Feasibility of Fish Passage at Alameda Creek Diversion Dam

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Feasibility of Fish Passage at Alameda Creek Diversion Dam4.4.1 SCREEN DESIGN TYPESScreen design at ACDD would include selecting the type of screen for use at ACDD, as well as alayout or configuration of screens suitable for use at ACDD. Screen configuration is addressed inSection 4.4.2. In this section, four types of fish screens are evaluated for their suitability at ACDD,and one screen type (vertical/inclined flat-plate screen) that is potentially most suitable for use atACDD is carried forward for further analysis in subsequent sections.ROTARY DRUM SCREENSRotary drum screens are typically used in open channel flow situations such as irrigation canals. Thistype of screen configuration, using a single or multiple drums, can be used for a fairly large range ofdiversions (up to 2,800 cfs [WDFW, 2000b]). In operation, water passes through a screen meshcovering a rotating cylinder (Figure 4-6). Automatic cleaning is provided by debris being picked upby the rotating screen and deposited downstream. A static brush may be added to the top of thescreen to provide additional cleaning if biological growth is determined to be a potential maintenanceissue. The screen rotation may be driven by electrical motor or mechanical means using apaddlewheel and drive mechanism.Figure 4-6 Rotary Drum Screen (WDFW, 2000c)Rotary drum screens must be continuously submerged by 65 to 85 percent, limiting application inareas with even moderately variable flow regimes. At ACDD, this would require operation of thediversion so that the water surface level behind the dam would vary no more than 2.8 feet for a14-foot-diameter screen. To maintain this narrow range of water surface elevation behind ACDD,ACDD Passage June 2009 Page 4-16
4.0 Design Components and Preliminary Analysisone or both of the gates at the upstream tunnel portals would need to be automatically operated toopen and close, thereby maintaining a near constant water level behind ACDD.An array of rotary drum screens could be incorporated into the existing facility or installed as a newstructure at ACDD. Advantages include the self-cleaning nature of the screen and the ability to operatewithout electricity (using a paddle wheel). Disadvantages include the requirement for relatively stableforebay conditions and the need for multiple structures within the diversion, both of which will limit thediversion capacity of this type of screen system in this application. Therefore, it appears that rotarydrum screens are not suitable for use at ACDD, and they are not studied further in this analysis.VERTICAL TRAVELING SCREENSA schematic of a typical vertical traveling screen is shown on Figure 4-7. Two types of screens arecommonly used: panel and belt. The difference in the two types is in the screening mesh. Panel typescreens have many discrete meshed panels hinged together, while belt types use a continuous beltmesh. Both types of screens can be driven by electric motors (WDFW, 2000b) or mechanically withpaddlewheel and drive mechanisms. Many types of cleaning systems can be used with the verticaltraveling screen, including a static brush mounted on top of the screen and/or water jets mounted onthe back of the screen. The use of water jets would require an electrical power source and jetpressurization equipment. Vertical traveling screens are effective and can be implemented readily aslong as careful consideration of the critical design criteria and specific nuisances are taken intoaccount during the design process.Figure 4-7 Vertical Traveling Screen (WDFW, 2000c)At ACDD, this type of screening system would require a series of screens mounted across the existingdiversion. These screens can be fabricated in a number of height and width configurations to meetthe needs of local site characteristics, submergence requirements, forebay fluctuation, and approachACDD Passage June 2009 Page 4-17
Page 1: T E C H N I C A L M E M O R A N D U
Page 4 and 5: Feasibility of Fish Passage at Alam
Page 11 and 12: 1.0 Introduction1 INTRODUCTION1.1 B
Page 13: 24Alamo680DanvilleAlameda CreekWate
Page 18 and 19: oleyriesSanCalaveras Creekalaveras
Page 20 and 21: (a)(b)Alameda Creek Diversion Dam (
Page 23 and 24: 2.0 Setting2.3.2.1 ALAMEDA CREEK DI
Page 25 and 26: 2.0 Settingalmost never submerged;
Page 27 and 28: 2.0 SettingRainbow trout are the sa
Page 29: 2.0 SettingA number of future proje
Page 42 and 43: (a) A view of the navigation lock a
Page 44 and 45: (a) A pickup truck adapted for haul
Page 57: Approximately 1.8 miles toCalaveras
Page 77 and 78: 6.0 Additional Considerations and A
Page 79: 6.0 Additional Considerations and A
Page 89 and 90: 9.0 Report Preparation9 REPORT PREP
Page 91 and 92: 10.0 References10 REFERENCESAACE (A
Page 93 and 94: 10.0 ReferencesHayes, Darrel, 2001.
Page 95 and 96: 10.0 ReferencesSak, B., San Francis
Page 97: 10.0 ReferencesWDFW (Washington Dep
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Feasibility of Fish Passage at Alameda Creek Diversion Dam

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