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This article summarizes the current status of known contamination arising from abandoned uranium mines (AUMs) within the Navajo Nation and examines the options for addressing the elevated risks to health that AUM waste poses to the people of the Navajo Nation. More specifically, this article provides the following: An overview of past uranium mining conducted on the Navajo Nation, the current status of AUM waste within the Navajo Nation, and the human health risks associated with uranium exposure. A discussion of Navajo Fundamental Law, the Dine (the Navajo People) Uranium Remediation Advisory Commission, and the Navajo Nation Department of Justice's position regarding institutional controls and cleanup of AUMs. A summary of cleanup actions taken to date to address AUM waste and the lessons learned from such actions. Options for cleanup of AUM waste consistent with Dine Fundamental Law, the Dine Natural Resources Protection Act of 2005, and the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA). The information summarized in this article was previously presented as an “Initial White Paper on Cleanup Options for Navajo Abandoned Uranium Mines,” prepared with participation from multiple stakeholders including the Navajo Nation Environmental Protection Agency (NNEPA), the Navajo Nation Department of Justice (NNDOJ), and the United States Environmental Protection Agency (US EPA). ©2016 Wiley Periodicals, Inc.

Leaking underground storage tank systems at service stations have resulted in tens of thousands of petroleum releases and associated groundwater chemical plumes often extending hundreds of feet off-site. Technical and engineering approaches to assess and clean up releases from underground tanks, product lines, and dispensers using technologies such as soil vapor extraction, air sparging, biostimulation, and monitored natural attenuation are well understood and widely published throughout the literature. This article summarizes life-cycle environmental response costs typically encountered using site-specific cost estimation or metric-based cost categories considering the overall complexity of site conditions: (1) simple sites where response actions require smaller scale assessments and/or remediation and have limited or no off-site impacts; (2) average sites where response actions require larger scale assessments and/or remediation typical of petroleum releases; (3) complex sites where response actions require greater on-site and/or off-site remediation efforts; and (4) mega sites where petroleum plumes have impacted public or private water supplies or where petroleum vapors have migrated into occupied buildings. Associated cleanup cost estimates rely upon appropriate combinations of individual work elements and the duration of operation, maintenance, and monitoring activities. These cost estimates can be offset by state reimbursement funds, coverage in purchase agreements, and insurance policies. A case study involving a large service station site portfolio illustrates the range of site complexity and life-cycle environmental response costs. © 2014 Wiley Periodicals, Inc.

Corporations often become potentially responsible parties (PRPs) at hazardous waste sites because of their past transportation or disposal of hazardous substances at such sites. Determining a PRP's potential liability for the assessment and cleanup of hazardous waste sites is a challenging effort and often results in disputes among other PRPs regarding appropriate allocation of response action costs to each party. Further, public companies have an obligation to report probable and reasonably estimable costs under Generally Accepted Accounting Principles (GAAP) for environmental liabilities at their current or prior hazardous waste sites. The first step in such an evaluation is to determine whether or not a PRP can extricate themselves from any association with the subject site or, alternatively, demonstrate de minimis status. This article describes the methods by which PRPs can extricate themselves from liability associated with response action costs at contaminated sites, including: evaluating a PRP's prior settlements or indemnifications with other PRPs; identifying insurance coverage or other financial assurance instruments for the disposal facility; and examining applicable statutes of limitations against when a PRP received notification from the regulatory agency. The article also presents a case study discussing how a PRP with a portfolio of 72 hazardous waste disposal sites was able to extricate itself from the majority of these sites, resulting in only four sites where the PRP was determined to be a PRP and where an associated allocable share was assigned. © 2014 Wiley Periodicals, Inc.

