Until about 1982, the landfill on Bradford Island was used to dispose of project waste materials like oil and grease, paint and 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. Household waste came from a small community of homes used by construction workers and later project personnel until 1976. The total landfill area is about a half acre in size (about one-third of a football field in area), and is estimated to hold about 8,800 cubic yards of material, including soil used to fill and cover the landfill. It is on the northeastern portion of Bradford Island, and is not in a public area.
The sandblast building was used for sandblasting and painting from about 1958 to 1995. The area impacted by sandblast grit includes the sandblast area and the transformer release area. A burn pit located southeast of the sandblast building and a septic system, not currently in use, northwest of the building are additional potential sources of contamination within the sandblast area. In addition, an area of previously unknown contamination was discovered in the course of soil sampling. Findings of a 2006 investigation conclude that the area contains an estimated 1500 cubic yards of contaminated material.
A small area, approximately 95 cubic yards, on the south side of the island was used for small arms target practice through the 1970s. Lead concentrations have been detected.
Hydrographic and underwater dive surveys in late 2000 led to the discovery of light ballasts on the Bulb Slope area off Bradford Island, impacting an area estimated at 100 cubic yards. Mercury is present, but the sediment has not been greatly impacted. The dive survey also revealed power transmission components containing significant levels of PCBs.