Appendix D: Case Study Questionnaire and Summaries
Case Study Questionnaire
To document how bioavailability is currently being used in site evaluations, a case study questionnaire was developed and distributed to members of the ITRC Contaminated Sediments Team; ITRC State Points of Contact; ITRC Industry Affiliates Program members; and federal representatives, including USEPA, Departments of Defense and Energy, USACE, and USGS. The main goal of the survey was to identify sites that used measures of bioavailability to gain regulatory acceptance. Associated questions that the ITRC Contaminated Sediments Team wanted to answer through its review of case study information were as follows:
- What types of bioavailability assessments are being conducted at contaminated sediment sites throughout the United States?
- How does the evaluation of bioavailability within exposure pathways affect the risk management decisions for a site?
- How have bioavailability considerations been used at contaminated sediment sites to establish or alter cleanup levels or to dictate how risk to a receptor or group of receptors is managed?
The survey was developed through an iterative review and revision process covering several months. The team identified the survey objectives and survey audience and defined how the collected data would be used. The survey was beta-tested among team members and a number of selected respondents and modified accordingly. The final survey was reviewed and approved by the ITRC Team Leader Liaison and State Engagement Coordinator according to the “ITRC Technical Team Survey Development Planning Information, Guidance and Request Template.” The survey information collection period lasted six weeks. The case study questionnaire was distributed in June 2008, and most responses were received by August 2008. Team members reviewed the questionnaires and developed a series of follow-up questions to establish how bioavailability was used at a site and to determine whether its use contributed to the development of cleanup levels. The results of follow-up questions were used to categorize the case studies according to the primary pathway where bioavailability was assessed and what tools were used during the assessment. The summary presented here represents only the information we received and is not intended to represent every sediment site throughout the United States.
Other sources of information are available. For instance, the Sediment Management Working Group has compiled a Major Contaminated Sediment Sites Database (www.smwg.org/MCSS_Database/MCSS_Database_Docs.html), which presents information on contaminated sediment remediation projects in the United States. This database was developed for major sediment sites and excludes smaller sites (e.g., those with contaminated sediment volumes less than 3000 yd3). Viewers should also make note of the dates that the database has been updated, as some information may be out of date.
A total of 35 case studies were received through the ITRC questionnaire from state and federal regulators as well as industry and other government interests. These also included information from an unpublished summary of cases compiled by Charles Menzie in 2008 in preparation for the SERDP-ESTCP Workshop on Bioavailability of Soils and Sediments (SERDP and ESTCP 2008). The case studies are briefly summarized in Table 9-1. A more detailed description and contacts for each case study is provided in this appendix.
From our limited number of sites reviewed, the benthic exposure pathway have been evaluated most often, followed by the human health and the pelagic pathways. Sediment chemistry and bioassays using benthic invertebrates are the most common tools used to assess bioavailability. Tissue sampling of various media (fish, bivalves, or other pelagic receptors) and pore-water chemistry were also commonly used to evaluate the bioavailability of contaminants at the sites reviewed. Pore-water chemistry was either predicted using EqP from bulk sediment, directly analyzed following centrifugation of bulk sediment, or measured using SPME or similar device.
In the majority of sites reviewed, more than one tool was used to assess a given exposure pathway. These tools included the following:
- bulk sediment chemistry
- pore-water chemistry, measured or derived through EqP toxicity testing
- tissue analysis
- bioaccumulation testing
- trophic modeling, including the derivation of BAFs/BSAFs
- benthic community survey
- SEM – AVS
An SQT approach (i.e., sediment chemistry, toxicity testing, and benthic community survey) was used at nine of the sites reviewed. COCs at the case study sites included the following:
- organics, including PAHs, PCBs, petroleum hydrocarbons, chlorobenzene/aromatic amines
- metals, including nickel, lead, copper, cadmium, arsenic, mercury, selenium
Bioavailability was incorporated in the decision-making process by helping to establish site- specific cleanup goals in approximately 50% of the case studies. For the other sites where bioavailability was assessed but not clearly used in decision making, it was generally reported that the cleanup goals or remedial decisions had not yet been made.
As previously mentioned, limited information regarding the case study information is provided in Table 9-1. This information includes the primary exposure pathways assessed, the COCs at the site, the methods or tools used to assess bioavailability, and whether the bioavailability information was used to make a regulatory site decision. More detailed summaries of each site reviewed, along with contact information for case managers and links to online documents, where available, are included below. These more detailed summaries may provide additional insight that is not included in the summary table.
Dwight Leisle, 360-396-0935, Dwight.Leisle@navy.mil
Primary Pathway: Human health
Contaminants: PCBs and mercury
Tools: Bulk sediment chemistry, fish tissue chemistry, methylation process study
How Bioavailability Was Used: Bioavailability will be a consideration now that a supplemental HHRA has determined there is a risk associated with mercury. A mercury cleanup level has not yet been set.
Regulatory and Stakeholder Challenges: The primary risk driver at this site was established in 1999 as a human health risk to subsistence finfish harvesters from PCB concentrations in bottom fish. A cleanup goal was established for PCB concentrations in surface sediment, which was assumed to eventually result in a reduction in PCB concentrations in marine tissue. The PCB sediment cleanup goal was not risk based, and no bioavailability determination was made. The PCB cleanup goal was instead based on a cost-benefit analysis.
A supplemental HHRA, recently conducted as the result of a recommendation in the second Five-Year Review, found unacceptable risk to subsistence harvesters from mercury in fish and shellfish tissue. A mercury source study, conducted in parallel with the risk assessment, will include an evaluation of the mercury methylation processes at the site that will help characterize mercury bioavailability. The overall objective of this study is to describe and quantify the biogeochemical processes that lead to the bioaccumulation of methylmercury into the base of the pelagic food web, methylation of mercury in sediments, and the release of methylmercury and ionic mercury from the sediments. USGS is performing this study with an estimated completion date of September 2011. This study will assist in the establishment of a mercury cleanup goal.
D-2. Bradford Island Disposal Site, Bonneville Dam Forebay, Cascade Locks, Oregon
Michael Gross, 503-808-4913, Michael.J.Gross@usace.army.mil
Site Description: Bradford Island is within the Bonneville Dam facility on the Columbia River, 40 miles east of Portland, Oregon. Various wastes associated with operations at the dam were disposed of on the island between the 1940s and 1980s. In 2000, electrical components were discovered in the river. These had apparently been dumped down the north slope of the island. Some of these contained PCBs. Three removal projects have been conducted between 2000 and 2007 to remove the equipment, debris, and contaminated sediment. Work is under way to evaluate the risk to human and ecological receptors posed by the remaining contamination.
Primary Pathway: Human health, pelagic, and benthic
Tools: Bulk sediment chemistry, tissue, and surface-water chemistry
Methods: Contaminant concentrations in sediment, benthic tissue, and fish tissue are being used to evaluate baseline risk. Trophic models may also be used to calculate acceptable contaminant concentrations.
How Bioavailability Was Used: Bioavailability is being evaluated based on long-term monitoring of tissue levels.
Regulatory and Stakeholder Challenges: Diver-assisted suction dredging of sediment was conducted in 2007 in areas totaling approximately 1 acre, where PCB concentrations exceeded 500 µg/kg. Contaminant concentrations in sediment and crayfish have declined significantly over the past several years. However, the most recent samples of fish tissue (smallmouth bass) showed elevated PCB concentrations averaging 2900 µg/kg. Future sampling will be required to determine whether these concentrations decline.
Mary Beth Ross, USEPA Great Lakes National Program Office, 312-886-2253, Ross.Marybeth@epa.gov
Site Description: The Buffalo River is located in Buffalo, New York and discharges into Lake Erie. The lower 6.2 miles of the Buffalo River and the adjacent City Ship Canal (1.4 miles) have been identified as a Great Lakes area of concern. A legacy of industrial activity during the last 150 years has lead to elevated chemical concentrations in the river sediments, including PAHs, PCBs, mercury, and lead.
Primary Pathway: Human health, benthic, pelagic
Contaminants: Indicator contaminants included PAHs, PCBs, mercury, lead.
Tools: Bulk sediment and pore-water chemistry, AVS/SEM, toxicity tests, fish tissue chemistry, benthic taxonomy surveys
Methods: The determination of a site-specific toxicity unit for PAHs was based on USEPA’s EqP approach using multiple data sets, including sediment toxicity testing and site-specific Koc values. It also included an evaluation of USEPA’s target lipid model approach using site-specific bioaccumulation data. The theoretical bioaccumulation potential model was used to understand the potential bioaccumulation of PCBs in fish tissue, and mercury and lead concentrations in Buffalo River fish tissue were compared to state criteria that have been determined to be protective of fish and piscivorous wildlife.
How Bioavailability Was Used: Multiple bioavailability tools were used to develop of a site-specific remedial goal for total PAHs, including pore-water measurements, sediment toxicity tests, bioaccumulation tests, and an evaluation of USEPA’s target lipid model. The development of a PAH remedial goal was based on USEPA’s EqP approach using site-specific partitioning information. Pore-water measurements demonstrated that aqueous PAH concentrations were less than what would have been predicted through models typically used to estimate chemical partitioning. For PCBs, a bioaccumulation potential model was used along with site-specific sediment chemistry data to determine a remedial goal that would be protective of fish-eating birds and mammals. Site-specific mercury and lead fish tissue data were compared to state criteria. Mercury and lead concentrations in Buffalo River fish tissue were well below the state criteria; thus, mercury and lead remedial goals were identified so that remedial options could be evaluated against current conditions. AVS/SEM also demonstrated very low metals bioavailability in Buffalo River sediment.
Jonathon Weier, CH2M HILL, 770-485-7503, firstname.lastname@example.org
Primary Pathway: Benthic, pelagic
Tools: Bulk sediment and surface-water chemistry, trophic modeling, macroinvertebrate chemistry
Methods: Sediment compared to benchmarks and benthic macroinvertebrate survey data. Surface water compared to benchmarks for the protection of amphibians and survey data for fish and other water column receptors.
How Bioavailability Was Used: No cleanup was done. The evaluation resulted in a conclusion of no risk (see comments).
Regulatory and Stakeholder Challenges: We conducted a baseline ERA for Site 89 (a stream) due to exceedances of benchmarks for sediment and surface water. The assessment involved collection of substantial data at four site locations and four reference locations. This stream was physically impacted due to anthropogenic influences other than the release, and we wanted to control for that in our analysis. We collected data on the physical character of stream, chemistry (i.e., contaminants), macroinvertebrates, water-quality parameters, and fish community and did food chain modeling and comparison of media concentrations to benchmarks. This may not be a “classic” type of bioavailability study. I do think that the case can be made that field surveys of biota relative to reference can be a indirect way at getting to bioavailability and a very direct way of assessing risk. No cleanup was done. The evaluation resulted in a conclusion of no risk.
A reference comparison method was used to measure bioavailability. We characterized the faunal community at the site and compared it to reference conditions, controlling for physical conditions of the watercourse. Cluster analysis was used to demonstrate the comparability of the reference and site stream sampling locations. Basically, we demonstrated the reference and site stream conditions in terms of physical character and biota were similar, suggesting that the release did not have any discernable effect. Mainly, the assessment of the physical features of the stream and the biota data collected in the field were used in the comparison study.
Timothy Drexler, 312-353-4367, email@example.com
The St. Regis Paper Company Superfund site is a former wood-preserving facility that operated 1957–1985. Groundwater, sediment, and soil on and in the vicinity of the site are contaminated as a result of the wood-preserving process and waste-disposal activities. The site consists of 125 acres within the exterior boundary of the Leech Lake Reservation, adjacent to the Chippewa National Forest, in the City of Cass Lake. Most of the site contamination is the result of pressure treatment of wood with pentachlorophenol. PCP affects the central nervous system, cardiovascular system, liver, and kidneys. Workers and some nearby residents may have been exposed to toxic levels of PCP when the plant was operating. Current concerns include soil contamination from PCP, PAHs, and dioxin/furans (“dioxin”). Dioxin/furans were impurities in the PCP. Dioxins cause cancers in soft tissues, neurological effects, immune system toxicity, and developmental disorders. The other concern, addressed by an existing treatment system, is groundwater contaminated with PAHs and PCP. Current activities at the site stem from reviews of response actions taken in the mid-1980s, some of which were found to be inadequate for protection of human health and the environment.
