Development of a depth-integrated sample arm (DISA) to reduce solids stratification bias in stormwater sampling

Water Environment Research
Wisconsin DNR
By: , and 

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Abstract

A new depth-integrated sample arm (DISA) was developed to improve the representation of solids in stormwater, both organic and inorganic, by collecting a water quality sample from multiple points in the water column. Data from this study demonstrate the idea of vertical stratification of solids in storm sewer runoff. Concentrations of suspended sediment in runoff were statistically greater using a fixed rather than multipoint collection system. Median suspended sediment concentrations measured at the fixed location (near the pipe invert) were approximately double those collected using the DISA. In general, concentrations and size distributions of suspended sediment decreased with increasing vertical distance from the storm sewer invert. Coarser particles tended to dominate the distribution of solids near the storm sewer invert as discharge increased. In contrast to concentration and particle size, organic material, to some extent, was distributed homogenously throughout the water column, likely the result of its low specific density, which allows for thorough mixing in less turbulent water.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Development of a depth-integrated sample arm (DISA) to reduce solids stratification bias in stormwater sampling
Series title Water Environment Research
Volume 83
Issue 4
Year Published 2011
Language English
Publisher Water Environment Federation
Publisher location Alexandria, VA
Contributing office(s) Wisconsin Water Science Center
Description 11 p.
First page 347
Last page 357
Online Only (Y/N) N
Additional Online Files (Y/N) N