The gravel or limestone placed on unpaved county roads contains a gradation of stone sizes as well as a quantity of clay which acts as a binder to stabilize the crushed stone. Traffic on unpaved roads during dry weather disturbs the clay and airborne dust is generated. The dust not only is a nuisance to adjacent property owners and obscures the vision of other drivers, but also escalates the deterioration of the road surface since the stone material lacks an adequate binder.
In order to reduce the amount of dust and preserve the road surface, the Livingston County Road Commission periodically sprays the road surface mineral with brine or liquid calcium chloride. Calcium chloride is a by-product of brine and is also purchased from a private vendor. The brine or calcium chloride absorbs and holds moisture, thus keeping the road surface damp and dust free for prolonged periods of time. The calcium chloride has a higher salt content and thus, is a more effective dust control material, however, it is also significantly more expensive.
The Road Commission applies brine to its unpaved Primary Roads at least three times per year. Townships pay the cost of the dust control material used on Local Roads and the type of material and frequency of application varies. As part of its dust control program, the Road Commission first thoroughly grades the road, and then sprays on approximately 2,000 gallons of brine or chloride per mile. Since subsequent gradings will mix the dust control material below the surface of the road, during summer months the Road Commission attempts to restrict gradings on unpaved roads unless these gradings are followed by new dust control applications.