Primary Pathway: For human health risk, soil, sediment, surface-water, and groundwater exposures to residents were evaluated, including those with tribal lifeways, children, and workers. For ecological risk, direct uptake from sediment and water by aquatic invertebrates and fish was evaluated. Dietary uptake by piscivorous, herbivorous, or omnivorous birds, mammals, and reptiles was also studied.
Tools: Bulk sediment and surface-water chemistry, sediment bioaccumulation assays, field bioaccumulation (plant, benthic invertebrates, and fish), and sediment toxicity tests including AVS-SEM
Methods: A new cleanup method is, as yet, unknown since a revised cleanup decision has not been reached for this site. A USEPA ROD is due in 2011. However, site investigations used to generate data to support the human health and ecological risk assessments did include the evaluation of contaminant bioavailability as follows:
- laboratory bioaccumulation—28-day Asiatic clam (Corbicula fluminea) and oligochaete (Lumbriculus variegates)
- field bioaccumulation—fish, crayfish, wild rice, cattail roots, and mussels
- sediment toxicity tests—10-day midge (Chironomus dilutes) and 10- and 28-d amphipod (Hyalella azteca)
How Bioavailability Was Used: From an HHRA perspective, contaminant bioavailability from sediments was evaluated by measuring the concentrations of contaminants in various foodstuffs (such as wild rice, bivalves, and finfish including eggs) that are growing or living in or near contaminated sediments. Also, potential human exposure through incidental ingestion of contaminated sediments was also evaluated. Calculation of ingestion exposures considered contaminant-specific RBA ([absorbed fraction from soil/sediment]/[absorbed fraction from dosing medium in toxicity study]).
- Field bioaccumulation data were used directly in food-chain exposure models (fish, crayfish, mussels, cattail root, and wild rice organic contaminants) or used to derive site-specific BSAFs (wild rice metal contaminants).
- Laboratory bioaccumulation data were used directly in food-chain exposure models (Corbicula and Lumbriculus).
- Sediment toxicity tests provided a line of evidence of sediment risk.
Comments: With regard to ecological risk, bioavailability was not directly measured with the exception of AVS-SEM, which was used as a part of the sediment toxicity testing, but the influence of bioavailability was captured through measurement of site-specific laboratory and field bioaccumulation and sediment toxicity.
Regulatory Agency: CERCLA/Pennsylvania Department of Environmental Protection
Frank Klanchar, 215-814-3218, Klanchar.Frank@epamail.epa.gov
Site Description: The 32-acre Centre County Kepone site, in State College, Pennsylvania, was a chemical manufacturing facility that produced the pesticide kepone in 1958, 1959, and 1963, and the pesticide mirex in 1973 and 1974. Process wastes were originally disposed of on site in a spray irrigation field, a concrete lagoon, and two earthen lagoons. Process wastes also were stored in drums on site. After leaks were discovered, the material in the lagoons was solidified and disposed of in the two earthen lagoons and capped. However, the material failed to solidify, and hazardous materials leached into the groundwater and surface water. Spring Creek is located adjacent to the site, and in 1982 a section of the creek was designated as a catch-and-release zone for fishing as a result of high levels of pesticides in fish.
Primary Pathway: Human health, benthic, pelagic
Contaminants: Mirex, kepone, photomirex
Tools: Bulk sediment chemistry, surface-water chemistry, fish tissue chemistry
Methods: Toxicity thresholds were identified or derived for relevant biota based either on existing or recommended guidelines (i.e., ambient water-quality criteria or sediment thresholds). Where published guidance was not available, toxicity thresholds were derived. The quotient method for characterizing potential risk was used [BAF = % lipid (Kow)/% carbon (Koc)]. Assuming receptors continuously inhabit the area, the ratio of measured (or estimated) exposure to the established (or estimated) toxicity threshold gives an indication of relative risk. Ratios of >1 were interpreted to indicate ecological risk, while ratios of <1 indicate negligible ecological risk.
How Bioavailability Was Used: The quotient method analysis showed ratios of >1 for all zones tested. Soil cleanup levels were set at the level established by USEPA to be protective of environmental receptors. Considering the BAF quotient, removal of sediment to meet USEPA’s cleanup level would ensure that fish tissue levels do not exceed Food and Drug Administration (FDA)–established fish-tissue action levels for mirex and kepone of 100 µg/kg and 300 µg/kg, respectively. A fish-tissue and sediment monitoring program is in place to evaluate future contamination trends.
Comments: The ERA carried out in the RI used the surrogate approach, which involves extensive assumptions as the basis for the models. Many of the assumptions were unjustified, resulting in an ERA that is not protective of ecological receptors as a whole. For example, the ERA used the assumption that the OC level of the soil is 5% and the lipid content of the earthworm is 0.85%. The carbon content of the site soil ranges 1%–4%, and the lipid content of the earthworms is 1.5%. Using the reasonable assumption that the average carbon content of the soil is 2.5% and entering the values of 2.5 and 1.5 into the calculations to derive the bioaccumulation factor for earthworms, the results increase nearly fourfold [BAF = % lipid (Kow)/% carbon (Koc)]. These changes exert a change in the environmental effects quotient from the 0.05 contained in the RI to 9.5. Thus using actual site data for organic content and lipids made a huge difference in how the site was handled from a regulatory and cleanup perspective.
Janine MacGregor, 609-633-0784, firstname.lastname@example.org
Site Description: From 1951 to 1969, the Diamond Alkali Company (subsequently known as the Diamond Shamrock Chemicals Company) owned and operated a pesticides manufacturing plant at Lister Avenue in Newark. The property has been used for manufacturing by numerous companies for more than 100 years. The mid-1940s marked the beginning of the manufacturing operations related to the current site conditions, including the production of DDT and phenoxy herbicides. Subsequent owners used the property until 1983, when sampling at the site and in the Passaic River revealed high levels of dioxin. Dioxin (also known as 2,3,7,8-tetrachlorodibenzo-p-dioxin, or TCDD) is an extremely toxic chemical and an unwanted by-product of the manufacture of certain chemicals which were produced at the site. USEPA added the site to the Superfund National Priorities List on September 21, 1984 because of hazardous substances present at the site and in the Passaic River, which borders the property.
The site comprises three parts: the former pesticides manufacturing plant and surrounding properties at 80 and 120 Lister Avenue, the Lower Passaic River Restoration Project Study Area, and the Newark Bay Study Area. Dioxin, pesticides, and VOCs, all of which can pose serious human health risks, were detected at the Lister Avenue properties. Occidental Chemical Corporation, a successor to the previous owner, the Diamond Shamrock Chemicals Company, performed interim cleanup work at the Lister Avenue properties and is performing a study of Newark Bay with USEPA oversight.
In 2004, USEPA formed a partnership with USACE, U.S. Fish and Wildlife Service (USFWS), NOAA, New Jersey Department of Environmental Protection (NJDEP0, and the New Jersey Department of Transportation and to conduct a joint study of the Lower Passaic River.
Primary Pathway: Human health, benthic, pelagic
Contaminants: PCBs, dioxin, dieldrin, chlordane, DDT, TCDD, mercury, copper, lead
Tools: Tissue chemistry, toxicity testing, BSAFs
Methods: Sampling of Passaic River sediments conducted during the RI/FS for the Diamond Alkali plant revealed numerous organic and inorganic compounds including, but not limited to, TCDDs and PCDFs, pesticides, PCBs, PAHs, and metals.
How Bioavailability Was Used: Bioavailability was factored into the risk assessment, but ultimately it was not used to determine a cleanup number. A feasibility study was performed to remove a major source of dioxin contamination from the lower Passaic River, eliminating the potential future threat that these harmful contaminants could pose to people’s health and the environment. The agreement calls for 200,000 yd3 of dioxin-laden sediment to be taken out of the river in the direct vicinity of the Diamond Alkali Superfund site in downtown Newark. This sediment is known to have the highest levels of dioxin in the lower Passaic. Cleanup levels are based on primarily the human health pathway through consumption of fish and crabs and secondly the benthic pathway.
Regulatory and Stakeholder Challenges: Direct contact exposures by sediment-associated receptors and indirect exposures associated with consumption of prey that have bioaccumulated sediment-borne contaminants. Bioavailability of contaminants were evaluated by looking at contaminant levels in biological tissue samples, toxicity testing, and development of site-specific BASF values. Sediment cleanup criteria have not been generated. Tissue testing and toxicity studies were used to measure bioavailability.
Comments: In June 2008, Occidental Chemical Corporation and USEPA signed an Administrative Order on Consent for a non-time-critical removal of approximately 200,000 yd3 of contaminated sediment from the Passaic River in the vicinity of the former Diamond Alkali plant in Newark, to be done in two phases. Phase 1 will include the excavation of 40,000 yd3 of contaminated sediment, which will be shipped off site for treatment and disposal. Phase 2 will include the excavation of 160,000 yd3 of contaminated sediment.
For further information, visit www.epa.gov/region2/superfund/npl/diamondalkali/.
Bob Schwarz, 541-298-7255 x230, email@example.com
Regulatory Agency: Oregon Department of Environmental Quality (DEQ)
Site Description In August 2000, approximately 2600 gallons of herbicide spilled, and an unknown portion of this entered Fifteenmile Creek when the truck carrying it crashed on the bridge above. Approximately 1200 feet of the creek, from the accident site to the confluence with the Columbia River, was affected. The herbicide is Goal 2XL, and its active ingredient is oxyfluorfen (2-chloro-1-(3-ethoxy-4-nitrophenoxy)-4-(trifluoromethyl) benzene). Although not very harmful to mammals or birds, oxyfluorfen is toxic to fish and other aquatic life. The Oregon Department of Fish and Wildlife estimates that about 5500 fish died as a result of the accident. Almost all of these were juvenile Pacific lamprey, which spend the first four to six years of their lives burrowed in sediment. Oxyfluorfen preferentially partitions to OC in sediment in aquatic environments. Emergency response measures focused on preventing contamination from escaping into the Columbia River. Remedial measures involved placement of booms, sandbag dams, and water-filled fabric dams; diversion of creek water from the affected area; and removal of contaminated sediment by suction dredging and dry excavation.
Primary Pathway: Benthic, wildlife
Tools: Bulk sediment chemistry, tissue chemistry, toxicity testing, histopathology
Methods: Effects on aquatic invertebrates were determined based community impairment using macroinvertebrate studies and toxicity using laboratory bioassays. Effects on larval lamprey were evaluated based on population density upstream and downstream and histopathology studies. Effects on other fishes were evaluated based on histopathology studies and in situ caged fish studies to measure survival rates and bioaccumulation. Impacts on terrestrial wildlife were based on ingestion doses.
How Bioavailability Was Used: Bioavailability was measured based on site-specific ratios between concentrations in sediment, water, and biota (juvenile lamprey burrowing in sediment and trout that were held in cages in the water column for 30 days).
Regulatory and Stakeholder Challenges: No information.
Site Description: The Fox River and Green Bay Site includes an approximately 39-mile section of the Lower Fox River, from Lake Winnebago downriver to the mouth of the river, and all of Green Bay, totaling approximately 2700 square miles. This stretch of the river and bay flows through or borders Brown, Door, Kewaunee, Marinette, Oconto, Outagamie, and Winnebago Counties in Wisconsin and Delta and Menominee Counties in Michigan. The site has been divided into discrete areas (OUs). The river portion of the site comprises OU-1 through OU-4, and the bay portion of the site is designated OU-5 for purposes of site management. PCBs, the primary risk driver, are contained in sediment deposits located in the river and the bay. More than 75 COPCs (metals, PCBs, dioxins, pesticides, and PAHs) were identified in the screening-level risk assessment conducted to evaluate which chemicals in the system pose the greatest degree of risk to people and ecological receptors.
