A.48 New Bedford, MA 1995
A.48.1 Summary
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Contaminants of Concern: |
Six hotspots exhibiting: PCBs: 4,000-200,000 ppm Metals: 0-4,000 ppm Metals are not targeted because they are co-located with PCBs. |
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Final Remedy: |
Hydraulic cutterhead dredge. Dredged material transported by pipeline one mile to a temporary CDF. The contaminants were later dewatered and disposed at an off-site TSCA-permitted landfill. |
A.48.2 Site Description
Year: 1995
Target Volume: 10,000 yd3
Actual Volume Removed: 14,000 yd3
A.48.3 Remedial Objectives
EPA calculated that by targeting 4,000 ppm, greatest percentage of PCB mass could be removed with least volume of sediment.
Contaminated sediment area: 5 acres
A.48.4 Remedial Approach
Hydraulic cutter head dredge
Dredge depth: 0–4 ft
Oil was trapped throughout the hotspot, so a shroud was put over the cutter head to catch the oil as it was released.
The use of silt curtains was abandoned because they appeared to be contributing to oil problems by continuous disturbance of the bottom in the varying tidal and weather conditions. High suction rate and slow auger rotation were emphasized to control resuspensionA renewed suspension of insoluble particles after they have been precipitated..
A.48.5 Monitoring
Performance: Goal was met. Post dredging sampling showed the five acre area to be well below the 4,000 ppm PCB goal.
A.48.6 References
USEPA Superfund Record of Decision Amendment: New Bedford EPA ID: MAD9807313335. Apr 1999. http://www.epa.gov/region1/superfund/sites/newbedford/9721.pdf.
USEPA. First Five-Year Review Report for the New Bedford Harbor Superfund Site. SDMS DocID 237034. Sep 2005. http://www.epa.gov/superfund/sites/fiveyear/f05-01005.pdf.
USEPA. Second Five-Year Review Report for the New Bedford Harbor Superfund Site. SDMS DocID 470549. Sept 2010. http://www.epa.gov/region1/superfund/sites/newbedford/470549.pdf.
Major Contaminated Sediment Sites Database; Sept. 2004 as updated 2008. http://www.smwg.org/MCSS_Database/MCSS_Database_Docs.html.
Publication Date: August 2014