From Model to Bench Test to Construction - Sediment Retention Best Management Practice for the Tijeras Arroyo Watershed
Storm events are not just a “wet season” phenomenon that generate runoff. In the southwestern United States, monsoon season starts in early July, bringing strong winds and driving rain that can generate flash floods and significant erosion. The Middle Rio Grande Valley, which includes Albuquerque, New Mexico, is regulated under an EPA Watershed Based MS4 permit issued in December of 2014. This permit has specific provisions requiring development and implementation of sediment management programs associated with a Total Maximum Daily Load restriction due to a Biological Opinion concerning the Rio Grande Silvery Minnow, an endangered species. The Tijeras Arroyo, located in the Middle Rio Grande Valley along the southern border of the City of Albuquerque, New Mexico, flows westward from the Sandia Mountains and discharges into the Rio Grande. Encompassing over 100 square miles of semi-developed watershed, this arroyo generates large quantities of sediment due to its sparse vegetative cover, particularly from within the confines of Kirtland Air Force Base and the Sandia National Laboratory complex, a Department of Energy managed facility. The Albuquerque Metropolitan Arroyo Flood Control Authority (AMAFCA) manages, develops and constructs flood control and storm water quality structures throughout the City and is working to address new sediment management requirements of the 2014 Watershed-based MS4 permit. A large scale sediment retention structure was designed to capture up to 50,000 cubic yards of material each year. The design was developed using a computer based digital model. The digital model findings were verified using a 1:60 scale physical model constructed at the University of New Mexico Hydraulics Laboratory. The physical model results clearly demonstrate the system efficiency and hydraulic behavior of this multiple basin system capable of handling the 100-year design storm and the Standard Project Flood required for U.S. Army Corps of Engineers certification. This presentation will report the results of the digital modeling produced in Flo2D® and the physical model operation at various flow rates in order to demonstrate how use of a physical model can help verify design basis l assumptions. Video of actual flows through the physical model will be shown. Phase 1 of the project has been constructed and aerial imagery collected by drone will be presented in order to give the audience a birds-eye-view of the project. The project is now operating to address runoff events for the 2017 summer monsoon season and available preliminary performance data from 2017 will also be discussed.
Brad Sumrall, PE is Weston Solutions' Director of Water Resources for the Western United States. He is a professional civil engineer in the State of New Mexico and has a background in Water Resource Engineering and Watershed Resource Management. As a trained engineer and natural resource scientist, he is passionate about water quality improvement, sustainable engineering design, and leaving a lighter footprint as a species.