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SECTION 5 Summary, Conclusions, and Recommendations This section presents the summary, conclusions, and recommendations of the ERA for the Bolsa Chica Lowlands. The objectives of the Bolsa Chica Lowlands project ERA consisted of adequately characterizing of contamination in the Lowlands, providing bioassay/bioaccumulation data necessary to assess ecological risks and to determine cleanup criteria, to assess potential and actual risks to ecological receptors using the Lowlands, and to aid in the design of wetland restoration. The ERA provides a format to achieve these objectives and uses all of the available site information to evaluate potential effects to aquatic, semi-aquatic, and terrestrial receptors under current and expected future conditions. 5.1 Summary The ERA was conducted using a phased/tiered approach that was consistent with established methodologies, but had been adapted to the specific needs of the Bolsa Chica project. Phase I included an initial review of available data and resulted in the CSP/ERA Work Plan (CH2M HILL, 1998a), and Scoping Assessment (CH2M HILL, 1998b). Phase II consisted of the ERA Sampling and Analyses whereby additional site-specific data were collected and evaluated resulting in the EEC Report (CH2M HILL, 1999 ) and Revised Work Plan (CH2M HILL, 2000). Phase III consisted of the Focused Sampling and Analyses, during which additional site-specific data were collected and evaluated to fill remaining data gaps, and completion of this baseline ERA. The analytical data used to characterize exposures consist of the sediment/soil, pore water, surface water, and biota collected previously by Tetra Tech (1996) and by CH2M HILL/Kinnetic Laboratories during the ERA Sampling and Analyses and the Focused Sampling and Analyses. The results of data quality evaluation processes indicated that overall, the project data quality objectives for precision, accuracy, representativeness, completeness, and comparability were met (Appendix C) and the data set was of high quality. The ERA Sampling and Analyses project component was designed to complete sampling for areas away from known or suspected sources of contamination (random sampling locations), to conduct toxicity bioassays and bioaccumulation studies using site-collected sediment and water from both random and focused sampling areas, and to analyze fieldcollected biota for chemicals that bioaccumulate. Random sampling was conducted in areas away from known or suspected contamination, while focused sampling was conducted at selected areas with known contamination. The Focused Sampling and Analysis phase of the ERA occurred in 2000 to conduct more detailed analyses of previously sampled “random” locations (sampled as part of the ERA Sampling), and to identify the nature of contamination associated with previously identified sources (such as sumps, wells, pipelines, maintenance areas, etc.) and potential sources. The focused sampling locations were divided into three main categories: (1) Random Follow-up sites, (2) Previously Uncharacterized sites (Cleanup Agreement and Release [CAR] sites), and (3) Partially Characterized sites. SAC/143368(005.DOC) 5-1 ERA REPORT 7/31/02
CHAPTER 5: SUMMARY, CONCLUSIONS, AND RECOMMENDATIONS This ERA Report was the culmination of the phased approach and incorporated/updated information obtained in previous reports, evaluated results of all phases of field sampling as well as data from the Tetra Tech Phase II Environmental Assessment (1996), and evaluated potential risks to aquatic and terrestrial representative species identified for the Lowlands. The major outputs from the ERA consisted of the development of the ecological conceptual site model (Problem Formulation), the exposure profile (Exposure Characterization), the stressor-response profile (Ecological Effects Characterization), and the risk description (Risk Characterization). Problem Formulation The major product of the Problem Formulation was the ecological conceptual site model. This model combined information on COPECs, potential ecological receptors, potential exposure pathways, assessment endpoints and measures to provide an overall picture of potential for exposure and risk at the site. This model (shown graphically in Figure 2-5) was then used to focus the remainder of the ERA. Exposure Characterization The potential exposure of receptors to COPECs in the Lowlands was determined via the Exposure Characterization. The primary product of the Exposure Characterization was the exposure profile. The exposure profile established a relationship between stressors and potential receptors through: (1) identification of potential sources of chemical stressors (the COPECs) and their spatial distribution across the site, (2) calculation of exposure point concentrations for various exposure media and receptors based on the most likely exposure scenario for each species, and (3) calculation of reasonable maximum daily dosages for chemical intake from abiotic and biotic sources by terrestrial and semi-aquatic birds and terrestrial mammals The Lowlands were divided into areas with similar habitat types under current and/or post-restoration conditions for purposes of evaluating potential risk. The specific Cells included in each area are: • Bolsa Bay – Inner Bolsa Bay (Cell IB) and Outer Bolsa Bay (Cell OB) • Full Tidal – Cells 1, 1A, 3 through 8, 15 through 18, 43, 44, 51, 58, 59, 61, and 62 • Future Full Tidal – Cells 14, 19 through 40, and 63 • Garden Grove – Wintersburg Flood Control Channel – Cell 52 • Gas Plant Pond Area – offsite areas downgradient from the former Gas Plant, south of Cells 11 and 12 • Muted Tidal plus Rabbit Island – Cells 41, 42, 45 through 50, 53, 55, 60, 66, and 67 • Seasonal Ponds – Cells 2, 9 through 13 • Sitewide (biota only) – terrestrial invertebrates that were composited from throughout the Lowlands ERA REPORT 5-2 SAC/143368(005.DOC) 7/31/02
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REVISED FINAL VOLUME I Ecological R
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CONTENTS 3. Analysis...............
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CONTENTS 3-21 Summary of EC 50 s an
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Executive Summary The Bolsa Chica L
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EXECUTIVE SUMMARY The ERA report ev
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EXECUTIVE SUMMARY “focused sampli
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EXECUTIVE SUMMARY Exposure point co
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EXECUTIVE SUMMARY sample. However,
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EXECUTIVE SUMMARY The chemicals in
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SECTION 1: INTRODUCTION • Sedimen
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SECTION 1: INTRODUCTION Assessment
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SECTION 1: INTRODUCTION Based on th
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SECTION 1: INTRODUCTION 1.5 Organiz
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SECTION 2:PROBLEM FORMULATION The L
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SECTION 2:PROBLEM FORMULATION 2.2.1
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SECTION 2:PROBLEM FORMULATION backg
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SECTION 2:PROBLEM FORMULATION The f
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SECTION 2:PROBLEM FORMULATION Benth
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SECTION 2:PROBLEM FORMULATION Fish
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SECTION 3: ANALYSIS The field sampl
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SECTION 3: ANALYSIS CAR Sites A tot
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SECTION 3: ANALYSIS 3.1.2 Data Eval
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SECTION 3: ANALYSIS questionable. T
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SECTION 3: ANALYSIS Pesticides were
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SECTION 3: ANALYSIS copper were det
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SECTION 3: ANALYSIS For five of the
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Page 117 and 118: SECTION 6 References Abbasi, S. A.
Page 119 and 120: SECTION 6: REFERENCES Dunteman, G.
Page 121 and 122: SECTION 6: REFERENCES Kauss, P. B.
Page 123 and 124: SECTION 6: REFERENCES RareFind. 199
Page 125 and 126: SECTION 6: REFERENCES U.S. EPA. 199
Page 127: SECTION 6: REFERENCES Wentsel, R. S
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