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PROJECT STARTUP <br />During the spring of 2005 a SPDC board member contacted an engineer at Reclamation's <br />Hydraulics Investigations and Laboratory Services Group (HILS) in Denver seeking <br />information on electronic flow measurement data collection equipment. As a <br />demonstration project, HILS agreed to install a low cost system that had been developed <br />in -house for an application at the East Bench Irrigation District in Montana. The device <br />which HILS staff called the Continuous Flow Meter (CFM) was assembled using a <br />programmable logic controller with integral display module that was marketed as a hobby <br />robot controller. <br />An analog signal from any of a range of readily available electronic level sensors could <br />be linked to the controller and calibrated to measure water level. A simple program <br />written in a BASIC programming language would first apply calibrated slope and offset <br />constants to an equation to calculate water level. This level value was then input into a <br />power equation with calibration constants appropriate for the flow measurement structure <br />at which the unit was installed. A desired measurement time interval; (i.e. 15 minutes), <br />input into the CFM program would trigger a measurement cycle. Once a flow rate had <br />been calculated, a volume increment was determined based on the measured flow and the <br />elapsed time from the previous reading. This volume increment would be added to a <br />previous running total value. With each reading cycle, the most recently measured flow <br />depth, flow rate, and total volume would be displayed on the CFM. <br />CFM units were installed at two locations on the SPDC recharge system to operate in <br />parallel with existing Stevens Type F paper chart recorders. A key shortcoming of the <br />CFM for this application was the limited on -board memory which was insufficient for <br />storing data logged values. The State Engineer's requirement of logging flow values at <br />15 minute intervals could not be met with this equipment. Approximately a month after <br />installation, both CFM units were removed. <br />DATA LOGGING AND TELEMETRY <br />During the same time frame the SPDC demonstration project was being initiated, HILS <br />engineers came in contact with Control Design Inc. (CDI) of Placitas NM. CDI produces <br />units that consist of a programmable logic controller coupled with a proprietary <br />communications modem plus a communications radio operating on UHF frequency. <br />Upon learning of the SPDC demonstration project, CDI offered use of equipment for two <br />field sites plus two office base units for the 2005 season. <br />The CDI programmable controllers are designed around radio communications operation. <br />All available on -board memory, including memory available for data logged values, is <br />configured as Modbus registers. CDI worked with HILS engineers to develop a flow <br />monitoring program for the demonstration project. A software program provided by CDI <br />named Project 3 was installed on a Windows -based computer at a SPDC office site as <br />well as at the Lower South Platte Water Conservancy District (LSPWCD) in Sterling CO. <br />Project 3 can be configured to direct CDI base units to periodically poll field sites and <br />2 <br />