The importance of recognizing Buffer Zones to lands being developed, restored, or remediated: on planning for protection of ecological resources.

Environmental management relies on many types of information before making decisions regarding remediation, restoration, or other land use decisions, including ecological data, such as risks to species, populations, communities, and ecosystems. The aim of this investigation was to describe the ecological information required within the context of making environmental decisions and providing visual communication tools for regulators, conservationists, and the public to understand the risk to ecological resources on- and off-site. It is suggested that ecological information used in environmental decisions is required to be transparent throughout the planning and execution of a project, which needs to include: 1) ecological information and evaluations within development areas or units (in this case, watersheds), and 2) resources in adjacent areas (Buffer Zones) that might be affected. The Melton Valley administrative watershed (Oak Ridge Reservation, TN) is used as a case study because this site still has active facility development and environmental remediation, and there are important ecological resources on and off-site. Data indicate that although there are important resources on Melton Valley administrative watershed, there are also significant resources in the Buffer Zone around the watershed. Compared to the Melton Valley administrative watershed, the Buffer Zone contains more Interior (and Buffer) Forest and greater value resources. The point is made that when remediation, restoration, or development occurs, it is equally important to consider resources that are adjacent to the site in a Buffer Zone, particularly when remediation and development might continue for many years or decades.

Comparing land cover and interior forests on contaminated land and the surrounding region: Oak Ridge Reservation as a case study.

Pressure from expanding populations has resulted in a need for protection, reclamation, and restoration of damaged land to productive, beneficial health uses. The objective of this investigation was to 1) compare land cover on the Department of Energy (DOE) Oak Ridge Reservation (ORR) with the surrounding region, 2) select an indicator to evaluate ORR's protection of ecological resources, and 3) develop and implement a method to compare the amount of the indicator on ORR with the regions using National Land Cover Database (NLCD). Data demonstrated that ORR has a higher % of forests (deciduous, coniferous, mixed) than the 10 km and 30 km areas surrounding ORR, suggesting that obligations are being met to protect the ecology and environment. The findings also indicate that the interior forest at ORR is fragmented more than is the interior forest in the 30 km buffer zone, suggesting a need for DOE and managers of other lands to take into consideration the importance of intact interior forest when developing land or planning roads. The study describes the basis for specific ecological parameters such as interior forest that are important to consider when planning and executing remediation, restoration, and other management actions.

Combining ecological, eco-cultural, and environmental justice parameters to create Eco-EJ indicators to monitor cultural and environmental justices for diverse communities around contaminated sites.

