The effect of particle size distribution on the design of urban stormwater control measures

Wisconsin Department of Natural Resources
By: , and 



An urban pollutant loading model was used to demonstrate how incorrect assumptions on the particle size distribution (PSD) in urban runoff can alter the design characteristics of stormwater control measures (SCMs) used to remove solids in stormwater. Field-measured PSD, although highly variable, is generally coarser than the widely-accepted PSD characterized by the Nationwide Urban Runoff Program (NURP). PSDs can be predicted based on environmental surrogate data. There were no appreciable differences in predicted PSD when grouped by season. Model simulations of a wet detention pond and catch basin showed a much smaller surface area is needed to achieve the same level of solids removal using the median value of field-measured PSD as compared to NURP PSD. Therefore, SCMs that used the NURP PSD in the design process could be unnecessarily oversized. The median of measured PSDs, although more site-specific than NURP PSDs, could still misrepresent the efficiency of an SCM because it may not adequately capture the variability of individual runoff events. Future pollutant loading models may account for this variability through regression with environmental surrogates, but until then, without proper site characterization, the adoption of a single PSD to represent all runoff conditions may result in SCMs that are under- or over-sized, rendering them ineffective or unnecessarily costly.

Publication type Article
Publication Subtype Journal Article
Title The effect of particle size distribution on the design of urban stormwater control measures
Series title Water
DOI 10.3390/w8010017
Volume 8
Issue 1
Year Published 2016
Language English
Publisher MDPI
Contributing office(s) Wisconsin Water Science Center
Description w8010017: 17 p.
Online Only (Y/N) N
Additional Online Files (Y/N) N
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