Characterization of Mud/Dirt Carryout onto Paved Roads from Construction and Demolition Activities

Several urban areas of the country in violation of the National Ambient Air Quality Standard (NAAQS) for particulate matter have identified fugitive dust generated by vehicular traffic on paved streets and highways resulting from mud/dirt carryout from unpaved areas as a primary source of PM-10 (particles ≤ 10 μm in aerodynamic diameter). Since little data are currently available on the amount of mud/dirt carryout deposited on paved roads, this work characterizes the process and evaluates selected control methods. These control technologies were evaluated for effectiveness in controlling mud/dirt carryout from an unpaved construction access area onto an adjacent paved road. The first control used a street sweeper to mechanically sweep the dirt and debris from the paved road surface. The second applied a 6to 12-in. (15to 30-cm) layer of woodchip/mulch material onto the access area of the construction site to a distance 100 ft (30 m) from the paved road. The third applied a 6-in. layer of gravel over the access area. Street sweeping was found to be only marginally effective (approximately 20%) in reducing average silt loading on the paved road lanes. Treatment of the access area with a buffer of woodchip/mulch was moderately effective, reducing average silt loading by 38 to 46%. The gravel buffer showed the greatest effectiveness, reducing the average silt loading by 57 to 68%. These silt loading reductions result in the following calculated PM-10 reductions: street sweeping, 14%; woodchips, 27 to 33%; and gravel, 42 to 52%. This Project Summary was developed by EPA's National Risk Management Research Laboratory's Air Pollution Prevention and Control Division, Research Triangle Park, NC, to announce key findings of the research project that is fully documented in a separate report of the same title (see Project Report ordering information at back).