Assessing environmental quality often requires selection of indicators that can be employed over large spatial scales and over long-time periods to assess the health and well-being of species, natural communities, and ecosystems, and to detect changes warranting intervention. Typically, the ecologic environment and the human environment are evaluated separately and selection of indicators and monitoring approaches are not integrated even though ecological indicators may also provide information on risk to human consumers from contaminants (e.g., eco-cultural indicators) or because of disease levels. This paper is a call for ecologists and managers to consider diverse cultural and environmental injustice disparities and health issues when selecting indicators for environmental assessment and monitoring. There is an opportunity for managers and community members to work together to preserve ecological and cultural resources and heritages. We propose a paradigm that selects indicators and monitoring approaches that lend themselves to the integration of human-diversity and uniqueness in the same manner that the selection of ecological indicators and monitoring approaches consider biological species diversity and uniqueness. The proposed paradigm builds on ecological risk assessment techniques, developing analogous endpoints for neighboring communities. For example, identification and protection of human communities, particularly culturally diverse and environmental justice communities, identification of contaminant corridors (e.g., through water or green corridors) into communities, and eco-monitoring of vulnerable communities are not routine at contaminated sites. Green corridors refers to a width of wild habitat (forest, grasslands) that connects other similar habitat paths (usually a corridor runs through an urban or suburban habitat). We coin the term Eco-EJ indicators for these endpoints, including examination of (1) unique cultural relationships to resources; (2) connectedness of on-site and off-site resources and habitats; (3) health of threatened, rare, and unique cultures and communities; and (4) linkages between ecological, eco-cultural, and public health for monitoring and assessment. We also propose that assessment and monitoring include these Eco-EJ indicators, especially for communities near facilities that have extensive chemical or radiological contamination.Developing these indicators to assess risk to culturally diverse and environmental justice communities would be an equivalent goal to reducing risk for significant ecological resources (e.g., endangered species, species of special concern). These Eco-EJ indicators are complementary to the usual human health-risk assessments, would include surveys of neighboring vulnerable communities, and require time and re-organization of current data and additional data collection at site boundaries and in adjacent communities, as well as rethinking the human component of indicators. This approach lends itself to addressing some diverse cultural and environmental justice issues with current indicator selection and biomonitoring, and helps identify specific hotspots of unique ecosystem risk and environmental justice community risk. We briefly discuss ecological and eco-cultural monitoring already on-going at three Department of Energy sites to illustrate how the addition of these indicators might work and add value to environmental management and to their relationships with surrounding communities. We recommend that managers of contaminated sites convene people from culturally diverse communities, environmental justice communities, local and federal government, Tribes, resource trustees, managers, and other stakeholders to develop appropriate site-specific indicators to address environmental inequities around contaminated facilities.

Development of a Geochemical Speciation Model for Use in Evaluating Leaching from a Cementitious Radioactive Waste Form.

Cast Stone has been developed to immobilize a fraction of radioactive waste at the Hanford Site; however, constituents of potential concern (COPCs) can be released when in contact with water during disposal. Herein, a representative mineral and parameter set for geochemical speciation modeling was developed for Cast Stone aged in inert and oxic environments, to simulate leaching concentrations of major and trace constituents. The geochemical speciation model was verified using a monolithic diffusion model in conjunction with independent monolithic diffusion test results. Eskolaite (Cr2O3) was confirmed as the dominant mineral retaining Cr in Cast Stone doped with 0.1 or 0.2 wt % Cr. The immobilization of Tc as a primary COPC in Cast Stone was evaluated, and the redox states of porewater within monolithic Cast Stone indicated by Cr are insufficient for the reduction of Tc. However, redox states provided by blast furnace slag (BFS) within the interior of Cast Stone are capable of reducing Tc for immobilization, with the immobilization reaction rate postulated to be controlled by the diffusive migration of soluble Tc in porewater to the surface of reducing BFS particles. Aging in oxic conditions increased the flux of Cr and Tc from monolithic Cast Stone.

Risk to ecological resources following remediation can be due mainly to increased resource value of successful restoration: A case study from the Department of Energy's Hanford Site.

