The impacts to the upland areas and to the river were evaluated in a Remedial Investigation completed in 2012. Further evaluation was conducted in the subsequent Baseline Human Health and Ecological Risk Assessments completed in 2016.
Four areas on the island were identified for study and evaluation of risks to humans and the environment.
- Landfill Area. From the 1940s until about 1982, a small landfill on Bradford Island was used to dispose of project waste materials. It is on the northeastern portion of Bradford Island, and is not in a public area. The landfill contains discarded materials such as oil, grease, paint, solvents, scrap metals, mercury-vapor lamps, cables, and sandblast grit. Some electrical transmission components like switchgear, insulators, and possibly light ballasts were also in the landfill. Some household waste came from a small community of homes used by construction workers and later project personnel until 1976. The total landfill area is approximately a half-acre in size (about one-third of a football field), and is estimated to hold about 8,800 cubic yards of material, including soil used to fill and cover the landfill.
- Pistol Range Area. The Pistol Range is located on the south side of Bradford Island. It was used for small arms target practice from approximately 1950 through 1970. Surface soils became contaminated with low concentrations of lead and zinc. The highest lead concentrations in soil are likely associated with bullet fragments that remain in the soil. The Pistol Range is now well vegetated and does not show evidence of soil erosion.
- Sandblast Area. The sandblast building was used for sandblasting and painting from about 1958 to 1995. Sandblast grit contains metals, and it primarily affected an area east of the sandblast building. The Sandblast Area also includes a place where transformer oil was released onto the ground in 1995, a former hazardous material storage area, a burn pit to the southeast of the sandblast building, and an out of service septic system northwest of the building. An investigation in 2006 concluded there is an estimated 1500 cubic yards of soil in the area with concentrations of metals and other industrial constituents.
- Bulb Slope Area. The Bulb Slope consists of a fan-shaped accumulation of glass and electrical light bulb debris that extends across approximately 1,900 square feet of a steep slope between the Columbia River and the Landfill access road. There is a thin layer of soil, up to 1 foot thick, that overlies bedrock and has low concentrations of PCBs, mercury, and lead from discarded light bulbs and other debris.
The Corps has completed the process of evaluating alternatives for the upland areas. It has been determined that the Landfill Area and the Pistol Range Area may pose risks to human health or the environment. However, it has been determined that there are no concerns at the Sandblast Area or the Bulb Slope Area. The Corps is currently in the process of evaluating alternatives for the portions of the site in the adjacent Columbia River.
The Corps continues to work with state and tribal health agencies to inform area subsistence fishers and recreational anglers about the danger of eating fish that may be contaminated.
Portland District released the final Remedial Investigation Report in 2012 that documents our investigation of upland and in-river contamination; identifies the sources, nature, and extent of the remaining contamination; and identifies potential concerns to human health and the environment.
The report concludes that contaminants both on land and in the water exceed risk screening levels and proposes that we perform a feasibility study of the in-water area to identify remedial actions that will lower concentrations to an acceptable risk level. It also proposes that we perform either a feasibility study of the land areas or a site-specific baseline Human Health Risk Assessment or Level III Ecological Risk Assessment to determine if risks to human health or ecological receptors are unacceptable.
Ultimately, a baseline risk assessment was completed for both the in-river area and the upland sites in 2016. A Feasibility Study for the land areas was also completed in 2017, and a Feasibility Study for the in-water area will be completed in 2018.
In 2012 the Corps published results of samples collected in the river in 2011 of sediment, clams, and fish tissue. The report was produced to determine whether contaminant levels had changed in the river area since the dredging project in 2007. The results showed that contaminant levels were not reduced by the dredging project.