© Copyright 2008 Tesco Controls, Inc..
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Woodbridge, California sits on the Mokelumne River, in the verdant Lodi wine appellation. Surrounded by leafy green vineyards and historic family wineries, the area's thirst for irrigation water is considerable. This thirst is slaked by the Woodbridge Irrigation District, who provides water from the river to farms and wineries throughout the area. However, agricultural needs must be balanced with ecological needs, specifically the needs of the spawning Chinook salmon and Steelhead trout of the Mokelumne.
Historically, downstream passage of young salmon and steelhead in the Mokelumne River has been affected by the Woodbridge Irrigation District (WID) diversion canal. The diversion canal was screened with an older-style drum screen, which was much less efficient than screen technologies which are currently available. This, along with other factors, resulted in salmon depletion in the Mokelumne.
The Woodbridge Irrigation District developed the Lower Mokelumne River Restoration Project to address this issue and restore the ecosystem of the Lower Mokelumne River. A major part of the project was to improve the fish passage at Woodbridge dam, to replace the fish screen at the diversion canal, and restore the ecosystem along the river's edge. The dam project was completed in 2006 and the fish screen project was completed in 2008.
Woodbridge Irrigation District had needs of their own, such as maintaining the proper levels for water delivery below the dam and in the diversion canal, while keeping operating costs minimal and maintaining or even reducing man-hours needed to operate the system. To meet these needs and tie the entire project together, WID chose Tesco Controls to integrate existing systems with added control automation and a SCADA system.
The Tesco Controls SCADA control system constantly monitors level and flow on the river and canal, and alleviates the need for WID employees to spend man-hours adjusting gates and valves which had become tedious, expensive and sometimes dangerous tasks.
The monitoring system consists of four Remote Telemetry Units (RTUs) with Tesco Controls L2000 PLCS. These units are installed at locations both above and below the dam in order to get a complete picture of the river's flow at the different control points along the river's path. They communicate with the WID office via secure wireless Ethernet.
The first of the RTUs on the system is located at the East Bay Municipal Utilities District's monitoring station below the dam at the Woodbridge Country Club. If the level on the Mokelumne is outside the set point in the SCADA system, an automated correction ismade on the 60 foot gate at Woodbridge Dam to regulate the flow of the river. Each adjustment is very small- just 4 CFS.
Another RTU is located upstream of the dam at the mouth of the diversion canal. This measures the flow through the fish screen and into the canal. The fish screen itself is "V"-shaped, with the bypass tunnel entrance at the base of the "V". The screen's two 10 foot tall, 100 foot long panels have 1.75mm gaps which allow water to pass, but funnels fish and fry within the screen area toward the bypass pipeline.
The bypass pipeline is a 30-inch diameter concrete tunnel that is buried along the left bank of the Mokelumne. Water flows from the diversion canal through the pipeline transporting fish over 1800 feet and depositing them safely just past the dam's spillway.
The L2000 PLC here has also been leveraged to automate the screen cleaning process. Once every 2 hours, or on demand via SCADA, a cycle begins that uses two vertically mounted travelling brushes to sweep debris away from the tiny openings in the screen.
A third RTU is located on the diversion canal 1.7 miles downstream from the fish screen. It is powered completely by solar energy. This site also has a level indicator that reports to the PLC every 3 seconds. If the level is outside the set point by more than 3/100 of a foot, the SCADA system adjusts the flow by moving the fish screen headgates about 1/8 of an inch.
All of these RTUs send telemetry back to the Woodbridge Dam site. At the dam, another Tesco L2000 PLC is leveraged to perform two functions; Front-End Processor for the wireless SCADA telemetry system, and daily operation of the dam's primary spillway gate.
During the planning for the wireless communications system, it was discovered that signals from some of the RTUs did not have a clear line of sight and could not reach the WID office, but the dam site had a clear path to all RTUs. To compensate for this problem, Tesco communication engineers changed their approach. Now the PLC at the dam also acts as a front-end processor, collecting information from all other PLCs. It then forwards that data just across the river to the Wonderware SCADA application server in the WID office.
The SCADA server allows WID operators to visualize levels and flow rates at the dam, the fish screen, the diversion canal and the downstream EBMUD monitoring point. Adjustments can be made (automatically or manually) at the server, rather than sending someone to the dam or diversion canal to operate the gates by hand.
After operating the dam for two years, WID envisioned a more efficient method for operating the dam's two gates.
Tesco redesigned the gate operating scheme, providing more precise adjustments by isolating the 60 foot floodgate in the center of the dam.
Previously the dam's operating scheme was to make the lake level the priority. The new operating scheme makes the downstream flow the priority measurement. The L2000 PLC tracks the downstream river level at the Woodbridge Country Club RTU and controls air compressors which inflate and deflate bladders, raising and lowering the gate.
This system co-operates with the original floodgate controls allowing for larger adjustments on both gates during times of high flow on the river.
Over the last few years California has suffered through a period of drought. The drought condition along with many other variables cause salmon and steelhead counts to continue to trend downward. It's the hope that the very wet winter of 2009-2010, along with ecologically conscious and environmentally sensitive projects such as this, will allow the salmon and steelhead population in California to flourish once again.
Established 1972 in Sacramento, Tesco Controls Inc. is a CSIA Certified advanced control systems integrator specializing in the water and wastewater industries. For over 30 years our business has been designing, manufacturing and integrating electrical and electronic systems for the control of water distribution and wastewater collection for utilities, industry and agriculture. In addition, our traffic division develops service pedestals and traffic signal battery backup systems for the electrical utility and traffic control industries.
Tesco Controls furnishes a competitive bid for integration services on every water/wastewater construction project, public or private, in all of California and many other states. We have become expert in many different engineering disciplines, such as:
Our staff of over 200 employee-owners is highly experienced, knowledgeable, and fully capable of designing and overseeing the implementation and integration of your control system.
Tesco Controls employs an open systems design approach for PLCs, RTUs, communications, programming and SCADA systems. Doing so allows us to take advantage of available technology and proven methods for software, communications and hardware integration.
Tesco Controls, Inc. has an extensive support program to provide resources, extended system coverage, maintenance services, telephonic support, technical expertise and 24-hour emergency services.
Tesco Controls became an Employee-Owned company in 2004, making every employee an owner and giving them a real financial stake in the company's performance, and the quality of our products & services. This has resulted in a team-oriented culture of ownership, and has allowed us to exceed over $40 million in sales last year.
In 2010, Tesco Controls moved into our new sales and manufacturing headquarters with 125,000 square feet of professionally planned manufacturing space. This will allow us to streamline operations by bringing all of our manufacturing and engineering assets under the same roof for the first time in nearly 20 years. This will enable us to meet the future needs of our customers, and help us maintain our standard of excellence in controls and systems integration.
For more information about industrial automation solutions from Tesco Controls, please visit our website at www.TescoControls.com or call us at 916.395.8800.
