Iowa Code § 459.311D: Stockpiling dry manure on karst terrain.

A person stockpiling dry manure on karst terrain shall comply with all of the following:

1. The person shall stockpile the dry manure at a location where there is a vertical separation distance of at least five feet between the bottom of the stockpile and the underlying limestone, dolomite, or other soluble rock.

2. A person who stockpiles dry manure for more than fifteen consecutive days shall use any of the following:

a. A qualified stockpile structure.

b. A qualified stockpile cover. However, the person shall not stockpile dry manure using a qualified stockpile cover at a long-term stockpile location unless the stockpile is located on reinforced concrete at least five inches thick.