Chloride transport and related processes at a municipal snow storage and disposal site

The practice of used snow disposal has evolved from indiscriminate snow dumping to storage and meltwater management at engineered snow disposal sites. The Town of Richmond Hill, Ontario, Canada, constructed such a snow disposal site in 2003. Environment Canada and the Town of Richmond Hill formed a partnership to investigate the operation of the Richmond Hill Snow Storage Facility (RHSSF) with respect to snowmelt flows, fluxes of chemicals contained in snowmelt and direct effects on the receiving water. Results of chloride monitoring during the winter of 2007 are presented here. Roughly 16 tonnes of chloride passed through the snow disposal facility in 2007, which in itself reflects only a small proportion of the total salt applied to roads that winter. The highest concentrations of chloride were present in early melt, with 50% of the chloride released within the first 30% of the meltwater. The remainder of the chloride was released in lower concentration, higher volume melt later in the season. As expected, conductivity measurements at the outlet of the stormwater pond indicate that the meltwater management system served to delay and dilute the chloride released, but not to remove the pollutant.