Characterization and Reuse of Residuals Collected from Street Sweeping Operations

Abstract

Street sweeping is a non-structural best management practice (BMP) implemented by the Virginia Department of Transportation (VDOT) in order to meet total maximum daily loads for the Chesapeake Bay watershed in Virginia. This BMP functions by removing the roaddeposited sediment and debris from the roadway before it enters receiving waters. Currently the material collected by VDOT during street sweeping operations is considered a solid waste and must be disposed at a lined landfill. As street sweeping activity continues to increase in order for VDOT to meet the increasing TMDL requirements, a significant cost increase for disposal and transportation to the landfill are expected. In order to curtail these costs, VDOT is seeking a Beneficial Use Determination (BUD) from the Virginia Department of Environmental Quality (VADEQ) for this material. This would allow VDOT to recycle the material for use as traction sand, soil amendment, or other suitable applications. In order to attain a BUD for this waste stream the VADEQ has a number of different criteria that the material must meet, including a physical and chemical characterization of the material to ensure it is not hazardous to the population or the environment. The purpose of this research is to provide a characterization of material collected from over 80 road sites of various average daily traffic loads and land uses. This material was tested for heavy metals including As, Ba, Cd, Cr, Se, Ag, Cu, and Zn as well as the 16 EPA priority polycyclic aromatic hydrocarbons (PAHs) and oil and grease. Concentrations of these metals ranged from 5.9X10 -3 -2.5 mg/kg, 0.225-64.9 mg/kg, 7.3X10 -4 -51.1 mg/kg, 4.8X10 -3 -108.1, 9.1X10 -3 -2 mg/kg, 7.3X10 -4 -1 mg/kg, 0-9.7 mg/kg, 0.3-273.5 mg/kg respectively. Concentrations of ∑PAHs ranged from 18.5 µg/kg to 87,208 µg/kg. Concentrations of oil and grease ranged from 33.6 mg/kg to 3,440.9 mg/kg. Based on the results of this characterization it was found that the concentrations of these contaminants cannot be reliably predicted based on the ADT and land use of the road and surrounding areas. Rather, the particle size of the road deposited sediment had a greater influence of the level of contamination. Given this information it is suggested that VDOT screen material collected during street sweeping to remove the fines associated with this contaminant load.