Primary Pathway: Human health and pelagic
Tools: Bulk sediment chemistry, toxicity tests, benthic community surveys, bioaccumulation/ bioassays, SEM/AVS
Methods: For benthic infauna, calculated HQs based on PCB SQOs were high. Benthic community analyses showed dominance of pollution-tolerant oligochaetes and chironomids. Sediment bioassays on bulk sediments collected from the same locations as benthic infaunal samples showed toxicity using the amphipod Hyalella azteca, the oligochaete Lumbriculus variegatus, the chironomid Chironomus riparius, and the mayfly Hexagenia limbata. Pore-water toxicity was also indicated in acute and chronic bioassays on the alga Selenastrum capricornutum, the invertebrate Ceriodaphnia dubia, the bacterium Photobacterium phosphoreum and the fathead minnow Pimephales promelas. Measured body burdens in native infauna showed uptake of PCBs but not dioxins or PAHs. By most measures, PCBs were impacting benthic resources. However, a TIE conducted on sediments from OU-4 and Green Bay demonstrated that ammonia, not PCBs, was responsible for most of the observed effects (Ankley, Katko, and Arthur 1990).
SEM/AVS ratio and metal concentrations in pore water revealed the bioaccumulation of copper, lead, zinc, cadmium, nickel, and chromium by L. variegatus held for an extended time in various sediment samples from the lower Fox River, Wisconsin.
How Bioavailability Was Used: PCBs were included as COCs for the ROD but did not factor into the setting of the remedial action levels for any of the OUs. The systemwide remedial action level was set to 1 ppm with a goal of achieving a surface-weighted average concentration (SWAC) of 0.25 ppm. It has been estimated that the removal of the contaminated sediment above 1 ppm will result in a SWAC of 0.26 ppm for OU-3 and of 0.16 ppm for OU-4.
Comments: The major components of the selected remedy include (1) removal of about 6,475,800 yd3 of contaminated sediment containing over 27,575 kg (60,660 pounds) of PCBs from OU-3 and -4 using environmental dredging techniques and (2) MNR of the residual PCB contamination remaining in dredged areas, undisturbed areas, and OU-5 until the concentrations of PCBs in fish tissue are reduced to an acceptable level. The long-term monitoring program covers various media (e.g., water, tissue, and sediment) throughout OU-3, -4, and -5 to determine the effectiveness of the remedy.
Bill Mason, 541-687-7427, firstname.lastname@example.org
Site Description: Glenbrook Nickel Company operated a nickel ore unloading, drying, and crushing facility on water-front property in Coos Bay. Ore was offloaded into receiving hoppers located on a free-standing dock, and over time ore and ore dust from the crushing operation collected in the bay sediments near the dock.
Primary Pathway: Benthic
Tools Used: Bulk sediment chemistry, grain size analysis
Methods: Nickel concentrations in uncontaminated sediments Coos Bay exceed the SQO, so the responsible party planned to use tissue sampling and bioavailability to establish a cleanup goal. However, due to the many uncertainties in the toxicity and bioavailability of nickel to benthic organisms and in the interests of time, the responsible party ultimately chose to base the sediment cleanup on background. Because background nickel concentrations varied with grain size (concentrations of nickel were lower in coarser sediments than in finer sediments), background was established relative to percent fines. Based on sediment quality data from a number of sampling events, the team found a linear, inverse relationship between nickel concentrations and sediment grain site (figure below), indicating that the coarse sediments near
the sites dock exceeded background values.
How Bioavailability Was Used: Bioavailability was not directly used in the cleanup level. Grain-size-adjusted background values for nickel were used as cleanup goals. Nickel concentrations in the immediate site area (between the docks and the site shoreline) were higher than expected relative to percentage fines. To the extent that this reflects a higher bioavailability of nickel near the site, cleanup did address contaminant bioavailability.
Regulatory and Stakeholder Challenges: The site contact indicated that if literature values describing unacceptable levels for nickel in clams or oysters could have been found, they would have relied on tissue sampling instead of background for cleanup levels.
Comments: Ultimately, a rather large population (>10,000) of native Oregon oysters were discovered during preparation work just before the sediment removal action took place, indicating that the high concentration (up to about 200 mg/kg, compared to the SQO of 16 mg/kg) was not affecting the oyster population.
Linda Martello, 510-420-2536, email@example.com
Site Description: Study Area 7 (SA7) is a 34-acre parcel in Jersey City, New Jersey, located on the eastern shore of the Hackensack River, at the confluence of the Hackensack River and Passaic Rivers entering Newark Bay. SA7 had been used for industrial and commercial purposes for more than 100 years. Elevated chromium concentrations in SA7 sediment is partly attributable to the historic disposal of chromium ore processing residue generated during chromate production.
Primary Pathway: Human health, benthic, pelagic
Tools: Bulk sediment and pore-water chemistry, AVS/SEM, benthic tissue analyses, in situ and laboratory toxicity and bioaccumulation testing, benthic community assessment
Methods: Various tools were used to assess chromium bioavailability, each of which contributed to a “multiple lines of evidence” evaluation that demonstrated the speciation, stability, and toxicity of chromium in SA7 sediments, as further described below.
How Bioavailability Was Used: Multiple bioavailability studies were used to evaluate potential environmental and human health risks associated with the presence of chromium in SA7 sediment and select an appropriate remedy for the site. Results from the sediment chemistry and biological evaluations showed conditions at SA7 favored the presence of the stable, insoluble trivalent chromium Cr(III) and not the toxic, water-soluble form hexavalent chromium Cr(IV). For example, AVS levels demonstrated reducing conditions in which chromium occurs as Cr(III) and not Cr(IV), and results from the pore-water analyses showed no detection of Cr(VI) in any of the pore-water samples, even when sediment total chromium concentrations were >370 mg/kg (NOAA’s ER-M for chromium). Chromium levels in benthic tissue collected in the vicinity of SA7 did not differ from benthic tissue chromium concentrations collected from reference locations further north in the Hackensack River, the lower Passaic River, and in Newark Bay. Likewise, benthic community survey results showed the abundance of organisms and the composition of species in the vicinity of SA7 was similar to reference locations. These results along with additional lines of evidence, demonstrated very low bioavailability of chromium in study area sediments and supported a sediment remedy of capping and MNR.
Stacey Ladner, 207-287-7853, firstname.lastname@example.org
Regulatory Agency: RCRA
Site Description: HoltraChem is a former chlor-alkali facility with multiple contaminants. The Penobscot River is adjacent to the site, and mercury was deposited in the river water and sediment. The river is tidal with an 11-foot tidal swing. The site is at the point in the river where it switches from being primarily salt water to primarily freshwater A wedge of salt water moves up and down in the site depending on the season. Bioavailability was used as one component of the cleanup decision relating to mercury. Mercury sediments from the cove in front of the site were used to conduct 28-day bioavailability toxicity testing. A site investigation determined that the HoltraChem property, including parts of the Penobscot River, is contaminated with mercury, chloropicrin, and several VOCs. Additional investigation will be done into the presence of additional areas of mercury contamination and PCBs.
Primary Pathway: Benthic, water-column vertebrates and invertebrates, human health
Tools Used: Bulk sediment chemistry, toxicity testing, benthic community (macroinvertebrate) surveys, bioaccumulation/bioassay
Methods: Mercury toxicity to macroinvertebrates, reproduction, conversion of Hg in sediment to methylmercury in the site environment using co-located samples.
How Bioavailability Was Used: An assessment was made to determine what concentration of Hg was needed to avoid establishing a fish advisory. The May 2009 updates of Phase I and II Reports of the Penobscot River Study prepared by Bodaly et al. (2009) at the request of Judge John Woodcock of U.S. District Court (District of Maine), Bangor, Maine confirmed that there was extensive harm to the river and bay south of the plant site as a result of mercury contamination. The studies were conducted to determine whether mercury levels in fish, shellfish, and wildlife found in the lower Penobscot River (Maine) and in Penobscot Bay are of concern with regard to possible human consumption or the species themselves, particularly in relation to the location of the HoltraChem site.
Comments: At the present time remedial options for the sediments are being negotiated. The cleanup goals for sediments include dredging of the most highly contaminated area of the river sediments—just under an acre—near the plant’s outfall pipe and several acres of more moderate contamination in an adjacent cove. In areas of the river below the southern cove, there are significantly lower concentrations of mercury. The on-site sediments that are highly contaminated will also be excavated and/or buried. Excavated soils would be either disposed of off site or consolidated on site under a cap designed to prevent infiltration and the discharge of contaminants. Additional investigation will be done into the presence of additional areas of mercury contamination and PCBs.
Nancy Hamill, 609-633-1353, email@example.com
Primary Pathway: Benthic, wildlife, and pelagic
Tools: Bulk sediment chemistry, tissue chemistry, toxicity testing, bioassessment survey, macroinvertebrate survey, bioaccumulation tests, sediment toxicity test
Methods: The AET approach and back-calculation from food chain models were used to develop site-specific risk-based sediment remediation goals. Risk-based goals were developed for numerous ecological receptors, but the most conservative cleanup number was used.
How Bioavailability Was Used: Risk-based remediation goals for marsh sediments were generated for several receptors using the AET approach. Both acute (survival) and chronic (reduction in biomass) endpoints were evaluated via sediment toxicity testing for the freshwater black worm, Lumbriculus variegatus, and the terrestrial earthworm, Eisenia fetida. Data from the black worm, as the more sensitive species tested, was used in setting the cleanup goal. A risk management decision made by USEPA/NJDEP enforced the use of the most conservative cleanup goal for the marsh environment (risk to black worm = 32 mg/kg arsenic).
A remediation goal for in-river sediment was calculated to be 192 ppm based on sediment toxicity tests using Leptocheirus plumosus; however, the actual cleanup goal was modified to 100 ppm to take regional background concentrations into account.
Risk-based remediation goals were also developed for the marsh wren and muskrat using site-specific insect and plant tissue data, respectively, and back-calculation from food chain models. Since these cleanup goals were less conservative than those for the black worm, they were not selected as the final remediation goal.
Comments: Bulk sediment chemistry, toxicity testing (USEPA protocol methods), 28-day chronic toxicity test on Raritan River sediment (test organism = L. plumosus), macroinvertebrate surveys (USEPA RBPs), tissue chemistry (tissue collection from Phragmites, small mammals, terrestrial invertebrates, fiddler crabs, estuarine minnows), bioaccumulation/bioassay (marsh and Raritan River sediments—black worm (L. variegatus) and earthworm (E. fetida). The AET approach was used to develop site-specific risk-based goals. The AET is determined for each COC and is defined as the concentration above which a specific biological effect is always found. In other words, the AET is the highest concentration with no effect. It is determined from sediments/soil chemistry data and sediment/soil toxicity test results that show statistically significant adverse effects. The black worm was picked as a sensitive species since it was a marsh environment and that species was more indicative of the terrestrial nature of that marshland. The remedial design was initiated in September 2009 for the marsh and river sediments.
Dennis Datin, 405-702-5125, firstname.lastname@example.org
Katrina Higgins-Coltrain, Remedial Project Manager, USEPA Region 6, 214-665-8143
Regulatory Agency: CERCLA/USEPA/Oklahoma DEQ
Site Description: The Imperial Refining Company (IRC) Superfund Site is the location of a 72-acre abandoned former petroleum refinery that operated 1917–1934. Numerous tanks and buildings were present on the site during refinery operation, but all of the tanks and most of the buildings were dismantled sometime between 1934 and 1948, leaving the property in much the same condition as it is in today, mixed wooded areas and open fields.
IRC is located on either side of State Highway 142 in northeast Ardmore, Oklahoma. In 1934 IRC declared bankruptcy and ceased operations and dismantled all tanks and storage equipment by 1948. Numerous pits, piles, and water impoundments are contaminated with metals and refining wastes. The site was listed on the National Priorities List in July 2000. The remedial process is a three-stage progression that defines the nature and extent of contamination, establishes the engineering plan to remedy the problems, and constructs the selected remedy for Superfund sites.
Primary Pathway: Benthic
Tools: Bulk sediment chemistry, toxicity testing, BSAFs, and tissue chemistry
Methods: Sediment chemistry and BSAFs were used to estimate tissue concentrations. The toxicity testing was used to identify ponds where an unacceptable risk was present.
