Assessment of pollutant removal

A.J. Erickson, P.T. Weiss, J.S. Gulliver, R.M. Hozalski

Most stormwater monitoring programs are implemented with the goal of assessing pollutants retained by the stormwater treatment practice. In addition to measuring discharge, assessing the capture of pollutants also requires sampling stormwater treatment practice influent and effluent. Data for several storms, often for two or more rainy seasons, are typically required to accurately assess pollutant removal performance with an acceptable range of uncertainty (see Sampling Methods).

The process for analyzing monitoring data starts with a single storm event. The pollutant concentrations from the samples collected during the storm event are used in conjunction with influent and effluent runoff volumes to determine the pollutant removal efficiency for that storm event. It cannot, however, be assumed that the calculated efficiency from a single storm event is applicable to all storm events. Therefore several storm events representing a range of conditions (e.g., discharge and pollutant concentration) must be monitored to accurately assess the long-term performance of stormwater treatment practices.

Continue to Analysis of individual storm events.