Tetra Tech specializes in characterizing potential human exposures to total petroleum hydrocarbons (TPH). For client projects, Tetra Tech has used a number of recommended approaches for evaluating potential risks from TPH exposure including: the Department of Toxic Substances Control petroleum risk approach; the American Society for Testing and Material (ASTM) Risk-Based Corrective Action (RBCA) Approach; the Massachusetts Department of Environmental Protection (MDEP) RBCA approach; as well as the American Petroleum Institute’s Decision Support System (API DSS).