Removal of pollutants from simulated highway runoff using a laboratory model of an exfiltration trench

摘要

This paper documents a laboratory study on the efficacy of the components of an exfiltrationtrench, a Best Management Practice (BMP) utilized by the Ohio Department of Transportation(ODOT), to reduce pollutants in post construction stormwater runoff. Runoff flows throughmedia layers of the trench, consisting of pervious concrete, aggregate and sand filter media. Alaboratory scale model consisting of a specimen of one of two mixes of pervious concrete wasused in a falling-head permeameter with the effluent subsequently filtered through a specimen ofsand or manganese greensand filter media in a constant-head permeameter.The ODOT specified media were first characterized and then pollutant removal tests wereconducted. Also, an alternative pervious concrete mix (recommended by the Ohio ReadyMixConcrete Association (ORMCA)) and filter media (green sand) were investigated.The ODOT pervious concrete mix removed on average 39% of TSS from the artificialrunoff, while the ORMCA mix achieved an average removal of 16%. The sand and greensandachieved over 75% and 90% removals, respectively, for TSS from artificial runoff. Thecomposite system of ODOT mix and sand averaged 84% removal of TSS and the Ohio ReadyMix and greensand combination averaged 92% removal. Computed system removals forODOT/greensand and ORMCA/sand were about 94% and 79%, respectively.The composite system provided 63% to 98% removal for seven heavy metals (Cd, Cr, Cu,Fe, Ni, Pb, and Zn). Greensand was superior to sand in removing metals from solution.