1.1 MB pdf - Bolsa Chica Lowlands Restoration Project

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SECTION 1: INTRODUCTION The ERA Sampling and Analyses (Figure 1-3) were designed to: • Complete the sampling for areas away from known or suspected sources of contamination (described as Random Sampling) • Conduct toxicity and bioaccumulation bioassays (using site-collected sediment or water from random and focused sites) • Analyze field-collected biota Samples were collected in all Cells within the Lowlands to facilitate characterizing the entire site. Co-location of field-collected biota (e.g., plants and wildlife) and abiotic exposure media (e.g., sediment and water) was emphasized, to the extent possible, to take the mobility of animal species into consideration. The data also were used to establish on-site background levels of metals (Section 3.1.1). The areas sampled for ERA purposes included material within the dredging footprint for the Full Tidal habitat, but only for that portion just below the depth of dredging (because that is where organisms would be exposed postrestoration). The bioassays for the ERA were designed to determine acceptable levels of inorganic and organic chemicals in abiotic exposure media to which ecological receptors might be exposed under current or future conditions. Bioassay media included sediment, pore water, and surface water from random and focused sampling sites as described in Sections 4.2, 4.3, and 4.4 of the Work Plan (CH2M HILL, 1998a and 2000) and summarized in Appendix A. The second round of sampling and analyses – the Focused Sampling and Analyses (Figure 1-3) – was designed to evaluate the nature and extent of contamination, if any, associated with previously identified known or suspected sources (such as sumps, wells, pipelines, maintenance areas, etc.). The focused sampling was conducted after the Scoping Assessment and the EEC Report had been completed, and results were used in this final baseline ERA. The findings of the ERA (especially the results from bioassays and background levels of inorganics derived from the ERA Sampling and Analyses) will be used to evaluate remediation needs. This ERA consists of three major components – the Problem Formulation, the Analysis (which includes the Exposure Characterization and the Ecological Effects Characterization), and the Risk Characterization. The relationship of these components is shown on Figure 1-4. The ERA followed established, scientifically sound protocols and methodologies. These protocols and methodologies were adapted to meet the specific needs of the Bolsa Chica project. One adaptation was the preparation of an interim report, the EEC Report (CH2M HILL, 1999), which included the Problem Formulation and Analysis components of the baseline ERA. This adaptation was implemented in response to recommendations from the Technical Committee to conduct site sampling in two phases so the results of the first phase (ERA Sampling and Analyses) could be evaluated to determine the most effective approaches for conducting the second phase (Focused Sampling and Analyses) at known or suspected sources of contamination. It was expected that reductions in the suites of analytes (because particular analytes were not found to be of concern in the Ecological Effects Characterization), using higher detection limits (because they would be sufficient to detect levels of concern), and implementing other strategies (such as evaluating correlations among chemicals) could be used to lower the costs for focused sampling and analyses. SAC/143368(001.DOC) 1-5 ERA REPORT 7/31/02
SECTION 1: INTRODUCTION Based on that recommendation, a programmatic decision was made to defer the Risk Characterization (and completion of the ERA) until the focused sampling and analyses were completed. This ERA identifies risk to ecological receptors by comprehensively evaluating existing information and data (as appropriate) as well as new data developed through the focused sampling and analyses. The assumptions and ecological endpoints outlined for the ERA are based on the ecological management goals for the site, which will become a state or federal refuge and will serve as mitigation of habitat losses elsewhere. Additional site delineation will be necessary once the ERA results are evaluated and clean-up goals are developed. 1.3 Guidance The ERA was performed, according to the following guidance documents and work plans: • Guidance for Ecological Risk Assessment at Hazardous Waste Sites and Permitted Facilities (Cal/EPA, 1996a and 1996b) • Framework for Ecological Risk Assessment (U.S. EPA, 1992a) • ECO Updates, Volume 1, Numbers 1 through 5 (U.S. EPA, 1991a, 1991b, 1992b, 1992c, and 1992d) • ECO Updates, Volume 2, Numbers 1 through 4 (U.S. EPA, 1994a, 1994b, 1994c, and 1994d) • ECO Updates, Volume 3, Numbers 1 and 2 (U.S. EPA, 1996a and 1996b) • Guidelines for Ecological Risk Assessment (U.S. EPA, 1998) • Work Plan for Confirmatory Sampling and Ecological Risk Assessment for Bolsa Chica Lowlands Project, Huntington Beach, California (CH2M HILL, 1998a and 2000) 1.4 Assumptions The ERA was conducted under the following major assumptions or constraints: • No additional remedial actions will be taken (i.e., the ERA will evaluate baseline conditions at the time sampling was conducted). • The media of primary ecological concern for terrestrial and semi-aquatic receptors were soil, surface water, and biota (for secondary consumers). However, because many portions of the site are seasonally flooded, soil and sediment were considered synonymously. • The media of primary ecological concern for aquatic receptors were sediment and surface water. • Chemicals for which analyses were not performed were not evaluated. ERA REPORT 1-6 SAC/143368(001.DOC) 7/31/02
Page 1 and 2: REVISED FINAL VOLUME I Ecological R
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Page 5 and 6: CONTENTS 3-21 Summary of EC 50 s an
Page 7 and 8: Executive Summary The Bolsa Chica L
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CHAPTER 5: SUMMARY, CONCLUSIONS, AN
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SECTION 6 References Abbasi, S. A.
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SECTION 6: REFERENCES Dunteman, G.
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SECTION 6: REFERENCES Kauss, P. B.
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SECTION 6: REFERENCES RareFind. 199
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SECTION 6: REFERENCES U.S. EPA. 199
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SECTION 6: REFERENCES Wentsel, R. S
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