Development of Adjustment and Scaling Factors for Measured Suspended Solids Removal Performance of Stormwater Hydrodynamic Treatment Devices

Suspended solids removal performance of a manufactured stormwater treatment device varies greatly with operating conditions and laboratory or field evaluation techniques. Laboratory testing and field monitoring protocols have been established to evaluate the performance (removal efficiency or effluent concentration) of manufactured stormwater treatment devices and other structural BMPs. However, deviations from the recommended evaluation conditions and techniques are expected and may lead to a significant difference in the measured performances. Range of the parameters/variables specified within the protocol itself may also have a significant effect on the measured performances. Potential effects of six variables are discussed in this paper: TSS vs. SSC methods, operating flow rate, size of the treatment unit, size and density of solid particles in the influent, solids concentration/loading in the influent, and initial volume of solids at bottom of the treatment unit. It is recommended that appropriate adjustment and scaling factors be developed to support certification of performance claims and to appropriately design the stormwater treatment system.