During a 30-year period ending in 1977, approximately 1.3 million pounds of PCBs (polychlorinated biphenyls) were discharged into the Upper Hudson River from two capacitor plants owned by General Electric (GE). In 1984, as a result of these direct discharges and other sources from the GE facility properties, the U.S. Environmental Protection Agency (EPA) placed 200 miles of the river, between Hudson Falls and the Battery in New York City, on the National Priorities List (Superfund) of the country’s most contaminated hazardous waste sites. PCBs are a probable human carcinogen and high levels of PCBs in fish tissue resulted in fishing bans and/or restrictions throughout the River. An initial EPA evaluation of potential remedial options in 1984 resulted in a decision of “No Action,” with the exception of covering so-called remnant deposits of PCB-contaminated soils in certain floodplain areas within a short distance downstream of the GE plants.
The U.S. EPA initiated a study of the Hudson River PCB Superfund Site in 1989 to reassess the interim No Action decision made in 1984. The purpose of the Reassessment Remedial Investigation/Feasibility Study (RI/FS) was to determine an appropriate course of action for the PCB-contaminated sediments in the River to protect human and ecological health. This study included a more extensive database that was used to better characterize the site, and investigation of the transport, fate and potential impacts of PCB contamination in the river.
LimnoTech played a key role in the RI Phase of the Study by developing and field-validating transport and fate mass balance models of the Upper Hudson River. These models were used to help EPA determine whether PCBs in fish could recover to levels judged safe for humans and the ecosystem under the No Action alternative, whether remedies other than No Action would significantly shorten recovery time, and whether contaminated sediments buried and sequestered from the food chain might become reactivated following a major flood. Later, during the FS Phase of the Study, LimnoTech used these models to support the development and evaluation of various remedial action alternatives.
In February 2002, EPA issued a Record of Decision (ROD) calling for targeted environmental dredging of approximately 2.65 million cubic yards of PCB-contaminated sediments from a 40-mile section of the Upper Hudson River. In 2009, Phase I of the dredging project was conducted by GE with oversight by EPA. After an extensive evaluation by an independent panel of scientists and input from a broad range of stakeholders, EPA developed plans for Phase 2 of the dredging project to remove the remaining contaminated sediments. During this process, LimnoTech assisted EPA with evaluation and revision of the Phase 1 dredging requirements, and review of data and modeling analyses conducted by GE and its contractors to support the design of the Phase 2 dredging.