Associations between stormwater retention pond parameters and pollutant (suspended solids and metals) removal efficiencies

Presented in this paper are the results of correlational analyses and logistic regression between metal substances (Cd, Cu, Pb, Zn), as well as suspended solids removal, and physical pond parameters of 19 stormwater retention pond case studies obtained from the International Stormwater BMP database. Included are cross-correlations between metals and solids in pond influent, effluent and removals. The findings provide insights fundamental to further development of improved models and design guidelines for stormwater ponds. Indications were that (i) pond efficiencies differed between high and low influent concentrations and masses, (ii) concentration was an invalid indicator of correlations between substances in pond influent and effluent as well as the fractions of substances removed within ponds, (iii) total cadmium, copper, lead, zinc and total suspended solids (TSS) were associated in surface runoff and similarly removed within ponds, (iv) statistically significant correlations were often only found in data groups either above or below a specific statistic (quartile value, median) for specific pond parameters, indicating that removals may have been differently influenced by pond parameters over different data ranges, and (v) the volume within the permanent pool was of greater importance to pond efficiencies than the volume captured during storm events.