Remediating Over 40 Miles of the Hudson River

In 1984, the US Envi­ron­men­tal Protection Agency (EPA) classified 200 miles of the Hudson River as a Superfund site. While the Industrial Revolution brought economic growth to the area—it ultimately cont­a­m­i­nated the riverway with hazardous manu­fac­tur­ing waste. 

Before they were found to be persistent organic pollutants and banned by the EPA in 1979, PCBs, manmade industrial chemicals, were commonly used as coolant fluid in manu­fac­tur­ing equipment. Between the 1940 and 1977, approx­i­mately 1.3 million pounds of poly­chlo­ri­nated biphenyls (PCBs) were discharged into the river by two capacitator manu­fac­tur­ing plants. Decades later, PCBs were still present in the river’s sediment, negatively affecting surrounding wildlife and residents and bringing much public scrutiny to the project. 

Remediation efforts started shortly after the materials were banned. CDM Smith first partnered with the New York State Department of Envi­ron­men­tal Conser­va­tion (NYSDEC) in 2009 for PCB removal, wetland mitigation, ecological risk assessment support, and habitat restoration along a 40-mile stretch of the river from Fort Edward to Troy in New York. This stretch is called the Upper Hudson River and contains many of the “hot spots” of cont­a­m­i­na­tion of the Superfund site. 

Since PCBs do not break down readily on their own in the environment, removing the chemicals requires excavating the PCB-cont­a­m­i­nated riverbed sediments and disposing or incin­er­at­ing the cont­a­m­i­nants. CDM Smith oversaw all aspects of the remedial dredging work, observing the mechanical envi­ron­men­tal dredging of PCB-cont­a­m­i­nated sediments. The dredged sediments were then transported and processed to separate clays and silts from granular and woody material. Cont­a­m­i­nants were then disposed of offsite, and the riverbed was backfilled with non-cont­a­m­i­nated sediment and repopulated with native aquatic plants.

Since the completion of dredging and recon­struc­tion in 2015, NYSDEC has asked CDM Smith to perform annual visual inspections of restored riverine fringing wetlands and submerged aquatic vegetation along the impacted shoreline. The end goal is to return to pre-dredging conditions to ensure that habitats are fully restored, and the banks are stabilized. Through the annual inspections, CDM Smith has identified recon­structed habitats in need of additional improve­ments and has offered recom­men­da­tions for adaptive measures to meet the goals of the project.

"This high-profile Superfund project exemplifies natural resources projects at CDM Smith, having involved many of our wetland scientists," said Conor Veeneman, CDM Smith environmental scientist. "This project represents a long standing and fruitful relationship between CDM Smith and NYSDEC."

“With stakeholder concerns in mind, NYSDEC and CDM Smith brought collective expertise to deliver an adaptive project with a positive envi­ron­men­tal outcome," shared Wayne Richter, research scientist for the Division of Fish, Wildlife and Marine Resources at NYSDEC. "CDM Smith’s smart and dedicated team made science-based decisions on what the resource needed and brought new and creative ideas to improve habitat restoration.” 

This project is still ongoing with monitoring and envi­ron­men­tal remediation activities. Learn more about the larger clean-up efforts on the EPA's website.