Improving Upon Decades of Poor-Quality Solids Data in Urban Stormwater through use of an Automated Depth-integration Sample Collection System

A new stormwater sample collection device was developed to improve representation of sediment and sediment-associated contaminants entrained in urban stormwater by integrating samples spaced vertically throughout the entire water column. Compared to traditional fixed-point sample collection methods, the depth-integrated sample arm (DISA) was better able to characterize suspended-sediment concentration and particle size distribution in a flowing water column. Use of the DISA resulted in generally lower suspended-sediment concentrations and finer particle size distributions with lower variance when tested in a controlled laboratory environment. This was duplicated in field tests at three independent study locations. Decreasing variability by use of the DISA helped improve statistical regression of particle size distribution to environmental parameters, such as precipitation depth and intensity, something that was unlikely using fixed-point sampling methods.