Cleanup Standard Research Articles

Allocating remedial costs at a superfund site using risk magnitude, geographic information systems, and Monte Carlo analysis

A method for allocating remediation costs among a number of potentially responsible parties (PRPs) was developed as part of a highly technical, complex Superfund litigation case involving a former hazardous waste disposal site located in the southern United States. The method was devised in response to questions from the U.S. district court regarding the volume and composition of wastes disposed, the “remedy drivers” (defined by the court as wastes or chemicals that most influenced the selection of the remedy), and the relationship between these factors and the various PRPs. A key element of the method was calculation of the Risk Magnitude, which was defined as the logarithm of the maximum concentration of a chemical in groundwater divided by its cleanup standard. Risk magnitude was linked to site remediation costs based on an analysis of remediation difficulty, data from remediation performance studies, and other sources. Key components of the allocation method included: (i) identifying remedy driver chemicals (RDCs) based on risk magnitude; (ii) quantifying the spatially adjusted cumulative risk magnitude associated with each RDC using a Geographic Information System (GIS); (iii) adjusting the risk magnitude to account for remediation difficulty of each RDC; (iv) correlating RDCs with the volume of different waste streams disposed by each PRP at the site; (v) developing an estimate for the waste volume for each PRP using multiple lines of evidence inside a Monte Carlo analysis; and (vi) apportioning final cleanup costs between PRPs based on their attributable volume and cumulative Risk Magnitude. The basic methodology was applied by the district court to develop a scientifically sound opinion that allocated site remediation costs between the PRPs—a decision that was upheld by the U.S. court of appeals. Though developed for a particular site, the method is adaptable, and its fundamental components could be applied to other sites where allocating remedial costs of complex chemical mixtures in environmental media is the objective.

In-situ zinc bioprecipitation by organic substrate injection in a high-flow, poorly reduced aquifer

We investigated if in-situ metal bioprecipitation (ISMP) is applicable to remediate a highly permeable zinc-contaminated aquifer at a metal-processing factory in Maasmechelen, Belgium. A large (more than 200m long and 70m wide) groundwater contamination plume has developed, with zinc concentrations in the range of 1-100mg/L, whereas the legal Flemish clean-up standard is 0.5mg/L. The estimated groundwater flow velocity is in the range 0.2-1m/d. The groundwater is relatively oxidized, naturally low in DOC (<1mg/L) and relatively low in sulfate (40-50mg/L). We conducted both laboratory feasibility tests as well as a long-term field pilot test in two sections of the plume. In the laboratory microcosm tests, zinc bioprecipitation (following addition of organic substrate and sulfate) removed more than 99% of the zinc from the water phase. Lactate, glycerol and vegetable oil were equally effective as substrates. 28-day anaerobic leaching tests indicated that the metal precipitates that were formed are stable, but they also suggested that substrate addition increases the solubility (leachability) of arsenic and manganese. In the field test, Zn concentrations were reduced by 2 to 3 orders of magnitude within the 232 day testing period and stayed low for the following 6 months in both pilot zones. In the field, no mobilization of arsenic occurred but manganese groundwater concentrations increased from 0.01-0.6mg/L to 0.4-6.5mg/L. Dissolved iron concentrations also increased markedly from below detection limits to concentrations as high as 67mg/L. Zinc concentrations in groundwater were closely correlated to pH and redox potential (Eh): plotting y=[Zn] against x=pH/log(Eh), an exponential relationship was found:

Hazardous Substances, CERCLA, and Nanoparticles – Can the Three be Reconciled?

Toxicology research in the nanotechnology area has focused primarily on human inhalation, ingestion or dermal exposure. Less research has been published on the impact to ecological systems resulting from a release of nanomaterials. Environmental laws such as CERCLA ("Superfund") address the release of "hazardous substances" by obligating the party releasing the substance to (a) report the release and (b) investigate the nature and extent of the release and to then remediate it to some objective cleanup standard. Applying this regime to the release of nanomaterials, however, is complicated. First, is the nanomaterial a hazardous waste, toxic substance, or hazardous substance as defined under the environmental laws? A compound that may be defined as hazardous or toxic could have properties at the nano level that are distinctly non-hazardous. Second, what constitutes a release of a nanoparticle that would require reporting under applicable environmental laws? Typically, release reporting is based upon the weight of the hazardous substance that is released, but for nanomaterials a weight threshold might be meaningless. Third, how do you sample nanoparticles in the field and analyze them using existing instrumentation? There are few approved tests for nanomaterials. Fourth, how do you determine an objective risk-based cleanup standard for the thousands of possible nanomaterials?

