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Denison steps up for water quality

Denison steps up for water quality
Denison City Manager Terry Crawford at a city parking lot that was divided into four green strips each containing a bioretention cell to help make runoff cleaner as it enters the nearby Boyer River.

Water quality in Iowa isn’t just a farm issue.

Cities are doing what they can to enhance the Iowa Water Quality Initiative. The action plan for the state’s Nutrient Reduction Strategy, the Water Quality Initiative uses a research-based collaborative approach to reduce nutrients in surface water in an effort to address hypoxia in the Gulf of Mexico.

In Denison, a $150,000 parking lot project improved water quality and solved a drainage problem, and it strengthened community bonds.

The parking lot sits in the heart of the Crawford County town of 8,300, providing parking spaces for business customers and owners.

It also routinely flooded basements in businesses on the south end of the lot.

Denison is a hilly town, and the parking lot has a 3.5- to 4-foot cross-slope. And the lot was not aging well.

A better solution

Derek Namanny, an urban conservationist with the Iowa Department of Agriculture and Land Stewardship (IDALS), who was then with a federal agency, approached the city about creating a project that was both cost-conscious and environment­ally friendly.

Namanny suggested utilizing the IDALS Water Quality Initiative Urban Demonstration Project grant program.

In all, 34 Iowa communities have seized the opportunity to improve urban water quality since 2015. Denison is one of the smallest.

The IDALS program has contributed $2.45 million, match­­ed by $6.22 million in other funding, for a diverse range of projects designed to reduce nutrients and improve water quality.

The program contributed $75,000 to the Denison project, one-half of the total cost of the two Water Quality Initiative practices employed.

To control and filter runoff, the parking lot is divided by four “green” strips, each containing a bioretention cell.

The design capitalizes on the natural water flow of the parking lot slope. “Driveway” curb openings along the north edge of each green strip al­­low water to run into beehive intakes, where the water needed to grow plantings of native flowering plants is controlled by stop logs in a vertical pipe.

As the water drains from the vertical intake, it is filtered through layers of rock, sand and soil. The system, designed for a 2.5-inch rainfall, categorized as a five- to 10-year storm for the Denison area, then runs into the city’s storm sewer and into the Boyer River.

“The water enters the river cleaner and filtered,” said Terry Crawford, Denison city manager. “And that benefits not just us, but everyone downstream. We’re always looking to improve water quality.”

In addition to the bioretention cells, the parking lot includes a strip of permeable pavers designed to catch water before it hits businesses located along the south, or downhill, side of the lot. Water drains through pavers spaced three-eighths to one-half inch apart into an arched storm water chamber.

Eave spouts on buildings bordering the parking lot drain directly into the underground drainage system, further controlling runoff by capturing rooftop water.

Enlisting help

The Denison parking lot project is a prime example of Iowa’s cities engaged in water quality efforts, but Crawford says they did not take on the mission alone. Crawford County Conservation Service, Crawford County Soil and Water Conservation District, and Natural Resources Conservation Service all played a role, as did local construction and design businesses.

When local Master Gardener Pam Soseman suggested plantings for the retention cells, the project took on a whole new life.

Soseman approached the Den­­ison High School FFA for help. Agricultural education in­structors Dana Weeda and Alise Meyers gave the project to their Ag II Horticulture class.

“It was harder than it sounds,” says Ryan Branning, a junior at Denison High School involved in the project. Students were charged with identifying and choosing plants that fit the parameters of the northwest Iowa growing region, preferably native species with deep roots and the ability to efficiently use available water in sandy soil. Design specs required nearly year-round flow­ering. City crews requested low maintenance.

In the Denison FFA program, students learn about on-farm water control and quality im­­provement measures like tiling, terraces, waterways and buffer strips. The chance to participate in creating the parking lot bioretention cells gave them an opportunity for first-hand experience in urban agriculture.

“We researched various plants and created the design we wanted,” says Branning. “We had to consider plant height, bloom timing, nutrient needs and drought resistance.” And availability. More than once, the students thought they had made sound choices only to find the desired plants weren’t available.

“Pam was an excellent re­source,” says Weeda. “She was patient and flexible and communicated well with the kids. When she had to say no, she did a great job of explaining why.”

A valuable experience

Branning says that was a valuable part of the experience. “For kids, sometimes when we get an idea shot down, we take it personally. With this, we learned to keep going and try another idea until it all worked.”

The planting project concluded on the last day of school in May 2017. “Around 30 kids planted 630 plants in one and a half hours,” says Weeda. “It was an amazing thing to see.”

But for Branning, pride in the project doesn’t end there. “We did this,” he says. “It will be here for a long time, and we’ll be able to drive by and know we were a valuable part of it.”

The project fit the chapter in many ways. FFA students in Denison have a history of helping with community service projects and provide produce for the school cafeteria by planting a small garden plot with plants left over from a spring plant sale fundraiser. “Last year we grew so much the cafeteria begged us to stop,” says Meyers.

But this project was different. It was a chance to adapt rural practices and knowledge to the urban environment in a program that includes more town kids than farm kids.

“The students, the city and others involved learned that conservation isn’t just for the farm, it’s for everyone,” says Meyers.

Queck-Matzie is a freelance writer in Greenfield.



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