The Tijeras Arroyo is located at the transition from an earthen channel to concrete conveyance draining runoff from over 100 square miles of watershed that the arroyo collects and conveys across a rural and urbanized area. The sediment retention project serves as the last line of defense in Albuquerque’s lower valley. The solution provides protection from extreme flood events while also addressing the Middle Rio Grande Watershed Based Municipal Separate Storm Sewer System (MS4) permit total maximum daily load for sediment. Weston’s design is based on a computational model (FLO-2D) and a physical model constructed in the University of New Mexico Hydraulics Laboratory. Directly downstream of the project area, the Tijeras Arroyo transitions from natural channel to a concrete-lined channel through two training dikes.
The design provides the necessary hydraulics and storage to facilitate sediment deposition of various flow rates prior to entering the concrete-lined section of the channel with the objective of capturing 50,000 cy of sediment. The digital and physical modeling efforts specifically identified the need for slope and bank protection of the surrounding area and the riprap-armored training dikes that transition from the sediment ponds into the concrete channel. The modeling efforts produced a design that maximized sediment retention without impacting a USACE- constructed levee system. Allowable freeboard for the Standard Project Flood storm was maintained, and construction was completed.