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The following provides several recommended options for controlling and measuring the <br /> inflow to recharge ponds: <br /> 1. One option is to adopt a flow measurement approach that has become the <br /> standard over the last decade with many canal companies, irrigation districts, <br /> and the U.S. Bureau of Reclamation. This structure is called the long-throated <br /> flume and is shown in Figure 5. This flow measurement structure is also called a <br /> "broad crested weir", a "ramp flume", or a "Replogle flume". The latter term has <br /> been used because much of the development work and current design standards <br /> were done at the Agricultural Research Service's Water Conservation Lab in <br /> Arizona under the direction of John Replogle. Further reference to this flume will <br /> be as the long-throated flume. <br /> The primary advantages of the long-throated flume for this circumstance are: <br /> • Lower cost than other flumes or weirs. <br /> • Greater accuracy at +/- 2%. <br /> • Very low head loss across the structure. <br /> • May be constructed in-situ within the canal. <br /> • Adaptable to a wide range of flows and canal conditions. <br /> Built flumes of this type are found in several locations near Greeley. Figure 5 also <br /> shows a flume installed with low-cost monitoring and control technology known <br /> as SCADA (Supervisory Control and Data Acquisition). SCADA is used to more <br /> efficiently monitor and control irrigation operations from a centralized location, <br /> which eliminates the need to collect and make adjustments in the field. This <br /> technology has become more affordable in recent years and would likely be <br /> useful in a recharge project. <br /> 2. Additional options include headgates that can also be used simultaneously as <br /> measurement structures. Unlike measurement flumes and weirs, such as the <br /> long-throated flume, these structures are primarily headgate structures than can <br /> also be used to measure flow. <br /> The Langemann gate is manufactured by Aqua Systems 2000, Inc. The design <br /> includes low power requirements (battery or solar panel power), various control <br /> capabilities, and overshot technology. The gate functions as a vertically <br /> adjustable weir with water level sensing and control system that can be operated <br /> manually or automatically. The gate includes a stilling well for flow measurement <br /> so no additional devices would be required. It can be installed in the existing <br /> concrete headwall with some minor modifications. Rubicon headgates can also <br /> be used to simultaneously control and measure water through the headgate <br /> structure. Both gate types can also be used with SCADA systems. <br /> 3. If it is determined that water needs to be pumped directly from the Union Ditch to <br /> the recharge pond, it will be necessary to install a flow meter on the pump to <br /> accurately measure the amount of inflow to the pond. An in-line totalizing flow <br /> meter or similar meter can be used for these purposes. <br /> It is recommended that the recharge project develop long-throated flumes to most <br /> accurately measure inflow to recharge ponds. While combination gate and measurement <br /> Aqua Engineering, Inc. Recharge Project Potential <br /> February 17, 2004 - 11 - <br />