Q: I need to replace the leaching bed for a septic system, but the only available spot is about 20 feet from a stand of bamboo. Will this be a problem?
A: Bruce Zaretsky, owner of Zaretsky and Associates, a full-service landscaping design/build firm in Macedon, N.Y., responds: In my area, the health-department engineers do not like us to plant anything with an extensive root system, including trees and large shrubs, on or near a septic field. We typically treat the ground above a septic field as a meadow, with plantings limited to perennials and grasses, or as a simple lawn.
Because septic leach fields are usually pretty shallow, almost any tree or bush can cause problems. I would avoid plants such as raspberries or honeysuckle, and other plants that tend to spread. Instead, limit plantings on or near the leaching field to perennials with a clumping growth pattern and grasses. These plants don’t pose any risks to the pipes or the leaching bed itself.
Although technically a grass, bamboo is a tenacious, aggressive plant that is difficult to control. It can be contained somewhat with a root barrier, which is a sheet of mylar that comes in 50- or 100-foot rolls and is available at agricultural supply houses or big-box stores. The barrier should extend a minimum of 30 inches into the ground and about 2 inches above the ground. But beware: Putting down root barrier is not a sure thing—especially with bamboo. If bamboo gets past the barrier unchecked, kiss the leach field goodbye.
In this particular case, it doesn’t seem like there is much of a choice where the leaching bed can be located. When the excavator digs out for the new leaching field, I would install the root barrier, letting it extend at least 3 feet down. Then if any bamboo escapes over time, keep it mowed down. Mowing won’t eliminate the bamboo, but it will help to keep it in check.