Many nations are faced with the need to remediate large contaminated sites following World War II, the Cold War, and abandoned industrial sites, and to return them to productive land uses. In the United States, the Department of Energy (DOE) has the largest cleanup challenge, and its Hanford Site in the state of Washington has the most extensive and most expensive cleanup task. Ideally, the risk to ecological resources on remediation sites is evaluated before, during, and after remediation, and the risk from, or damage to, ecological resources from contaminants should be lower following remediation. In this paper, we report the risk to ecological resources before, during, and as a consequence of remediation on contaminated units requiring cleanup, and then examine the causes for changes in risk by evaluating 56 cleanup evaluation units (EUs) at the Hanford Site. In this case, remediation includes a restoration phase. In general, the risk to ecological and eco-cultural resources is currently not discernible or low at most contaminated units, increases during remediation, and decreases thereafter. Remediation often causes physical disruption to ecosystems as it reduces the risk from exposure to contaminants. Most new remediation projects at the Hanford Site include ecological restoration. Ecological restoration results in the potential for the presence of higher quality resources after remediation than currently exists on these contaminated lands and facilities. Although counter-intuitive, our evaluation of the risk to ecological resources following remediation indicated that a significant percentage of units (61%) will be at increased risk in the post-remediation period. This increased risk is due to DOE's successful remediation and restoration that results in a higher percent of native vegetation and higher ecological value on the sites in the post-remediation period than before. These newly-created resources can then be at risk from post-remediation activities. Risks to these new higher quality resources include the potential for spread of invasive species and of noxious grasses used in previous cleanup actions, disruption of ecosystems (including those with state or federally listed species and unique ecosystems), compaction of soil, use of pesticides to control invasive species, and the eventual need for continued monitoring activities. Thus, by greatly improving the existing habitat and health of eco-receptors, and maintaining habitat corridors between high quality habitats, the ecological resources in the post-remediated units are at risk unless care is taken to protect them. Many of the negative effects of both remediation and future monitoring (or other future land uses) can be avoided by planning and management early in the remediation process. We suggest DOE and other agencies convene a panel of managers, remediation scientists, regulators, environmental and ecological scientists, Native Americans, economists, and the public to develop a generic list of performance metrics for the restoration phase of remediation, including evaluation of success, which could be applied across the DOE complex.

A paradigm for protecting ecological resources following remediation as a function of future land use designations: a case study for the Department of Energy's Hanford Site.

Since the late 1980s, there has been a US federal mandate to clean up contaminated sites remaining from the Second World War, the Cold War, and abandoned industries. One determinant of cleanup standards for remediation is future land use-how will the land be used and by whom? Land use decisions may be consensus documents developed by site owners, state and federal agencies, and local stakeholders. Often there are competing views and/or claims on how remediated sites should be used, including as open or green space. Large sites are likely to have more ecological heterogeneity within similar land use designations because of differences in climate, geology, topography, and history of human use. This paper uses the Department of Energy's (DOE) Hanford Site as a case study to examine how and whether future land use designations will protect species, species diversity, heterogeneity, and ecosystems once remediation is complete. The objective of this paper is to describe "future land use designations" on a large, complex site (DOE's Hanford Site) and to examine the following: (1) how future land use designations were made and have changed over time, (2) how land use designations included the value of ecological resources, (3) how risk evaluations of ecological resources from remediation were made, and (4) how future land use may affect the health and well-being of ecological resources on site in the post-remediation period. The paper provides a paradigm for integrating ecological protection into future land use designations such that rare and sensitive resources are protected throughout the process. The paradigm includes the following: (1) developing future land use designations, (2) defining resource levels (values), (3) relating resource levels to land use designations and management, (4) defining risk evaluations, (5) determining the likelihood that valuable resources will occur on each land use type after remediation, and (6) evaluating the potential risk to those resources that results from activities allowed under future land use designations. The paper discusses the importance of each step, the implications for protection of ecological resources, and the importance of land use designations in the assessment of risk to ecological resources from both continued monitoring and maintenance by DOE (or other land owners) and the activities permitted by the established future land use designations.

Evaluation of ecological resources at operating facilities at contaminated sites: The Department of Energy's Hanford Site as a case study.

