A.67 St. Lawrence River, NY

A.67.1 Summary

Environment:	Freshwater
Scale:	Field
Contaminants of Concern:	PCBs: 0.04-10,000 ppm before dredging
Final Remedy:	Hydraulic dredging. Some boulders pulled up were power washed and added to shore reconstruction. Sediment with concentrations >10ppm were transported by rail, 2190 miles to Tooele, UT. The remaining sediment was put in a lined on-site landfill.

A.67.2 Site Description

GM Massena Hydraulic dredging

St. Lawrence River near shore flow rates up to 2.0 fps.

Year: 1995

Water Depth: 0–30 ft

Target Volume: 29,000 yd³

Actual Volume Removed: 13,800 yd³

A.67.3 Remedial Objectives

PCBs: 1 ppm

Contaminated sediment area: 11 acres, 2,500-foot long near shore area in the St. Lawrence River

A.67.4 Remedial Approach

Some boulders pulled up were power washed and added to shore reconstruction.

A.67.5 Monitoring

Resuspension:

Silt curtains tried for containment, but were unable to withstand river currents. Redesigned system consisted of interlocking steel sheet pile panels enclosing dredged area reducing potential for off-site migration.

Residuals:

Postdredging concentrations were met in all but one of the six divided regions. That one region was backfilled with clean sand to meet the cleanup goal.

A.67.6 References

USEPA. Realizing Remediation II an Updated Summary of Contaminated Sediment Remediation Activities at Great Lakes Aras of Concern. July 2000. http://www.epa.gov/glnpo/sediment/realizing2/RR2report.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