Remediating Large Plumes: Overcoming the Scale Challenge

Introduction The remediation industry, now three decades old, continues to evolve. This is driven by many factors: technological developments, a need to address emerging contaminants, regulatory changes, economic factors, and sustainability considerations. These have created both challenges and opportunities at different stages of the industry’s evolution. Although many things have changed with time, one of the most difficult practical challenges remains—namely, how to deal with large dissolved plumes (referred to as “large plumes” throughout this article). Presumptive thinking emphasizes containment and management of these large plumes rather than focusing on mass removal and site closures. The term large plume obviously highlights scale as being the critically defining attribute; however, it is worth identifying other attributes that are discussed in this article:

Support for selection of a methamphetamine cleanup standard in Colorado

Methamphetamine production for illicit use occurs in makeshift labs and is associated with the release of numerous chemicals, including methamphetamine residues. These methamphetamine residues may pose a health risk to residents who reoccupy these structures after property seizures. Several states have established technology-based cleanup standards for methamphetamine, but none have examined the health-protectiveness of these standards. In response to Colorado House Bill 04-1182, exposure intakes correlated with three technology-based standards were calculated for various groups of individuals. Intakes were assessed for a 1-year-old infant, 6-year-old child, and a female of childbearing age. Exposure intakes were compared to toxicity reference values developed from developmental endpoints following methamphetamine exposure from the available literature. Uncertainty factors were applied to the lowest adverse effect levels observed in these studies to arrive at the toxicity reference values. These reference values were greater than the calculated intakes from each proposed technology standard, suggesting that all of the proposed standards would be protective of human health exposure. The cost and practicality of attaining each of the proposed standards was also factored into the decision making process. In their final regulation (6 CCR 1014-3), the CDPHE selected 0.5 μg/100 cm 2 as the final cleanup standard for methamphetamine residues.

Comparison of Soil Clean-up Standards for Trace Elements Between Countries: Why do they differ? (9 pages)

Goal, Scope and Background In the nineteen nineties most European countries issued legislation on soil protection, including soil contamination. In the case of a presumed contamination, soil investigation mostly follows a stepwise approach starting with a preliminary investigation, then an in-depth investigation and, finally, remediation. Soil clean-up standards are often foreseen as trigger criteria to determine the need for an in-depth soil investigation or for remediation. There are however large differences in soil clean-up standards. This is partly because of the different roles of soil clean-up standards in each legislative framework and partly because of differences in the soil clean-up standard (SCS) derivation procedures. Despites these differences there are large similarities in the concepts of the derivation procedures for clean-up standards. A better understanding of the differences in clean-up standards is needed. In order to clarify the variation, the background of the clean-up standards for a selected number of countries was investigated. The objective of this paper is to investigate the underlying reason why country-wide generic soil and groundwater clean-up standards of eight trace elements (cadmium, chromium (III), copper, mercury, lead, nickel, zinc and arsenic) differ between the selected countries.

A proposed guideline for verifying the attainment of soil remediation for Taiwan

This paper proposes a technical guideline for evaluating the success of soil remediation efforts. Statistical methods have been emphasized because there is a practical need for decisions regarding whether a site has met a cleanup standard in spite of inherent uncertainty. Uncertainty arises because only small portions of the soil at the site can be sampled and analyzed while the decision for the entire site is solely based on the few samples available. To overcome this bias, statistical methods were designed to permit extrapolation of the results from a few samples in order to make a statement regarding the entire site. Our proposed guideline, being tested in four cases, can provide a technical interpretation of data analysis methods acceptable for verifying the attainment of a cleanup standard of soils media. The guideline includes four parameters: first, the concentration of every sample should be less than the control standard; second, the concentration of 97.5% probability of cumulative curve should not exceed the control standard; third, the median concentration of sampling should be below the monitoring standard; and fourth, the indicator of evenness for the remediation works should be less than two. In comparison with traditional methods, our proposed guideline is shown to be effective in verifying remediation results.

