Uncontrolled Hazardous Waste Sites Research Articles

Containment of Sources of Groundwater Contamination: Analysis of Mass Fluxes.

Cutoff walls and liners are used frequently as barriers to isolate contaminants at both controlled and uncontrolled hazardous waste sites. Neville and Andrews (2006) presented a containment criterion for contaminant isolation by a barrier. The analysis of Neville and Andrews (2006) yields the inward Darcy flux that balances the diffusive mass flux from the source so that the net mass flux is zero. A requirement of zero net mass flux may not be achievable in all situations. The analysis developed by Neville and Andrews (2006) is extended to develop straightforward expressions for the long-term mass fluxes across a barrier for any conditions. In cases where it may not be possible to satisfy a criterion of zero net mass flux, the results from an exact solution for transient solute transport are used to show how the mass fluxes evolve to their long-term values.

Recent Trends in the Selection of Remedies for Groundwater, Soil, and Sediment at Superfund Sites

Recent Trends in the Selection of Remedies for Groundwater, Soil, and Sediment at Superfund Sites

Dechlorination of pentachlorophenol (PCP) in aqueous solution on novel Pd-loaded electrode modified with PPy-SDBS composite film.

Pentachlorophenol (PCP) is a persistent pollutant and a suspected human carcinogen. It can be found in the air, water, and soil and enters the environment through evaporation from treated wood surfaces, industrial spills, and disposal at uncontrolled hazardous waste sites. Ecotoxicity of PCP necessitates the development of rapid and reliable remediation techniques. Electrocatalytic hydrogenolysis (ECH) has been proven as a promising method for detoxification of halogenated wastes, due to its rapid reaction rate, low apparatus cost, mild reaction conditions, and absence of secondary contaminants. Challenge for the application of ECH is to prepare a Pd-coated cathode with high stability, high catalytic activity, and low Pd loading level. In this work, Pd/polypyrrole-sodium dodecyl benzene sulfonate/meshed Ti (Pd/PPy-SDBS/Ti) electrode was prepared and was characterized by cyclic voltammetry, scanning electron microscopy, X-ray diffraction, and inductively coupled plasma-atomic emission spectrometry. Electrochemically reductive dechlorination of PCP on the Pd/PPy-SDBS/Ti electrode in aqueous solution was investigated. Pd microparticles were uniformly dispersed on PPy-SDBS film which was previously electrodeposited on the meshed Ti supporting electrode. The loading of Pd on the electrode was 0.72 mg cm(-2). Electrocatalytic dechlorination of PCP was performed in a two-compartment cell separated by cation-exchange membrane. The PCP removal on the Pd/PPy-SDBS/Ti electrode could reach 100 % within 70 min with dechlorination current 3 mA when PCP initial concentration was 10 mg L(-1) and initial pH was 2.4. Conversion of PCP on the Pd/PPy-SDBS/Ti electrode followed pseudo-first-order kinetics, and the apparent activation energy was 13.0 kJ mol(-1). The removal of PCP still kept 100 % after 70 min dechlorination when the Pd/PPy-SDBS/Ti cathode was reused ten times. The electrode exhibited promising dechlorination potential with high electrocatalytic activity, good stability, and low cost.

Spatial disparity in the distribution of superfund sites in South Carolina: an ecological study

BackgroundAccording to the US Environmental Protection Agency (EPA), Superfund is a federal government program implemented to clean up uncontrolled hazardous waste sites. Twenty-six sites in South Carolina (SC) have been included on the National Priorities List (NPL), which has serious human health and environmental implications. The purpose of this study was to assess spatial disparities in the distribution of Superfund sites in SC.MethodsThe 2000 US census tract and block level data were used to generate population characteristics, which included race/ethnicity, socioeconomic status (SES), education, home ownership, and home built before 1950. Geographic Information Systems (GIS) were used to map Superfund facilities and develop choropleth maps based on the aforementioned sociodemographic variables. Spatial methods, including mean and median distance analysis, buffer analysis, and spatial approximation were employed to characterize burden disparities. Regression analysis was performed to assess the relationship between the number of Superfund facilities and population characteristics.ResultsSpatial coincidence results showed that of the 29.5% of Blacks living in SC, 55.9% live in Superfund host census tracts. Among all populations in SC living below poverty (14.2%), 57.2% were located in Superfund host census tracts. Buffer analyses results (0.5mi, 1.0mi, 5.0mi, 0.5km, 1.0km, and 5.0km) showed a higher percentage of Whites compared to Blacks hosting a Superfund facility. Conversely, a slightly higher percentage of Blacks hosted (30.2%) a Superfund facility than those not hosting (28.8%) while their White counterparts had more equivalent values (66.7% and 67.8%, respectively). Regression analyses in the reduced model (Adj. R2 = 0.038) only explained a small percentage of the variance. In addition, the mean distance for percent of Blacks in the 90th percentile for Superfund facilities was 0.48mi.ConclusionBurden disparities exist in the distribution of Superfund facilities in SC at the block and census tract levels across varying levels of demographic composition for race/ethnicity and SES.

