Installation Practices, Trenching, and Site Preparation
Layout, trenching, and site preparation
Installation begins before the shovel. Call the utility locate service and wait the required period; irrigation lines are routinely cut into power, gas, and fiber. Walk the site for grade, trees, and drainage, then stake head locations so spacing is head-to-head - one head's throw reaching the next - because that is what produces uniform coverage.
Depth: bury laterals below the local frost line and typically 8–12 in. deep, with mainlines deeper; sleeve lines under driveways and walks. Slope trench bottoms so lines drain, bed pipe in fine material free of rock, and never leave a sharp bend at a fitting.
On slopes, install check valves and consider a flush point at the low end. Compact backfill in lifts and settle with water rather than leaving soft trenches. Set heads to final grade, not rough grade, and use swing pipe so they can be adjusted after sod or mulch goes down.
Safety: keep spoil piles at least 2 ft from the trench edge and provide a protective system once a trench reaches 5 ft.
Worked example: a 40-ft lateral on a 5% slope drops 2 ft; without a check valve the lowest head drains the line and puddles after every cycle. Traps: heads set too low fill with soil, trenches on slopes should follow the contour where possible, and watering should begin the day of installation.