Environmental professionals are often tasked with projecting the cost to bring a contaminated site or portfolio of sites to regulatory closure. Fortunately, there are a number of useful guidance documents and industry publications available to assist in such cost projections. However, the usefulness of such tools is limited when adequate costing information is lacking, such as (a) the nature and extent of contamination; (b) regulatory requirements; (c) the remedial approach to be implemented; and/or (d) the duration of operation, maintenance, and monitoring activities. Despite the lack of such information, cost-to-closure estimates are nevertheless routinely needed and generated for internal assessments or audits, regulatory disclosures, property acquisitions, insurance claims, litigation, and other business transactions. Cost estimates are also often needed in bankruptcy proceedings where the trier of fact must estimate the total future costs associated with an environmental legacy portfolio to determine the overall value (or solvency in the case of evaluating the potential bankruptcy) of a company. This article presents a solution for developing cleanup costs for single sites or a portfolio of sites using a comprehensive, three-tiered method that is effective over a wide range of site information. Real-world examples of the successful application of this method are then provided, based on detailed environmental analyses that were completed for a recent bankruptcy proceeding and a case in which an estimated cleanup cost was needed in a legal proceeding. © 2013 Wiley Periodicals, Inc.

The most current state regulations and guidance documents governing the assessment and clean‐up of petroleum release sites were obtained from state agencies between November 1996 and December 1996. The regulations were evaluated to determine the risk‐based methodology (if any) each state uses to establish groundwater clean‐up levels at such sites. Six categories were identified with respect to the use of risk‐based corrective action (RBCA) across the United States: (1) ASTM RBCA without modification; (2) modified ASTM RBCA; (3) state‐specific risk‐based approach; (4) non‐specific risk‐based approach; (5) case‐by‐case determination; and (6) no risk‐based approach used for groundwater. These varying approaches reflect the differing priorities, criteria, and approaches established by state government with respect to assessing and cleaning up petroleum release sites.

In-situ sparging has been accepted as a method to rapidly remediate groundwater at considerably lower costs compared to remedies based on groundwater recovery alone. The success of in-situ sparging depends on effective mass transfer between air and contaminated media in the subsurface. Factors affecting mass transfer include advective airflow, diffusive transport, interphase chemical partitioning, and chemical and biological reaction rates between sparged gases and subsurface contaminants, minerals, and naturally occurring organic compounds. Understanding these factors can increase the design efficiency of in-situ sparging and assist in developing sparging systems that use gases other than air (i.e., oxygen, ozone, and methane).

A combination of technical approaches and forensic tools can determine historic causes, timing, and impacts of site contamination.

A variety of remediation technologies are available to address hydrocarbon contamination, including free product recovery, soil venting, air sparging, groundwater recovery and treatment, and in situ bioremediation. These technologies address hydrocarbon contamination distributed between free, adsorbed, and dissolved phases in both the vadose and saturated zones. Selection of appropriate technologies is dependent on a number of factors, including contaminants, site‐specific characteristics, clean‐up goals, technology feasibility, cost, and regulatory and time requirements. This article describes a decision framework for selecting appropriate remediation technologies at hydrocarbon‐contaminated sites in a structured and tiered manner. Decision modules include (1) site characterization and product recovery; (2) vadosezone treatment: soil venting, bioremediation, and excavation; (3) saturated zone treatment: sparging, bioremediation, groundwater recovery, and excavation; and (4) groundwater treatment...

The growth response of the green alga, Selenastrum capricornutum to varying additions of either sewage or reconstituted water containing equivalent levels of inorganic nitrogen and phosphorus, was compared to algal growth levels calculated from the inorganic nutrient concentrations of these additions using the algal yield factor of the test alga. The additions resulted in a linear increase in algal growth with percent of sewage or chemical equivalent solution addition which was in close agreement to the values predicted from the total soluble inorganic nitrogen concentration in the algal cultures alone. Thus, the Algal Assay: Bottle Test (AA:BT) did not permit sufficient organic mineralization during incubation, owing to the exclusion of heterotrophic bacteria and protozoa by the test procedure. This occurrence could result in an underestimation by the AA:BT of the algal growth potential occurring from the entry of a wastewater containing inorganic and organic nitrogen and phosphorus compounds into the aq...

The microbial changes occurring in the upper 1 cm of the solid sediment surface in intensively fed and aerated fish ponds located in northern Israel were examined. The bacterial groups enumerated included: total aerobes, total anaerobes, sulfate and iron reducing bacteria, ammonia and nitrite oxidizing bacteria, acid forming bacteria, and denitrifying bacteria. With the exception of the nitrifying bacteria, large microbial populations were observed in the pond sediment even prior to fish stocking. All the different groups enumerated displayed a rapid change in number during the first 2–8 days following fish stocking, and a subsequent approach toward a steady state. Since both microbial and chemical steady states were approached within a relatively short period of time, it does not appear that these components of the sediment are related to the inhibition of fish growth occurring 50–70 days after fish stocking. While the practice of pond draining and air drying the sediment does oxidize some of the accumulated organic material, it does not appear to affect the resident microbial flora significantly to an extent that could decrease the rate of reestablishment of the microbial community. Therefore, upon establishment of anaerobic conditions a large microbiological community is present capable of mediating the chemical reduction of SO 4 2− to H 2 S, or other transformations resulting in products which contribute to fish growth inhibition commonly observed in such intensively stocked and fed fish ponds.

