Lower water levels in underground piping systems
Few underground piping systems require complete draining to protect from freezing in most of Michigan and Indiana. Lowering the water within the system so that the water is two to three feet below soil surface will prevent freeze damage in most situations.
Water can be pushed out of the system by compressed air pumps available from most irrigation dealers or may be pumped from the underground pipe system using a common fertilizer style transfer pump.
As a Michigan State University Extension and Purdue Extension irrigation educator, I have found an easy way to do this is by using a gas powered transfer pump at the lowest access point in the underground piping system. A one and one forth inch tube slid down inside a riser or two inch access in the manifold where air relief is, can be piped to the intake of the pump.
Drain travelers and big guns
Travelers and stationary big guns often have portions of their system that hold water. Drain and roll-up hoses, unhook and drain ends couplers and drain water drive piston and motors/impeller drive systems that may be damaged by freezing.
Trickle and drip lines and tape
Trickle and drip lines and tape are designed to be self-draining but manifolds and supply systems need attention to make sure no water pockets remain to freeze. Winter rodent damage can turn usable drip tape and trickle line into junk rapidly. Lines that are to be moved for next year are best stored in the barn. Lines over wintering in the field stand less rodent damage if not covered by plastic, plant material or mulch.
Pump down or drain underground pipe lines
Most underground pipe lines are buried deep enough to prevent freeze damage but they often require pumping or draining enough water from them to empty the upper portion of Z-pipe risers and pump manifolds. This is typically done by purging the system with air or modifying a fertilizer transfer pump to pump system at its lowest outlet or inlet points. Remember to cap all pipe inlets and outlets to prevent animals from entering.
Drain the pumping plant
Drain pumps and manifolds to the lowest point they can hold water. Replace brass drain plugs if damaged. Good designed pumping installations will be easy to drain without striping drain plug threads or the need for air purging. Inspect gauges, supply and control wires for needed repairs. Service the engine with attention to engine oil, bearing and seal lubrication. Check the cooling system for adequate anti-freeze level and concentration. Drain the fuel tank to reduce water accumulation in fuel tank and potential theft.