Carsey Perspectives: Saving Salt, Protecting Watersheds, in Winter Road Maintenance
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Summary
Every winter, the surface of the earth in the northern United States becomes considerably more salty. The reason is, for availability, cost, and effectiveness, nothing beats salt-based deicers for keeping roadways clear of ice. But the effects of road salt on aquatic ecosystems, freshwater drinking supplies, infrastructure, and vehicles is significant. When chlorides get into groundwater, it can be very difficult to get them out. They do not biodegrade over time, and the accumulation in soils can be retained for decades.1 As few as 50 pounds of salt can contaminate 10,000 gallons of water.2 The New Hampshire Department of Environmental Services estimates that there are almost 50 chloride-impaired watersheds within the state, and it lists over 100 of the state’s drinking water sources as contaminated due to chlorides.3 Groundwater experts suggest that the chloride problem may be much larger than we know, due to limited testing and the cumulative impact of the chemical.
Therefore, given what we know about the harmful effects of salt, it makes sense to use it sparingly. But as any homeowner who has tossed it on a sidewalk knows, it is hard to estimate the right amount to use and, if anything, we err on the side of caution, resulting in liberal applications. Municipalities have an even tougher time getting it right. A public works department must deploy dozens or hundreds of spreaders, managing them so they do not miss a road and adjusting their management approach to accommodate changing temperatures and the unique weather fluctuations of each winter event. When trucks are moving through complex road systems it can be challenging for operators to know the last time deicing material was applied to a particular surface. When in doubt, operators apply more material.
It was in seeing that there was significant opportunity for innovation within the winter road maintenance industry that I decided to launch a company where we could work to help address some of the industry’s challenges. In 2012, I launched the New Hampshire based company, Sensible Spreader Technologies LLC (SST), and we are currently helping municipalities and private contractors increase efficiency, increase safety, and reduce deicer waste by showing operators in real time what’s been covered and what hasn’t. SST’s Coverage Indication Technology (CIT) uses mobile devices, wireless sensors, cloud computing, and real-time electronic maps to show operators the concurrent locations of other vehicles in the fleet and the plowing and deicing operations that have taken place over specific intervals. SST developed this technology after measuring the regular occurrence of material-based overlap within short time durations at multiple municipal locations.
Material-based overlap occurs when operators reapply material in areas that have already received sufficient quantities of deicing material. We observed that the highest likelihood for overlap occurred in and around grid-type infrastructure, typical of urban environments, but overlap was also observed in rural settings.