25 Aug 2020

PUBLICATION NOTICE: Fine-Grained Sediment within Olcott Harbor, Eighteenmile Creek, NY

Abstract: Olcott Harbor, located at the mouth of Eighteenmile Creek and Lake Ontario, and a Great Lake Area of Concern, provides a temporary sink for contaminated, fine-grained sediment transported downstream from the Superfund site near Lockport, NY. The volume of fine-grained sediment currently stored in Olcott Harbor and Eighteenmile Creek is unknown, complicating remediation efforts. The US Army Corps of Engineers (USACE), Buffalo District (LRB), has partnered with the New York State Department of Environmental Conservation to address the mitigation of contaminated sediment accumulating within Eighteenmile Creek. As part of this effort, researchers from the US Army Engineer Research and Development Center (ERDC) collaborated with LRB to delineate fine-grained sediment regions from coarse-grained regions in Olcott Harbor and Eighteenmile Creek via a geophysical survey in July 2017. Where possible, ERDC also estimated the thickness of the fine-grained sediment areas to determine overall fine-sediment volume. Sidescan sonar was used to map the surface transition from the coarser-grained sediment in the outer harbor to the finer-grained sediment in the inner harbor. Chirp sub-bottom profiles successfully imaged the subsurface transition from coarse- to fine-grained sediment in some areas but provided only limited thickness data. This technical note summarizes the field effort, data processing, and final interpretations.