TRANSPORTATION RESEARCH DIGEST
ARIZONA TRANSPORTATION INSTITUTE
Recommendations for Winter Traction Materials Management on Roadways Adjacent to Bodies of Water by James Mark Staples, Laura Gamradt, Otto Stein, and Xianming Shi, Western Transportation Institute, P.O. Box 174250, Montana State University, Bozeman, MT 59717-4250; Phone: (406) 994-6114 (Montana Department of Transportation, 2701 Prospect Avenue, PO Box 201001, Helena MT 59620-1001) (Dec 2004)
The detrimental impacts of sand generally outweigh the negative impacts of chlorides.
The most applicable structural BMPs seem to be dry ponds, wet ponds, wet extended detention ponds, constructed wetlands, vegetated swales, and vegetated filter strips.
This report has reviewed best management practices for managing winter traction materials and for reducing their impacts on adjacent bodies of water through a literature review, a survey, and appropriate consultations. Because highway runoff is the primary vehicle through which pollutants from winter maintenance activities impact adjacent water bodies, this report has focused on the structural best management practices (BMPs) designed to capture traction materials carried by such runoff. To reduce the amount of traction materials applied on roadways, non-structural BMPs have also been reviewed.
The detrimental impacts of sand generally outweigh the negative impacts of chlorides. This conclusion provides good news because chlorides are generally difficult to remove from highway runoff, whereas suspended solids such as sand are much easier to remove.
The Montana Department of Environmental Quality (DEQ) and Montana Fish, Wildlife & Parks (FWP) become most
concerned when particle sizes are less than 6.35mm in diameter. According to expert opinions, particle sizes less than 2mm become especially problematic, as they will block the movement of oxygen into streambed gravels and thus endanger the aquatic wildlife. Sand free of much finer particles (ones that pass through the #200 sieve, or 0.075mm in diameter) provides better traction and is easier to capture with many structural BMPs.
Best Management Practices
BMPs can be categorized as either structural or non-structural, of which some may be more applicable for use in Montana and other rural areas with cold climates.
Geographical and climatic conditions on Montana's roadways present the challenge of providing winter mobility while balancing traveler safety with economical and environmental concerns. High volumes and high velocities of spring runoff, combined with freezing winter conditions, hinder the effective use of many structural BMPs. Although much data and research is available on structural BMPs in temperate regions, limited quantitative data are available for structural BMPs in cold regions. More research is needed in this area to develop specific design criteria and to justify the investment of structural BMPs in cold regions. For instance, for many of the BMPs mentioned in this paper, no cost-benefit analysis has been done.