Donnellson, Iowa Coordinates with the Lee County NRCS Office for a Joint Water Quality Improvements Project
The City of Donnellson and the Lee County Natural Resources Conservation Service (NRCS) office worked with the engineering firm of French-Reneker-Associates, Inc. of Fairfield, Iowa to complete a joint project to reduce the pollution into Sugar Creek in Lee County.
The joint project included building terraces in crop fields and encouraging the planting of cover crops in the fields around Donnellson, building erosion control features at the Donnellson ball fields, and building bio-retention cells in Donnellson.
Terraces, cover crops, and the soil erosion features at the ball fields reduce soil erosion and collect sediment which reduce soil, nitrogen, and phosphorous in downstream water bodies.
The bio-retention cells are a newer technology for pollution control. These were built in ditches next to four blocks of streets in Donnellson. First tile was installed under the ditches and backfilled with rock. Then the top 2½ feet of dirt was removed and replaced with a mixture of sand, topsoil, and compost; and the area reseeded to drought tolerant lawn grasses. Runoff from the streets and the house yards soaks through the rock cleansing the water and then into the tile where it is drained to a stream. Bio-retention cells provide about 75% reduction of hydrocarbon runoff from the streets, 50% reduction of suspended solids and nitrogen fertilizer, and 25% reduction of phosphorous fertilizer, from the streets and house yards.
Bio-retention cells also provide a secondary benefit. Donnellson is a flat town. After a rain, the street ditches hold water for days. The water soaks away quickly in the bio-retention cells. This eliminates ponding water where mosquitos would breed, and dries the ditches next to the street so the streets stay stable longer meaning less money spent fixing potholes and re-sealcoating of the streets.
For more information or to tour the project, contact the Donnellson City Hall at 319-835-5714.
Role of French-Reneker-Associates, Inc. in the Project
French-Reneker-Associates was a key player throughout this project.
Sponsored projects are an offshoot of a larger Clean Water State Revolving Fund (SRF) project. French-Reneker was the engineer for the project to upgrade the City’s wastewater treatment plant which led to the opportunity for a sponsored project.
We worked with the City of Donnellson to discuss the potential project and develop concepts. We then met with the Lee County Soil and Water Conservation District to explain the project to them and invite them to be a partner. They were eager to be a partner and ready to provide information and technical expertise to rural landowners.
We then prepared the application for funding. The application included making a watershed assessment. The watershed assessed is 1,266 acres. The watershed assessment shows on the average the watershed contributes 4,700 tons of sediment and 6,110 pounds of phosphorous to the downstream Sugar Creek annually. The quantity of nitrogen runoff varies annually dependent upon the amount of nitrogen application and the amount, intensity, and timing of rainfall events.
The City was awarded funding and we moved into the design phase. The design of improvements on the agricultural fields was completed by the Natural Resources Conservation Service (NRCS) Staff. We provided field survey, final design, drawings, specifications, and contract documents for the projects adjacent to the ball fields and the in-town work.
We also provided the engineering during construction for the projects we designed and provided assistance for the grant administration and project cost reimbursement applications.