Ground Gas Handbook

Emissions of toxic gases are expected to be encountered in a variety of geologic settings, for example: (1) engineered waste disposal sites, which are nominally required to incorporate design measures for capture and control; (2) all manner of dumps and other un-engineered and/or uncontrolled waste disposal sites; (3) derelict industrial sites and their plant and off-plant dump and discharge points; and (4) certain natural bodies, in particular, shallow oil fields, or deposits of toxic mineral compounds formed and/or released during the geologic history of the site. Geologists, therefore, are the natural choice for the professional needed to predict and discover these ground gas situations worthy of constant environmental consideration. These gases emanate as volatile releases from toxic compounds, natural or man-made, under conditions of vapor-pressure release (i.e., volatilization) and are subject to release under changing geochemical conditions, most often due to contact with perched or vadose groundwater. Some of these releases occur along geologic pathways of transport, while others constitute near-direct transmission into various “confined spaces” frequented by unsuspecting human receptors. What the Book Offers Considering the over-riding geologic parameters related to generation and release of toxic gases, this book can be useful, in a practical sense, for geoscience professionals involved in all aspects of waste-management facility design, construction, and compliance, and/or in the remediation of uncontrolled hazardous waste sites. The content of the book will not tax the reader's capacity to understand or to act upon the contents; the reader will merely need to discover how to integrate their own “needs.” The professional backgrounds of the …

Horizontal Diffusion, Vertical Diffusion, and Internal Pressure in State Environmental Policymaking, 1989-1998

Throughout the 1980s, states developed policies to address the growing problem of abandoned and uncontrolled hazardouswaste sites. Not surprisingly, some states have adopted stringent policies that are similar to the federal Superfund program, whereas others have developed different approaches. In this article, we develop and test empirically a model of the strength of state hazardouswaste programs, which we depict as a function of both internal determinants and external diffusion. For internal determinant explanations we consider the effects of problem severity, internal political factors, interest group pressure, and socioeconomic and demographic variables. We also include variables representing regional and top-down (national) diffusion. Our results indicate the importance of both internal determinants and external diffusion. Strong state hazardous waste programs are a function of state wealth and the severity of internal hazardous waste problems, as well as external determinants, with regional diffusion as a particularly influential factor.

Review of Impact of hazardous waste on human health: Hazard, health effects, equity, and communications issues by Barry L. Johnson

Cleanup of uncontrolled hazardous waste sites can be a contentious local environmental issue, especially when a site poses risks so high that it is added to the U.S. Environmental Protection Agency’s National Priorities List. The fireworks over these socalled ‘‘Superfund’’ site cleanups can be spectacular. Scientific risk assessments, economics, and community interests all have to be balanced by the public health officials responsible for coordinating the remediation effort. The process isn’t pretty, and the outcomes may not always reflect the best science. The Superfund law—properly known as the Comprehensive Environmental Response, Compensation, and Liability Act—is intended to protect human health and prevent further damage to natural resources and environmental quality. It is perhaps best known by the controversy that ensues when a site is discovered and parties potentially responsible for the mess are asked to pay for its cleanup. The overriding focus on litigation loses sight of a considerable body of good science that has been developed on the health impacts of uncontrolled hazardous waste sites and the best way to tailor public health responses. In Impact of Hazardous Waste on Human Health, Johnson tries to shed light on how public health programs fit into the volatile mix that arises when uncontrolled hazardous waste sites are discovered and remediated. The author was the assistant administrator of the Agency for Toxic Substances and Disease Registry and holds the rank of assistant surgeon general ~retired! in the U.S. Public Health Service. He spent the better part of 13 years involved in the public health aspects of the Superfund law. The book shows his extensive familiarity with the body of scientific information that informs public health responses to hazardous waste sites. The author intends to ‘‘provide up-to-date depictions of the human health impacts of hazardous waste and attendant public health responses.’’ The book’s intended audience is policymakers, environmentalists, toxicologists, public health officials, academic personnel, and health care providers. To make the technical information more accessible to the lay reader, Johnson provides explanations of key concepts in epidemiology, toxicology, and risk assessment. As someone who falls into the policymaker category and is moderately familiar with the jargon of the public health community, I found it tough going at times. Familiarity with some of the basic public health principles might help readers get the

Remedy Selection for Cleanup of Uncontrolled Waste Sites

Selection of remedy for uncontrolled hazardous waste sites involves comparisons of various technological approaches for minimization of threats and achievement of cleanup action levels. Approaches specified in the Comprehensive Environmental Response, Compensation and Liability Act (SUPERFUND Law) National Contingency Plan (40 CFR 300) are broadly labeled as actions, alternatives, and technologies. We have found considerable perplexity in denoting the rank-hierarchy of these approaches and have developed a classification system for dealing with the totality of available measures for consideration in selection of remedy.