The U.S. and other developed nations are faced with many contaminated sites remaining from World War II, the Cold War, and abandoned industries, that require remediation and restoration to allow future land uses with minimum acceptable risk to humans and ecological resources. For large Department of Energy (DOE) sites with massive remediation tasks remaining, it is important for managers to be able to assure regulators, Tribal Nations, and the public that human and ecological health are protected. Hanford Site has the largest and most expensive cleanup task within the DOE complex; cleanup will continue beyond 2090. Cleanup involves the use of operating facilities, which also may present a risk to humans or ecological resources. We present a brief description of a methodology to evaluate risks to ecological receptors at the Hanford Site from remaining remediation tasks, and evaluate the risk to ecological resources that operating facilities present currently, during active cleanup of these facilities, and during the post cleanup period. Operating facilities include current, active operations that are located on the site and aid in site cleanup, including both storage and treatment operations. At the Hanford Site, they include waste treatment plants, sludge basins, waste trenches, Central Waste Complex, storage facilities, and disposal facilities, among others. Risk ratings for ecological resources are highest during the remediation phase. Risk ratings for the operating facilities at the Hanford Site range from not discernible to medium currently, from not discernible (ND) to high during active cleanup, and from not discernible to medium following cleanup. The highest ratings are for the Waste Treatment and Immobilization Plant that is being constructed to stabilize radioactive and chemical wastes, and the Liquid Effluent Retention and Treatment Facility that removes and deactivates hazardous contaminants from waste water. Higher ratings in the post-cleanup period are largely due to restoration of ecological resources during cleanup, which increases the potential for injury (if these resources are harmed) because a site will then have higher quality resources after cleanup than it did before. Assessing the value of ecological resources, and determining potential consequences during active remediation and after remediation is essential for compliance with state and federal laws. Understanding the risks to ecological resources from now until clean-up is completed at these facilities is important because of the potential for ecological resources of high value to be degraded, and because cleanup completion is not expected until 2090 or later. The methodology can be applied to any contaminated site requiring a rapid method of assessing potential damages to ecological resources from proposed management actions.

Impact of oxidation and carbonation on the release rates of iodine, selenium, technetium, and nitrogen from a cementitious waste form.

Evaluation of the long-term retention mechanisms and potential release rates for the primary constituents of potential concern (COPCs) (i.e., Tc, I, Se, and nitrate) is necessary to determine if Cast Stone, a radioactive waste form, can meet performance objectives under near-surface disposal scenarios. Herein, a mineral and parameter set accounting for the solubility of I and Se in Cast Stone was developed based on pH-dependent and monolithic diffusion leaching test results, to extend a geochemical speciation model previously developed. The impact of oxidation and carbonation as environmental aging processes on the retention properties of Cast Stone for primary COPCs was systematically estimated. Physically, the effective diffusion coefficients of 4 COPCs in Cast Stone were increased after carbonation and/or oxidation, reflecting an increase in permeability to diffusion. Chemically, i) pH & pe conditions in the original Cast Stone were favorable for the stabilization of Tc, but not for I, Se, and N; ii) oxidation (with/without carbonation) of Cast Stone changed the pe & pH conditions to be detrimental for Tc stabilization; and iii) carbonation (with/without oxidation) of Cast Stone modified the pH & pe conditions to be beneficial for the stabilization of I (in system with Ag added) and Se.

Evaluating the impact of drying on leaching from a solidified/stabilized waste using a monolithic diffusion model.

The release rates of constituents of potential concern from solidified/stabilized cementitious waste forms are potentially impacted by drying, which, however, is not well understood. This study aimed to identify the impacts of drying on subsequent leaching from Cast Stone as an example of a solidified cementitious waste form. The release fluxes of constituents from monoliths after aging under 100, 68, 40, and 15 % relative humidity for 16, 32, and 48 weeks, respectively, were derived from mass transfer tank leaching tests following EPA Method 1315. A monolithic diffusion model was calibrated based on the leaching test results to simulate the leaching of major and redox-sensitive constituents from monoliths after drying. The reduction in physical retention of constituents (tortuosity-factor) in the unsaturated zone was identified as the primary impact from drying on subsequent leaching. Fluxes of both major (i.e., OH-, Na, K, Ca, Si, and Al) and redox-sensitive constituents (i.e., Tc, Cr, Fe, and S) from monoliths during leaching were well described by the model. The drying-induced reduction of tortuosity-factor and concomitant changes in porewater pH and redox conditions can significantly change the subsequent release fluxes of pH- and redox- sensitive constituents.

Application and uncertainty of a geochemical speciation model for predicting oxyanion leaching from coal fly ash under different controlling mechanisms.