How Bioavailability Was Used: Bioavailability was not used directly. Toxicity study data drove the cleanup with removal of sediment in areas where an unacceptable risk was present. Based on the low survival rate results in the toxicity study and lack of associated site-specific chemistry, these areas will be removed, and a second effects level for benzo(a)pyrene of 0.782 mg/kg will be used as the pond sediment cleanup level. This value is analogous to an LOAEL.
Comments: Sediment concentration and toxicity studies data were used in the measurement/ calculation of bioavailability. No benthic invertebrate tissue data were collected. The COPEC concentration in benthic invertebrate tissue was assumed to be equivalent to the COPEC dry weight concentration in sediment multiplied by a BSAF obtained from the literature. The 90th percentile BSAFs for all organisms developed by ORNL (Bechtel Jacobs 1998) were used to conservatively estimate COPEC concentrations of benthic invertebrate tissue. Benthic invertebrates were assessed as an important part of the diet of the raccoon and the marsh wren potentially using the ponds, Sand Creek, and wet areas for foraging. The toxicity studies conducted in the ERA showed a significant and immediate risk to sediment-dwelling organisms in the on-site ponds. Survival rates during the toxicity studies were less than 70%. Based on the low survival rate results in the toxicity study and lack of associated site-specific chemistry, a second effects level for benzo(a)pyrene of 0.782 mg/kg will be used as the pond sediment cleanup level. This value is analogous to an LOAEL.
Source: Dr. Nick Basta, School of Environment
and Natural Resources, Ohio State University
Steve Clough, 603-391-3341, email@example.com
Primary Pathway: Human health
Tools: In vivo extraction to estimate RBA
Site Description The Industri-plex site was once occupied by the former Merrimac Chemical Co., which was once the nation’s leading producer of lead arsenate, the main insecticide used in apple orchards in the 19th century. Prior to completion of the HHRA, an arsenic bioavailability study was performed to assist in the quantification of sediment risks. An in vitro extraction test was first performed on fine-sieved sediment obtained from four locations along the Aberjona River to measure the amount of arsenic that dissolves in a reactor that simulates the stomach fluid of humans. The amount of arsenic that solubilizes after 1 hour was used as a preliminary indicator of potential of the in vivo RBA. The results from this test indicated arsenic from dried material was more bioavailable than that from wet sediment. Microprobe analysis suggested that the presence of iron oxide was associated with higher arsenic concentrations and lower in vitro bioaccessibility, while the presence of the iron-zinc sulfate complexes saw lower arsenic concentrations and higher in vitro bioaccessibility.
Source: Dr. Stan Casteel, College of Veterinary
Medicine, University of Missouri
Based on the in vitro tests, sediment test material samples TM2 and TM3 were measured to have arsenic levels of 313 and 676 mg/kg, respectively. Varying weights of each material were fed in dough balls to three groups (N = 4/dose) of immature swine so that the target doses were equivalent to 300, 600, and 900 µg/animal/day. When exposure began (day 0), the animals were about 6 weeks old and weighed an average of about 12.1 kg. Samples of urine were collected from each animal for three consecutive 48-hour periods on days 6/7, 8/9, and 10/11 of the study. Positive controls were fed equivalent doses of sodium arsenate. Laboratory analyses were submitted in a blind fashion, and measurements accounted for all forms of arsenic (i.e., As(III), As(V), and methylated species). The RBA of arsenic in the sediment samples was calculated by dividing the absolute bioavailability (ABA = amount absorbed/amount ingested) of the three test sediments by the ABA of the sodium arsenate. The RBA of TM2 and TM3 were 37% and 51%, respectively. The risk assessment toxicity factors were, accordingly, adjusted using the most conservative relative bioavailability factor of 0.51 (i.e., USEPA IRIS reference dose was divided by 0.51, and the cancer slope factor multiplied by 0.51).
Regulatory Agency: Delaware Department of. Natural Resources and Environmental Control
John Cargill, 302-395-2622, firstname.lastname@example.org
Primary Pathway: Benthic
Tools: Bulk sediment chemistry, pore-water estimates using EqP, and narcosis theory
Methods: TU approach
How Bioavailability Was Used: Cleanup levels based on the EqP-TU approach were calculated for intertidal sediments contaminated with NAPL and dissolved-phase, diesel-range organics that resulted from a diesel fuel spill from a leaking underground pipeline into the Indian River sediments. The pipeline was taken out of service, and a sheet pile wall with sealed interlocks was installed to preclude the future migration of residual oil into the river sediments. Subsequent investigation work consisted of identifying the extent of impact, assessing risk to aquatic receptors, implementing a remedial action, and restoring the shoreline.
For each sample collected during the investigation of impact extent, bulk sediment chemical measures of PAH parent compounds and alkylated homologs were first normalized to the TOC concentrations at each corresponding sample point. Pore-water concentrations of these compounds were then predicted using EqP and were subsequently divided by analyte-specific acute and chronic values calculated from narcosis theory. For each sample, the TUs for individual compounds were summed to yield total acute and chronic TUs. TUs >1 indicated that pore-water exposure concentrations were potentially high enough to cause toxicity to benthic organisms. The state required excavation of all sediments with chronic TUs >1, which corresponded to a total PAH cleanup criterion of 2 mg/kg. In total, approximately 480 yd3 of sediment was ultimately removed from the Indian River shoreline, and confirmatory samples indicated that the calculated cleanup criteria were met. Excavated sediments were replaced with clean material of similar grain-size composition and were allowed to be naturally reworked and contoured over several tidal cycles prior to revegetation efforts.
Comments: A long-term monitoring program was subsequently established to ensure that the remedial efforts would remain protective of ecological receptors and included regular visual site inspections to monitor erosion and health of vegetation, photomonitoring of vegetative growth and site development, vegetation sampling for various parameters, and sediment sampling for PAHs and TOC.
Jennifer Sutter, 503-229-6148, email@example.com
Regulatory Agency: Oregon DEQ
Site Description: Johnson Lake extends over 18 acres and is directly connected to the Whitaker Slough, which in turn flows to the Columbia Slough, a quiescent waterway located south of the Columbia River. Several environmental investigations have been conducted at the site, beginning in 1994 with the collection of three sediment samples from Johnson Lake as part of a broader sediment sampling event conducted by the City of Portland for the Columbia Slough project. Analytical results indicated elevated PCBs, metals, and PAHs in lake sediment. Follow-up investigations conducted between 1998 and 2004 confirmed the sediment contamination and provided information on contaminant distribution. In 2005 and 2007, Owens conducted additional sediment sampling of the lake for chemical characterization and bioassays. Tissue samples were also collected and analyzed to assess the degree to which bioaccumulative contaminants were present in lake biota.
Primary Pathway: Benthic, human health, wildlife
Contaminants: PCBs, metals, PAHs, PHCs
Tools: ODEQ concluded that sediment contamination in Johnson Lake poses an unacceptable risk to human health based on the risk associated with ingestion of PCB-contaminated fish. ODEQ calculated a potential excess lifetime cancer risk via this pathway of 1 × 10–4 using risk associated with individual PCB congeners. Pertinent assumptions used in this evaluation include the following:
- a fish ingestion rate of 45 g/day based on a Columbia Slough consumption survey
- an assumption that fish caught from Johnson Lake would make up approximately 11% of the diet of someone who regularly fishes from the Columbia Slough
- no contaminant losses during cooking
- consideration of dioxin-like cancer risk posed by particular PCB congeners
Tissue concentrations of PCB congeners were also predicted to cause unacceptable risk to birds, and bioassays suggested toxicity to benthic organisms in one area of the lake.
Methods: Bulk sediment and tissue chemistry, toxicity testing
How Bioavailability Was Used: A comparison of tissue levels to a weighted-average sediment concentration throughout the lake was used to develop a site-specific BSAF. This value was used to estimate the area of sediment that would require remediation such that the residual lakewide sediment concentration would result in a projected risk of 1 × 10–5 excess cancer risk based on human ingestion of fish. Source control and natural recovery were expected to bring the concentration down even further over time.
Comments: Additional sediment data were collected during remedial design to better determine the depth of sediment that would need to be removed and improve PCB concentration delineation. These data indicated that a much larger volume of sediment would need to be remediated to achieve the lakewide goals established in the original ROD. Consequently, the remedial action was reevaluated, and the ROD amended to require thin-layer capping of the entire bottom of the lake. Permitting is currently under way, and the capping is expected to occur in the summer of 2011. The ROD can be viewed at http://www.deq.state.or.us/Webdocs/Forms/Output/FPController.ashx?SourceId=1311&SourceIdType=11.
Craig Zeller, 404-562-8827, Zeller.Craig@epamail.epa.gov
Agency: USEPA Region 4
Primary Pathway: Human health via fish consumption, benthic
Tools: Bulk sediment, sediment deposition, and bioaccumulation modeling; fish and benthic tissue chemistry
Site Summary: The affected areas are a 7-mile stretch of Twelvemile Creek and 56,000-acre Lake Hartwell (man-made reservoir created by the construction of Hartwell Dam across the Savannah River) (USEPA 2004b). Twelvemile Creek is the primary tributary into the headwaters of the lake and contains three masonry impoundments (private dams) along its length. Sediment in both Twelvemile Creek and Hartwell Lake contains PCBs that originated from a Sangamo Weston capacitor plant that discharged PCB-containing wastewater into Town Creek, a tributary to Twelvemile Creek. Sediment PCB concentrations in the lower 7-mile stretch of Twelvemile Creek, interchangeably known as the Twelvemile Creek Arm and Seneca Creek Arm, and a depositional area, were originally measured in the 1–3 ppm range at the surface and higher in deeper sediments. Portions of the Twelvemile Creek Arm were found to contain up to 61 ppm PCBs. In 1991/92, maximum PCB concentrations measured in sediment core samples from the upper section of Lake Hartwell (where Twelvemile Creek enters) exhibited concentrations of 5–11 ppm; PCB concentrations in sediment in the lower part of the lake were typically <1 ppm.
In June 1994, a ROD was issued for the site that specified MNR supplemented by institutional controls as the selected remedy. The selected target cleanup standard for sediment was 1 ppm PCBs based on technical feasibility; the affected area covers approximately 730 acres with a total estimated volume of 4.7 million yd3 of PCB-contaminated sediment. For fish, the FDA action level of 2 ppm PCBs was selected, also based on technical feasibility. A carcinogenic risk-based approach was evaluated by determining the concentration levels in largemouth bass that would result in acceptable risk to anglers through ingestion of fish. Using USEPA risk assessment methods, a fish tissue concentration of 0.036 ppm was associated with a 10–4 risk. The risk-based fish cleanup goal of 0.036 ppm was determined to be technically impracticable. Natural recovery of largemouth bass within Hartwell Lake to below the FDA action level of 2 ppm PCBs was predicted by modeling to occur within 12 years (by 2004).
Methods: Sediment cores were collected in Lake Hartwell and provided data used to determine the vertical profile of PCBs in the sediment column. These data indicated that higher PCBs were being buried beneath sediment with lower PCB concentrations. Two long-term fate and bioaccumulation models were constructed to enable predictions of PCB concentrations in sediment and fish in Lake Hartwell over time under various potential remedial approaches. A water-quality model was developed to determine the fate of PCBs in the system over time, and results of this model indicated that PCB concentrations in the water column and sediment of Lake Hartwell would generally decrease over time, even in the absence of any intrusive remediation. The primary mechanisms for PCB reductions over time were boundary transport and burial. A bioaccumulation model was also constructed to complement the water-quality model and to estimate PCB concentrations in fish tissue over time. The results from this model indicated that largemouth bass PCB levels would decrease to <2 ppm (in fish weighing greater than 3.4 kg) in 12 years under an MNR scenario. Results from these models were used in establishing the ROD for the site.
How Bioavailability Was Used: Bioavailability was used at this site to determine that PCBs in lake sediment are generally higher at depth and lower at the sediment surface where PCBs would be bioavailable. Modeling was employed to estimate the fate of PCBs over time and the modeling showed that bioavailable PCBs are expected to reduce over time, resulting in lower PCB levels in lake water and resident fish species. Results of monitoring at the site since the 1994 ROD are summarized below.
