Question:Of course, the flow numbers given in your article (“Depth Charge,’’ October 2007) are for trenches ... reflecting a common attitude (bias) found in many areas that all normal systems are trenches. A drainfield is, in this view, a network of trenches. But, in New Hampshire and Maine, with thin, rocky soils often with shallow water tables, trench systems are rare. Many contractors have never installed one. We have installed leach beds as a mainstay system since the beginning of design rule, with other types as a less common alternative, until the advent of the fabric-based systems in the ’90s.