The Toxicologic Hazard of Superfund Hazardous-Waste Sites

Uncontrolled hazardous-waste sites are a major environmental and public health concern in the United States and elsewhere. The remediation of and public health responses to these sites is mandated by the federal Superfund statute. Approximately 40,000 uncontrolled waste sites have been reported to U.S. federal agencies. About 1,300 of these sites constitute the current National Priorities List (NPL) of sites for remediation. Findings from a national database on NPL sites show approximately 40% present completed exposure pathways, although this figure rose to 80% in 1996. Data from 1992 through 1996 indicate that 46% of sites are a hazard to public health. Thirty substances are found at 6% or more of sites with completed pathways. Eighteen of the substances are known human carcinogens or reasonably anticipated to be carcinogenic. Many of the 30 substances also possess systemic toxicity. The high percentage of sites with completed exposure pathways and the toxicity potential of substances in these pathways show that uncontrolled hazardous-waste sites are a major environmental threat to human health. Findings from the United States' experience in responding to uncontrolled waste sites are relevant to other countries as they address similar environmental and public health concerns.

Alternative modeling approaches for contaminant fate in soils: uncertainty, variability, and reliability

The fate of contaminants in soils is an issue that is relevant to the management of both uncontrolled hazardous waste sites and to engineered facilities that accept hazardous materials. Addressing long-term potential human exposures requires the use of models. Large uncertainties are associated with predictions from these models. Some of this uncertainty derives from uncertainty about chemical properties and transformation half-lives and some derives from the variation among sites. The purpose of the paper is to consider two alternative modeling approaches and the reliability with which each approach can represent variations of contaminant behavior in the California landscape. One approach is based on the exact solution of the dispersion/advection differential equations that describe contaminant fate in the soil. The second approach is based on a mass-balance approach with less resolution in the soil layers. Incorporation of trichloroethylene (TCE) in the top ten meters of soil is used as a case study to consider how well the two models can be expected to predict cumulative inventory in this ten-meter zone over five years. Using rank correlation as a measure of the importance of parameter uncertainty, it is demonstrated that these two models represent variability of contaminant behavior in the California landscape with comparable reliability.

Chemical mixtures released from hazardous waste sites: implications for health risk assessment

Uncontrolled hazardous waste sites (HWS) and exposure to hazardous substances continue to pose complex public health problems. This paper presents an overview of chemicals, including chemical mixtures, that have been released into environmental media in the vicinity of HWS. We describe how this type of information is being used to assess the public health implications of exposures to chemical mixtures and to develop an integrated program of applied research to more accurately characterize the potential health effects of chemical mixtures. A narrative, weight-of-evidence approach, incorporating mechanistic insights on chemical interactions is described. The utility of this information in the context of risk analysis and public health practice is discussed.

Remote optical sensing instrument monitoring to demonstrate compliance with short-term exposure action limits during cleanup operations at uncontrolled hazardous waste sites

Remote optical sensing (ROS) is an emerging analytical technique. ROS provides the capability to remotely monitor and measure trace atmospheric gases by transmitting a beam of radiation across a parcel of air several hundred meters in length (e.g., open-path Fourier transform infrared spectroscopy). The information gained from these measurements can be used to calculate emission rates from sources, which can be modeled to determine downwind air quality impacts. Traditionally, two monitoring methods were available to estimate air quality impacts: receptor measurements and source measurements. Receptor measurements are air monitoring or sampling methods that directly determine concentrations at downwind locations of concern (e.g., absorbent tubes collected at a school). Source measurements are air monitoring or sampling at or immediately downwind of a source to determine an emission rate (e.g., stack sampling at a facility). This emission rate is then used for estimating concentrations at downwind locations of concern. The path-integrated approach has been utilized at Superfund sites to examine source emission impacts during full-scale remediation operations and during pilot-scale studies. The emission rates for the various compounds were modeled to determine if health-based action levels for the targeted compounds were exceeded at designated distances downwind of the monitoring. Utilization of ROS during these types of operations provided near real-time data to demonstrate compliance with short-term exposure action limits. The data were also used to determine the overall daily average fence line concentration and compare it with longer-term, exposure-based action limits.