Annual biota and sediment monitoring has been implemented in the spring of each year since 1994. This effort has included (1) surface sediment sampling at 21 locations in Twelvemile Creek and Lake Hartwell; (2) fish tissue analyses at six stations in Lake Hartwell for largemouth bass, catfish, and hybrid bass; (3) fish tissue analyses on forage fish species at three locations in Lake Hartwell; and (4) 28-day caged corbicula analyses at seven stations in Twelvemile Creek. Reportedly, sediment data indicate that surficial sediment PCB concentrations in Twelvemile Creek have decreased steadily since 1990 due to ongoing physical processes such as burial, mixing/dispersion, and PCB dechlorination. However, the USEPA Five-Year Review of the site performed in 2004 concluded that, although sediment concentrations continue to measurably decrease, PCB concentrations in largemouth bass, channel catfish, and hybrid bass have not responded as measurably to the decreased surface sediment trends.
A 2006 technical agreement between the Natural Resource Trustees and the principal responsible party, Schlumberger Technology Corporation, requires among other things the removal of two of three dams (Woodside 1 and 2) on the Twelvemile Creek Arm of Lake Hartwell. An Explanation of Significant Differences was issued in 2009 to support this aspect of the project as it is expected to enhance the ongoing natural transport of clean sediment downstream to speed burial of the PCB-contaminated sediment in Lake Hartwell.
Scott Manzano, 503-913-1484, Manzano.Scott@deq.state.or.us
Regulatory Agency: USEPA/ODEQ
Site Description: The McCormick & Baxter Creosoting Company site operated 1944–1991, treating wood products with creosote, pentachlorophenol, and inorganic (arsenic, copper, chromium, and zinc) preservative solutions. Historically, process wastewaters were discharged directly to the Willamette River, and other process wastes were discharged to ground surface, contaminating soil and groundwater across the site.
An impermeable, subsurface barrier wall surrounding 18 acres of the site was installed in 2003 to contain a large portion of the primary source areas of groundwater contamination and minimize horizontal seepage of creosote into the Willamette River. The site remedy was complete in September 2005 and includes a soil cap over approximately 40 acres of land and a sediment cap over approximately 22 acres of contaminated sediments beneath the Willamette River. Creosote continues to be recovered at the site by manual methods; approximately 6300 gallons has been recovered since 1996.
Primary Pathway: Human health, benthic, pelagic
Contaminants: PAHs, pentachlorophenol, metals
Tools: Bulk sediment chemistry, surface-water chemistry, fish tissue chemistry, toxicity tests
Methods: Fish and crayfish surveys were conducted at this site (Pastorok et al. 1994). To assess the effects of the residual creosote-derived contaminants including PAHs and dioxins, the assessment included sediment chemistry, bioassays, tissue residues in fish and crayfish and fish histopathology. Sediment chemistry and toxicity testing indicated that a substantial area of the Willamette River sediments proximal to the site was likely to be toxic (USEPA 1996n). By contrast, tissue residue values for PAHs in crayfish (Pacifastacus leniusculus) and large-scale sucker (Catastomus macrocheilus) collected near the site show slight elevations of dioxins/ furans and low-molecular-weight PAHs compared with fish and crayfish samples collected in other parts of the Willamette River. Visual examination of fish tissue showed no adverse effects from exposure to site-related contaminants other than mild inflammation, which was also observed in fish collected in other areas of the Willamette River.
How Bioavailability Was Used: Sediment chemistry and bioassay data, as well as continuing NAPL discharges from sediments to the Willamette River, were used as the basis for the remedial action at this site. The ROD required containment of NAPL by means of NAPL recovery with a subsurface barrier wall contingency and a (permeable) sediment cap (USEPA 1996n). During remedial design of the sediment cap, an organophylic clay was specified for placement over the remaining NAPL seep areas.
Comments: The Oregon Department of Human Services issued a health advisory for commercial harvesting of crayfish taken within 1000 feet of the site shoreline in 1991. Crayfish collected on 2003 before the sediment cap construction contained approximately twice the health advisory criteria of 0.9 ppt for 2,3,7,8-TCDD TEQ. Crayfish samples taken in 2006 and 2008, after the sediment cap was constructed, contained less than half the health advisory criteria. The advisory was lifted in 2009.
DEQ is now conducting SPME sampling to establish a baseline concentration of PAH contaminants in pore water within the sediment cap sand. Using that and previous pore-water data obtained using conventional Henry samplers, DEQ will consider future SPME sampling events to compare to the SPME baseline to ensure that the sediment cap is continuing to perform as designed.
Chris Ferguson, 371-234-2833, lcferguson@idem.IN.gov
Primary Pathway: Human health, benthic, fish
Tools: Bulk sediment and surface-water chemistry, benthic, plankton, wildlife and fish surveys, fish tissue chemistry, pore-water sampling
Methods: Screening of sediment analytical data against Indiana Tier II residential cleanup goals and sediment ecological screening benchmarks, screening of surface water analytical data against surface-water quality standards, comparison of fish tissue concentrations with background fish tissue concentrations from the White River and USEPA Region III risk-based concentrations, comparison of pore-water concentrations with surface-water ambient water quality criteria
How Bioavailability Was Used: Bioavailability was evaluated as part of a human health and ecological risk assessment by measuring metals in the whole bodies and filets of pelagic fish species. Pore-water concentrations were collected as part of a post-remedial monitoring program to evaluate the effectiveness of the remedy (i.e., partial excavation followed by placement of a sand cap) in preventing exposures to residual metals impacts in the sediment.
Regulatory and Stakeholder Challenges: Mocks Pond is an abandoned limestone quarry in Muncie, Indiana, which had formerly received lime-stabilized, spent, pickle-liquor sludge related to the manufacture of galvanized (zinc-coated) wire products composed of iron, and other insoluble metal hydroxides. The resultant “sediment” was a very fine iron-rich material with low TOC. While constituents of interest in the pond included select heavy metals (e.g., antimony, arsenic, cadmium, chromium, copper, lead and zinc) at concentrations exceeding their respective sediment screening values, previous testing suggested that the materials deposited in the bottom of the pond were stabilized and not biologically available.
Ecologically, the pond bottom consisted principally of unconsolidated sediment that was largely devoid of organic material and bottom-dwelling macroinvertebrates. As a result, bottom-feeding fish species (e.g., carp, catfish) were not common in the pond. Also, despite the presence of shallow, permanently submerged habitat, the margins of the pond were devoid of rooted or floating vascular vegetation (e.g., cattails).
In contrast to the sediment conditions, surface water exhibited relatively good quality (i.e., metals concentrations in surface water were below screening criteria). The pond contained a relatively diverse and healthy water-column aquatic community including a variety of pelagic fish, snapping turtles, and other turtle species and a diverse aquatic-dependent wildlife community. Institutional controls for human exposure were in place in the form of a large fence surrounding the site.
It was hypothesized that sludge-sediment itself would not support aquatic life and that the metal hydroxides were not biologically available through dissociation in pore water or surface water. While the physical/chemical conditions in the deposited materials were not conducive for benthic-dependent insects or fish, metals in the sediments were believed to be biologically unavailable to upper trophic level organisms. Human health and ecological risk assessments were completed to test this hypothesis. Bioavailability was evaluated as part of a human health and ecological risk assessment by measuring metals in the whole bodies and filets of pelagic fish species. The risk assessment activities determined that lead concentrations in sediment and arsenic concentrations in fish tissue may pose a significant consumption risk to construction workers and recreational anglers, respectively.
Based on the results of the risk assessment studies, a decision was made to dredge the sludge-impacted sediment to a clear water depth of 10 feet followed by placement of a sand cap with the objective of establishing a suitable habitat for benthic reestablishment and for potential future access to the site for recreational purposes. A remedial goal of the project was to demonstrate that the metals present in the residual impacted sediment were biologically unavailable following dredging and placement of a sand cap over the entire pond bottom.
Bioavailability was subsequently evaluated following implementation of the remedy as part of a post-remedial monitoring program designed to monitor cap performance (i.e., ability to restrict the migration of constituents into the biotic zone) by measuring metals concentrations in pore water. Large-volume “peepers” were used to collect pore-water samples. These devices consisted of dialysis tubing filled with reagent-grade water placed into a protective sheath and then inserted into the sediment to a depth of 10 cm. In addition, surface-water and sediment sampling was completed as part of the post-remedial monitoring to assess functional effects on the water column community and to confirm isolation of the residual metals-impacted sediment, respectively. Results from the post-remedial monitoring confirmed that metals were tightly sequestered and not partitioning into pore water or surface water.
The primary risk driver at this site was established in 1999 as a human health risk to subsistence finfish harvesters from PCB concentrations in bottom fish. A cleanup goal was established for PCB concentrations in surface sediment, which was assumed to eventually result in a reduction in PCB concentrations in marine tissue. The PCB sediment cleanup goal was not risk based, and no bioavailability determination was made. The PCB cleanup goal was instead based on a cost-benefit analysis.
A supplemental HHRA recently conducted as the result of a recommendation in the second Five-Year Review found unacceptable risk to subsistence harvesters from mercury in fish and shellfish tissue. A mercury source study, conducted in parallel with this risk assessment, includes an evaluation of the mercury methylation processes at the site to help characterize mercury bioavailability. The overall objective of this study is to describe and quantify the biogeochemical processes that lead to the bioaccumulation of methylmercury into the base of the pelagic food web, methylation of mercury in sediments, and the release of methylmercury and ionic mercury from the sediments. USGS is performing this study with an estimated completion date of September 2011. This study will assist in the establishment of a mercury cleanup goal.
Regulatory Agency: USEPA Region 10
Primary Pathway: Benthic, human health
Contaminants: PCE, TCE, DCE, VC
Tools: Diffusion-based samplers in pore water
Site Summary: The Lower Duwamish Waterway Superfund site investigation focused principally on bedded-sediment contamination, but the site is also considered to be impacted by continuing releases to the system from surface-water and subsurface-groundwater discharges. Groundwater releases were principally evaluated by sampling seeps during low-tide sequences and by placing piezometers and peepers in the sediment. These approaches were not effective at all locations due to the need for rapid characterization over tidal cycles at a finer spatial grade. Peepers placed subtidally were also not thought to adequately capture VOCs at one particular site, the Myrtle Street Embayment Study Area.
Two overlapping discharging solvent plumes were identified at the Myrtle Street Embayment: a shallow aerobic plume that was mostly PCE and TCE and a deeper anaerobic plume of daughter compounds such as DCE and VC. Wells located 50 feet inland indicated that the plumes ranged from the top of the aquifer (at about 10 feet bgs) to more than 45 feet bgs. The groundwater well concentrations were up to 1000 times groundwater cleanup levels, while in-seep samples concentrations were up to 100 times cleanup levels. However, as the freshwater plume encountered the tidal salt water wedge, the groundwater discharge area narrowed and rose over the wedge. In the process, the discharge area where benthic infauna would be exposed narrowed from 35 vertical feet to about 10 vertical feet. USEPA and the Washington Department of Ecology were concerned that the “worst” groundwater was discharging deeper in the waterway and therefore polluting the sediments.
Diver-placed diffusion samplers (GORE® Modules) were used to characterize the discharge to the embayment through localized seeps and generalized upwelling beneath the embayment. GORE Modules consist of GORE-TEX® membrane tubes housing hydrophobic adsorbents which capture and measure VOCs, and SVOCs. The modules were housed in a sediment insertion probe and inserted into the sediments (see Table C-T2). They were deployed in a systematic close-grid fashion across the embayment, known seeps, and potential critical discharge areas (see photo). Over multiple tide cycles, the samplers were able to identify an expanded seep discharge face near the top of the saltwater wedge but demonstrated lack of a subtidal embayment discharge.
How Bioavailability Was Used: The results demonstrated that there was no complete transition from groundwater to the bioactive layer of the sediment zone. Therefore, a complete exposure route did not exist between the contaminated groundwater seeping into the bay and the estuarian benthic community. The investigation showed an incomplete exposure pathway to subtidal organisms, and, although a direct measure of bioavailability could not be discerned, the lack of detection of COPECs by the GORE Modules did prove the null hypothesis, i.e., that potential receptors were not exposed and therefore there can be no risk to these receptors or their predators in the waterway. Without the investigation, the discharge area would have been assumed to be lower and more diffuse that it actually was, making it likely that additional biological sampling would have been placed in areas where exposure was limited.
