From Contaminated Sediments News, Issue 22 - Fall 1998
EPA Region 2
More than 400 million cubic yards of sediments are dredged from U.S. waterways each year, and close to 60 million cubic yards are disposed of in the ocean. The need to protect the environment from the undesirable effects of sediment dredging and disposal is gaining increased attention from the public and government agencies.
The handling of contaminated sediments in the Port of New York/New Jersey exemplifies this problem. Each year, between 4 million and 7 million cubic yards of sediment must be dredged there to permit safe navigation and commerce. That sediment contains contaminants that are among the highest concentrations in the country. Heavy metals, chlorinated pesticides, polynuclear aromatic hydrocarbons, polychlorinated biphenyls, and dioxins/furan are the major contaminants of concern. Several contaminants detected in the sediments and in fish and shellfish have resulted in fishing advisories.
A Team Approach
The program has progressed through demonstrations of various technologies at the bench and pilot scales and is now moving toward the construction of commercial-scale facilities. This step-wise procedure has reduced the number of participants through specific selection criteria, including technical performance, demonstration costs, public-private cost sharing, beneficial reuse of treated material, and corporate evaluations of the business potential for sediment decontamination.
Federal funding available under WRDA provides assistance to the commercialization process, but the private sector will provide the capital needed for facility construction and operation. The program participants believe this type of cooperative approach will be useful in the New York and New Jersey region—and may have features of interest to other U.S. ports that must dispose of contaminated sediments.
Dumping Options Dwindle
Current proposed solutions to the port's dredged material disposal problem include:
A complete solution to the dredging problem will likely include a combination of many, or all, of these alternatives. Decontamination is one component of the overall dredged material management strategy. It can reduce the magnitude of the contamination, and may provide a treated product that can be sold for reuse, thus simplifying disposal and possibly reducing the overall cost of treatment.
Bench- and pilot-scale tests of various technologies were completed in December 1996. The technologies included thermal destruction and desorption processes, stabilization/solidification, sediment washing, advanced chemical treatments, solvent extraction methods, and manufactured soil production. The development of an overall conceptual plan for implementing a large-scale facility is underway.
Various contaminants are present at a wide range of concentrations in material dredged from the New York/New Jersey Harbor. This fact necessitated the development of several types of decontamination technologies to provide comprehensive treatment. In each case, the processed materials have beneficial uses and can be sold to offset a portion of the decontamination costs.
In 1998, the WRDA Program is focusing on a system of low- to high-temperature technologies that can accommodate a range of sediment contamination. These approaches include a sediment washing method developed by BioGenesis Enterprises, Inc., a high-temperature process developed by the Institute of Gas Technology (IGT) to destroy organic compounds and bind metals into a cementitious matrix, and a Westinghouse plasma-arc vitrification process. Work also is being done on manufactured soil production; the U.S. Army Corp of Engineers Waterways Experiment Station is using untreated sediment for that purpose, and BioGenesis is looking at using treated sediment from the harbor.
The blended cement produced by the IGT high-temperature Cement Lock™ Technology exceeds the American Society for Testing and Materials requirements for portland cement. It can be used in concrete for general construction applications.
Environmentally safe decontamination technologies also must be economically viable. Currently, dredged material is stabilized with fly ash and used for construction material and cover at several locations in New Jersey. The total cost of dredging, stabilization, and disposal ranges from $40 to $50 per cubic yard. Current disposal costs in the Newark Bay confined disposal facility are about $35 per cubic yard.
WRDA Program managers are confident that costs of sediment washing and cement production will be competitive—at or below $35 per cubic yard—when full-scale operation is underway.
For More Information
Editor's Note: This article is based on the paper "Maintaining Access to America's Intermodal Ports/Technologies for Decontamination of Dredged Sediment: New York/New Jersey Harbor," by Eric A Stern, EPA Region 2; Keith W. Jones, Brookhaven National Laboratory; Kerwin Donato, U.S. Army Corps of Engineers - New York District; John D. Pauling, P.E., and John G. Sontag, Jr., P.E., Roy F. Weston, Inc.; Nicholas L. Clesceri, Rensselaer Polytechnic Institute; Michael C. Mensinger, ENDESCO Services, Inc.; and Charles L. Wilde, BioGenesis Enterprises, Inc.