Proposed Abstract Title

Assessing the performance of an activated carbon sediment amendment to remediate contamination at a site located in Sinclair Inlet, Puget Sound, WA

Type of Presentation

Oral

Session Title

General oceanography

Location

2016SSEC

Description

The performance of an activated carbon sediment amendment was assessed after intervals of approximately one, two and three years after placement to document physical, geochemical, and biological conditions using autonomous benthic chambers (Sediment Ecotoxicity Assessment (SEA) Rings), Sediment Profile Imaging (SPI) system, benthic infauna sampling, and geochemical analysis. In October 2012, the half-acre target area, located at the end of Pier 7 in the Puget Sound Naval Shipyard & Intermediate Maintenance Facility (PSNS&IMF) Bremerton, WA, was amended with powdered activated carbon (PAC) using the AquaGate+PAC™ composite aggregate to decrease the bioavailability of polychlorinated biphenyls (PCBs), mercury, and other contaminants. Baseline monitoring was conducted in August 2012 and post-placement monitoring was conducted in August 2013, July 2014, and July 2015. For each monitoring event, ten SEA Rings were placed at the site to conduct 14-day in-situ bioassays using clams (Macoma nasuta) and polychaete worms (Nephtys caecoides), deploy solid phase micro-extraction (SPME) devices, and collect sediment samples. The SPI surveys were used to verify the presence and thickness of the amendment and infaunal community census was used to assess benthic conditions. Data from the study are still being processed, nevertheless tissue residues measured in clams and worms showed statistically significant reductions in Total PCBs which were reduced compared to baseline concentrations by 68-87% after 10 months, 82-89% after 22 months, and 95-97% after 33 months. Similarly, pore water concentrations of PCBs measured by SPME devices also decreased relative to baseline concentrations. The SPI surveys showed the amendment was effectively incorporated into bottom. Infaunal analysis showed gradual improvement and recovery of the benthic community following the initial disturbance from placement. Based on the available data, it appears that amendment has achieved the performance objectives and improved benthic community health at this active harbor site.

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Assessing the performance of an activated carbon sediment amendment to remediate contamination at a site located in Sinclair Inlet, Puget Sound, WA

2016SSEC

The performance of an activated carbon sediment amendment was assessed after intervals of approximately one, two and three years after placement to document physical, geochemical, and biological conditions using autonomous benthic chambers (Sediment Ecotoxicity Assessment (SEA) Rings), Sediment Profile Imaging (SPI) system, benthic infauna sampling, and geochemical analysis. In October 2012, the half-acre target area, located at the end of Pier 7 in the Puget Sound Naval Shipyard & Intermediate Maintenance Facility (PSNS&IMF) Bremerton, WA, was amended with powdered activated carbon (PAC) using the AquaGate+PAC™ composite aggregate to decrease the bioavailability of polychlorinated biphenyls (PCBs), mercury, and other contaminants. Baseline monitoring was conducted in August 2012 and post-placement monitoring was conducted in August 2013, July 2014, and July 2015. For each monitoring event, ten SEA Rings were placed at the site to conduct 14-day in-situ bioassays using clams (Macoma nasuta) and polychaete worms (Nephtys caecoides), deploy solid phase micro-extraction (SPME) devices, and collect sediment samples. The SPI surveys were used to verify the presence and thickness of the amendment and infaunal community census was used to assess benthic conditions. Data from the study are still being processed, nevertheless tissue residues measured in clams and worms showed statistically significant reductions in Total PCBs which were reduced compared to baseline concentrations by 68-87% after 10 months, 82-89% after 22 months, and 95-97% after 33 months. Similarly, pore water concentrations of PCBs measured by SPME devices also decreased relative to baseline concentrations. The SPI surveys showed the amendment was effectively incorporated into bottom. Infaunal analysis showed gradual improvement and recovery of the benthic community following the initial disturbance from placement. Based on the available data, it appears that amendment has achieved the performance objectives and improved benthic community health at this active harbor site.