UI students’ research helps with wetland projects


This storm water outlet along Business 151 at Riverside Gardens causes erosion and scouring. The UI students proposed a $185,000 project to create a native swale. (Photos by Kim Brooks)

The 12-acre site behind Dollar Fresh contains a pond with stagnant water. The UI students proposed a $444,000 project to re-shape the pond and connect it with a swale on the east side of the property.
By: 
Kim Brooks
Express Editor

     University of Iowa graduates with the CEE (civil and environmental engineer) program have been working with the City of Monticello and the Maquoketa River Watershed Management Authority (WMA) and Limestone Bluffs RC&D to explore options at two wetland sites in Monticello.

   The preliminary work started back in mid-February, and took 16 weeks to complete. They met with Parks and Recreation staff, as well as city officials.

   The students presented their final project to the Monticello City Council during their May 16 meeting.

   The work the students took on through a partnership WMA and the UI. A grant was awarded to WMA in 2021 through the DNR. The grant also helped to cover the costs for a watershed coordinator.

   The students, Chuck Smith, Lara Gavin, Grant Hemphill, met with the council to highlight their two areas of study in Monticello:

   • Riverside Gardens

   • The 12-acres and pond behind Dollar Fresh

   “You have a storm water outlet that is a concern for us,” noted Smith of Riverside Gardens. “You also have a storm water outlet that basically shoots right toward Kitty Creek,” in reference to the Dollar Fresh property. “Both storm water outlets present a bit of a contamination concern for us. That’s what we considered when we made our designs to our wetland improvements and your trail improvements.”

   The storm water outlet at Riverside, which sits along Business Highway 151, causes extreme erosion. The students said that’s a huge concern.

   “It does outlet pretty close to the road and travels along the concrete channel until it gets to a drop point,” explained Gavin. “There is really no treatment occurring when water just passes over the concrete. Passing over the concrete is actually making the water travel faster. When it gets to the end at that speed and drops off, it causes a lot of scouring and erosion to occur, which just adds a lot of pollution.”

   She said a fix to this issue is the creation of a bio-swale.

   “It’s basically a glorified ditch,” Gavin said of the swale. “But you can really control the plantings you put in there. Those plantings can treat the water and slow it down in order to control what’s going out and to the river better. And also add some nature back into this environment.”

   “Are you suggesting eliminating the concrete?” asked Council member Tom Yeoman.

   “We would tear out the concrete and replace it with native plantings,” offered Gavin.

   The original concrete was in place initially to divert water away from the road/old highway.

   “According to DOT standards, with the average daily traffic for this road, we would want to design it to have a freeboard of 1 foot, which is the distance between the top of the water and the top of the roadway for a 50-year storm,” continued Gavin. “That means that storm would occur twice every 100 years.”

   She said some rain events might cause the water to spill over into the gardens. However, this sitting water would be short-lived.

   “That’s just a natural thing that would happen with the channel to begin with. In a major storm event, it would still back up a bit into the gardens,” Gavin said.

   “The concrete was put there to prevent all of the erosion,” said Mayor Dave Goedken. “I just don’t see what you could put in there that we can maintain and keep decent. It’d be nice to preserve the area the way it is.

   “There is a massive amount of scouring that has happened,” continued Goedken. “We fought it for years. The cement seemed to be the answer.”

   Gavin said the scouring could be prevented still.

   “You could maintain the concrete up until a certain point and once you have more space, you would open up into a forebay. This would detain the water a bit and allow the sediment to fall,” she explained. A forebay is built with a concrete bottom/base.

   “You have to be able to figure out a way to slow the water down, even during a low rain event,” she urged.

   Gavin said they considered merging the swale with the Riverside wetland, but a swale is a cheaper option.

   The cost for the Riverside project would be around $185,000.

   At the 12-acre site behind Dollar Fresh, Gavin indicated that the detention pond is a problem.

   “It was never engineered; it was a hole that was dug out. It doesn’t have an outlet to anywhere,” she noted. “The water sits; algae and mosquitos really thrive in this area. There is a lot of wasted potential.”

   The students proposed slightly reshaping and connect it with the current swale on the east side of Dollar Fresh, which would also help with the continued expansion of Willow Trail.

   “We’d use the trail as a berm in order to stop the water and move it and redirect it into a constructed wetland,” said Gavin. “This swale would utilize natural plantings in order to treat the water. The wetland should have a permanent pool and elevation.”

   The expansion of the trail behind Dollar Fresh and over toward Riverside Gardens is proposed at DOT standards at 10 feet wide and ADA compliant.

   The project behind Dollar Fresh is estimated at $444,000.

Category:

Subscriber Login