Newton plans to construct detention basin in area known for its flooding

To be better prepared for the next heavy rainfall event and avoid future flooding along a specific intersection on First Avenue East, the City of Newton is planning to build a detention basin to collect stormwater at a problematic area of town. The proposal was shared in a presentation at the May 19 city council meeting.

Public Works Director Joe Grife said it would be a two-phase project that could be bid and constructed in the upcoming fall or winter seasons. In addition to building the 0.75-acre basin, the city would also reconstruct sanitary and storm sewer conflicts in the area, which caused issues during the May 2024 floods.

“We had significant flash flooding throughout mostly the northeast part of town,” Grife said while showing a picture of the intersection at First Avenue East and 12th Street East near Walgreens and Scooters. “…And if you remember, not long before this event, we had shared our stormwater study.”

Lo and behold this intersection was one of the locations identified in the study for staff to take a better look at. The storm fueled the city’s efforts to find a solution. Public works teamed up with HR Green, a civil engineering company, to create digital modeling of the neighborhood that was heavily affected by the flooding.

Using the existing conditions as a base, the digital modeling showed the effects of a 500-year storm in that area. Grife said the models lined up exactly with what the city saw the day of the floods: two to four feet of water on First Avenue and five to six feet of water in the nearby empty lot.

Funding for the project would come from urban renewal area TIF funds. The city estimates the first phase of the project will cost $700,000 to construct.

The basin would be located on city property north of Walgreens.

“So just about 18 months from that storm we’re going to be moving dirt out of there and getting some problems solved with that issue,” Grife said. “This will be a dry basin. It won’t hold water other than during rain events. There won’t be any safety issues … It will be maintained, mowed just like area is now.”

When the detention basin is built, the severity of the flooding drops dramatically, according to the digital modeling from HR Green. The second phase of the project would upgrade the existing storm sewer and constructs a new concrete box culvert. The second phase would cost $1.8 million. Funding is undetermined.

“We’ll be upgrading what’s existing and building some new ones,” Grife said.