Proper Siting of an Animal Feeding Operation using karst terrain and alluvial soils maps
The DNR has developed the AFO Siting Atlas to help livestock and poultry producers who are planning a new animal feeding operation, or the expansion or modification of an existing operation. This application gives a quick overview of the landscape features that must be considered when planning construction. The application can be especially helpful in determining the locations of alluvial soils, karst topography and sinkholes.
Alluvial soils and karst describe areas in Iowa that may be vulnerable to flooding or groundwater contamination. Alluvial soils formed from materials deposited by running water, thus a site located in alluvial soils may be in a floodplain. Karst terrain refers to areas where soluble bedrock lies close to the ground surface. Karst areas are often characterized by sinkholes and losing streams. Water and contaminants in these areas can travel quickly through underground passageways to wells, springs, and streams.
Iowa laws have specific requirements for building, expanding or modifying open feedlots and confinement feeding operations located in the 100-year floodplain. Knowing if a potential site has alluvial soils is one step in determining if the site could be in a floodplain and if building restrictions could apply. Depending upon specific site conditions, construction may be prohibited or a floodplain permit may be required.
All animal feeding operation structures have a "high damage potential," meaning flood protection (both structural integrity and elevation of the lowest opening) must be provided to the level of the 100-year floodplain plus one foot. In addition, the construction must allow for the conveyance of flood flows.
Iowa law prohibits placing confinement feeding operations within 1,000 feet of a sinkhole, and sets specific separation distances from other protected waters. Also, animal producers who plan to build, modify or expand a confinement feeding operation structure will need to find out if the proposed location is in karst terrain.