Risks Posed from a Highway Truck Spill. J. Y. Joyner and T. A. Ayers, Geraghty & Miller, Inc., 2840 Plaza Place, Raleigh, NC 27612; and S. B. Ellingson, Geraghty & Miller, Inc., 105 South Fifth Avenue, Minneapolis, MN 55401
A tanker truck carrying virgin toluene and a petroleum hydrocarbon distillate (varsol) overturned and released its contents in the median of a major far-lane highway. Impacted soil was sampled and delineated following a grid system, and an excavation volume was estimated. A private water supply well downgradient of the spill was replaced, thus removing an exposure pathway to the nearest receptor. We were able to demonstrate that contact with soil was the only complete exposure pathway. A comparison of soil concentrations to USEPA Region III Risk-Based Concentrations indicated that the soil concentrations were below the risk-based screening levels. Discussions with the regulatory agency concerning the risks posed to human health led to an agreement that the risks of traffic accidents due to traffic control measures during excavation outweighed the risk to human health based on the soil concentrations. The investigation of the soil remediation was closed based on risk-based concentrations.