Confined spaces BMPs were discussed in regard to hydraulic and pollutant removal performances. Various filter media having potential for use in filtration vaults were evaluated. Column tests using fifteen types of filter media (aquarium rocks, cedar bedding, charcoal, corn cobs, gardenbark, glass beads, kitty litter, iron oxide coated sand, peat moss, persolite, sand, CH zeolite, XY zeolites and/steel wool, and WSU compost) were run with a synthetic stormwater runoff influent. Effluent samples were collected over time and analyzed for cadmium, copper, lead, zinc, nitrate, phosphate, pH, TSS, and TPH. Results indicate that garden bark, peat moss, sand, and WSU compost are the best filter media for treating stormwater runoff in vaults. Initially, they have acceptable hydraulic properties to pass water through the filters and have good pollutant removal abilities. Over time, however, evidence of clogging can be seen. Further field testing is recommended to determine actual operation and maintenance schedules. Design guidelines are included for the recommended filter media.
Washington State Transportation Center (TRAC)
Bark, Best practices, Compost, Filtration, Filters, Heavy metals, Hydraulic properties, Infiltration, Peat soils, Pollutant control, Runoff, Sand, Soil remediation.