In soils of low structural stability, transport by water of soil particles into drainage tube can contribute to collapse of drainage systems, which must be avoided with the adequate use of envelope, considering the drainage importance for a sustainable agricultural production. Thus, this research was accomplished with the purpose of studying the behavior of three envelope materials, being two of them widely used, the bidim OP-20 and the zero crush, and other composed of foam with 5.0 mm of thickness, which is a non-conventional material. The drainage tubes used were the Drenoflex and the Kananet, with nominal diameter of 65 and 75 mm, respectively. The envelopes performance was evaluated by the entrance resistance and discharge, parameters traditionally recommended for this kind of analysis. It was verified that evaluated envelopes presented satisfactory hydraulic performance, being the zero crush superior envelope, followed by the foam material. Then, it is concluded that the foam can be used as an alternative envelope material in drainage, presenting inclusively, a superior hydraulic performance to bidim OP-20 envelope.
drainage systems; non-conventional materials; entrance resistance
