Unformed (Earthen) Manure Storage Design and Construction Table 1- Missouri's earthen manure storage design and construction requirements Facility Type Storm Water Containment Requirement CAFO w/ wet handling system Design storm event can be the 25-year, 24-hour storm; the 10-year, 10-day storm; the 10-year, 365-day rainfall, or 365-day rainfall minus evaporation Minimum 1-foot depth on the surface of the storage required to provide for storage of the catastrophic rainfall event Minimum 1-foot freeboard above the emergency spillway required Freeboard, storage, and load requirements for CAFOs with wet handling systems specify that the top of the berm must be at least 2 feet above the maximum depth of the lagoon. The additional storage volume maintained with the 10-year, 10-day storm requirement provides greater water quality protection by providing storage volume to accommodate chronic storm events. Lagoons must be pre-filled to protect the liner, to prevent weed growth, to reduce odor, to allow measurements of percolation losses and to maintain moisture content of the seal. Return to Step 3  |   Return to Overview