State Water Resources Research Institute Program

Project ID: 2008UT105B
Title: Low-Level Outlet Works Air Vent Sizing Requirements for Small to Medium Size Dams
Project Type: Research
Start Date: 3/01/2008
End Date: 2/28/2009
Congressional District: UT 1
Focus Categories: Models, Water Quantity, Management and Planning
Keywords: Air Venting, Low-Level Oulet Works, Cavitation, Dam Safety
Principal Investigators: Tullis, Blake P.; Barfuss, Steven L.
Federal Funds: $ 12,604
Non-Federal Matching Funds: $ 32,603
Abstract: State regulators who approve dam designs, report having little or no information regarding requirements for sizing air vents for low-level outlet works. Some work has been done by the US Army Corps of Engineers (USACE) in conjunction with air vent sizing for vertical slide gates in outlet tunnels. Limited amounts of field data were used to validate the model. The gate/intake geometries for small to medium sized dam low-level outlet works typically do not feature a vertical slide gate but rather have slide gates mounted on the sloping upstream face of an earth fill dam, followed by a mitered elbow transition.

The USACE method uses water flow rate through the gate as an independent variable. No information, such as discharge coefficient data (with or without air venting), has been found related to inclined slide gates. Consequently, determining water flow rates through such control structures cannot be conveniently done. In an effort to develop a better understanding of air demand in low-level outlet works and verify the accuracy of the USACE and provide improvements where possible, this study will include a laboratory testing, a CDF modeling, and a field data collection effort. The results of this study should be beneficial to all parties involved in dam safety (designers, regulators, and owners).

Progress/Completion Report, PDF

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