Sediment Dredging at Superfund Megasites Assessing the Effectiveness (2007) / Chapter Skim
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5 Monitoring for Effectiveness: Current Practices and Proposed Improvements
5 Monitoring for Effectiveness: Current Practices and Proposed Improvements
Pages 178-239
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From page 178... ...
5 Monitoring for Effectiveness: Current Practices and Proposed Improvements MONITORING FOR EFFECTIVENESS The effectiveness of environmental dredging in reducing risk, as predicted when the remedy was selected, can be verified only through monitoring. Monitoring includes • Monitoring of potential short-term risks due to dredging.
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From page 179... ...
Monitoring for Effectiveness 179 cause sediments typically pose long-term risks, monitoring often must span decades to assess risk reduction. The ultimate goal of monitoring is protection -- that is, ensuring that short-term and long-term risks are minimized, by providing sufficient information to judge that the remedy is effective, or to adapt site management to optimize the remedy's performance to achieve risk-based objectives.
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180 Sediment Dredging at Superfund Megasites a. Appropriate metrics need to be chosen, measuring suc cess against expectations based on the conceptual site model.
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Monitoring for Effectiveness 181 ways, and receptors have been well characterized by the time a remedy is selected, including bioavailability and food-web relationships as applicable, and there has been sufficient pilot testing or other means of anticipating site-specific field conditions and implementation challenges, well-designed monitoring should indicate the remedy has performed as expected. If not, monitoring can help to identify important elements that are missing from the conceptual site model so that its predictions can be made more accurate and site management can be adapted accordingly, as recommended in EPA's Contaminated Sediment Remediation Guidance (2005a)
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From page 182... ...
182 Sediment Dredging at Superfund Megasites BOX 5-1 Estimated Monitoring Costs for Lower Fox River and Green Bay, Wisconsin, ROD Remedy The costs of construction monitoring (including verification sampling) and long-term monitoring (including an initial pre-dredging baseline survey of affected media and surveys of the same media continuing for decades after the remedy)
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Monitoring for Effectiveness 183 form a fair and conclusive evaluation of remedy effectiveness and risk reduction, and resources and energy should be focused on this objective. Information developed from the monitoring program should be used to guide future decision-making in a manner which balances a realistic assessment of the projected environmental benefit relative to anticipated costs.
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From page 184... ...
184 Sediment Dredging at Superfund Megasites Consistent with its role in supporting hypothesis-testing, the monitoring protocol should be rigorous enough to allow managers to evaluate critically the potential adverse effects of dredging on human and ecologic receptors and potential risk reductions due to removal of contaminated sediment. For example, proper reference sites or reference conditions should be established to allow comparison of affected media with pre-dredging or nondredged controls.
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Monitoring for Effectiveness 185 urements and techniques and to guide the design of monitoring programs for a contaminated sediment site undergoing remediation. Monitoring Parameters and Techniques Monitoring involves combinations of physical, chemical, and biologic methods.
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186 Sediment Dredging at Superfund Megasites BOX 5-2 Common Physical, Chemical, and Biologic Measurements Used To Characterize Contaminated Sediments Common physical measurements include • Sediment geophysical properties, such as bulk density, particle size, and shear strength. • Pre-dredging and post-dredging bottom elevations, and sediment bedforms.
