Project Backgrounds

The recently constructed Diversion Dam/Intake Structure/Fish Passage is a key element of the City of Albuquerque Drinking Water Project. These Diversion Facilities will divert water from the Rio Grande to a Raw Water Pump Station to be built east of the Riverside Drain and thence to the Water Treatment Plant.

Sediment management has been identified as a major concern of the Diversion Facilities. The Diversion Dam adjustable gates will create a pool of water three feet deep that will reach approximately to the Alameda Bridge. River flow velocities will decrease at the pool and sediments will deposit, filling most of the pool.

Two primary performance goals were identified in the design phase regarding sediment depositions:

· Maintain flow to the Intake Structure and Fish Passageway.

· Allow full bank-to-bank river flow during a major storm event.

The Diversion Dam and Intake Structure configuration was developed in conjunction with the Bureau of Reclamation Water Resources Research Laboratory (WRRL) in Denver. Physical modeling by the WRRL was performed to investigate aspects of sediment management. Hydraulic numerical simulation modeling by URS and the University of New Mexico (UNM) studied hydraulic conditions at the Diversion Dam and in the Rio Grande.

The inherent limitations of physical and numerical models and the unique nature of these Diversion Facilities dictate that all aspects of sediment behavior cannot be fully predicted prior to actual operation of the Facilities. This Draft Sediment Management Plan identifies nine operational strategies to manage sediment. A series of experimental strategies are proposed under various flow conditions. A Trial Operations Program is proposed under which these strategies can be tested with the recognition that actual river flows during the testing period (November 2006 through October 2007) will control some of the test strategies. The strategies for moving sediment past the Diversion Dam will differ depending on the season and the river flow rates at a particular time. Sediment is expected to fill most of the pool during most yearly flow conditions. Larger flows from either storms or spring runoff will allow most or all of the Diversion Dam gates to be lowered and the upstream sediment build-up to be washed downstream.The results of the Trial Operations Program will then be used to develop specific Operations and Maintenance guidance to the City.

Graphical Depiction of Diversion Dam and Adjustable Height Gate