Regulators outside of the United States either have not setcleanup goals for Total Petroleum Hydrocarbons (TPH) andother chemicals in soil, or they have proposed very lowconcentrations based on reviews of European and NorthAmerican regulations. Soil TPH or oil and grease cleanuplevels range from 50 to 10,000 ppm (mg/kg) in North Americaand Europe. This reflects that not all jurisdictionsacknowledge differences between types of hydrocarbonmixtures (e.g., gasoline and crude oil), not all jurisdictionsrecognize that soil organic matter can report as TPH, and thatnot all jurisdictions utilize a risk analysis approach forevaluating human health and environmental impacts. Inaddition to these issues, there has been until recently nostandardized, scientifically defensible procedure forinterpreting risk associated with complex mixtures ofhydrocarbons like TPH. However, recent efforts by the TPHCriteria Working Group (TPHCWG) and the PetroleumEnvironmental Research Forum (PERF) have establishedprocedures to derive human-health Risk-Based ScreeningLevels (RBSLs) for refined petroleum products and crude oils.In 1999, the Nigeria Department of Petroleum Resourcesproposed using Intervention and Target Values established bythe Dutch Ministry of Housing, Spatial Planning, and theEnvironment for soil remediation at oil impacted sites inNigeria. They proposed using the Dutch Target Value formineral oil of 50 mg/kg; however, since that time the Dutchhave adopted an approach similar to that of the TPHCWG.This paper discusses the new approach being used by theDutch, as well as the Risk-Based Corrective Action approachfor TPH and other chemicals being used by many stateregulators in the United States. A modified approach fordeveloping Nigeria specific RBSLs for oil impacted soil isproposed.
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