Field evaluation of an innovative stormwater treatment device—the StormvaultTM system

StormvaultTM is a new volume-control-based underground stormwater treatment system, which is well suited for implementation in urban areas. In order to evaluate the hydrologic and hydraulic function of the system and assess the pollutant removal capacity of the system, a field monitoring program was implemented during both wet and dry weather conditions for 2 years. The pollutants of interest were total suspended solids (TSS), chemical oxygen demand (COD), total phosphorus (TP), and orthophosphate (OP). Data of 35 storms obtained were then analyzed by using several methods, such as the efficiency ratios, the summation of loads, and the relative achievable efficiency (RAE) methods to obtain estimates for the pollutant removal efficiencies of the StormvaultTM unit. Results show the following average efficiencies: TSS 82.46%, COD 73.10%, TP 47.37%, and OP 52.54%. Statistical significance and variation of removal efficiency with inlet concentration were also examined.