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Monitoring for Effectiveness 187 FIGURE 5-1 Sediment profile imagery (SPI) equipment (two left photos)
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188 Sediment Dredging at Superfund Megasites tant to monitor those parameters that affect chemical bioavailability, such as total and dissolved organic carbon, acid volatile sulfides (AVSs) , grain size, and pore water fractions because organisms are exposed only to the bioavailable fraction (NRC 2003)
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Monitoring for Effectiveness 189 They are robust, simple, and inexpensive and have a short equilibration time (Booij et al. 1998; Adams 2003)
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190 Sediment Dredging at Superfund Megasites TABLE 5-1 Strengths and Limitations of Methods for Assessing Biologic Effects in Aquatic Ecosystems Effect Assessment Method Advantages Limitations Criteria or Proven utility and ease of use Assume single chemical effect; based on laboratory guidelines exposures; causality link uncertain Biotic-ligand Proven utility and ease of use Insufficient research and model for accounting for metal validation for use with bioavailability in surface water sediment Empirically Proven utility and ease of use Bioavailability not accounted based guidelines for; may lead to incorrect conclusion of presence or absence of risk Equilibrium- Regulatory support; predictive Not applicable in dynamic based guidelines capability systems; does not consider all critical binding phases Species sensitivity Use of all available data for Lack of sufficiently large and distributions derivation of EQC or PNEC diverse sediment-toxicity datasets Indigenous biota Target receptors; lack of Habitat and other natural laboratory extrapolation; long- stressors or linkages term measure; proven utility; confound causality linkage; public interest; colonization inherent variability; loss of and transplant methods colonization units possible increase stressor diagnostic because of flow and power and experimental vandalism power Tissue residues and Documents exposure; use for Adaptation, acclimation, and biomarkers food web and risk models; metabolism confound widely used; very sensitive interpretations; uncertain and timely adverse- effect threshold levels Biomimetic Accumulates organics or Selectivity varies with devices: metals from waters and different chemicals; may not semipermeable sediments through diffusion mimic bioaccumulation of all membrane devices; and sorption; amounts organisms; some are subject
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From page 191... ...
Monitoring for Effectiveness 191 TABLE 5-1 Continued Effect Assessment Method Advantages Limitations solid-phase accumulated on these inert to fouling, depending on microextraction; materials are similar to ecosystem; not standardized Tenax; diffusive amounts bioaccumulated in gradient transport fish tissues; can be placed in situ for short to long periods and then directly analyzed in laboratory Toxicity assays Bioavailability indicator; Causality link uncertain; (laboratory) proven utility; integrates laboratory-to-field effects of multiple chemicals; extrapolation; individual-to does not measure natural community extrapolations; stressors does not measure natural stressors; cost of chronic assays Toxicity and More realistic exposure, which Most methods are not bioaccumulation reduces artifact potential; standardized; limited use; assays (field)
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192 Sediment Dredging at Superfund Megasites Biologic testing often has both field and laboratory components -- organisms collected from the field are identified and enumerated or, in marine systems, exposed to sediment-bound or water-borne chemicals in a laboratory (e.g., Barbour et al. 1999; EPA 2001a; Adams et al.
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Monitoring for Effectiveness 193 sediment sites (Greenberg et al. 2002; Burton et al.
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194 Sediment Dredging at Superfund Megasites chemistry to effects datasets to predict the probability of or the presence and absence of adverse or toxic effects (Word et al.
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Monitoring for Effectiveness 195 resolved, they will see continued and greater use in toxicity evaluations, comparative risk analyses, and in remedial decision making. MONITORING-PROGRAM DESIGN Selection of the appropriate monitoring measures and design of a monitoring program depend on the development of clear hypotheses to be tested or questions to be answered that are directly linked to a detailed conceptual site model characterizing sources, pathways of exposure, and receptors that may be exposed during or after remediation.
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From page 196... ...
196 Sediment Dredging at Superfund Megasites dredger and site manager and to develop a compliance history spanning the various phases of the project. With available technologies, some contaminant release and transport is inevitable during dredging (EPA 2005a)
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Monitoring for Effectiveness 197 ing dredging operations. In some of the projects, increased exposure occurred during dredging in connection with the physical disruption of contaminated sediment.
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198 Sediment Dredging at Superfund Megasites protect human health. When members of the surrounding community comply with those restrictions, exposures of concern during dredging are limited to other pathways, such as releases to the atmosphere and surface water.
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Monitoring for Effectiveness 199 BOX 5-3 Monitoring of Conditions During Hot-Spot Dredging at the New Bedford Harbor Superfund Site for Effects on Human Exposure The New Bedford Harbor Superfund site has been the subject of extensive efforts to understand the effects of harbor contamination on aquatic species and people living near the harbor. In addition, EPA developed a plan to monitor the effects of dredging a contaminated hot spot on water quality, air quality, and bioaccumulation by benthic invertebrates.
