Alternative Tile Intakes
Brown County contains some of the most productive soils in Minnesota. However, heavy clay loam soils have a high water holding capacity and require extensive artificial drainage to produce profitable crops.
Conventional surface tile intakes are installed on agricultural fields to limit the risk of flooding to crops. A section of tile is connected to the subsurface tile line and is installed upright, and leveled at the soil surface. This system is designed to remove surface water run off quickly. Although very effective in removing excess water from a corn/soybean field they do possess drawbacks:
- Due to the low profile and visibility of tile there is a possibility of damaging the surface intakes and equipment. Resulting in costly repair bills for the producer.
- Surface inlets increase the delivery rates of sediments, nutrients, and chemicals to streams and ditches during heavy rainfall.
Producers do have the option to limit the undesirable traits of surface intakes. One of those is the rock inlet.
Although rock inlets have been around for many years the simple design has been modified to increase the efficiency of moving surface water to the existing tile. The basic installation is accomplished by removing the upright tile and replacing it with a 3-4 foot wide by 3-4 foot deep by 12 foot long trench along with a connected muck pipe tile and synthetic sock covering. The trench is then filled with pea rock to one foot above ground level. The design has many advantages over conventional surface intakes:
- The ease at which field equipment can be used on, near, and around the structures without harming equipment or intakes.
- Crops can be planted through these structures, allowing crops to be planted in straight rows.
- Tillage equipment can run through them.
- Water quality improvement. Research has shown that during intense rainfall, 15% to 20% of contaminants can be retained compared to open tile intakes. Reducing phosphorus, sediment and residue loss from fields to rivers.
- Rock inlets increase drainage effectiveness through larger surface areas. Draining subsurface water around the inlets between rain events and during winter months. Crops are less stressed due to unsaturated conditions, and more infiltration when heavy rains occur.
Currently there is a limited amount of funding through RCRCA for rock inlets that are within the Cottonwood River Watershed in Brown County. Funding is currently not available for cost-share on rock inlets county wide, but it may become available soon. Anyone interested should contact the district office at (507) 794-2553 to determine eligibility or to be put on the waiting list
Rock Intake Designs: