Have you ever removed your sand trap or flushed your pivot?
It may surprise you, but this is a question we often ask
when people are having trouble with sprinklers on overhangs and we are
questioned in return “What is the sand trap?”
Sand trap location shown by red arrow
Every centre pivot and lateral irrigator should have a sand
trap just after the last tower and immediately before the overhang. You’ll
often find it directly below the boost pump for the end gun.
During normal operation, any sand and fine particles that
make their way into the irrigator will travel through the spans and then settle
in the sand trap. For this reason, the sand trap is designed with a ring-lock
mechanism so that it can be quickly and easily removed, inspected, emptied and
replaced.
Components that make up the sand trap
How much sand and fine debris is pumped through your irrigator will determine how often you will need to empty the sand trap. How quickly the sand trap fills is something you will learn from experience. Note that the amount of sand pumped out of a well can change over time and may be affected by events such as earthquakes. You should never let your sand trap fill completely as this will mean sand will go past your sand trap and continue to go down into the overhang.
If you’ve got an exceptionally sandy water-source, or you’ve neglected to empty your sand trap for some time, your overhang may be filling with sand. This adds weight to your irrigator increasing mechanical stress and in extreme cases blocks entirely and stops water from coming out of the sprinklers on the overhang. If your overhang has a build-up of sand, you can remove the plate on the end of the overhang and pump a small amount of water through your irrigator to flush the sand out.
Of course, proper maintenance and emptying of the sand trap will avoid having to flush your machine. Sand also does all sorts of other damage to irrigators. We’ll look at what sort of damage it does and how to mitigate this in a future post.
Stu Bradbury