Prefiltration of natural water samples through XAD-8 and Tenax GC macroreticular resins removed, selectively, hydrophobic carbonaceous organic materials without significantly effecting hydrophilic nitrogenous organic substances. Hydrophobic carbonaceous adsorbates competitively decrease adsorption of hydrophilic materials. This phenomenon permits high recoveries of organic nitrogen while simultaneously removing humic material.

Fitchburg, Massachusetts sanitary landfill leachate was subjected to toxicity tests using: fathead minnows (Pimephales promelas), zooplankton (Daphnia magna), green algae (Selenastrum capricornutum) and aerobic luminescent bacteria (Photobacterium phosphorium). The leachate was highly toxic to the test bacteria, moderately toxic to daphnids, and slightly toxic to fathead minnows. Algal cells, unable to grow at the 10-percent leachate exposure level, recovered after centrifugation and reinnocuation into algal nutrient medium. Low-flow summer hydrological data indicated that the leachate contributed about 7% to the total flow of the receiving stream, Flagg Brook, and about 0.6% to Sawmill Pond water located further downstream from the leachate outfall. These data, together with observed toxicity values for the test organisms, indicate that the leachate concentration in Flagg Brook impacts the diversity of aquatic life in this system, but may be less severe in Sawmill Pond where increased dilution results in leachate levels below the acutely toxic level. The considerable variation between toxicity test results obtained with the four test organisms, demonstrates the importance of conducting several such toxicity tests using organisms from different trophic levels, to assess the potential impact of a pollutant discharge on an aquatic ecosystem.

Dense algal growth and large diurnal oxygen variations in both free flowing and impounded reaches of the Housatonic River in Connecticut and Massachusetts prompted a concentrated study to assess the need for a comprehensive basin wide phosphorus abatement program and the contribution of point source discharges to eutrophication of the river. Inorganic nutrient levels and bioassay data indicated a predominance of nitrogen limitation below Pittsfield, MA resulting from discharges of phosphorus-rich, municipal and industrial wastewater into the river. N:P ratios suggested that the nutrient status of the river varied, to some extent, even over as short an interval as 2 months and was probably attributable to flow variations in the river. Algal assays of water samples confirmed the nutrient limitation predicted by N:P ratios in 10 out of 13 cases. Additions of varying percentages of untreated, and alum-treated Pittsfield domestic wastewater treatment plant effluent to Housatonic River water, resulted in a linear increase in algal yield that was within 20% of values predicted by inorganic nutrient content. No significant reduction in algal growth response was observed, however, in the alum-treated sewage since its N:P ratio was not sufficiently shifted to phosphorus limitation after 66% phosphorus removal (Al:P equal to 1.3:1). Phosphorus removal at Best Practicable Technology levels would therefore probably not change the nutrient status of the Pittsfield wastewater to phosphorus limitation.

Formation d'organochlores lors de la chloration des eaux, ces composes peuvent reagir avec les reactifs analytiques utilises pour determiner le chlore libre disponible et donc conduire a une sous-estimation du niveau presume de desinfection

Low dosages of chlorine rapidly produced high levels of NPOX, but very little POX was formed. Chlorine dioxide produced over 80 percent less TOX than chlorine. TOX formation at low chlorine dosages was a function of the chlorine dose whereas, in the presence of excess chlorine it vas a function of the DOC. Low dosages of chlorine dioxide and ozone had little effect on TOX precursors directly and did not enhance GAC adsorption of TOX precursors. Use of high dosages of chlorine dioxide or ozone prior to GAC increased the DOC adsorption capacity of the carbon.

