Superfund and Mining Megasites Lessons from the Coeur d'Alene River Basin (2005) / Chapter Skim
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7 Ecological Risk Assessment
7 Ecological Risk Assessment
Pages 284-326
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From page 284... ...
In the case of the Coeur d'Alene River basin, the hazardous substances in question represent historic and continuing releases of dissolved and particulate materials from mining operations that have been distributed from the upper and middle basin throughout the study area. The study area addressed in the ERA includes the Coeur d'Alene River and associated tributaries, Lake Coeur d'Alene, and the Spokane River downstream to the Spokane arm of Lake Roosevelt.
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From page 285... ...
In addressing the charge, this chapter reviews the Coeur d'Alene River basin ERA with respect to the following criteria: · Consistency with agency guidance for ERAs · Consistency with best scientific practice in ERA · Validity of conclusions In addition, the chapter addresses the extent to which the proposed remedy is consistent with the conclusions of the ERA and the likelihood that the selected remedy will significantly improve ecologic conditions in the Coeur d'Alene River basin. In performing its review, the committee found it neither necessary nor appropriate to evaluate all of the underlying scientific studies or to identify all of the aspects of the ERA that could have been improved.
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From page 286... ...
, and Ecological Risk Assessment and Risk Management Principles for Superfund Sites (EPA 1999)
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ECOLOGIC RISK ASSESSMENT 287 FIGURE 7-1 ERA process.
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From page 288... ...
288 SUPERFUND AND MINING MEGASITES and temporal patterns of exposure to the end point species and communities identified in problem formulation. In effects analysis, a combination of literature-derived toxicity information, toxicity tests performed on organisms present at the site, and field studies of the characteristics of exposed individuals, populations, and communities are used to estimate the ecologic effects of chemical exposures.
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From page 289... ...
were selected using a two-step procedure. In the first step, the available data on concentrations of chemicals in soil, sediment, and surface water were subjected to a data-quality review.
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, Lake Coeur d'Alene (CSM 4) , and the Spokane River (CSM 5)
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From page 291... ...
It is possible that some of the methods used in the ERA may have been selected because they were consistent with existing data rather than because they were the best approach for quantifying risks to the assessment end points. Also, because the expansion of the Superfund site vastly increased the geographic extent of the site, ecologic effects in some areas may have been incompletely described.
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From page 292... ...
. As discussed later in this chapter, the PRGs for aquatic organisms in sediment and water provided in the ERA are lower-bound thresholds as
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From page 293... ...
As a result of historical flood events, particulate lead has been deposited in streambeds, lakes, riparian zones, and floodplains throughout the lower basin, Lake Coeur d'Alene, and the Spokane River. Based on the environmental concentration data and comparisons to screening levels, as described above, the selection of COPECs was reasonable.
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From page 294... ...
Impacts of physical disturbances, including non-mining-related disturbances, would still have to be considered during remedy selection and implementation, but they need not be explicitly addressed during the risk assessment component of the RI/FS process. Characterization of Existing Ecologic Conditions The Coeur d'Alene River basin is a complex ecologic zone consisting of the Coeur d'Alene River and tributaries, lateral lakes, Lake Coeur d'Alene, and the Spokane River.
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From page 295... ...
These studies, in combination with necropsy findings, have characterized the acutely toxic effect of metals-contaminated sediments on waterfowl. Far less information about the aquatic communities in the lower basin is available.
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From page 296... ...
of soil, sediment, water-quality, foodsource, and habitat conditions supportive of individuals of special status biota (including plants and animals) and migratory birds (species protected under the Migratory Bird Treaty Act)
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From page 297... ...
Specific measures of exposure defined for the site included concentrations of chemicals in sediment, soil, surface water, and biota. The types of assessment end points found in each CSM unit and habitat type were summarized (CH2M-Hill and URS Corp.
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From page 298... ...
A database of metals concentrations in surface water was compiled for the RI from which expected values for metals loading through the basin were determined.3 Metals loading diagrams are presented in the ERA and demonstrate that the original Bunker Hill Superfund site (the box) is the portion of the system contributing the largest loads of dissolved zinc, followed by Canyon and Ninemile Creeks.
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From page 299... ...
2000 for ecologic receptors and the large body of paired blood lead and environmental data for children that was developed as part of the Bunker Hill Box residential areas cleanup) , understanding speciation was not necessary to evaluate health risks" (EPA 2004)
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From page 300... ...
The committee could not conduct a case-by-case review of this process and the database and resulting statistics; however, it was determined that the data-reduction technique eliminated chemical data for surface water in the main body of Lake Coeur d'Alene.5 The end product of the data-qualification process is important as these data are used in the ERA to determine risk on the basis of water concentrations of the metals (CH2M-Hill and URS Corp.
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From page 301... ...
Mean lead concentrations were high est in samples collected from the Ninemile and Canyon Creek sediments with biofilm lead > 25,000 µg/g and 12,000 µg/g, respectively. Mean lead concentra tions in whole perch collected in the lower basin were much lower than those measured in sediments, biofilm, or invertebrates; however, body burdens of lead were measured at greater than 50 µg/g.
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From page 302... ...
External exposures for birds and mammals evaluated in the ERA are primarily through contact with contaminated soils and sediments. Extensive studies characterizing the concentrations in these media existed for use in the ERA, particularly for habitats in the lower basin.
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From page 303... ...
Total doses of each metal were obtained by summing the contribution of each food type. To apply the models, concentrations of metals in sediment/soil and water for all samples collected within a given CSM unit and habitat type were used to generate summary statistics.
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From page 304... ...
