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Chloride Released from Three Permeable Pavement Surfaces after Winter Salt Application
Citation:
Borst, M. AND R. Brown. Chloride Released from Three Permeable Pavement Surfaces after Winter Salt Application. Presented at World Environmental & Water Resources Congress (EWRI 2013), Cincinnati, OH, May 19 - 23, 2013.
Impact/Purpose:
This abstract will highlight the results from chloride being released from the three different types of permeable pavement at the Edison Environmental Center's permeable parking lot.
Description:
EPA does not classify chloride as a priority pollutant. It is often unregulated in stormwater runoff but has been a target stressor for Total Maximum Daily Load (TMDL) allotments developed for multiple waterbodies. Previous research has shown that road salt applications increased chloride concentrations in surface water. Few studies exist on how infiltration-based stormwater control measures react to salt applications. In 2009, EPA constructed a 0.4-ha parking lot surfaced with three types of permeable pavement (interlocking concrete pavers [ICP], porous concrete [PC], and porous asphalt [PA]). Each permeable surface has four equally-sized, lined sections that direct infiltrate to collection tanks that enable composite sampling for water quality analysis. Samples were collected during two winter salting seasons and for the remainder of each year. The chloride concentrations measured in the permeable surface infiltrate samples exceeded the EPA acute criterion for aquatic life (860 mg/L) in the winter months. Concentrations in the infiltrate remained measureable year round but did not exceed the EPA chronic threshold of 230 mg/L in samples collected after April. The chloride concentration decreased with cumulative rainfall depth since previous snow event. The chloride concentration deceased most rapidly in the infiltrate from the PC and most slowly in the infiltrate from the PA. The mean infiltrate concentrations from the ICP and PC were not significantly different from each other. The infiltrate concentrations from each surface were notably different from impervious hot mix asphalt runoff concentrations. The salt applied to the hot mix asphalt is flushed rapidly from the surface by the subsequent events and was often (>77%) undetected in samples, including in the winter months (undetected in three of six events).