Three primary mechanisms (adsorption to iron oxides or analogous surfaces, co-precipitation with Ca, and substitution in ettringite) controlling oxyanion retention in coal fly ashes (CFAs) were identified by differentiating the leaching behavior of As, B, Cr, Mo, Se, and V from 30 CFAs. Fidelity evaluation of geochemical speciation modeling focused on six reference CFAs representing a range of CFA compositions, whereby different leaching-controlling mechanisms of oxyanions were systematically considered. For three reference CFAs with low Ca and S content, calibration of adsorption reactions for the diffuse double-layer model for hydrous ferric oxides improved the simultaneous prediction of oxyanion leaching, which reduced uncertainties in Se and V predictions caused by nonideal adsorption surfaces and competitive adsorption effects. For two reference CFAs with intermediate Ca content, the solubility constants for Ca-arsenates from literature and postulated phases of B, Cr, Se, and V were used to describe co-precipitation of oxyanions with Ca-bearing minerals under alkaline conditions. For the reference CFA with high Ca and S content, an ettringite solid solution was used to capture the simultaneous retention of all oxyanions at pH> 9.5. Overall, the simultaneous leaching predictions of oxyanions from a wide range of CFAs were improved by calibration of adsorption reactions and controlling solid phases.

Impact of carbonation on leaching of constituents from a cementitious waste form for treatment of low activity waste at the DOE Hanford site.

Carbonation can be a major aging process during disposal of alkaline cementitious waste forms and can impact constituent leaching by changes in material alkalinity, pore structure, and controlling mineral phases. The effect of carbonation on the leaching of major and trace constituents from Cast Stone, a cementitious waste form developed to treat high salt content low activity waste, was studied through a combination of leaching experiments and reactive transport simulations. Diffusive transport of constituents in the waste form was evaluated using reactive transport modeling of diffusion-controlled leaching test results and a geochemical speciation model derived from pH-dependent leaching. Comparisons between Cast Stone materials aged under nitrogen, air, and 2% carbon dioxide in nitrogen showed that carbonation impacts solubility, physical retention and observed diffusivity of major and trace constituents. Carbonation under 2% CO2 decreased the diffusion-controlled leaching of chromium by two orders of magnitude. Modeling results suggest that carbonation may also decrease solubility of technetium while changes to microstructure by carbonation increases effective diffusivity of constituents in Cast Stone.

The influence of redox conditions on aqueous-solid partitioning of arsenic and selenium in a closed coal ash impoundment.

A closed coal ash impoundment case study characterized the effects of field redox conditions on arsenic and selenium partitioning through monitoring of porewater and subsurface gas in conjunction with geochemical speciation modeling. When disposed coal ash materials and porewater were recovered for testing, oxidation led to lower arsenic and higher selenium concentrations in leaching test extracts compared to porewater measurements. Multiple lines of evidence suggest multiple mechanisms of arsenic retention are plausible and the concurrent presence of several redox processes and conditions (e.g., methanogenesis, sulfate reduction, and Fe(III)-reduction) controlled by spatial gradients and dis-equilibrium. Geochemical speciation modeling indicated that, under reducing field conditions, selenium was immobilized through the formation of insoluble precipitates Se(0) or FeSe while arsenic partitioning was affected by a progression of reactions including changes in arsenic speciation, reduction in adsorption due to dissolution and recrystallization of hydrous ferric oxides, and precipitation of arsenic sulfide minerals.

Demonstration of the use of test results from the Leaching Environmental Assessment Framework (LEAF) to develop screening-level leaching assessments.

