This brings me to the point that good systems long outlast those who designed them. Many of these old systems when investigated are still working. Those old boys knew a thing or two about drainage which many of today s cowboys could emulate with advantage. Another facet which bears mention is that it is generally a mistake to lay a new system over an older one, which may have become blocked. Drainage from the shallower system will often find the old blocked one and then neither works.
Outfalls are the most important part of any drainage.
All too often they are neglected and silting up starts. Too many schemes specify too many outfalls, as for instance where drains are run into an open ditch. Far better to construct a collecting drain across the ends of the field drains in the bank above the ditch, so that there is only one outfall which can be properly maintained. This is in preference to a score of outfalls, which become lost or rendered ineffective if the ditch bank subsides or is cleaned. Good drainage contractors are scarce, they have inherited skills, an unfailing eye for levels and a vast experience to deal with such problems as running sand.