Cost of Remediation of Nitrogen-Contaminated Soils Under CAFO Impoundments

Wastewater in manure storage basins or anaerobic treatment lagoons at confined animal feeding operations (CAFOs) may contain high levels of nitrogen, primarily in the ammoniacal form. Kansas law allows seepage from such impoundments at a rate of 1/8 to 1/4 inch per day (3.2 to 6.4 mm/d). Kansas State University researchers have recently characterized an ammonia plume at a depth of 10 feet or more under several CAFO lagoons and have modeled the potential for deeper penetrations in sandy subsoils. If the plume is not removed or contained after wastewater is removed from the impoundment, then exposure to oxygen from air or dissolved in precipitation will drive the transformation of ammonium to nitrate, which is mobile in the vadose zone. Based on a cleanup standard of 25 mg/kg of NH4-N, the total cost to remove or contain the nitrogen beneath federally permitted swine and dairy wastewater management basins now in operation in Kansas would be about $56 million. In most cases, the preferred remedial option would be the excavation and spreading of the contaminated material on farmland. However, deep plumes in sandy soils and limited access to farmland may dictate use of the backfill-and-cover option. The remedial cost for some operations not currently required to provide financial assurance for closure is estimated to range from $500,000 to $650,000.

Survey of States' 2000 Soils Cleanup Standards for Petroleum Contamination

The establishment of cleanup standards for petroleum-contaminated soils (PCS) at the state level in the U.S. has had a fairly recent history beginning in the mid-1980s. Kostecki et al. (1988) surveyed the 50 states in 1985 and found of the 22 states that reported having established levels of cleanup for PCS, only five states considered the levels formal. The remaining 18 states considered the levels informal with 8 states considering establishing formal levels. Only 1 state had a formal numerical cleanup standard, and 3 had informal numerical standards. One state directly applied federal groundwater standards directly to soils. A follow-up survey in 1987 (Bell et al., 1989) indicated the rapid development of myriad different cleanup standards between and within states, including action levels, remediation goals, cleanup levels, etc. With the implementation of EPA's Office of Underground Storage Tanks final rules for regulating underground storage tanks in 1988 and the existing state of confusion regarding policies, rules and regulations for the cleanup of PCS at the state level, the Association for the Environmental Health of Soils (AEHS) began conducting state-by-state surveys of environmental regulatory agencies in 1990 to determine cleanup standards for PCS for use by the regulated community.The following tables represent AEHS' compilation of state data for PCS cleanup standards for 2000. The Survey was conducted by telephone interviews and submission of written information by the appropriate listed agencies. Many of the states' programs have changed to or are in the process of changing to Risk Based Corrective Action (RBCA) approaches. Thus, the format of the summaries are less standardized than past surveys in order to accurately reflect the states' program. Every attempt has been made to accurately represent states' cleanup standards, however, users should be cautioned to the limitations of compiling complex regulatory information into tabular form. The information should only be used as a reference guide and legal, economic or technical decisions should be based on specific information obtained directly from the appropriate agency in each state for each specific site.

Estimation of cleanup time in layered soils by vapor extraction

Soil vapor extraction (SVE) is a standard remediation technique for cleaning up soils contaminated by volatile organic compounds (VOCs). A key parameter for planning SVE operations is the time required to reach the desired cleanup standard. In this paper, an approximate analytical solution is developed, which allows the fast estimation of cleanup times in layered unsaturated zones. The contaminants are assumed to be dissolved in the pore water, sorbed on the soil matrix and mixed with the soil air. Liquid organic phase is absent. For partitioning between gas and water and water and solid, local-equilibrium is assumed. The analytical solution is based on the well mixed reservoir model and on the plug flow model. It is shown that, for a number of scenario cases, the results of the analytical solution are, for practical purposes, in reasonable agreement with a numerical solution of the partial differential equations for the local-equilibrium advection–dispersion model of mass transport in porous media by Fickian diffusion and Darcian air flow. The results are displayed in terms of Peclet number of molecular diffusion (PNMD). In the analytical solution three different approximations are used. The PNMD range is divided into three intervals, representing different transport regimes. At low PNMD, molecular diffusion dominates transport in both layers. In this interval cleanup time is estimated by the average of the plug flow time for one pore volume through the layer of higher permeability, and the cleanup time estimated by the mixed reservoir model. At intermediate PNMD values, advective transport dominates in the more permeable layer and molecular diffusion in the less permeable. Consequently, cleanup time is limited by diffusive mass transfer from the less to the more permeable layer. In this interval, the estimation of cleanup time is entirely based on the mixed reservoir model. At high PNMD values, transport is governed in both layers by advection. Here, cleanup time is estimated by applying the plug flow model to the layer of lower permeability. The range of soil permeability values, for which such high PNMD values can be achieved, as well as the range of the actual air flow rates, are identified. The limitations of the validity of local-equilibrium assumption at high PNMD values are discussed using the relationship between desorption rates and gas advection fluxes. Further, the sensitivity of cleanup time estimates with respect to the independent dimensionless parameters characterizing the SVE configuration considered, is studied.