Darren Newton, Navy Base Closure and Realignment, 619-532-0963, firstname.lastname@example.org
Site Description: Hangar 1 was constructed in 1932 to house the giant airship U.S.S. Macon. Its floor space covers 8 acres (the equivalent of 10 football fields) and it stands 200 feet high. Over the years, the hangar provided space for maintenance of aircraft, training facilities, and offices for both the Army and Navy. Hangar 1 is part of the property transferred to National Aeronautics and Space Administration Ames Research Center in 1994. It formerly housed the Moffett Field Historical Society Museum and was used as a display space for air shows, open houses, and various commercial and public functions.
The building materials and paint used to construct Hangar 1 contain PCBs, asbestos, lead, and zinc. The hangar is aging, and its paint and building materials are deteriorating. As a result, the contaminants in these materials moved into the environment around the hangar and, ultimately, reached Site 25 sediments in a storm-water retention pond and storm-water settling basin (located at nearby wetlands) through the Moffett Field storm drain system. To ensure the protection of human health and the environment, in 2003 the Navy completed an interim control measure called a time-critical removal action, which included applying a specialized coating to the exterior surface of Hangar 1 to seal the materials on the building surface.
In 2007, the Navy issued a draft revised engineering evaluation/cost analysis (EE/CA) recommending removal of the Hangar 1 siding and coating the structural steel frame. The previous EE/CA (2006) had recommended complete demolition of the hangar. The revised EE/CA was finalized in July 2008. In January 2009, the Navy signed an action memorandum declaring that the Navy will proceed with the proposed EE/CA alternative, removing the siding and coating the frame. The Navy has prepared cleanup action work plans and has initiated actions in 2010 with a completion date of 2011.
Primary Pathway: Benthic
Contaminants: PCB Aroclor 1268, asbestos, and lead
Tools: Bulk sediment chemistry, tissue chemistry, bioaccumulation testing, food chain modeling
Methods: Site-specific BAF and food chain model used to back-calculate sediment cleanup numbers
How Bioavailability Was Used: The relative bioavailability was determined by establishing the relationship between benthic organisms and sediment concentrations.
Comments: Sediment bioassays were used to estimate bioaccumulation. The estimated bioaccumulation was used to calculate a site-specific BAF, which was then used to back-calculate an acceptable sediment value.
Robert Nunes, 212-637-4254, email@example.com
Site Description: Onondaga Lake itself is a 4.6-square-mile, 3000-acre lake, approximately 4.5 miles long and 1 mile wide, with an average water depth of 36 feet. The lake has two deep basins, a northern basin and a southern basin, that have maximum water depths of approximately 62 and 65 feet, respectively. The basins are separated by a saddle region at a water depth of approximately 56 feet. Most of the lake has a broad, near-shore shelf in water depths of less than 12 feet. This near-shore shelf is bordered by a steep, off-shore slope in water depths of 12–24 feet.
Primary Pathway: Human health and benthic
Contaminants: Metals, PAHs, PCBs
Tools Used: Bulk sediment chemistry, pore-water chemistry, toxicity testing, macroinvertebrate surveys, tissue chemistry, bioaccumulation/bioassay
Methods: Bioavailability was used in the form of bioaccumulation pathway analysis for mercury to address the risk to wildlife and humans from consumption of contaminated fish. To the extent that acute toxicity test reflect bioavailability, PRGs were developed based on site-specific SECs for the most sensitive species tested.
How Bioavailability Was Used: Separate PRGs based on site-specific SECs were developed for benthic, wildlife, and human health protection.
Toxicity Testing: Acute sediment toxicity testing procedures (which imply but do not directly measure bioavailability) using benthic macroinvertebrates (Hyalella azteca and Chironomus tentans) were used to establish PRGs for COCs (metals [including mercury], aromatics, chlorinated benzenes, PAHs, and PCBs). C. tentans were found to be the more sensitive test, and acute toxicity data were used to develop the five site-specific SECs that included ER-L, TEL, ER-M, PEL, and AET. From the geometric mean of these five SECs, a single consensus-based PEC was calculated for each contaminant. The SECs and PECs do not consider the potential effects that could occur throughout the food web as a result of bioaccumulation. However, bioaccumulation is considered in the development of PRGs for fish tissue and for a sediment quality value for mercury.
Bioaccumulation: Mercury in fish is derived from a combination of food sources such as benthic macroinvertebrates, uptake from the water column through skin or gills, and incidental intake of suspended particles in the water column. Together, these exposure pathways result in the bioaccumulation of mercury in fish. To address the risk to wildlife and humans from consumption of contaminated fish, a bioaccumulation sediment quality value (BSQV) was developed for this contaminant, based on the most sensitive ecological receptor for assessing bioaccumulation.
Comments: The ROD can be viewed at www.dec.ny.gov/chemical/34481.html. The sediment PRG is based on five site-specific SECs and one consensus-based PEC for the chemicals of potential interest evaluated in the RI and risk assessments. The SECs and PECs were calculated using data from acute sediment toxicity testing using benthic macroinvertebrates. To evaluate sediment quality in Onondaga Lake, toxicity of the sediment to sediment-dwelling (benthic) invertebrates was tested. Laboratory tests involved exposing the midge C. tentans and the amphipod H. azteca to Onondaga Lake sediments and observing their growth and survival. Since the results for C. tentans were found to be the more sensitive test, these acute toxicity data were then used to develop the following five site-specific SECs:
- Effects range-low—The concentration that represents the lowest 10th percentile of the concentrations at which toxic effects were observed. At concentrations below the ER-L, toxic effects are rarely expected.
- Threshold effects level—The geometric mean of the concentration that represents the lowest 15th percentile of the concentrations at which toxic effects were observed and the 50th percentile (median) of the concentrations at which no toxic effects were observed. At concentrations below the TEL, toxic effects are rarely expected.
- Effects range-median—The concentration that represents the 50th percentile (median) at which toxic effects were observed. At concentrations above the ER-M, toxic effects are likely to occur.
- Probable effects level—The geometric mean of the ER-M and the 85th percentile of the concentration distribution for the no-effects data. At concentrations above the PEL, toxic effects are likely to occur.
- Apparent effects threshold—The concentration of a chemical in sediment above which a particular toxic effect (e.g., increased mortality or decreased biomass) is always significant compared to reference concentrations. At concentrations above the AET, toxic effects are predicted to always occur.
The geometric mean of these five Onondaga Lake SECs was calculated to provide a single consensus-based PEC for each contaminant. At concentrations above the PEC, adverse effects in sediments are expected to frequently occur. The derivation of these site-specific values is presented in the Onondaga Lake baseline ERA. SECs and PECs were calculated for each of the chemicals of potential interest in the baseline ERA. For mercury, the following SEC values were calculated: 0.51 mg/kg for ER-L, 0.99 mg/kg for TEL, 2.8 mg/kg for ER-M, 2.84 mg/kg for PEL, and 13 mg/kg for AET. Based on these five SECs, the PEC for mercury is 2.2 mg/kg. As discussed in the baseline ERA, the SECs and PECs do not consider the potential effects that could occur throughout the food web as a result of bioaccumulation. However, bioaccumulation is considered in the development of PRGs for fish tissue and for a sediment quality value for mercury.
Bioaccumulation: The mercury in fish is derived from a combination of food sources such as benthic macroinvertebrates, uptake from the water column through skin or gills, and incidental intake of suspended particles in the water column. Together, these exposure pathways result in the bioaccumulation of mercury in fish. To address the risk to wildlife and humans from consumption of contaminated fish, a BSQV was developed for this contaminant; the BSQV of 0.8 mg/kg represents a concentration in sediments that, if not exceeded, is predicted to result in mercury concentrations in fish below levels of concern for wildlife that consume fish. The selected BSQV for mercury of 0.8 mg/kg was based on the most sensitive ecological receptor for assessing bioaccumulation. This value is expected to be protective of other ecological receptors and adult human consumers of fish.
Dave Barclift, 215-897-4913, firstname.lastname@example.org
Commissioned in 1942 as Cunningham Field, Marine Corps Air Station (MCAS) Cherry Point is located in southeastern Craven County, North Carolina. The installation covers approximately 13,164 acres on a peninsula north of the Core and Bogue Sounds and south of the Neuse River. The station’s primary mission is to maintain and operate support facilities and services to the 2nd Marine Aircraft Wing, Naval Aviation Depot, and Naval Hospital.
Environmental impacts at the site stem from past waste disposal and storage practices of industrial chemicals, waste, and fuels. These past practices at MCAS Cherry Point have resulted in several contaminated groundwater plumes and soil contamination from numerous smaller waste-disposal units.
Primary Pathway: Benthic
Contaminants: Organics, metals
Tools: Bulk sediment chemistry, toxicity testing, benthic community surveys, tissue chemistry, bioaccumulation
Methods: Used amphibian and invertebrate sediment toxicity test and used data for the most sensitive (invertebrate) to set cleanup level. The amphibian test was cost-effective in reducing the uncertainty and showing amphibians not at risk.
How Bioavailability Was Used: Amphibians were unaffected in 10-day exposures and determined to be not at risk. Data for the more sensitive invertebrate (midges) effects was used to set cleanup level.
Comments: The COCs are mixed contamination (metals, organics). Toxicity identification evaluation tests were not performed; therefore, the toxicity tests would represent exposure to mixed contamination. Amphibians were considered because they are present at the site and are important ecological receptors. Northern leopard frog tadpoles were used in the amphibian studies and are expected to have similar sensitivity to southern leopard frogs, which are more prevalent in the study area. Other than toxicity data, it is unclear what method was used to measure/calculate bioavailability (i.e., BCF, BAF, BSAF, SEM/AVS). However, on follow-up, respondent noted that usually SEM/AVS is a typical component of Navy ERAs.
Michelle Yoshioka, 808-472-1431, email@example.com
Primary Pathway: Benthic, human health, fish and water-column invertebrates, birds
Contaminants: Metals, PCBs, PAHs, chlorinated pesticides
Tools Used: Bulk sediment chemistry, tissue chemistry, pore water, toxicity tests, benthic community surveys, bioaccumulation/bioassay, BSAFs, surface-area weighted-average concentration, GIS-based kriging interpolation
Methods: The relationship between sediment and benthic receptors was used in the risk assessment. Sediment, tissue chemistry, surface-weighted average concentration, and GIS-based kriging were used to delineate areas for further consideration in the FS stage.
How Bioavailability Was Used: AVS-SEM analysis was used to evaluate metal bioavailability in the RI Addendum. A cleanup level has not been established yet; it is still in the RI stage.
Regulatory and Stakeholder Challenges: The project is still in the RI stage, so no cleanup levels have been established. Updated bioavailability was evaluated using collocated sediment and tissue chemistry in the RI Addendum, using linear fit relationships between TOC-normalized sediment and lipid-normalized tissue data. Cleanup levels will be developed in the FS stage based on risks to human health, ecological receptors, and background.
David Barclift, 215-897-4913, firstname.lastname@example.org
Site Description: The Philadelphia Naval Reserve Basin at the Philadelphia Naval Business Complex is a mooring basin used for inactive Navy vessels. The basin opens to the Schuylkill River 0.5 km north of the confluence of the Schuylkill and Delaware Rivers and serves as a moorage for the Navy’s inactive ships. A history of industrial use has led to the investigation of possible ecological impacts due to pollutant releases from Navy operations. Concurrently, the Navy mission required deepening of the basin to allow deeper draft vessels to be accommodated by April 2008. Hence, an additional focus of the study was to address the navigation dredging requirements.
Primary Pathway: Human health, benthic, wildlife, pelagic
Contaminants: Metals (copper), PCBs, PAHs
Tools: Bulk sediment, pore-water, and tissue chemistry; SEM/AVS; macroinvertebrate survey; bioaccumulation tests; sediment toxicity test
Methods: Used SEM/AVS to predict metals availability. Presence of PCBs in fish tissue was used as an indicator of its bioavailability.
