We recently received an inquiry from a local neighborhood with a dozen cottages located off from an aggregate road. Two years ago the neighborhood funded a salt brine application on the road, which effectively reduced the amount of dust generated by vehicle traffic. They are now considering oiling the road, thinking it might be a more effective means of providing longer term control of the dust. Concerned about the impact to the lake and watershed, they asked GLA to share any research or recommendations made available to us:
Mike Litch, Chair of the Water Quality Committee, solicited advice and received the following information:
Tip of the Mitt Watershed Council recommends utilizing dust control methods that result in the application of the least volume of chemicals at the least frequency and chemicals with the least potential impacts.
Dust control agents can pose threats to the aquatic ecosystem. Studies conducted by the EPA show that more than half of the used oil applied to roads for dust suppression enters the environment through runoff or with blowing dust. Alternative stabilization agents are recommended and include: water, calcium chloride, sodium chloride, mixture of the two (calcium chloride and sodium chloride), magnesium chloride, emulsion products, lignin derivatives, and resins. While these are listed as alternatives to used oil, it does not necessarily mean they are “environmentally safe.”
Environmental effects of dust suppressant application depend upon many factors including the physical characteristics of the suppressant, its chemical composition, concentration, soil composition, and climate conditions before and after application. The potential environmental impacts for some of the more common suppressants are below:
Salts, Brine, Calcium Chloride – While the impact of products containing chlorides can be minimized if the proper buffer zone exists between treated area and water, potential water quality impacts include possible elevated chloride concentrations in streams downstream of application areas and shallow groundwater contamination. Chloride concentrations as low as 40 ppm have been found toxic to trout and concentrations up to 10,000 ppm have been found to be toxic to other fish species. Some plants species such as pine, hemlock, poplar, ash, spruce, and maple can have negative impacts if near the application area. Given the potential negative effects on the water resources, we would recommend reducing the amount of chlorides used in road maintenance activities.