2017 South Plant NPDES Outfall Sediment Sampling Event: Final Results November 2018 Alternate Formats Available 2017 South Plant NPDES Outfall Sediment Sampling Event: Final Results Prepared for: King County Wastewater Treatment Division Department of Natural Resources and Parks Submitted by: Wendy Eash-Loucks Marine and Sediment Assessment Group King County Water and Land Resources Division Department of Natural Resources and Parks 2017 South Plant NPDES Outfall Sediment Sampling Event: Final Results Citation King County. 2018. 2017 South Plant NPDES Outfall Sediment Sampling Event: Final Results. Prepared by Wendy Eash-Loucks, Water and Land Resources Division. Seattle, Washington. King County Science and Technical Support Section i November 2018 2017 South Plant NPDES Outfall Sediment Sampling Event: Final Results Table of Contents Executive Summary............................................................................................................................................. vi 1.0 Introduction .............................................................................................................................................. 1 2.0 Site Description and Monitoring History ....................................................................................... 2 2.1 1995 Monitoring Event .................................................................................................................... 3 2.2 1997 Monitoring Event .................................................................................................................... 4 2.3 1999 Monitoring Event .................................................................................................................... 5 2.4 2001 Monitoring Event .................................................................................................................... 6 2.5 2011 Monitoring Event .................................................................................................................... 6 3.0 2017 Sediment Monitoring Event .................................................................................................... 8 3.1 Sampling Design ................................................................................................................................. 8 3.2 Data Quality Objectives .................................................................................................................... 8 3.3 Sample Collection .............................................................................................................................10 3.3.1 Station Positioning ....................................................................................................................10 3.3.2 Sampler Deployment and Retrieval ....................................................................................11 3.3.3 Sample Processing .....................................................................................................................11 4.0 Laboratory Analysis .............................................................................................................................13 4.1 Sediment Chemistry ........................................................................................................................13 4.1.1 Conventionals ..............................................................................................................................13 4.1.2 Metals .............................................................................................................................................14 4.1.3 Organic Chemicals .....................................................................................................................14 4.1.4 Sediment Chemistry Quality Assurance/Quality Control...........................................14 4.2 Sediment Toxicity ............................................................................................................................18 4.2.1 Sediment and Water Quality Parameters .........................................................................18 4.2.2 Acute Amphipod Bioassay ......................................................................................................19 4.2.3 Acute Larval Echinoderm Bioassay.....................................................................................19 4.2.4 Chronic Juvenile Polychaete Bioassay ...............................................................................20 4.2.5 Bioassay Test Quality Assurance/Quality Control ........................................................21 4.3 Benthic Taxonomy ...........................................................................................................................21 5.0 Sediment Chemistry Results.............................................................................................................22 5.1 Conventionals ....................................................................................................................................22 King County Science and Technical Support Section ii November 2018 2017 South Plant NPDES Outfall Sediment Sampling Event: Final Results 5.2 Metals ...................................................................................................................................................23 5.3 Organic Chemicals ...........................................................................................................................24 5.3.1 Polar Organic Chemicals..........................................................................................................24 5.3.2 Nonpolar Organic Chemicals .................................................................................................26 6.0 Sediment Toxicity Data.......................................................................................................................29 6.1 Acute Amphipod Bioassay ............................................................................................................29 6.2 Acute Larval Echinoderm Bioassay ..........................................................................................29 6.3 Chronic Juvenile Polychaete Bioassay .....................................................................................31 7.0 Benthic Taxonomy Data .....................................................................................................................33 7.1 Benthic Community Indices .........................................................................................................33 7.1.1 Abundance ....................................................................................................................................33 7.1.2 Biomass ..........................................................................................................................................34 7.1.3 Richness .........................................................................................................................................35 7.1.4 Shannon-Wiener Diversity .....................................................................................................36 7.1.5 Pielou’s Evenness .......................................................................................................................36 7.1.6 Swartz’s Dominance ..................................................................................................................36 7.2 Comparison to Other Datasets ....................................................................................................38 8.0 Summary ..................................................................................................................................................40 9.0 References ...............................................................................................................................................42 Figures Figure 1. South Wastewater Treatment Plant and outfall locations with predominant tidal currents indicated (based on NOAA et al., 2009). ................................................. 2 Figure 2. 1995 South Plant NPDES sediment monitoring program sampling stations. ...... 4 Figure 3. 1997 South Plant NPDES sediment monitoring program sampling stations. ...... 5 Figure 4. 1999 and 2001 South Plant NPDES sediment monitoring program sampling stations. ............................................................................................................................................ 6 Figure 5. 2011 South Plant NPDES sediment monitoring program sampling stations. ...... 7 Figure 6. 2017 South Plant NPDES sediment monitoring program sampling stations with predominant tidal currents based on NOAA et al. (2009). ................................ 9 Figure 7. Particle size distribution of sediment samples collected near the South Plant outfalls in 2017 and 2018. ..........................................................................................23 King County Science and Technical Support Section iii November 2018 2017 South Plant NPDES Outfall Sediment Sampling Event: Final Results Figure 8. Summary of 2017 and 2018 South Plant sediment monitoring results highlighting exceedances of the SQS criteria for benzoic acid. ................................26 Figure 9. Benthic invertebrate abundance (average of three replicates per station) by major taxonomic group at eight stations surrounding the South Plant outfall. .............................................................................................................................................34