Environmental due diligence projects conventionally commence with a Phase I Environmental Site Assessment (ESA). Should this assessment reveal Recognized Environmental Conditions (RECs), a Phase II ESA may be conducted, which includes soil, soil-gas, and/or groundwater sampling and analysis for suspected Contaminants of Concern (COCs). If COCs are detected above laboratory detection limits, they are compared to state or Environmental Protection Agency (EPA) screening levels. While numerous consultants base their recommendations solely on this comparison, it is imperative to note that screening levels are intentionally conservative and may not account for real-world exposure factors at the site. Furthermore, some state agencies utilize less stringent hazard quotients and target risk factors to determine actionable cleanup criteria, meaning that exceeding screening levels may not necessitate mitigation.
The EPA’s Risk-Based Screening Level (RSL) and Vapor Intrusion Screening Level (VISL) calculators can determine site-specific actionable levels using the latest scientific data on toxicity and chemical properties. This approach develops screening and cleanup levels that consider chemical-specific nuances and site-specific scenarios and media, providing clear guidance for risk management decision-making.
At AZ-RI Consultants, we integrate EPA’s RSL/VISL calculations into our findings to ensure that decisions related to COCs are scientifically sound.