Human health and ecological risk assessments guide site restoration, waste-management, and regulatory decisions at Brownfields, Resource Conservation and Recovery Act (RCRA), and Superfund sites. Risk assessments are conducted by Tetra Tech scientists and engineers to guide effective data acquisition efforts, to direct feasibility studies, to determine cost-effective remedial actions, and to set clean-up goals that match intended land-use. With over 25 years of experience, Tetra Tech is adept at solving difficult problems for our clients and dealing with persistent toxic chemicals including chlorinated solvents, arsenic, polycyclic aromatic hydrocarbons (PAHs), pesticides, pentachlorophenol, dioxin, benzene, and hexavalent chromium. Tetra Tech has developed numerous specialized computer models and statistical tools to help clients evaluate the migration of these and other chemicals in the environment and to develop cost-effective approaches for achieving client-specified objectives such as site closure or site redevelopment.

Human Health Risk Assessment

Tetra Tech has more than 25 years of experience conducting human health risk assessments at a broad array of commercial/industrial sites, hazardous waste sites, Brownfield sites, schools, military bases, mines, ports, airports, and manufactured gas plant (MGP) sites. We are experienced at using advanced fate and transport models to predict chemical migration in the environment. Our statisticians design sampling programs and analyze existing data to screen out chemicals from our risk assessments that are not elevated above background levels, and our toxicologists provide expert knowledge on the toxicity and mode of action for chemicals of concern. Tetra Tech has established a reputation for technical excellence in regard to identifying efficient, cost-effective measures for achieving client-specified objectives such as regulatory approved site closure. As part of this work, Tetra Tech developed a computer model (RISK-M) to rapidly evaluate potential human health risks and derive risk-based cleanup goals.

Ecological Risk Assessment

Ecological risk assessments (ERAs) evaluate the potential for adverse biological effects that may occur as a result of exposures to environmental stressors (e.g., hazardous chemicals, invasive species, pathogens). The ERA process systematically evaluates and organizes data, assumptions, and uncertainties to predict relationships between environmental stressors and ecological effects to support the site clean-up and restoration decisions at many sites. Tetra Tech’s ecologists, toxicologists, and wildlife and aquatic biologists conduct these assessments for a wide range of biogeographic zones, including deserts, grasslands, wetlands, marine habitats, and temperate forests. Based on their wealth of experience, Tetra Tech staff developed an ERA computer model (RISK-E) that rapidly integrates toxicity and wildlife exposure factors to assess potential risks and derive cleanup goals protective of ecological endpoints.

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