Applications of dendrochronology and sediment geochronology to establish reference episodes for evaluations of environmental radioactivity

Dendrochronology and sediment geochronology have been used to demonstrate retrospective monitoring of environmental radioactivity at United States Department of Energy (DOE) sites. 14C in annual growth rings of sagebrush preserved the temporal and spatial patterns of 14C resulting from dispersion downwind of a nuclear fuel processing facility at the Hanford Site in Washington State. As far as 10 km downwind of the facility, 14C concentrations were significantly higher in growth rings formed during a fuel processing episode than in rings produced during preoperational or postoperational episodes. An episode of uranium mill tailings deposition in pond sediments at the Grand Junction Office in Colorado was reconstructed using 210Pb geochronology constrained by a marker of peak 137Cs fallout. Uranium concentrations in ponds sediments deposited after the processing episode provide a reasonable cleanup standard. These reference episodes of environmental radioactivity reconstructed from measurements taken within contaminated environments can improve or replace reference area data as baseline information for dose reconstructions, risk assessments, and the establishment of cleanup standards.

On-Site Treatment of Contaminated Soils: An Approach to Bioremediation of Weathered Petroleum Compounds

A bench-scale investigation was conducted prior to on-site bioremediation of 52,000 cubic yards of contaminated soil containing weathered, structurally complex petroleum compounds from an inactive oil refinery. Addition of bulking agents was required to improve soil physical properties. A supplemental study was also conducted to evaluate the effectiveness of bio-enhancement products. Loss of n-alkanes was rapid in soil mixtures containing a high nitrogen sludge compost, but very slow in mixtures containing wood products as bulking agents. By completion of the study at day 110, the isoprenoids pristane and phytane had nearly disappeared from mixtures containing sludge compost. Clearly, pristane and phytane are inadequate biomarkers when conditions favor an advanced stage of biodegradation. Nearly half the complex branched and cyclic alkanes in the unresolved complex mixture also degraded. After 70 days, depletion of dibenzo-thiophenes and phenan-threnes was 75 and 90%, respectively. The most stable PAHs within each group were the highly methylated homologues. Because of their complex structures, both steranes and hopanes were stable in all soil mixtures. Data were normalized to hopanes as a conserved internal standard or biomarker. Use of hopane-normalized data successfully eliminated much of the data variability and permitted a more accurate assessment of biodegradation. A relatively slow decline in total hydrocarbons occurred later in the study. This slowing tendency of microbial utilization is caused not only by substrate depletion, but also because remaining hydrocarbons are structurally more complex and persistent. Because of this, it is important to avoid using kinetic data from early stages of bioremediation to predict later hydrocarbon losses, such as the time required to attain a cleanup standard. In the supplemental study, an oleophilic fertilizer product accelerated hydrocarbon degradation when compared with a conventional fertilizer. This product will be tested in combination with organic bulking agents under field conditions to determine its cost effectiveness.

Cleanup levels for dioxin‐contaminated soils

AbstractEPA's use of a 1 part per billion (ppb) level for dioxin contamination in residential soils is shown to be too high and not protective of public health. It was derived in a 1984 cancer risk assessment by another federal agency, but it is inconsistent with risk‐based levels of 2 to 4 parts per trillion (ppt) obtained by using EPA's standard risk assessment methods. EPA has called the 1 ppb level a policy‐based level, which correctly distinguishes it from a risk or health‐based cleanup standard. The 1984 assessment is shown in this article to have considerable shortcomings. For over a decade, dioxins have been left in soils at levels posing health risks and sometimes at levels that EPA is legally required to address. Moreover, noncancer effects have been ignored, but recent work has shown them to support action at low ppt levels. To protect public health, be consistent with current scientific knowledge and other EPA policies, reduce confusion in the environmental management community, and be responsive to public demands for stringent dioxin cleanups, new EPA policy guidance for dioxin soil cleanups is needed, and key elements are presented in this article. In an ad hoc fashion, EPA Region 4 has recently used a 200 ppt dioxin cleanup level for residential soil, acknowledged to correspond to a one‐in‐ten‐thousand cancer risk, at two Superfund sites, which environmental professionals should be aware of. This suggests a shift in EPA policy.