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200 Sediment Dredging at Superfund Megasites BOX 5-3 Continued start and stop dates for dredging of contaminated New Bedford Harbor sediments. Plots are adjusted for child's sex, maternal age, birthplace, smoking during pregnancy, previous lactation, household income, and diet (consumption of organ meat, red meat, local dairy, and dark fish)
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Monitoring for Effectiveness 201 sels deployed in mesh bags have been used in the long-term monitoring program at the New Bedford Harbor Superfund site to monitor trends in PCB bioaccumulation and evaluate the impact of dredging operations (Bergen et al.
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202 Sediment Dredging at Superfund Megasites The use of natural resident populations collected during and immediately after dredging is an alternative to caging studies. For example, resident spottail shiners collected during the 2005 dredging operations at the Grasse River showed significant increases compared to sampling conducted during several years prior to dredging and the year following dredging (see Chapter 4, Figure 4-10 and associated text)
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Monitoring for Effectiveness 203 The dredging projects evaluated by the committee include numerous examples of sites where dredging generated substantial residual contamination. Verification sampling is needed to detect and quantify generated residuals.
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204 Sediment Dredging at Superfund Megasites BOX 5-5 Delineating the Dredge Prism in the Fox River, Wisconsin Sediment remediation areas and volumes were delineated for the remedial design of the lower Fox River, WI, between Operable Unit 2 and the mouth of Green Bay with an advanced interpolation method called full-indicator kriging. Full-indicator kriging provided a probability distribution of depth of contamination to the ROD cleanup level at each sediment location.
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Monitoring for Effectiveness 205 BOX 5-6 Verification Sampling of Dredging Residuals at the Head of Hylebos Site, Commencement Bay, Washington Discrete sediment samples were collected on a daily basis immediately behind the operating dredge to provide immediate evaluation of the post-dredging residual layer for the Head of Hylebos project. Nearly 1,000 discrete samples of the residual layer were collected using a Marine Sampling Systems 0.3m2 Power Grab (Power Grab)
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206 Sediment Dredging at Superfund Megasites achieved. Superfund remedies at sediment sites are typically subject to review at 5-year intervals when, following remediation, contamination exists that could limit potential uses of the site (EPA 2001b)
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Monitoring for Effectiveness 207 When a dredging remedy is implemented, surface sediment concentrations can be affected by a combination of sediment removal, backfilling with clean material, and natural recovery processes. At larger sites, where remediation may proceed over a period of years, there is value in determining the relative importance of each of those processes in reducing surface concentrations.
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208 Sediment Dredging at Superfund Megasites BOX 5-7 Dredging and Later Sedimentation at Manistique Harbor, Michigan After dredging ended at Manistique Harbor, 3-7 ft of sediment were deposited from 1996 to 2005 (Weston 2005)
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Monitoring for Effectiveness 209 BOX 5-8 Collecting Aquatic Samples for Monitoring Human Exposure Fish and Shellfish • Sample the species commonly eaten by the local population and be sure to include species known to accumulate high concentrations of chemicals of concern. • Catch the size range of fish harvested by the local population, being sure to include the larger fish usually harvested because larger (older)
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210 Sediment Dredging at Superfund Megasites BOX 5-8 Continued Sediment • Collect from accessible locations where people are likely to fish, swim, or engage in other activities (sediment samples in deep water, for example, may be relevant to the food-chain exposure pathway but not the direct-contact pathway)
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Monitoring for Effectiveness 211 monitored over time to estimate expected cumulative cancer risk and noncancer hazards. If monitoring during or after dredging indicates that cleanup levels will not be met in the long run, site managers can use adaptive management to change this trend.
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212 Sediment Dredging at Superfund Megasites exposures over the remediation area. Several of the dredging projects (such as Waukegan Harbor, Grasse River, Black River, the Puget Sound Naval Shipyard, and GM Massena)
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Monitoring for Effectiveness 213 gate for fish (Arthur and Pawliszyn 1990; Huckins et al. 1990; Zhang et al.
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214 Sediment Dredging at Superfund Megasites tistical problems associated with field biomonitoring studies (Clark and Clements 2006)
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Monitoring for Effectiveness 215 maximizing statistical power (Mason et al.
