South Dakota Administrative Rules
Title 74 - Department of Environment And Natural Resources
Article 74:02 - Water rights
Chapter 74:02:09 - Chemigation
Section 74:02:09:01 - Definitions

(1) "Check valve," a device that provides a positive (absolute) closure which prohibits the flow of material or liquid in the opposite direction of that desired when operation of the irrigation system pumping plant or chemical injection unit fails or is shut down;

(2) "Interlock," the arrangement or interconnection of the irrigation pump, chemical injection units, and other pumps or supply tanks so that total shutdown of the system will occur if any component malfunctions or fails;

(3) "Low-pressure drain," a self-activating device to drain that portion of an irrigation pipeline or conduit whose contents could potentially enter the water supply when operation of the irrigation system pumping plant fails or is shut down;

(4) "Vacuum relief valve," a device that automatically relieves or breaks vacuum in an irrigation pipeline or conduit due to system failure or shutdown.