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-25- <br />• filled with the debris from the cut face. Over a long period <br />of time, proper functioning of the drainage ditch would be <br />prevented. <br />There are several ways to eliminate this problem. It is <br />possible to maintain the space below the cut and to clean it <br />periodically. If this maintenance is not desirable, another <br />concept of the protection could be accepted. In such case, <br />a catching toe bench is constructed immediately below the cut. <br />This catching toe bench is added to the design width of the <br />road; it serves as a catching space for the debris sloughed <br />from the cut face only. The maintenance of the catching bench <br />is required only when the bench becomes totally filled with <br />• the sloughed material. <br />The concept of the catching toe bench was developed in <br />highway engineering as a means of protecting the highways <br />against rockfall. It has been shown that a single catching <br />toe bench is frequently more efficient than several catching <br />benches located at intermediate intervals of the cut slope. <br />The concept of one single toe bench is frequently applied in <br />geological conditions similar to those of the Munger Canyon <br />area where rocks are weathered and a bench located within these <br />weathered rocks would be subject to erosion and seepage of the <br />surface water. A bench in such geological conditions would <br />probably fail during the lifetime of the cut. <br />• <br />