E 682 Benches and Terraces

Revised on 10-14-2024

The main function of benches and terraces is to intercept water flowing down the side slopes and divert it by means of a drainage disposal system. This considerably reduces the volume and velocity of the water hitting the lowest level or bottom of the slope as well as the scouring and erosion of the side slopes. Benches and terraces are also used on side slopes to break up the high cuts and fills into smaller sections. If a section of the side slope starts sliding, it may terminate at the next bench or terrace immediately below, rather than continuing down to the bottom and possibly creating an avalanche and a collapse of the entire cut or fill section.

The need for benches and the design of their widths and vertical spacing should be determined only after an adequate soil investigation. In general, horizontal benches 10 feet in width should be constructed on cut and fill slopes at vertical intervals of not more than 25 feet.