Portland Harbor Environmental Data Portal

Abstract:

Geosyntec Consultants (Geosyntec) collected twenty surface sediment samples at Swan Island Lagoon in March 2016 to assess whether surface sediment concentrations of polychlorinated biphenyls (PCBs) had decreased through the natural recovery process in the Portland Harbor Superfund Site. Seventy-five percent of these samples show reduced PCB concentrations, with an average of 61 % reduction, when compared with samples collected over a decade earlier by the Lower Willamette Group (L WG). These results also confirm trends seen with PCB concentrations found in surface sediment samples collected by Kleinfelder in 2014. Together, the Geosyntec and Kleinfelder sampling indicates that newly deposited sediments are covering and/or mixing with the older surface sediments both river-wide and in Swan Island Lagoon. As this recent data has not been incorporated in the EPA's Final Remedial Investigation (RI) (February 6, 2016), Feasibility Study (PS) (June 2016), or Proposed Plan (June 2016), the repeated characterization of Swan Island Lagoon by the EPA as an area where natural recovery is prohibitively slow-acting is not correct. These recent data show that the viability of monitored natural recovery within Swan Island Lagoon needs to be reassessed prior to the issuance of the Record of Decision (ROD), as the Proposed Plan specifically and incorrectly prohibits the selection of monitored natural recovery within the Swan Island Lagoon sediment decision unit. More holistically, these data demonstrate that natural processes occurring within the Willamette River are effectively and expeditiously reducing the risk posed to humans and the environment by PCBs in the Portland Harbor Superfund Site.

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Title	Filename	Size (kB)	Document Type
Dataset for Sediment Sampling Data Report Swan Island Lagoon	Geosyntec2016_dataset.xlsx	47	Data File
Read me file	readme.txt	0	Data File
Sediment Sampling Data Report Swan Island Lagoon Portland, Oregon	Geosyntec Swan Island Sediment Sampling Data Report.pdf	41,103	Report