How Bioavailability Was Used: Bioavailability used as a line of evidence in determining contaminant risk at sampling stations. The bioavailability study influenced and demonstrated the need for the development of an ecology-based inorganic (copper) cleanup goal and the human health-based organic (PCBs) cleanup goal. Fish tissue was collected as an indirect measure of bioavailability, and site-specific information was used in the human health risk assessment, which was used to develop the cleanup goal.
Comments: The bioavailability study influenced and demonstrated the need for the development of an eco-based inorganic (copper) cleanup goal. The same could also be said for the human health–based organic (PCBs) cleanup goal. We collected fish tissue as part of the study (indirect measure of bioavailability), and site-specific information was used in the HHRA, which was used to develop the cleanup goal. Bioavailability was used as a line of evidence in determining the risk of sampling stations.
The metals partitioning and bioavailability study assessed dissolved and particulate phases of metals in elutriates prepared from Reserve Basin sediments to describe differences with respect to water-quality criteria. This information provided a more detailed evaluation of the reduction in ecological risks afforded by removing sediments with concentrations greater than the PRGs. Results indicated that elutriate preparations had greater dissolved-metal concentrations than occurs in situ from sediments to pore water. Therefore, risk conclusions based on elutriate preparations are likely conservative with respect to predictions of in situ solubility and toxicity from copper in Reserve Basin sediments.
Bioavailability of copper was further investigated in light of seasonal AVS concentrations. AVS can sequester divalent metals such as copper and is therefore compared to SEM concentrations; an excess of AVS with respect to SEM indicates potential for divalent metals to be bound in the sulfides and unavailable to ecological receptors. Results indicated seasonally (spring) low AVS may be insufficient to completely sequester metals in the sediment, contributing to increased pore-water concentrations and potential for toxic effects. Results helped justify the derivation of the PRG for copper to protect ecological receptors.
Some of the measures we took at this site can be viewed as costly to some people; often this is the type of data that we need to collect at complex sediment sites to ensure that we are following Navy policy and guidance.
Jennifer Peterson, 503-229-6770, email@example.com
Site Description: Portland Harbor is a heavily industrialized stretch of the Willamette River north of downtown Portland, Oregon, that was listed on the National Priorities List in December 2000. Sediments in the river are contaminated with various toxic compounds, including metals, PAHs, PCBs, chlorinated pesticides, and dioxin. Levels of these pollutants in the river appear to be highest near contaminated sites that sit adjacent to the river on the shore (often referred to as “upland” sites). Contaminant sources include petroleum refining, gas manufacturing, pesticide manufacturing, steel production, port activities including dry-dock operations, storm-water runoff, and many other current and historical industrial activities.
Primary Pathway: Benthic, pelagic, human health, wildlife
Contaminants: Dioxins and furans, PCBs, pesticides, PAHs, total petroleum hydrocarbons, metals, tributyltin
Tools Used: Bulk sediment chemistry; surface-water, pore-water and benthic/pelagic tissue chemistry; toxicity testing. Clam tissue was collected from the site and analyzed with co-located sediment. In addition, 28-day bioaccumulation testing with the oligochaete Lumbriculus variegates and the clam Corbicula fluminea were undertaken for several areas of concern within the study area. Crayfish whole-body tissue was also analyzed at many locations. Several species of fish were analyzed, including sculpin, smallmouth bass, black crappie, peamouth, northern pike minnow, large-scale sucker, carp, juvenile Chinook salmon, Pacific lamprey ammocoetes, and juvenile white sturgeon to provide empirical measures of bioaccumulation and exposure for different receptors areas of the site.
Methods: It is anticipated that BSAFs will be developed using the data. For the benthic pathway the principal responsible parties have developed a predictive toxicity model that characterizes the relationship between sediment chemistry and benthic invertebrate toxicity. For some species, a site-specific Gobas model was developed to predict tissue concentrations.
How Bioavailability Was Used: This site consists of several different sites that are physically distinct from one another in terms of bioavailability and COCs. Therefore, cleanup levels for benthic risk will likely consider empirically derived estimates of toxicity along with predictive models. For bioaccumulative COCs, a food web model was used to back-calculate initial sediment PRGs. Cleanup levels have not yet been set.
Regulatory and Stakeholder Challenges: This is a large CERCLA site and is still in the RI phase. See the following link for site status and updates: www.deq.state.or.us/lq/cu/nwr/portlandharbor/index.htm. See the following link for more information about the benthic toxicity testing: http://yosemite.epa.gov/R10/OEA.NSF/af6d4571f3e2b1698825650f0071180a/100a7a3d5fe2ebf388256c78007a66bb?OpenDocument.
Jim Rea, 717-705-4850, firstname.lastname@example.org
Primary Pathway: Benthic
Contaminants: VOCs, PAHs
Tools Used: Bulk sediment chemistry and screening values, followed by a bioassessment evaluation possibly using RBA protocol
Methods: Temporal trends of the bioassessment survey were used to determine whether additional cleanup was necessary. This was a release with some cleanup following the release.
How Bioavailability Was Used: Direct bioavailability measurements not used in cleanup level. COPCs assessed for bioavailability are #2 heating oil compounds, specifically, benzene, toluene, ethyl benzene, cumene, naphthalene, fluorene, and phenanthrene. Surface-water and sediment samples were collected during the course of this investigation. The surface-water analytical results were compared of our Chapter 16 surface-water quality standards. Sediment results were compared to the NOAA SQuiRT table TEL/PEL values as well as the USEPA assessment and remediation of contaminated sediments TEL/TEC values. Since the surface-water and sediment samples exceeded several of their respective standards/screening values, an ecological assessment of the stream was completed by a qualified biologist on two occasions. These investigations monitored the diversity and quantity of benthic macroinvertebrate species as well as signs of impacts from #2 fuel oil (sheen, free product, etc.). Ultimately the final decision concerning the status of the stream/sediments was based on observations of the overall health of the stream. Due to the size and nature of the stream, it was determined that remediation beyond the initial response activities would be more detrimental than allowing the remaining fuel oil to attenuate naturally. Initially, the stream was determined to be “moderately impaired.” Within a year, however, the stream had rebounded to “nonimpaired” status. Under Kansas Act 2 program, all of the exposure pathways must be addressed, including impacts to the critters, ecology, humans, etc.
Vicki Meredith, 307-332-6924, email@example.com
Site Description: The Soda Lake Area RFI focused on identifying the extent and nature of impacts in soil, groundwater, surface water, and sediments in both the Inlet Basin and Main Lake. The purpose of the sediment and pore-water investigations was to define the nature and extent of former refinery-related COIs in the Inlet Basin and Main Lake. The lines of evidence used for the evaluation included screening media concentrations against conservative surface-water, sediment, pore-water, and phytotoxicity screening levels. Additional lines of evidence included modeling of PAHs and mercury bioaccumulation, total PAH toxicity using narcotic toxicity and OC normalization, and evaluation of sediment bioassays.
Primary Pathway: Benthic, pelagic, wildlife
Tools: Bioassays, bulk sediment chemistry, trophic modeling, pore-water and tissue chemistry
Sediment Screening Level Evaluation
- Organic COIs detected in surface and subsurface sediments included pyrene, benzene, chrysene, phenanthrene, benzo(a)anthracene, fluoranthene, naphthalene, total xylenes, and phenol. Phenol was the only organic compound present that exceeded benthic ecological high screening criteria. All other detected organic COIs exceeded the benthic low screening criteria only, and the stations that exhibited these compounds were further tested using solid-phase bioassay tests.
- Metal COIs detected in Main Lake sediment included arsenic, cadmium, chromium, mercury, nickel, and zinc. Cadmium, chromium, nickel, and zinc concentrations exceeded the benthic ecological low screening criteria. Metals that exceed the ecological low screening criteria did not show a pattern consistent with a refinery source, indicating these metals are of natural origin.
- COIs present in pore water included acetone, phenol, carbon disulfide, arsenic, antimony, manganese, selenium, silver, and vanadium. Acetone is believed to be a laboratory artifact. As discussed above, the metal distribution was ubiquitous throughout the lake; metals are of natural origin.
Solid-Phase Bioassay Testing was conducted to measure acute and subchronic toxicity of surface sediments. In addition, pore-water chemical testing was conducted on those stations that underwent bioassay testing. Low-level toxicity and nonrecurring toxicity in some samples were observed and could be related to laboratory artifacts and procedures.
- Bioassays were conducted on surface-sediment stations to further evaluate risk to benthic and epibenthic organisms. There was no consistency between the stations where chemical data exceeded screening levels and where the bioassays showed potential effects. Low-level toxicity and nonrecurring toxicity were observed in some samples and could be related to laboratory artifacts and procedures.
- There were differences between the control bioassays when compared to bioassays from site sediments; the bioassay data indicate there are no acute risks and negligible subchronic risk to benthic and epibenthic organisms near the underflow weir. Chronic risks were not evaluated.
Benthic and Epibenthic Community Evaluations: Organisms were evaluated for growth in the site sediments compared to control sediments, and the comparison was indeterminate. However, growth was observed in the area of potential impact indicating population growth and survival.
- Quantitative benthic community surveys within the Main Lake showed low diversity but high abundance. Low diversity was believed to be attributed to poor-quality habitat (low oxygen, high ammonia, and sulfide content of sediment).
- Qualitative assessments of epibenthos showed a rich and diverse assemblage, including sensitive Odonata, Ephemeroptera, Plecoptera, in addition to the daphnids, copepods, and amphipods described above.
Equilibrium Partitioning Evaluations
- Site total PAHs were evaluated relative to OC-normalized total PAH threshold effects criteria (Swartz 1999) and showed no exceedances.
- Probability modeling was conducted and demonstrated that there were negligible risks to benthic invertebrates from sediment PAH in the Main Lake, based on a “worst-case” analysis.
- Total and alkyl PAHs were evaluated relative to USEPA’s narcotic toxicity criteria, when a conservative estimate (factor of 16) of unmeasured, alkyl PAHs was included. Only one location exceeded the toxicity criteria, based on nondetected data with an elevated detection limit.
How Bioavailability Was Used: Bioavailability measures were used to show selenium is not in the bioactive zone and is not migrating up the food chain. The data show that COIs are present in the Main Lake sediments and pore waters. The results of the toxicity testing of Main Lake sediments suggest that there is negligible to no acute or subchronic toxicity of the Main Lake sediments to the test organisms. The lines of evidence indicate there is negligible to no risk to aquatic invertebrates based on risk evaluations, which is also supported by the presence of epibenthic and benthic invertebrates. For the Main Lake, multiple lines of evidence approach contributed to the selection of NFA as the site remedy. A copy of the remedy decision can be found at http://deq.state.wy.us/shwd/HW/Downloads/fact%20sheets/2012/RD3final011002.pdf.
Bob Cleary, 508-836-7275, RCleary@NiSource.com
Site Description: The former Springfield Public Works Facility, located at 274 Taylor Street, consisted of six buildings on 5.6 acres of land. The brick masonry buildings, owned by the City of Springfield, were constructed between 1907 and 1923 and were used for storage, painting, vehicle maintenance, and offices. Prior to its use as a public works facility, the land hosted a variety of uses during the 1800s, including housing, coal sheds, an asphalt-mixing plant, and railroad facilities belonging to the New York and North East Railroad. Sanborn maps (digital maps) indicate that the city operated a wagon shed and carriage house on the property during the late 1800s. The entire property was used by the Springfield Department of Public Works 1924–1999, when all of the buildings were demolished.
Primary Pathway: Benthic
Tools Used: Bulk sediment chemistry, pore-water chemistry (using SPME), and toxicity testing.
Methods: Chemical measurement of total dissolved PAHs was used as a predictor of PAH bioavailability.
How Bioavailability Was Used: In progress—the principal responsible party plans to use bioavailability data to proposed flexibility in interpreting visible harm and readily apparent harm to focus remediation on areas that pose actual threats to the environment.
Comments: The State of Massachusetts thinks that pore water is a better indicator than bulk sediments, and that is what it was primarily focusing on.
