1.1 MB pdf - Bolsa Chica Lowlands Restoration Project

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EXECUTIVE SUMMARY • LC 20 and LC 50 for survival of aquatic invertebrates in sediment – Derived from the regression analyses conducted on amphipod toxicity bioassay results • NOECs for survival of aquatic invertebrates in sediment – Calculated from polychaete worm toxicity bioassay results • EC 20 and EC 50 for larval development of aquatic invertebrates in pore water – Derived from the regression analyses conducted on bivalve toxicity bioassay results • NOECs for survival and growth of fish in surface water – Calculated from fish toxicity bioassay results • NOECs and/or LOECs for survival/growth, reproduction, and/or fecundity of aquatic invertebrates in surface water– Calculated from Ceriodaphnia and Mysidopsis toxicity bioassay results Risk Characterization (Section 4) The Risk Characterization presents the evidence linking COPECs to potential adverse effects in the <strong>Lowlands</strong> including calculation of HQs and evaluation of site-specific toxicity bioassays and bioaccumulation studies to provide a weight-of-evidence for potential risks and identify COECs. The identification of COECs is presented in Figure ES-1. All COPECs that exceeded any available RTV as well as chemicals that showed significant bioaccumulation in Nereis clam worms were retained as COECs. The overall risk posed by a COEC in a given medium and evaluation area was determined based on the types of RTVs that were exceeded (i.e., no-effect levels vs. low-effect levels and chronic effect levels vs. acute effect levels). The overall risk categories were defined as follows: • Unknown – RTVs were not available, so risk could not be quantified. • None – Exposure does not exceed any of the available RTVs. • Uncertain – Exposure exceeds a no-effect level, but risk could not be fully quantified because a low-effect level was not available (Category U). • Some Possible Risk – Exposure exceeds a no-effect level, but not a chronic low-effect level (Category C). • Possible Risk – Exposure exceeds a chronic low-effect level, but not an acute effect level (Category B). • Probable Risk – Exposure represents the highest level that could be quantified. Exposure exceeds an acute effect level or showed significant bioaccumulation in Nereis clam worms (Category A). The COECs in each medium for terrestrial and aquatic receptors are presented in Tables ES- 1 through ES-3. The chemicals in sediment/soil showing potential for risk to terrestrial receptors consisted of metals, PAHs, and potentially dieldrin (Table ES-1). The highest level of risk that could be quantified for terrestrial receptors was Category B (possible risk) because RTVs were limited to chronic no-effect and low-effect levels; acute RTVs were not identified. ERA REPORT ES-10 SAC/143368(ES.DOC) 7/31/02
EXECUTIVE SUMMARY The chemicals in sediment/soil that showed the highest potential for risk (Category A) to aquatic receptors included metals, pesticides, some PAHs, and TPH-diesel and waste oil (Table ES-2). In addition, significant bioaccumulation of metals and pesticides in Nereis clam-worms was observed for several evaluation areas. All COECs that also had significant bioaccumulation were considered to pose a probable risk (Category A) based on comparisons to RTVs, with the exception of lead and vanadium in the Full Tidal area. These chemicals were estimated to pose a possible risk (Category B) to aquatic receptors. The chemicals in surface water that showed probable risk (Category A) to aquatic receptors were limited to copper and endrin as these two chemicals were the only ones that exceeded the CA-WQS acute level (Table ES-3). Possible risk (Category B) was estimated for several other metals, pesticides, and TPH-diesel and waste oil. Conclusions and Recommendations (Section 5) The overall conclusion to the ERA is that several chemicals pose various levels of risk to terrestrial and aquatic receptors. Most notably, metals, pesticides, PAHs, and TPH-diesel and waste oil consistently show possible (Category B) and probable (Category A) risks to receptors. COECs identified in each area of the <strong>Lowlands</strong> are recommended for further evaluation or remediation. Clean-up goals should be developed for each COEC based on the receptors that may be at risk. Once clean-up goals are drafted, the extent of contamination exceeding clean-up goals within each area should be determined so that clean-up efforts will focus only on those areas or portions of areas that cause risk. SAC/143368(ES.DOC) ES-11 ERA REPORT 7/31/02
Page 1 and 2: REVISED FINAL VOLUME I Ecological R
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Page 9 and 10: EXECUTIVE SUMMARY The ERA report ev
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SECTION 3: ANALYSIS dieldrin. These
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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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