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216 Sediment Dredging at Superfund Megasites diation, however, it is essential to consider trends that would occur regardless of dredging (for example, natural decreasing or increasing trends in contaminant concentrations in sediment or fish)
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Monitoring for Effectiveness 217 followup statistical analyses to include possible spatial dependence and make the appropriate adjustments when necessary. In the dredging projects reviewed, the committee found that the quantity and quality of available and accessible monitoring data varied considerably.
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218 Sediment Dredging at Superfund Megasites • Closely link exposure data (that is, chemical data) with biologic effect.
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Monitoring for Effectiveness 219 (such as PCBs) because the measurement is robust and quick and may be automated.
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220 Sediment Dredging at Superfund Megasites metric detection, could be carried out in the field with a test kit and portable equipment [Ta 2001]
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Monitoring for Effectiveness 221 BOX 5-9 Biodynamic Modeling to Predict Organism PCB Concentrations If an organism is considered a single compartment for contaminant uptake, the following biodynamic equation describes its accumulation of a toxic contaminant (McLeod et al.
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222 Sediment Dredging at Superfund Megasites biodynamics and contaminant metabolism, combined with data on species availability for community recruitment. Understand and Model Reduction in Human Exposure Monitoring programs should include measurement of surface sediment, surface water, edible aquatic species, and other environmental media found in the baseline risk assessment to present unacceptable human health risks through either direct or indirect exposure.
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From page 223... ...
Monitoring for Effectiveness 223 lowup is needed to meet risk-based cleanup levels. Downtime for dredging equipment and operators is expensive, but verification sampling and laboratory analysis can be slow and laborious and require dredgers to move on to other locations and return when results are available and have been reviewed.
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224 Sediment Dredging at Superfund Megasites To estimate the combined effects of backfilling and burial on bioavailability, organic-chemical concentrations in surface layers should be organic-carbon normalized, and acid-volatile sulfide analyses of metals should be conducted. Emerging field methods of pore water and bioavailability analysis should also be applied as they become more reliable and widely available.
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Monitoring for Effectiveness 225 pre-remedial time-trend analysis is needed to judge remedial effectiveness. • In most cases reviewed by the committee, monitoring has not been adequately designed or implemented.
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226 Sediment Dredging at Superfund Megasites RECOMMENDATIONS The committee offers the following recommendations for improving monitoring of dredging effectiveness: • EPA should ensure that monitoring is conducted at all contaminated sediment megasites to evaluate remedy effectiveness. That will require a commitment of resources commensurate with the scale and complexity of the site.
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Monitoring for Effectiveness 227 • Pre-remediation baseline monitoring methods and strategies should be developed to allow statistically valid comparisons with future monitoring datasets that rely on time-series data. The ultimate goal is to assemble a consistent long-term dataset for conducting evaluations.
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228 Sediment Dredging at Superfund Megasites Anchor and LimnoTech.
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Monitoring for Effectiveness 229 Booij, K., H.M. Sleiderink, and F
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230 Sediment Dredging at Superfund Megasites Conder, J.M., and T.W. La Point.
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Monitoring for Effectiveness 231 Elzinga, C.L., D.W. Salzer, and J.W.
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232 Sediment Dredging at Superfund Megasites EPA (U.S. Environmental Protection Agency)
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Monitoring for Effectiveness 233 Emergency Response, U.S. Environmental Protection Agency.
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234 Sediment Dredging at Superfund Megasites mil/oai/oai? &verb=getRecord&metadataPrefix=html&identifier=ADA22944 2 [accessed Jan.
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Monitoring for Effectiveness 235 Kelaher, B.P., J.S. Levinton, J
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236 Sediment Dredging at Superfund Megasites Long, E.R., and D.D. MacDonald.
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Monitoring for Effectiveness 237 Nichols, F.H., and J.K. Thompson.
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238 Sediment Dredging at Superfund Megasites G.T. Shimmield, M
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Monitoring for Effectiveness 239 Yount, J.D., and G.J. Niemi.
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