Questions addressed include whether the underlying studies conform to best scientific practices, whether all the available and relevant data were considered, and whether the data were properly interpreted. Aquatic Receptors Metals have long been understood to be toxicants and substantial data exist in the literature on the effects of metal exposures on aquatic organisms.
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From page 305... ...
determined that water samples from South Fork Coeur d'Alene River near Wallace downstream of Canyon Creek were acutely toxic to hatchery-reared rainbow trout, whereas South Fork River water collected at stations upstream from Wallace (near Mullan and near the river's headwaters) did not have a toxic effect.
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From page 306... ...
However, an integrated laboratory and field study designed specifically to support the ERA could have provided a much stronger foundation for the PRGs developed in Section 5 of the ERA. The available data for fish and invertebrates in the lower basin are substantially more limited than for the upper basin and do not appear sufficient to support any meaningful conclusions about the existence and magnitude of risks.
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From page 307... ...
The ROD (EPA 2002) states that 95% of the wetland habitats in the lower basin have lead concentrations greater than 530 mg/kg.
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From page 308... ...
Multiple species of wildlife, in particular birds, ingest contaminated sediment, resulting in high levels of lead in their tissues. A variety of studies presented in the ERA document adverse biochemical and physiologic effects to Coeur d'Alene wildlife as well as mortality.
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From page 309... ...
Evaluation of the toxicity of forage contaminated by smelter emissions to horses For fish and other aquatic organisms, the principal line of evidence used was comparison of measured concentrations of COPECs in surface water with hardness-adjusted national AWQC. This quantitative evaluation was supplemented with qualitative evaluation of results of site-specific toxicity tests and field surveys conducted in the basin.
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From page 310... ...
Field surveys of amphibian species assemblages and relative abundance in wetlands of the lower Coeur d'Alene River basin and Lake Coeur d'Alene For terrestrial plants, the following three lines of evidence were used: 1. Comparisons of concentrations of COPECs in soil and sediment with site-specific and literature-derived toxicity benchmarks 2.
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From page 311... ...
However, only very limited comparisons between benthic communities in contaminated versus reference stream reaches were possible because the surveys conducted in different areas utilized inconsistent sampling techniques. Potential receptors in the sediments of Lake Coeur d'Alene receive very little attention in the ERA, although ample evidence exists about the extent and magnitude of sediment contamination in Lake Coeur d'Alene (Funk et al.
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From page 312... ...
Although lead concentrations found in livers of song sparrows in the assessment area were significantly greater than those in the reference sites, effects of these differences were not examined. Sediments collected from Killarney Lake were used in a 3-week feeding trial to test the bioavailability of lead from contaminated sediment in northern bobwhites (Colinus virginianus)
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From page 313... ...
. Therefore, because of the strength of the waterfowl data and the wellestablished causal relationship between lead-contaminated sediment and waterfowl mortality, models predicting waterfowl risk based on sediment concentrations are appropriate to develop cleanup levels.
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From page 314... ...
However, in the Coeur d'Alene River basin, these stressors are of limited importance to assessment of wildlife toxicology. Moreover, habitat, particularly for waterfowl in the lower basin, is not a limiting factor.
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From page 315... ...
The 10th percentile of the resulting distribution of sediment concentrations was chosen as the PRG. For aquatic biota exposed to contaminated sediment and water, the only PRGs provided were freshwater sediment screening values recommended by National Oceanic and Atmospheric Administration (NOAA)
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From page 316... ...
The PRGs for aquatic biota, and especially for sediment, appear more questionable and do not appear to be consistent with EPA guidance. For surface water, the AWQC are potentially applicable or relevant and appropriate requirements (ARARs)
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From page 317... ...
then combined their exposure equation with data on blood lead con centrations measured in lead-intoxicated tundra swans in the basin and estimated that some mortality would occur at a sediment lead concentration as low as 1,800 mg/kg. EPA made a risk management decision to use the site-specific protective value lead concentration of 530 mg/kg as the benchmark cleanup criterion for the soil and sediment in the lower basin for protection of waterfowl.
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From page 318... ...
Substantial channel alterations have occurred in the upper South Fork for the purposes of flood control, remediation, and road building. Historically, much of the floodplain of the South Fork of the Coeur d'Alene River was forested, particularly with large cedars.
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From page 319... ...
it was more extensive and detailed than are many ERAs. However, there were some potentially significant exceptions that limit the adequacy of the ERA for supporting appropriate remedial actions.
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From page 320... ...
and fish (zinc and other dissolved metals) ; support for conclusions about other receptors is much more uncertain.
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From page 321... ...
Information is particularly lacking on effects to benthic invertebrate and fish communities in the lower basin, the magnitude and spatial extent of risks to riparian and upland communities, and the condition of benthic communities in Lake Coeur d'Alene in relation to contaminated sediments. Recommendation 2 Further research is needed on the influence of transport and transformation processes on the fluxes and bioavailability of particulate lead and dissolved metals.
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From page 322... ...
2001. Final Ecological Risk Assessment: Coeur d'Alene Basin Remedial Investigation/Feasibility Study.
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From page 323... ...
1999. Issuance of Final Guidance: Ecological Risk Assessment and Risk Management Principles for Superfund Sites.
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From page 324... ...
1995. Effect of mining and related activities on the sediment trace element geochemistry of Lake Coeur d'Alene, Idaho, USA.
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From page 325... ...
Bunker Hill Mining and Metallurgical complex Operable Unit 3.
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From page 326... ...
U.S. Geological Survey, Columbia Environmental Research Center, Jackson, WY; R2 Re sources, Redmond, WA; City of Seattle City Light, Seattle, WA; U.S.
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