Characterization of Residuals Collected From Street Sweeping Operations

About the report:

Street sweeping is a routine roadway maintenance activity conducted by the Virginia Department of Transportation (VDOT). It also provides an added benefit as a non-structural stormwater best management practice implemented by VDOT to meet total maximum daily loads for the Chesapeake Bay watershed. This best management practice functions by removing pollutants from the roadway before they can enter receiving waters. Currently the material collected by VDOT during street sweeping operations is considered a solid waste and is disposed of at a lined landfill.

Given the benefits street sweeping provides in achieving total maximum daily load requirements, it is an activity that continues to increase. As street sweeping activity increases, additional residuals will be generated, requiring management. VDOT is evaluating options to manage street sweeping residuals efficiently through reuse and recycling. Part of this evaluation requires characterization of the material to determine (1) its regulatory status; (2) whether it can be reused within the criteria established by the Virginia Department of Environmental Quality (VDEQ) Division of Land Protection and Revitalization State-wide Variance Guidance Memo No. LPR-SW-04-2012; or (3) whether the material might qualify for reuse following the VDEQ beneficial use determination (BUD) process. Potential reuse/recycling options might include using the material as traction sand, a soil amendment, beneficial fill, or other suitable application. VDEQ has a number of criteria the material must meet to qualify for a BUD, including a physical and chemical characterization of the material to demonstrate that the material does not present a hazard to human health or the environment. This study provides the needed characterization of material collected from 79 road sites of various average daily traffic loads and land cover. The material was tested for arsenic (As), barium (Br), cadmium (Cd), chromium (Cr), selenium (Se), silver (Ag), lead (Pb), copper (Cu), and zinc (Zn); the U.S. Environmental Protection Agency’s 16 priority polycyclic aromatic hydrocarbons; and oil and grease.

Based on the results of this characterization, the study found that the concentrations of these constituents cannot be reliably predicted based on average daily traffic or land cover. Rather, the findings indicate a negative correlation between the particle size of the road deposited sediment and the concentration of detected constituents. Further, the average concentration of these constituents was found to exceed the screening levels administered by VDEQ’s Division of Land Protection and Revitalization State-wide Variance Guidance Memo No. LPR-SW-04-2012.

The study recommends that VDOT’s Environmental Division not pursue a BUD for this material at this time. Further, upon the request of VDOT’s Environmental Division, the Virginia Transportation Research Council should conduct a survey of VDOT’s districts, residencies, and area headquarters to determine the volume of this material collected by VDOT field offices during street sweeping activities. Such a survey would provide a better picture of the need for reuse of the material. Further, if the survey findings indicated a great enough need for reuse, it is recommended that additional research be conducted to determine the effectiveness and feasibility of processing methods (such as screening) to remove these constituents.

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