International Dredging Review

International Dredging Review

The New York State Department of Environmental Conservation (DEC) announced that the third season of dredging and capping of contaminated sediments in Onondaga Lake in New York resumed for the season in April. Preparation work began prior to that with all the needed machinery and equipment including continued reduction measures put in place.

Sevenson Environmental Services under contract to Responsible Party Honeywell is performing the dredging. With the material dredged in 2013 (approximately 940000 cubic yards) and system modifications made by contractor Honeywell over the winter including improvements to the piping system controls and pumps it is possible that the remaining dredging expected to include 800000 cubic yards of material could be completed in 2014. The capping of the dredged areas is scheduled for completion in 2016.

Other companies working on the project are the Parsons O’Brien & Gere and Anchor QEA. State University of New York College of Environmental Science and Forestry (SUNY-ESF) Syracuse University Audubon and Freshwater Institute are also involved.

Contaminated dredged material is pumped to a consolidation area at a former industrial property in Camillus New York for drying and longterm safe isolation. The cleanup plan calls for the dredging of up to 2.65 million cubic yards of contaminated sediments to a depth that will allow for a cap to be built without losing any lake surface area. The cap will cover 450 acres of lake bottom. A total of about three billion gallons of water will have been treated in the course of the project more than 1.1 million plants trees and shrubs planted and more than 50 acres of wetlands enhanced.

The $451 million Superfund remediation project has undergone five years of design and engineering; approximately 1.2 million cubic yards of lake material have been removed since dredging commenced in 2012. Honeywell International is conducting the project with oversight from DEC the New York State Department of Health (DOH) and the U.S. Environmental Protection Agency (EPA).

In 2013 40000 cubic yards of capping material were placed 26 million gallons of water had been treated and 1250 plants shrubs and trees were planted.

Short and long-term air monitoring is being conducted in accordance with a Community Health and Safety Plan and data is continuously reviewed by DEC EPA and DOH. The data collected to date does not indicate a community health concern; all levels are lower than concentrations established for the protection of public health.

The health and safety plan was drafted in May 2012 when dredging began. The air monitoring program takes into consideration EPA’s human health risk assessment conducted in 2010. The results indicated that operations at the consolidation area which holds material removed from the lake would result in unacceptable risk for the surrounding community. In turn the work is closely monitored to ensure that air quality is maintained.

The air quality monitoring system operates continuously 24 hours per day seven days per week at the consolidation area and at the lakeshore whenever dredging takes place. There are eight fixed monitoring locations along the consolidation area perimeter and up to five monitoring stations along the lakeshore (two or three will operate at any one time depending on where dredging is taking place).

Air is monitored for dust mercury sulfides and total volatile organic compounds (TVOCs) to ensure concentrations at the perimeter of the work zones remain below the criteria established by the Community Health and Safety Plan. Regulators have established short-term (hourly average) and long-term (12-month average) criteria for this project. Sampling for individual VOCs (referred to as speciated VOCs) is being conducted as part of the long-term monitoring program. Long-term monitoring takes place every six days over a 24-hour period at four pre-determined locations along the consolidation area work zone perimeter to determine individual VOC concentrations. All 12-month averages of individual VOCs were below regulatory criteria for the first year of operations.

Odors are checked at the air monitoring stations along the work perimeters of the consolidation area and lakeshore. Trained professionals conduct inspections at each station once every six hours 24 hours per day seven days per week (when dredging is active). When odors are detected at the site perimeter controls described above can be applied. Depending on the nature of the complaint odor monitoring will occur at and possibly beyond the work perimeters. The goal is to prevent odors from occurring in the community by proactively applying odor controls if /when odor levels increase at the site.