Irrigation System Start Up

We are filling up the irrigation system this week.  There are miles of pipe in the ground and it must be filled slowly to avoid damaging the pipe and irrigation heads.  To relieve any air that is trapped in the pipe we must turn on the irrigation heads for a few seconds at a time.  Rain is likely today and tonight but what little water we turn on to relieve the pressure in the system will not be enough to wet the ground.  Having the irrigaton system back up will allow us to fill ponds that are low, wash equipment, fill the sprayer, water in fertilizer and weed prevention products, etc....It is important that we start the process now in order to have the water available for next week.