNR reported.

The treatment plant, located on the city’s north side amid newer residential neighborhoods, is about 50 years old and has become increasingly less capable to treat the wastewater of the growing Des Moines suburb.

Grimes’ population increased about 87% from 2010 to 2020, when the U.S. Census counted about 15,400 residents.

The DNR began noting violations for inadequately treated wastewater from the plant in late 2019, according to the department’s recent administrative order that levied the fine. The water flowing from the plant into Little Beaver Creek has routinely had elevated levels of ammonia — in some months, more than 10 times the allowed amount. It was determined several times to be acutely toxic to aquatic life, although the DNR did not document any fish kills.

In February and March 2022, the DNR noted abnormally high amounts of solid material and bacteria in the wastewater.

“They’ve been in significant noncompliance, which is what led to the recent administrative consent order,” said Tom Atkinson, a senior environmental specialist for the DNR who has been monitoring the treatment plant. “They’ve made some improvements at the plant to maintain compliance as best as possible and have been pretty successful with that in the last few months.”

Little Beaver Creek flows east to Beaver Creek in Johnston, which flows southeast to the Des Moines River. The Des Moines River is a drinking water source for the metro area, but water is drawn upstream of its confluence with Beaver Creek.

Grimes had considered upgrading its treatment facility but in 2020 decided to connect its sewer system with the Des Moines Metropolitan Wastewater Reclamation Authority, which treats most of the metro area’s wastewater at a plant on the east side of Des Moines.

That requires constructing a massive, 7-mile-long pipe from the Grimes plant to a connection point in Urbandale. Grimes began awarding contracts for the $39 million project in December 2021 and expects the work to be complete by the end of 2023.

In 2020, the city said it planned to have the project finished by July 2022, but the coronavirus pandemic and acquiring land easements, among other factors, delayed it.

“There were a number of challenges that we had along the way,” said Alex Pfaltzgraff, development services director for Grimes.

He said Urbandale and Waukee are paying about $4 million of the project cost to install larger-than-necessary pipe that can be used to expand their wastewater capacities in the future. The remaining amount is being paid with increased sewer rates, he said.

When the new pipe is functional, the old treatment plant will be shuttered, and none of the city’s wastewater will flow into Little Beaver Creek.

The creek’s malodorous situation in September 2021 was partially the result of a lack of rainfall, when the city’s wastewater sat in stagnant pools and biodegraded. Atkinson said the DNR fielded numerous complaints about the creek at the time but said the creek was clear when he checked Thursday.

Pfaltzgraff said the city has taken steps to ensure it doesn’t happen again before the new pipe is functional.

“It’s something we take very seriously, and I think the DNR recognizes that,” he said.

The DNR order said discharges to the creek are required to cease by September 2024.