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inside: PARTICLE SIZE AND SETTLING <br />VELOCITY DISTRIBUTIONS IN <br />SPOTLIGHT , URBAN STORMWATER RUNOFF <br />Particle Size and Velocity Distributions Contributed by Eric Hettler <br />(Contact: John Gulliver at gu11i003@umn.edu} <br />Stormwater Impacts on Groundwater Funded by: Minnesota Pollution Control Agency, Local Road Re- <br />PA{-Is in Wet Pond Sediments search Board, Mississippi Watershed Management Organization, <br />and Minnehaha Creek Watershed District <br />EVENTS 3 The research team is currently working to apply simple, effective meth- <br />Stormwater education programs ods to characterize the particle size distribution and settling velocity <br />distribution in urban stormwater runoff. Since many best manage- <br />Presentations ment practices depend on settling velocity, a better understanding of <br />the settling velocity distribution can lead to more efficient and more <br />site-specific designs. An elutriation device developed by Walling and <br />PUBLICATIONS 4 Woodward (1993) and Krishnappan and Marselek (2004) is being mod- <br />ified and tested to determine its effectiveness in measuring the settling <br />Maintenance of Stormwater BMPs velocity distribution of solids in stormwater. In the elutriation device, <br />stormwater is pumped vertically through a column of a known diam- <br />Road Salt Usage in Twin Cities Metro eter, and the upward velocity can be calculated for a given flaw rate. <br />EfFects of Road Salt on Water Quality Solids with a settling velocity greater than the upward velocity settle <br />in the column while solids with a smaller settling velocity are flushed <br />to Lakes through the column. Initial experiments show the elutriation device can <br />be effective in separating solids based on settling velocities. Work on <br />the elutriation device and other po- <br />tential solutions is ongoing. <br />*Desrgn adapted from <br />Waf(rng and <br />Collected Woodward {9993) and Once a cheap, simple, and effective <br />Stormwater ~~ Ktrshnappan and method to characterize settling ve- <br />Marsalek (21706) locity distribution is developed, the <br />I; research team hopes to work with <br />a <br />~ ~ ~,, consultants and watershed districts <br />-~ •--i '~'': to apply the methods in the field. <br />(~ Peristaltic <br />Effluent <br />,,ff ~ * DZ Pump Collection <br />`YCnJumn 4 <br />~coGrnm - <br />`4enlmm~ <br />Set#ling Columns <br />Increasing D <br />~ ~~,~./v,~ic.un-inr.r~u!r,~~tlc~~.c-~~~ic•In~~ti~~-.iFi ~rr~p~~~e«~ncl~i <br />Stormwater Management Praetice Assessment Project <br />