Nature, extent, and impact of superfund hazardous waste sites

Uncontrolled hazardous waste sites are major environmental and public health concerns in the United States and elsewhere. The identification and remediation of and public health responses to these sites are mandated by the U.S. federal Superfund statute. Since its enactment into law in 1980, approximately 40,000 uncontrolled waste sites have been identified in the United States. Approximately 1,300 of these sites constitute the current national Superfund priority list of sites for remediation. Results from analyses are described that characterize the priority hazardous substances released from Superfund sites and the extent of hazard posed to residential communities. Findings from the United States' experience in responding to uncontrolled waste sites are relevant to other countries as they address similar environmental and public health concerns.

Risk assessment: A site‐specific approach to establishing acceptable soil cleanup levels

AbstractIn 1980 the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) was passed to instigate the cleanup of uncontrolled hazardous waste sites. CERCLA necessitated the development of a set of criteria for estimating the severity of the contamination at these sites, the potential impact on human health and the environment, and establishing appropriate cleanup levels for the contaminated media. The risk assessment (RA) format was developed to meet these challenges.Though RAs vary dramatically in their scope, emphasis, and regulatory application, there are two primary objectives common to all RAs: (1) to evaluate potential risks to human health and the environment posed by the release of hazardous substances and (2) to evaluate and establish safe cleanup levels based primarily on the number and type of potential receptors, the toxicity and mobility of the contaminants, and the types of exposure pathways present.Achieving these objectives may be a relatively simple task or an extremely complex and difficult one depending on the type of material released and our understanding of its behavior in the environment, the site conditions, and the governing regulations.This article presents an approach for establishing acceptable cleanup levels for subsurface soils and illustrates the application of this approach to three different regulated sites.

Contamination of public ground water supplies by Superfund sites

Multiple sources of contamination can affect ground water supplies, including municipal landfills, industrial operations, leaking underground storage tanks, septic tank systems, and prioritized uncontrolled hazardous waste sites known as “Superfund” sites. A review of Superfund Records of Decision (RODs) in the United States was conducted in this study to obtain information concerning incidents of public ground water supply contamination. Approximately 450 separate RODs or their abstracts were reviewed, and 49 cases with municipal water well contamination were identified. In addition to the 49 pertinent cases, a significant number of RODs listed contaminated ground water as a potential threat to local public water supply wells. The 49 cases were geographically distributed in 21 states throughout the United States. The main source of contamination was industrial operations and other activities associated with industries. In 34 of 49 relevant Superfund cases, industry and related activities were identified ...

Hazardous waste storage, disposal, remediation, and closure

Hazardous waste storage, disposal, remediation, and closure

Why Did You Take That Sample?

Over the past decade, substantial federal, state and private sector resources have been expended to address uncontrolled hazardous waste sites. While these efforts are aimed at protecting human health and the environment from uncontrolled releases of toxic chemicals, it is often difficult to ascertain how activities that have occurred at a hazardous waste site have or will achieve the objectives of protecting human health and the environment. Success in achieving these goals of hazardous waste site cleanup argues for focused data collection that yields the appropriate information for toxicological interpretation. This article describes an effort to focus site characterization to yield information that can be employed in a standard toxicological evaluation.

Ten Years of Progress In the Superfund Program

Superfund celebrated its tenth anniversary in December 1990. The Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA)—popularly known as Superfund—was passed into law in December 1980 in the wake of such incidents as Love Canal and the Valley of the Drums. The program was designed to clean up uncontrolled hazardous waste sites and, during the past ten years, thousands of actions have been taken to protect human health and the environment from the hazards posed by those sites. The trials and successes of the evolving Superfund program are described in this article.

Soil Remediation Techniques at Uncontrolled Hazardous Waste Sites

Soil Remediation Techniques at Uncontrolled Hazardous Waste Sites

Soil Remediation Techniques at Uncontrolled Hazardous Waste Sites

The objective of this critical review is to address soil remediation techniques at uncontrolled hazardous waste sites with regard to the following areas: 1) important regulatory and technical issues and information needs concerning soil remediation at uncontrolled hazardous waste sites; 2) approaches for selection of remediation techniques; and 3) the current state of knowledge regarding soil remediation techniques, including applications and limitations. The areas identified above are addressed with regard to current information, selected milestone publications, and specific applications of technologies to provide a synthesis of the topic. The information concerning current issues, approaches, and soil remediation techniques presented was critically reviewed in order to: 1) identify deficiencies in current approaches; 2) develop a conceptual framework for remediation; and 3) recommend improved approaches for selection of remediation technologies.