Syracuse, New York
The Onondaga Lake Superfund Site is one of the largest environmental remediation projects undertaken in USEPA Region 2. Onondaga Lake is a 4.6 square mile (2,944 acre) lake located in Syracuse, New York. In 1946, Allied Chemical started a mercury cell process that resulted in waste streams containing mercury and heavy metals being discharged from the facilities at Willis Avenue and Bridge Street. The lake was placed on the NPL in December 1994 due to the extensive pollution as the lake was a recipient of industrial and municipal sewage discharges for more than 100 years. COCs included mercury, heavy metals, PCBs, and contaminants discharged from the municipal WWTP.
Sevenson hydraulically dredged over 2.14M CY of contaminated sediment; placed a 2.3M CY active sediment cap, which consisted of sand and rock in 29 different areas of Onondaga Lake with a custom-built slurry system; and installed 1,600 LF of sheet pile wall in sediment with low shear stress. Sevenson mechanically removed an additional 33,740 CY of contaminated material from a wetland/bank area along the shoreline and placed a 900,000 CY active sand cap consisting of sand/gravelly sand and GAC for bank controls. Safe and successful project completion earned Sevenson four awards/certificates: 2014 WEDA Annual Safety Award; 2017 Dredging and Port Construction Innovation Award – Innovation in Project Design for Inland Dredging presented by HIS Markit; 2017 WEDA Environmental Excellence Award for Environmental Dredging; 2018 Outstanding Civil Engineering Achievement Award from Syracuse section of ASCE.