1.1 MB pdf - Bolsa Chica Lowlands Restoration Project

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CHAPTER 5: SUMMARY, CONCLUSIONS, AND RECOMMENDATIONS and evaluation area was determined based on the types of RTVs that were exceeded (i.e., noeffect 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 were presented in Tables 4-5 through 4-7. Terrestrial Receptors The primary chemicals in sediment/soil showing potential for risk to terrestrial receptors consisted of metals and some PAHs (Table 4-5). 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. Therefore, it is possible that the risk is underestimated for terrestrial receptors at the Bolsa Chica site. These risks are located throughout the terrestrial portions of the existing and future restored site including parts of the Future Full Tidal, Gas Plant Pond, Muted Tidal, and Seasonal Pond areas. Aquatic Receptors and Sediment Exposure 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 4-6). In addition, significant bioaccumulation of metals and pesticides in Nereis clamworms 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 Future Full Tidal area had both the greatest number of COECs present and the highest magnitude of risk overall due to sediment /soil contamination, whereas Bolsa Bay and the Garden Grove channel had fewer COECs and a lower magnitude of risk from sediment/soil contamination. SAC/143368(005.DOC) 5-5 ERA REPORT 7/31/02
CHAPTER 5: SUMMARY, CONCLUSIONS, AND RECOMMENDATIONS Aquatic Receptors and Water Exposure The chemicals in surface water that showed probable risk (Category A) to aquatic receptors were limited to copper, zinc, and endrin as these chemicals were the only ones that exceeded the CA-WQS acute level (Table 4-7). Possible risk (Category B) was estimated for several other metals, pesticides, and TPH-diesel and waste oil. The Future Full Tidal area had both the greatest number of COECs present and the highest magnitude of risk overall due to surface water quality, whereas the Gas Plant Pond and Muted Tidal areas had few COECS present and none that exceeded acute level RTVs. Overall Metals, some PAHs and petroleum products (TPH-diesel and waste oil) were found to consistently exceed toxic levels in many areas of the site for many receptors (terrestrial and aquatic). These chemicals are consistent with those that are associated with the oil and gas exploration, production and processing activities that have occurred on the site for many decades. Pesticides were also found to be widespread throughout the site. On-site pesticide application is known to have occurred for mosquito control in previous decades. Additionally, urban and agricultural run-off from surrounding areas has likely contributed to certain metal and pesticide concentrations found on-site. 5.2 Conclusion Because this ERA identified a link between exposure to chemical concentrations on this site and adverse effects to plants or wildlife that occur there, it has established that on-site availability of contaminated sediment/soil or water presents a risk of adverse effects to important ecological resources. Many chemicals were identified that pose 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. Based on the results concerning the geographic extent of the contamination, the number of individual COECs and the pathways of exposure, the risk to plants and wildlife on the Bolsa Chica site from sediment/soil contamination is likely greater than from surface water contamination. Similarly, the risk of adverse effects to aquatic and semi-aquatic receptors is likely greater than the risk to terrestrial receptors. Without remediation, the impacts to plants and wildlife in certain areas of the Bolsa Chica site will remain high including continuing contaminated habitat for certain benthic species at chemical concentrations causing chronic or acute impacts, continuing chemical contamination in the food chain resulting in chronic or acute impacts to wildlife feeding on the site and bioaccumulation of certain chemicals into higher trophic levels possibly causing reduced productivity. The results of the ERA provide the basis for determining appropriate clean-up goals for the Bolsa Chica site. The level of risk to terrestrial and aquatic receptors can be reduced from current conditions (presence of known concentrations exceeding acute [or chronic] effects levels) to a future restored state that would reduce the risk by reducing exposure ERA REPORT 5-6 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 The e
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SECTION 2:PROBLEM FORMULATION 2.2.1
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SECTION 2:PROBLEM FORMULATION tern
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SECTION 2:PROBLEM FORMULATION backg
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SECTION 2:PROBLEM FORMULATION 2.4.1
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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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SECTION 3: ANALYSIS the subsurface
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SECTION 3: ANALYSIS 3.1.4 Exposure
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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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