Environmental management often benefits from leaching assessment as a predictive tool for estimating constituent leaching from solid and waste materials. The Leaching Environmental Assessment Framework (LEAF) provides both validated tests methods for characterizing materials and a methodology for developing screening assessments based on material characterization results. The use of LEAF data in a screening-level environmental assessment approach is demonstrated through a hypothetical case study of copper/lead smelter soil remediation. The LEAF test methods characterize leaching behavior from a wide range of materials as either constituent liquid-solid partitioning as functions of pH and liquid-to-solid ratio (L/S) or as a rate of constituent mass transport. In this study, leaching characteristics of a contaminated smelter soil and the same soil treated by solidification/stabilization with Portland cement were compared to hypothetical environmental thresholds. Screening assessments were developed for total content, available content, and maximum concentrations over relevant pH domains and L/S ranges. Assessment ratios for barium, beryllium, and fluoride indicated that estimated leaching would be less than thresholds in both materials and these constituents were removed from further analysis. Similarly, chromium (in soil) and zinc (in solidified material) were screened from further analysis. For the remaining constituents, scenario-based assessment could refine estimated leaching concentrations by considering anticipated conditions of leaching scenario.

Methodology for scenario-based assessments and demonstration of treatment effectiveness using the Leaching Environmental Assessment Framework (LEAF).

A methodology for developing scenario-based leaching assessments as part of the Leaching Environmental Assessment Framework (LEAF) is illustrated using a hypothetical management/treatment scenario of contaminated soil from a copper and lead smelter. Scenario assessments refine the process beyond screening-level assessments by considering site- and scenario-specific information about the disposal or utilization environment. LEAF assessments assume (i) granular materials leach at local equilibrium with percolating water, while (ii) monolithic materials (e.g., low permeability solidified/stabilized soils) leach by diffusion-based mass transport toward surrounding contact water. Leaching concentrations, estimated using LEAF leaching test data and estimated or measured scenario information, are compared to threshold values. Demonstration results indicate that leaching from untreated soil is significantly (>10x) greater from solidified/stabilized soil than treated material, except for highly soluble constituents (Cl-, NO3-2) or when constituents have similar equilibrium concentrations in both materials (As, Pb). Comparison between wet and dry environments show that while dry environments lead to lower COPC mass-based rates of leaching, the leaching concentrations may be higher due to lower liquid-to-solid ratios. The presented assessment methodology can be used to evaluate treatment effectiveness when both physical and chemical retention characteristics of the material are altered.

The costs of delaying remediation on human, ecological, and eco-cultural resources: Considerations for the Department of Energy: A methodological framework.

Remediation and restoration of the Nation's nuclear legacy of radiological and chemical contaminated areas is an ongoing and costly challenge for the U.S. Department of Energy (DOE). For large sites, such as the Hanford and Savannah River Sites, successful remediation involves complex decisions related to remedies, end-states, timing, and sequencing of cleanup of separate and related contaminated units within a site. Hanford Site cannot clean up every unit simultaneously due to limits in funding, personnel, and technology. This paper addresses one of the major considerations - the consequences of delaying remediation of a unit on different receptors (e.g. people, ecological, and eco-cultural resources), using the DOE Hanford Site as a case study. We develop a list of attributes that managers should consider for successful remediation, examine how delaying remediation could affect workers, the public and ecological resources (including water resources), and use some examples to illustrate potential effects of delays. The factors to consider when deciding whether and how long to delay remediation of a unit include personnel, information and data, funding, equipment, structural integrity, contaminant source, and resource vulnerability. Each of these factors affects receptors differently. Any remediation task may be dependent on other remediation projects, on the availability of transport, containers, interim storage and ultimate disposition decisions, or the availability of trained personnel. Delaying remediation may have consequences for people (e.g. workers, site neighbors), plants, animals, ecosystems, and eco-cultural resources (i.e. those cultural values that depend upon ecological resources). The risks, benefits, and uncertainties for evaluating the consequences of delaying remediation are described and discussed. Assessing the advantages and disadvantages of delaying remediation is important for health professionals, ecologists, resource trustees, regulators, Tribal members, recreationists, fishermen, hunters, conservationists, and a wide range of other stakeholders.