Coarse Solids Management 2

This chapter emphasizes the value of considering the particle size distribution of solids and their associated pollutants when designing and analyzing stormwater treatment projects. Studies show particle size affects the type of treatment techniques best suited for removing pollutants and indicates a series of practices may be necessary to meet the more stringent goals required by Total Maximum Daily Loads (TMDL) and the National Pollutant Discharge Elimination System (NPDES) regulations. Also emphasized in this chapter are methods to calculate particle transport, calculations for including gross solids in efficiency calculations, and impact of the size distribution in designing filter systems to remove particles. The problems associated with collecting representative samples that include the variety of stormwater particle sizes, including the largest sizes, in studies conducted using automatic water quality samplers are also discussed. The contribution of gross solids (>100 um) has been overlooked in most stormwater monitoring efforts.