Jim Moras, 518-402-9814, firstname.lastname@example.org
Primary Pathway: Benthic
Contaminants: Chromium, copper, lead, mercury, zinc
Tools: Bulk sediment chemistry, SEM/AVS, pore water, benthic community survey, tissue chemistry, toxicity testing, bioaccumulation tests, sediment toxicity test
Methods: Sediment chemistry exceeded New York screening levels, triggering latest round of testing. Cleanup level will be established after current round of testing is completed.
How Bioavailability Was Used: Cleanup levels are not yet established pending latest round of testing. The samples collected will help get to that point. Data collected included SEM/AVS, pore water, benthic community survey, bioaccumulation (clams/mussels, where they were encountered during sampling), sediment toxicity.
Regulatory and Stakeholder Challenges: AVS typically might be compared to the sum of five SEMs (cadmium, copper, nickel, lead, zinc). However, the respondent indicated through follow-up that nickel was not a COC at the site and thus would not have been included in any AVS comparisons. Mercury was listed as a COC, but according to respondent, bioavailability for mercury was not assessed.
Paul Seidel, 503-667-8414 X 55002, seidel.paul@DEQ.state.or.us
Regulatory Agency: Oregon DEQ
Site Description: Oregon DEQ is overseeing investigation and remediation of the Tektronix Beaverton Creek site. A portion of the property undergoing investigation includes the location of the former RCRA treatment, storage, and disposal unit located adjacent to an urban stream. An investigation of sediment in Beaverton Creek was done to refine a remedial alternative presented in the feasibility study.
Beaverton Creek is a channelized, fourth-order urban stream that flows east to west through the southern portion of the property. The creek enters the site after flowing through residential neighborhoods and, after leaving the site, flows through a commercial area before flowing into the Tualatin Hills nature park located about ½-mile downstream, and eventually discharges to the Tualatin River.
Historic operations at the Tektronix, Inc., Beaverton campus included management of process chemicals, chemical treatment, metal recovery, and process waste. Sludge was generated as a result of waste management and was land-applied at various locations around the campus. These historic practices resulted in releases to Beaverton Creek and elevated concentrations of metals that have been measured in sediments during the site RI.
Based on elevated concentrations of metals in sediment, it was initially presumed that remedial action would be required. However, planning for sediment remedial action demonstrated a variety of complexities. Metals were detected at elevated concentrations in sediment throughout the stretch of Beaverton Creek flowing through and downstream of the site, as well as in stream bank soil, suggesting wide-scale remediation might be required. In addition, implementation risk associated with resuspending sediments and potentially mobilizing contaminants that might subsequently be transported toward the Tualatin Wildlife Refuge was an issue associated with removal. ODEQ recommended further, more detailed consideration of toxicity and bioavailability of contaminants as a means to refine the scope of any potential remedial action in sediment.
Primary Pathway: Benthic
Contaminants: Cadmium, copper, chromium, lead, mercury, nickel, silver, zinc
Tools: Bulk sediment chemistry, AVS-SEM, and bulk sediment toxicity bioassays
Methods: The bioavailability and sediment toxicity study consisted of two primary, sequentially implemented elements of investigation: First, additional sediment samples were collected for analytical chemistry, including bulk sediment metals concentrations and measurement of AVS and SEM as metrics that could be related to the bioavailability, and hence potential for toxicity. Second, toxicity tests were performed in a subset of these samples based on consideration of the potential for toxicity as measured by AVS-SEM, total metals, and spatial representativeness throughout the relevant stretch of Beaverton Creek.
How Bioavailability Was Used: Sediment samples for analytical chemistry were collected at 20 locations throughout the study reach, and two upgradient reference samples. Two toxicity tests, the 10-day mortality sediment toxicity test with the amphipod Hyalella azteca and the 10-day growth and mortality sediment toxicity test with the midge Chironomus dilutus, were performed on 13 surface sediment samples collected at a subset of 11 locations within the site and at the two upstream locations. Average bulk sediment concentrations measured in 2007 were similar to those measured in the 2004 sampling event, although the spread or range in values was narrower than those collected in 2004.
According to USEPA guidance, the sum of the molar concentrations of SEM cadmium, copper, lead, nickel, silver, and zinc may be used as a predictor of potential toxicity. The USEPA guidelines state that benthic organisms in freshwater sediments should be adequately protected if the sum of the molar concentrations of SEM cadmium, copper, lead, nickel, silver, and zinc is less than or equal to the molar concentration of AVS (i.e., SEM – AVS < 1).
As a second metric, the presence of OC was considered along with AVS, and the SEM – AVS difference was normalized by the foc in sediment. Again, according to USEPA guidance, any sediment for which the SEM – AVS difference normalized by the foc is <130 μmol/goc should pose low risk of adverse biological effects. For any sediment where the SEM – AVS difference normalized by the foc is >3000 μmol/goc, adverse biological effects resulting from cadmium, copper, lead, nickel, silver, and zinc may be expected.
As measured by these evaluative criteria, the sediment results indicated a low potential toxicity but did not clearly rule out potential for toxicity in most samples. Therefore, follow-up toxicity testing was performed.
Toxicity Testing: Based on interpretive criteria currently in use, none of the sediment samples had an adverse effect on amphipods or midges based on the H. azteca mortality endpoint or C. dilutus growth endpoint. Based on the C. dilutes mortality endpoint, a few of the samples did show a weak response. Using the RSET and USEPA interpretive criteria, the results did not appear to be attributable to any measure of metals in the sediments.
In summary, the bulk sediment chemistry data indicated exceedances of screening criteria. Additional measures of bioavailability were collected and suggested an overall low potential for toxicity. Toxicity testing performed to validate and further clarify this prediction indicated no toxicity that could be related to any measured sediment metal concentrations. Therefore, it was concluded that site sediments do not pose risks to benthic organisms and sediment remediation was deemed unnecessary.
Robert T. Angelo, Ph.D., 785-296-8027, bangelo@KDHE.state.ks.us
Regulatory Agency: USEPA
Site Description: The Tri-State Mining District lies in southwestern Missouri, southeastern Kansas, and northeastern Oklahoma. For nearly 50 years, it was the world’s richest producer of lead and zinc ores. More importantly, it was located next to the coalfields of southeastern Kansas. Coal was essential for smelting, the process of removing spelter—metallic zinc—from ore. The first zinc smelter in Kansas was built in Wier City in 1870.
Primary Pathway: Benthic
Contaminants: Cadmium, lead, zinc
Tools Used: Bulk sediment chemistry, pore-water chemistry, toxicity test (using mussels and clams)
Methods: Toxicity testing using site-collected sediment and pore water
How Bioavailability Was Used: A cleanup level is planned to be calculated based on sediment and pore-water concentrations that correspond to a 10%–20% nonsurvival rate for benthic organisms (clams and mussels).
Comments: The work plan will be completed soon and the USEPA Remedial Project Manager (David Drake, 913-551-7626, email@example.com) will provide when finalized.
Craig Nathe, 805-605-0577, firstname.lastname@example.org
Vandenberg AFB, California, Installation Restoration Program, 30 CES CEVR
Site Description: Installation Restoration Program (IRP) Site 5 Cluster includes Bear Creek Pond, a freshwater emergent/aquatic habitat covering approximately 15 hectares. This habitat consists of Bear Creek Pond and a portion of lower Bear Creek, an ephemeral creek. Although the pond is generally undisturbed, it is downgradient of and receives surface-water runoff from the formerly active launch pads at IRP Sites 5 (Space Launch Complex 3 East) and 6 (Space Launch Complex 3 West). Potential sources of contamination include chlorinated solvents and metals from sandblast grit. Metals were investigated as primary sources of risk in sediments of Bear Creek Pond. The frequency of inundation, duration, and depth of surface water in the pond vary from year to year; during some years the pond contains little or no water. In some years, Bear Creek Pond provides potentially suitable habitat for a variety of wildlife, including benthic and aquatic invertebrates, amphibians, and shorebirds. Several metals in pond sediments were initially predicted to pose potential risks to benthic invertebrates. However, sediment bioassays did not provide any evidence of adverse impacts to invertebrates. These results indicate that there is a negligible risk to benthic invertebrates at Bear Creek Pond as compared to ambient conditions.
Primary Pathway: Benthic
Tools Used: Bulk sediment chemistry, toxicity testing
Methods: Eight sediment samples were collected for sediment toxicity bioassays. Ten-day survival and growth bioassays using the amphipod Hyallela azteca were performed on four sediment samples from Bear Creek Pond and four upstream reference locations. These bioassays did not show any adverse effects to the test species in comparison to reference sediments collected from upgradient areas of Bear Creek. These results were supported by bulk sediment chemistry analyses, which included AVS analysis.
How Bioavailability Was Used: Bioavailability was indirectly assessed by toxicity testing. These sediment bioassays indicated that there is a negligible risk to benthic invertebrates at Bear Creek Pond as compared to ambient conditions. In addition, AVS analyses indicated that metals in site-specific sediments likely exhibit limited bioavailability.
Reference: Tetra Tech, Inc. 2002. “Results of Sediment Bioassays Performed for the Site 5/7 Sediment Bioassay Focused Feasibility Study, Vandenberg Air Force Base, California.” Letter to Capt. Sean O’Brien, Department of the Air Force, HQ AFCEE/ERD, Brooks Air Force Base, Texas, 28 March.
Stephen Geiger, 703-297-9118, email@example.com
Site Description: The Washington Navy Yard (WNY) opened officially in 1799, and ship building and repair operations were ongoing by 1822. During the 1800s, ordnance production, research, and other industrial activities were prevalent at the yard. In 1886, the WNY was redesignated as the Naval Gun Factory. During the next 20 years, considerable expansion of the WNY occurred, and production of ordnance remained the primary operational activity at the facility during this time. Significant areas of adjacent marshlands were filled to accommodate the WNY.
Wastes generated at the site include metals used in ordnance production and paint-spraying, solvents use in cleaning, cyanide and phenols use in the cooling process, creosote used in wood treatment, petroleum products and wastes, and PCB-containing oils in storage tanks and electrical equipment. Contamination also likely occurred during storage and handling of raw materials. Sediment sampling of the river showed elevated concentrations of PAHs. The WNY is on the National Priorities List as a hazardous waste site.
A field demonstration was conducted under Environmental Security Technology Certification Program (ESTCP) to assess the applicability of using a direct method of analyzing PAHs in sediment pore water as a robust method of evaluating the bioavailability of PAHs to benthic invertebrates.
Primary Pathway: Benthic
Tools: Bulk sediment chemistry, direct analysis of pore-water chemistry using SPME, and benthic invertebrate toxicity testing
Methods: USEPA provides a tiered conceptual approach for evaluating the bioavailability of PAHs to benthic invertebrates in the document Evaluating Ecological Risk to Invertebrate Receptors from PAHs in Sediments at Hazardous Waste Sites (Burgess 2007). This demonstration project estimated the bioavailability of sediment PAHs using the USEPA’s tiered approach. The first tier was the comparison of total PAH concentrations to sediment quality thresholds (threshold and probable effects levels) as well as estimating PAH pore-water concentrations using EqP and then comparing the estimated pore-water concentrations to biota-specific effects concentrations (FCVs). The second tier compared pore-water PAH concentrations that were directly analyzed using SPME (USEPA SW-846 Method 8272/ASTM Method D-7363-07) and comparing these to the FCVs. The third tier was aquatic toxicity testing using a surrogate benthic invertebrate Hyalella azteca.
How Bioavailability Was Used: The sediment quality thresholds overestimated the toxicity of the sediments when compared to the results of the aquatic toxicity tests, indicating that the use of these thresholds alone would have resulted in an incorrect decision. The use of EqP also overestimated the toxicity of the sediments (i.e., TUs were all >1 although only one sample was toxic to H. azteca). The SPME direct analysis of pore water method accurately predicted the results of the aquatic toxicity tests (i.e., TUs <1 where there was no toxicity to H. azteca, and TUs >1 where there was toxicity).
Comments: The demonstration results agree with those from other field sites (mostly manufactured gas plants and smelter sites), which show that the use of total PAH concentrations does not accurately reflect the bioavailability of PAHs when anthropogenic carbon is present and that a direct pore-water analysis method is a better and more accurate option for evaluating PAH bioavailability to benthic organisms in industrial/urban waterways.