Abstract: Modern drainage systems should have updated backfill specifications. Don’t live in the past.
A quick way to start a golf course argument is to discuss drainage tile backfill materials. Perforated HDPE pipe needs a permeable backfill to move water from the existing soil into the holes in the pipe. The battle lines are drawn between two parties; the peastoners and the sand backfillers.
The peastoners believe that peastone, or pea gravel, moves water through voids created by the spacing between the small chunks of rock. This is true. Water does move through permeable stone columns.
The sand backfillers use high-percolation sand and HDPE pipe coated with a geofabric membrane.
I’ve seen screaming golf supers jump up and down while discussing drainage backfill. I tell my clients it is their decision, but I’m a sand backfiller, although I was a peastoner for many years.
My conversion began when I worked with a sports turf drainage consulting firm from Canada. They develop complex drainage plans that involve thousands of short test holes in a grid pattern. This information is plotted on an overlay of the problem turf area, and an interception scheme is designed.
They insist on using high-percolation drainage sand as a backfill. He hates fine silt, and he likes sand that percolates at 40 inches per hour.
I’ve installed three systems using this process, involving over 4 miles of pipe. The systems works. The sand layer intercepts fine silt leaching from the existing subsoil The geofabric keeps the sand out of the piping, although you must be sure to install the geofabric in a dry trench. Coffee-colored water clogs the geofabric liner.