Appropriate Methods in Determining the Event Mean Concentration and Pollutant Removal Efficiency of a Best Management Practice

Abstract

This study attempted to develop and suggest a more appropriate method for the determination of event mean concentration (EMC) and pollutant removal efficiency of a stormwater best management practice (BMP) considering rainfall.The stormwater runoff and hydrologic data gathered from 22 storm events during a 28-month monitoring period on a swirl and filtration type of BMP were used to evaluate the developed methods.Based on the findings, the modified EMC method resulted in lower (average) values than the overall EMC, although the differences were not significant (P>0.05).By comparison, the developed 'Rainfall Occurrence Ratio' (ROR) method was most significantly correlated (r=0.967 to 988, P<0.009) with the other existing removal efficiency determination methods such as the 'Efficiency Ratio' (ER), 'Summation of Loads' (SOL) and 'Regression of Loads' (ROL) methods.In addition, the ROR method gave the highest efficiency values, with no significant differences with any of the pollutant parameters, unlike the other three methods.These results were obtained because the ROR method integrated both pollutant loading and rainfall, which are not considered by the other three methods.Therefore, this study proved the suitability of the modified EMC and ROR methods for application in other BMP monitoring studies.