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Design and Testing of a Device To Introduce a Lag-time Treatment Between the Inflow and Outflow Hydrographs of a Sedimentation Basin

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  Paper number  022232,  2002 ASAE Annual Meeting . (doi: 10.13031/2013.10463) @2002
Authors:   David A. Bidelspach, Albert R. Jarrett
Keywords:   Sedimentation basin, Lag-time, Sediment, Erosion, Skimmer, Electronic controls

Research has demonstrated that sediment basins retain more sediment when their dewatering was delayed from 2 to 172 hrs. Thus a practical, low-cost, solar-powered device was designed and tested that would switch the outflow water on and off, at operator pre-set intervals, to control the delay between an inflow runoff event and the start of dewatering. This device was designed and built to continuously sense the depth of water, to logically receive and send electronic signals, and to open a valve on the sediment basins outlet. The device was built as one self-dependent unit to minimize the amount of human interaction needed to produce a desired lag-time response.

The device was mounted on a skimmer, and solar powered with the components of a 12-volt livestock fencer. A valve in the basin outlet controlled the effluent flow and was controlled by a 12-volt windshield wiper gear motor. The gear motor was controlled by a combination of four 40-amp normally closed solid-state relays. The relays were opened by a signal from a programmed electronic logic Basic-X chip that was powered by the components from the fencer, and received a continuous input voltage drop from an ultrasonic sensor. The ultrasonic sensor was mounted in and calibrated to a marked standpipe to record the depth of water within the basin.

Testing of the solar powered electronic logic arm valve occurred by connecting the basic X chip to a laptop computer and recording the depth of water, change in depth of water with time, and opening and closing of the valve. The device was tested and confirmed to complete five functions; a sediment storage and reset function, a high flow-rate function, a low flow-rate practical zero flow function, a timer valve function, and a percent default open function.

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