Determining urban storm water BMP effectiveness

The goal of this U.S. EPA-funded cooperative research program with the ASCE is to develop a more useful set of data on the effectiveness of storm wate r best management practices (BMPs) used to reduce pollutant discharges from urban development. BMP monitoring data gathered at a particular site shoul d not only be useful for that site, but also need to be useful for comparin g the effectiveness of similar and different types of BMPs at other locatio ns. Most BMP effectiveness studies in the past have provided data that is d ifficult, if not impossible, to use in comparing BMP design effectiveness a nd in the selection among individual BMP types to meet desired goals. This paper describes some of the comparability problems encountered between diff erent BMP effectiveness studies. Also discussed are considerations that aff ect data transferability, such as methods used for determining efficiency a nd statistical significance. It outlines the efforts used to establish and analyze the currently available data and proposes protocols for future anal yses, when more studies that have data are available. Finally, it recommend s that effluent quality appears to be a much more robust measure of BMP eff iciency than the currently used "percent removal" metrics.