Figure 12.13 Riprap Lined Drop Structures (adapted from Tate, 1991)
an effective alternative to the standard riprap or concrete structures (Hanson et al., 1986).
Agostini et al. (1988) provides design criteria for vertical, stepped, and sloped type gabion
grade control structures, as well as examples of completed works. Guidance for the
construction of gabion weirs is also provided by the Corps of Engineers' ETL 1110-2-194.
Another alternative to the conventional riprap or concrete structure which has gained
popularity in the southwestern U.S. is the use of soil cement grade control structures. These
structures are constructed of on site soil-sand in a mix with Portland Cement to form a high
quality, erosion resistant mixture. Soil cement grade control structures are most applicable
when used as a series of small drops in lieu of a single large-drop structure. Experience has
indicated that a limiting drop height for these structures is on the order of three feet. Design
criteria for these structures is presented by Simons, Li, & Associates, Inc. (1982).