Validation of a Low Cost Flow Measurement System for Monitoring Vegetative Treatment System Performance
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In 2006, the Iowa Department of Natural Resources issued National Pollution Discharge Elimination System (NPDES) permits to six feedlots participating in research on the use of vegetative treatment systems (VTSs) to control beef feedlot runoff. While Iowa State University monitors releases from the research portion of these sites, the producers are required to monitor releases from the non-research portions. Additionally, non-research site producers with VTSs and NPDES permits are required to monitor system releases. They are required to measure release volume and collect a sample for analysis. Automated, research oriented open channel flow measurement systems typically cost $7,500 to employ. Muhlbauer et. al (2007) developed a low cost monitoring system (LMS) designed to measure open channel flow from a VTS with a total cost of $1,600. Testing of the LMS by Muhlbauer et. al. (2007) across flow events ranging from one to six hours indicated a mean accuracy of 90.6% in comparison to a flow meter equipped ISCO 6712 portable sampler using a .46m (18”) fiberglass H-flume. Further cost reduction options for a producer include fabrication of a metal H-flume, reducing total system cost to $850. This paper compares the performance of the LMS for estimating both short and longer duration flow events and performance of the fabricated metal flume. The LMS flow measurements were compared to an ISCO 6712 portable sampler and a Krohne Optiflux 4000 flow meter in twelve field tests lasting one and six hours with an accuracy of 88.5% in comparison to the Krohne. Relative to a commercial fiberglass flume, the three fabricated flumes had a mean percent accuracy of 98%.
This is an ASABE Meeting Presentation, Paper No. 084048.