Data quality objectives for surface-soil cleanup operation using in situ gamma spectrometry for concentration measurements.

In situ gamma spectrometry is an efficient method for monitoring the progress of cleanup activities for radioactive contaminants in surface soil and for evaluating the attainment of cleanup standards. However, desired data precision and accuracy must be specified for such a detection system prior to the operation to ensure that the level of uncertainty associated with the concentration measurements is acceptable. A method for developing data quality objectives is described in this paper for in situ gamma spectrometry to achieve numerical goals for data precision and accuracy for cleanup operations. Concentration measurement for a radionuclide at its cleanup level must have a precision commensurate with the importance of cleanup decisions. The 95% lower limit of detection of the system is suggested to be about one tenth the expected system response at the cleanup level. The count time required to achieve the preferred 95% lower limit of detection, and hence the desired precision, can then be determined. The accuracy error arises from the overall calibration factor, which relates the detector responses (e.g., count rate) to physical quantities of interest (e.g., radionuclide soil concentration). The major source of error for the calibration factor using in situ gamma spectrometry is the misidentification of the type of the depth profile of radionuclide concentration in soil. If surrogate radionuclides are used, such as 241Am for plutonium, the variation in the concentration ratio would be another significant source of error. Soil sampling programs performed prior to a cleanup operation will greatly reduce the accuracy error for an in situ detection system, and the analysis of system errors may determine the degree of sampling required. The planning of such a program is discussed in the study. Uncertainty analysis using a Latin Hypercube sampling technique for the calibration factor is also demonstrated. The quantitative result of the uncertainty analysis is useful for determining a nuclide's maximum peak count rate using gamma spectrum that ensures the attainment of the cleanup standard for that nuclide with a pre-specified confidence level (e.g., 95%). The cleanup operation of 239,240Pu in surface soil in the safety shot areas at the Nevada Test Site serves as an example to illustrate the data quality objectives development.

Recommended methodology for measurements of PCDD and PCDF in the nordic countries

In April 1986 the Nordic Council of Ministers recommended that the Nordic countries use a specific method for measurements of polychlorinated dibenzo- p-dioxins (PCDD) and dibenzofurans (PCDF) in flue gas emissions from waste combustion. The recommended protocol, which will be re-evaluated in a years time, includes the following. A one week registration period during which the plant is studied by continuous registration of a number of operating and emission parameters. The sampling period is included in this time. A sampling procedure based on a heated filter followed by a condenser, a bottle for the condensate and an adsorbent column. Before the sampling, at least two labelled PCDD are added to the filter. No specified analytical procedure. A labelled PCDF is added before the clean-up procedure and an injection standard before the final analysis. The laboratory is free to use any method that gives at least 25% recovery of the sampling standards and 50% recovery of the clean-up standard. Reporting requirements include homologue specific results for PCDD and PCDF containing four to eight chlorine atoms as well as isomer-specific results for the “dirty dozen”. The results should be compensated for incomplete recoveries and the factors used should be reported.

Recommended Methodology for Measurements of PCDD and PCDF in the Nordic Countries

In April 1986 the Nordic Council of Ministers recommended that the Nordic countries use a specific method for measurements of polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans (PCDF) in flue gas emissions from waste combustion. The recommended protocol, which will be re-evaluated in a years time, includes the following. A one week registration period during which the plant is studied by continuous registration of a number of operating and emission parameters. The sampling period is included in this time. A sampling procedure based on a heated filter followed by a condenser, a bottle for the condensate and an adsorbent column. Before the sampling, at least two labelled PCDD are added to the filter. No specified analytical procedure. A labelled PCDF is added before the clean-up procedure and an injection standard before the final analysis. The laboratory is free to use any method that gives at least 25% recovery of the sampling standards and 50% recovery of the clean-up standard. Reporting requirements include homologue specific results for PCDD and PCDF containing four to eight chlorine atoms as well as isomer-specific results for the "dirty dozen". The results should be compensated for incomplete recoveries and the factors used should be reported.