Hamilton Island Landfill covers 240 acres in Skamania County, Washington, near the Columbia River. It operated as an unlined landfill from 1977 to 1982, receiving about 19 million cubic yards of material. That material included soil from powerhouse construction at the Bonneville dam, demolition debris from a nearby town, and chemical waste, paints, and degreasers. The site sits within a federally designated National Scenic Area. About 900 people draw drinking water from wells within four miles, and the Columbia River runs adjacent to the property.
Early sampling found that site activities had contaminated soil, sludge, groundwater, and surface water with hazardous chemicals. A later remedial investigation found four contaminants of concern, all polycyclic aromatic hydrocarbons (PAHs) in soil: benzo(k)fluoranthene, benzo(a)anthracene, benzo(a)pyrene, and chrysene. Despite their presence, the investigation ultimately determined that hazardous substances at the site do not pose a risk to human health or the environment. Groundwater is not a concern.
The Army Corps of Engineers owns and manages the site. It fenced a portion of the property in 1987 to restrict public access. EPA added the site to the National Priorities List (NPL) in 1992. Investigations starting in fall 1993 detected no hazardous wastes requiring cleanup. A Record of Decision issued on March 30, 1995, selected no action as the cleanup approach for the remedial operable unit. EPA, the Washington Department of Ecology, and the Army agreed that no further action was necessary. EPA deleted the site from the NPL on May 25, 1995.
All cleanup goals for current and reasonably anticipated future land uses have been achieved. There are no unacceptable human exposure pathways, required land-use restrictions and controls are in place, and site monitoring is not required. EPA confirmed the site as ready for anticipated use in 2006. The Superfund Redevelopment Program supports productive reuse of the property.
Community members with questions can contact the Remedial Project Manager. The Community Involvement Coordinator is also available for questions. The complete Administrative Record can be obtained through the lead agency or the site's Public Information Repository.