Nitrogenous organic compounds are of environmental significance because of their potential as both trihalomethane (THM) and nonpurgeable organic halide (NPOX) precursors. They additionally lead to falsely positive tests for free available chlorine (FAC) and are components in the reaction of chlorine to form dihaloacetonitriles (DHANs). A large number of naturally occurring nitrogenous compounds additionally react readily with aqueous chlorine exerting significant chlorine demand. Such reactions generally involve the substitution of chlorine for hydrogen on a nitrogen atom. Additionally, N-chloroorganic materials may be produced even when the precursor concentration is low owing to the rapid specific rate of formation. While previous attention has been largely focused on nonpolar chlorinated organic contaminants such as THMs, the wide distribution of N-organic compounds in water, as well as their general reactivity towards aqueous chlorine, warrant further attention and study to this group of materials. Preliminary studies on the chlorination of several N-organic compounds at a few chlorine-to-compound molar ratios at pH 7 and 4.7 over several reaction intervals are presented. NPOX formation was quite rapid and comprised the greatest proportion of the total organic halide formed for the conditions studied.

The presence of nitrogenous organic compounds in raw water sources for municipal supplies is of environmental concern because many of them exert significant chlorine demand, while some produce complex stable mutagenic products upon chlorination or are precursors to haloform formation. Seven N-organic compounds have been identified in municipal water concentrates (adenine, 5-chlorouracil, cytosine, guanine, purine, thymine, and uracil) at concentrations ranging from 20 to 860 μg/L. Eight compounds (adenine, cytosine, purine, pyrrole, thymine, tryptophan, tyrosine, and uracil) have been found in filtrates from cultures of either Anabaena flos aquae or Oscillatoria tenuis . Calculated CHCl 3 levels which might have formed at pH 7 in the water supplies were well below the maximum contaminant level (MCL) of 0.1 mg/L proposed by the U.S. Environmental Protection Agency (USEPA) for total trihalogenated methanes. Calculated levels of CHCl 3 which might have been formed under more alkaline conditions, however, were more than 10% of the MCL and were therefore significant. Calculated levels of combined forms of chlorine yielding falsely positive tests for free chlorine in some samples were slightly less or exceeded the 0.5 mg/L free chlorine residual generally taken as an acceptable level of disinfection. The demonstration of a parallel increase in organic nitrogen content with population density in two laboratory grown blue-green algal cultures, and the finding of elevated organic nitrogen values in a water supply sample collected during the occurrence of a blue-green algal bloom, suggested that summer algal bloom occurrence can add considerably to the organic nitrogen content and the trihalomethane potential of water supplies.

The presence of nitrogenous organic compounds in raw water sources for municipal supplies is of environmental concern because many of them exert significant chlorine demand (1), while some produce complex stable mutagenic products upon chlorination (2, 3) or are precursors in haloform formation (1). To assist in assessing the importance of this problem high performance liquid chromatography (HPLC) was utilized to identify trace quantities of N-organic contaminants in concentrated samples of municipal water supplies of northeastern Massachusetts. Chromatographic resolution of complex mixtures was achieved on a reversed phase column (Zorbax C-8, DuPont Co.) using a 0.05 M phosphate buffer (pH = 6.9) or a 0.05 M borate buffer (pH = 8.9) to 50% methanol gradient. Constituents of concentrated samples were identified by the amount of time required for elution from the analytical column (retention position), and the positions of maximum and minimum U.V. absorbances, which were measured by stoppedflow sp...

Chemical and microbiological data from four characteristically acidic streams in southern New Jersey were used to evaluate seven factors related to the proclivity of each stream to nitrify under the influence of secondary sewage effluent. pH, water temperature, and dissolved oxygen were used as indicators of a stream conditions while neutralization of alkalinity, nitrogen species trends, BOD/NOD incubations, and nitrifying bacteria densities served as actual nitrification indicators. Hay Stack Brook showed strong evidence for nitrification on the basis of all four nitrification indicators while Landing Creek was nitrifying little if at all. Hammonton Creek is apparently nitrifying, but because of uncertainty in the downstream trends of the nitrogen species, and a lower level of alkalinity neutralization, it is nitrifying less than Hay Stack Brook. Squankum Branch showed some evidence for nitrification on the basis of the BOD/NOD incubations. The acidic character of these streams does not appear to be an exclusive factor in determining whether the stream will undergo nitrification.