Assessment of soil and wash water quality beneath salt-spreader racks

The Virginia Department of Transportation's (VDOT) winter maintenance program hinges primarily on the use of granular NaCl for deicing. On average, VDOT applies more than 300,000 tons of NaCl each winter season. The majority of this salt is spread by way of salt-spreaders attached to dump trucks. The spreaders require cleaning and lubricating after each use. The purpose of this research was to determine if VDOT should provide an impermeable surface beneath the spreaders to prevent potential contamination resulting from lubrication and, if so, to determine if washing could occur on the same impermeable surface, thus reducing the number of times the spreaders are handled by providing a single location for washing and lubricating. The results showed that potentially significant volumes of excess lubricants can be generated by way of the spreader lubrication process and that this excess should, therefore, be captured. In the majority of cases, this could be done by means of a drip pan or similar device. Because of dilution, if washing and lubrication were to occur at the same location and the wash water and lubricant mixture were contained and conveyed to the nearby salt ponds, lubricant concentrations found in the pond water would be relatively low. Although laboratory results indicate that these concentrations could be reduced even further by way of an in-line organoclay filter, this method of lubricant capture would be more expensive and labor intensive than the simple use of drip pans. Although paving beneath existing spreader racks was not advised unless other provisions for washing at the spreader racks are also made available, proposed best management practices were developed for three different site conditions that are likely to be found at VDOT's maintenance facilities. The benefits of following these practices include decreased potential for soil contamination beneath spreader racks and decreased potential for wash water runoff contamination and associated salt pond contamination.