Columbia Slough Sediment Analysis 2006 Sampling Prepared by: City of Portland Bureau of Environmental Services January 2009 Prepared for: Oregon Department of Environmental Quality Page intentionally left blank EXECUTIVE SUMMARY The City of Portland, Bureau of Environmental Services (BES) and the Oregon Department of Environmental Quality (DEQ) have been engaged in investigating and improving sediment quality in the Columbia Slough for over ten years. During this time, extensive remedial investigations, focused investigations, and feasibility studies have been conducted. BES is currently participating in the state’s Voluntary Cleanup Program to address contaminated sediments in the Slough. As part of the program, BES and DEQ signed an Intergovernmental Agreement (IGA) which describes the actions each agency will take to address sediment quality including conducting long-term monitoring. The Long-term Monitoring Plan, which is an element of the remedial approach for the Columbia Slough, includes sampling fish and sediment every 10 years to assess progress in achieving protective levels, evaluate spatial and temporal trends, and identify areas where more focused remedial efforts may be warranted. During the summer of 2006, BES collected 78 surface sediment samples for analysis of contaminants of interest (COI). The sediment samples were analyzed for polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), metals, and pesticides. The first broad-scale sampling event was conducted in 1994. These data were comprised of sediment samples from 10 segments/reaches throughout the slough. The 2006 samples consisted of 78 sediment samples from the same reaches. In the 2006 sediment data, metals and PAHs were nearly always detected, pesticides ranged widely in percent detection, and many PCB Aroclors were never detected in any sample while others were detected infrequently. For the pesticides, several DDT compounds, chlordanes, aldrin, dieldrin and endosulfan II were some of the more frequently detected contaminants, and were detected in over half of samples. The 2006 sediment data were compared to the Columbia Slough Screening Levels. For the metals, chromium, copper and zinc showed the highest exceedence of the screening levels, with approximately 20% of the samples exceeding for each. The PAHs were typically measured at levels above the screening levels. For the pesticides, gamma chlordane (63%), 4,4’-DDE (62%), alpha chlordane (58%) and dieldrin (51%) were the analytes most frequently detected above their screening levels. Since PCBs were infrequently detected they did not have a high percentage of samples above screening levels, but for Aroclors 1248 and 1260 all detected values were above the screening level (i.e., % detection was equal to % exceed). A little less than half of the detected values for Aroclor 1254 exceeded the screening level. Spatial analysis of the 2006 data indicate a number of areas within the Slough with elevated contaminant concentrations. Whitaker Slough had high levels of DDT compounds, chlordanes, aldrin, dieldrin, endosulfan II, endosulfan sulfate and many PAHs in comparison to the rest of the Slough. The Lower Slough in the I-5/MLK reach had high levels of PAHs, PCB Aroclors 1248 and 1254, copper and zinc. The eastern end of Wapato Slough had the highest concentration of PCB Aroclor 1248, chromium, copper, lindane, heptachlor, naphthalene and nickel. For nickel, the level at this station was over an order of magnitude higher than the rest of the Slough. For lindane and heptachlor, it was the only of the 78 stations across the entire Slough where these two analytes were detected, and the detected value at this site was over two orders of magnitude higher than the detection limit. In general the pattern of sediment contamination in 2006 is consistent with the pattern of sediment contamination in 1994. The key risk drivers and contaminants of concern identified in 1994 continue to exceed screening levels in 2006. Spatial variability in contaminants was roughly similar in the two sampling events. However, there was a consistent pattern of higher contaminant concentrations in 2006 than in 1994. Many contaminants were detected at significantly higher concentrations in 2006 than in 1994. i TABLE OF CONTENTS EXECUTIVE SUMMARY ............................................................................................................... i 1. INTRODUCTION...............................................................................................................1 1.1. Report Organization .......................................................................................................1 2. BACKGROUND ................................................................................................................2 2.1. Site Background .............................................................................................................2 2.2. Previous Studies.............................................................................................................4 2.2.1. 1994 SLRA Sampling of Entire Slough................................................................4 2.2.2. 1995 Buffalo Slough Investigation .......................................................................5 2.2.3. 1997 Wapato Wetland Investigation ....................................................................5 2.2.4. 1998 Peninsula Drainage Canal ..........................................................................5 2.2.5. 1998 Marx-Whitaker Slough Investigation ...........................................................6 2.3. Contaminants of Potential Concern................................................................................6 3. SAMPLE COLLECTION AND FIELD ACTIVITIES ...........................................................6 3.1. Sediment Collection Locations .......................................................................................6 3.2. Sampling Procedures .....................................................................................................8 3.3. Sediment Collection Activities ........................................................................................8 4. 2006 SAMPLE ANALYSES...............................................................................................9 4.1. Analytical Constituents ...................................................................................................9 4.2. Data Usability .................................................................................................................9 5. GENERAL SUMMARY OF THE 2006 SEDIMENT DATA ..............................................10 5.1. Percent Detection for each analyte ..............................................................................10 5.2. Percent Exceedence of Columbia Slough Screening Levels........................................13 6. EVALUATION OF SELECTED CONTAMINANTS..........................................................15 Metals....................................................................................................................................16 6.1. Copper..........................................................................................................................16 6.2. Lead..............................................................................................................................22 6.3. Zinc...............................................................................................................................26 PCBs.....................................................................................................................................27 6.4. PCB 1248 .....................................................................................................................27 6.5. PCB 1254 .....................................................................................................................28 6.6. PCB 1260 .....................................................................................................................29 General Observation on PCB Aroclors .................................................................................30 Pesticides..............................................................................................................................32 6.7. Alpha Chlordane...........................................................................................................32 6.8. Gamma Chlordane .......................................................................................................33 6.9. Dieldrin .........................................................................................................................34 6.10. Sum of DDTs ................................................................................................................37 6.11. Individual 4,4’-DDX Compounds ..................................................................................38 ii Semi-Volatiles .......................................................................................................................43 6.12. Total PAHs ...................................................................................................................43 6.13. Benzo(k)fluoranthene ...................................................................................................45 6.14. Bis(2-ethylhexyl)phthalate ............................................................................................46 6.15. Summary