Technical Integrity / Collaboration / Exceptional Results

Site Investigation and Risk Assessment at Former Wood-Treating Facility

Integral provided strategic and technical leadership for human health and ecological risk assessments at a former wood-treating site in northern Minnesota. The site, which was originally remediated in the late 1980s, resurfaced as part of a five-year review under CERCLA. Residual risk drivers in soil at the site include dioxins and furans, polycyclic aromatic hydrocarbons, pentachlorophenol, and metals. Other technical issues include potential migration and/or uptake of site-related chemicals to secondary media, including sediment, surface water, plants, aquatic and terrestrial invertebrates, and fish.

Integral developed programmatic work plans for the site investigation and risk assessments and assisted the client in negotiating a focused, sound technical approach with federal, state, and tribal representatives. Complex negotiation issues included the sufficiency of historical cleanup methods, exposure and risks from dioxin (given EPA’s ongoing dioxin reassessment, changing regulatory climate, and scientific uncertainties in dioxin toxicity), regional background exposure to bioaccumulative chemicals in fish tissue, statistical evaluation and ecological significance of sediment toxicity bioassays, and the identification and evaluation of appropriate subsistence exposure scenarios for the local Native American community. Integral’s careful, site-specific risk evaluation demonstrated that ecological risks are limited, and that present-day risks to nearby residents, including tribal populations, are within or below EPA’s acceptable target risk range for protection of human health.

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