In Situ Stabilization/Solidification (ISS) of Contaminated Coal Tar Impacted Sediments in Gowanus Canal
In Situ Stabilization/Solidification (ISS) of Contaminated
Coal Tar Impacted Sediments in Gowanus Canal
Jeff Gentry and Juliana Hess (CH2M)
Timothy Olean (Natural Resource Technology, Inc. (NRT) an OBG Company)
Christos D. Tsiamis (U.S. Environmental Protection Agency)
Jeff Gentry is a Senior Principal Engineer with 30 years of experience in the evaluation, design, and construction of NAPL-related remedies in sediment and in upland sites. Jeff provides technical direction on a large number of projects dealing with NAPL-impacted sediment for private and government clients and has implemented NAPL management technologies including permeable barrier walls, capping, and other methods. His projects range from large Superfund sites to individual commercial waterfront properties. He is the leader for CH2M in the development of NAPL migration laboratory methods and works closely with university researchers to bring the latest innovative methods to field applications.
With several large, complex urban water ways and rivers impacted with NAPLs, ISS is being considered to help reduce remedial costs, minimize short and long term impacts and lower carbon footprint. ISS of sediment has been included as a component of the overall remedy, along with dredging and active capping of sediment, for the Gowanus Canal Superfund site in Brooklyn, New York. The Record of Decision for the site calls for the application of ISS of targeted areas of the native sediment to reduce the NAPL mobility so as to extend the life of the overlaying active cap and to limit the amount of deep dredging that is required. This has been the first application of large scale ISS in a saline water environment. ISS treatment of Gowanus Canal sediments was implemented at the pilot scale. In addition to being the first large scale sediment ISS field demonstration project in a saline environment, this is also the first project to evaluate the implementation of ISS from a barge, through the water column and the in-place accumulated soft sediment prior to its dredging. Application of ISS for treatment of Gowanus Canal sediments was successfully demonstrated in June 2015. The equipment size and configuration were appropriate and capable of treating impacted sediment through the water column and overlaying sediment with reasonable production rates without negative impacts to canal water quality or bulkhead stability. Performance criteria for leaching reduction of contaminants, strength and hydraulic conductivity were met using a variety of ISS amendments.