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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 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...

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

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.