Chemical Characterization of Street Sweeping Residuals in Florida for Disposal and Reuse

摘要

The management of residuals created by the maintenance of paved roads (commonly known as "street sweepings") has been raised some environmental concerns in many states including Florida. The management practices commonly employed for residuals management are either landfilling or stockpiling for potential future use. Because of the large soil content as well as cost associate with the disposal of these materials, there is a desire to beneficially use them in land application scenarios such as clean fill. Prior the land application of these residues, potential risk to human health and the environment associated with such use must be assessed. To properly characterize and assess land application potential of these residues, 11 sampling trips were conducted to facilities that produce or stockpile these residuals. Total metal content (arsenic, barium, cadmium, chromium, copper, lead, mercury, nickel, selenium, silver, and zinc) and organics (volatile organics, semi-volatile organics, herbicides, and pesticides) in the residuals were examined. The synthetic precipitation leaching procedure (SPLP) test was also performed to determine leachability of pollutants such as metals and organics. To assess risk associated with direct exposure to these residuals, the total chemical concentrations were compared the risk based Florida soil clean-up target levels (SCTLs). The concentrations of chemicals detected in the SPLP extracts were compared to the Florida groundwater clean-up target levels (GWCTLs) to assess potential leaching risks associated with the consumption of contaminated groundwater. For the total metal analysis (more than 150 sample analyses), most of the samples for selected metals typically did not exceed the respective SCTLs with an exception of arsenic samples. In the leaching experiments, four metals (arsenic, barium, lead and zinc) were commonly detected above their respective detection limits in a number of samples. While lead often exceeded its GWCTL (0.015 mg/L), the other three metals did not exceed their respective GWCTLs. The results of organic analyses indicate that the organic chemicals in street sweeping residuals were not of a major concern in terms of human risk and leaching risk to groundwater under reuse and contact scenarios.