Abstract: Golf greens with heavy soils usually have drainage problems that complicate turf management. Installation of drainage pipe in existing greens is an effective but expensive option.
I grew up on a golf course with poorly drained greens. After a heavy rain, high iron shots usually landed with a muffled thwack. Golf courses can improve subsurface drainage with the following procedures.
Flat Pipe: Several manufacturers offer flat drainage pipe in rolls. The pipe includes an 8” wide by 3” high HDPE corridor that looks like crushed conventional pipe. The corridor is covered with a geofabric mesh.
The flat pipe is installed wide side down on the green subgrade, not in a trench. After determining existing subgrade slopes, drainage lines are marked on the golf green. Sod is removed and numbered with chalk to insure that it is replaced in the exact location.
Next, green mix is removed down to the subgrade level. I recommend removal of all the green mix in the green core during this process, but some remove only green mix on the trench line. Complete green mix removal is expensive, but trench-only excavation may cause problems with dissimilar compaction.
The flat pipe is connected to a 4” smile drain at the low point of the green collar. The smile drain exits away from the green complex.
Fat pipe is more expensive than conventional pipe. Connecting fittings are more expensive than conventional round fittings.
Round pipe: Conventional double wall perforated HDPE pipe is used in many green renovation projects. Installed in a herringbone pattern, the pipe is placed in the green floor. After centering the pipe in a one-foot excavation, the trench is backfilled with 3/8” pea stone.
Removing all the green mix permits accurate slope survey insuring positive draining. Many modify the green mix during this process.
Slit drains: Some superintendents install slit drains in existing greens. After removing and numbering the sod, 2” single wall perforated pipe with a geofabric envelope is installed in a 12” trench. A small trenched can do the work. Line the trench with plywood to limit green damage. The pipe is backfilled with new green mix blended with a higher percentage of sand.
I’ve seen drastic drainage improvements with this method. Skilled crews reinstall sod making trench lines invisible. Some experience trench line discoloration caused by the use of sandy green mix in the trenches.