Emily Sarver

Inhibition of Copper Pitting Corrosion in Aggressive Potable Waters

Copper pitting corrosion can lead to premature plumbing failures, and can be caused by aggressive potable waters characterized by high pH, free chlorine residual and low alkalinity. In such waters and under continuous flow, certain inhibitors including phosphate, silica or natural organic matter may greatly reduce pitting occurrence. In the current work, 1 mg/L phosphate (as P) completely prevented initiation of pits, and 5 mg/L silica (as Si) significantly decelerated pitting. However, much lower doses of these inhibitors had little benefit and actually accelerated the rate of attack in some cases. Effects of organic matter were dependent on both the type (e.g., natural versus ozonated humic substances) and dosage. Dose-response effects of free chlorine and alkalinity were also investigated. Based on electrochemical data, pits initiated more rapidly with increased free chlorine, but even moderate levels of chlorine (~0.4 mg/L) eventually caused severe pitting. High alkalinity decreased pit propagation rates but did not prevent pit formation.

A GIS-based methodology for identifying sustainability conflict areas in mine design – a case study from a surface coal mine in the USA

Through proper design, coal mining operations can contribute to the social, economic and environmental aspects of sustainable development. The regulatory and permitting programmes for coal mining in the United States, which often focus on several largely environmental parameters, are barriers to holistic consideration of these three sustainability pillars. Some changes in the current US regulatory framework may be necessary to allow for systematic consideration of economic, environmental and social factors in order to achieve more sustainable development of mineral and energy resources. In the quest towards more sustainable mining activities, it has been suggested that mine design may be optimised in the context of sustainability using a systems engineering approach that simultaneously considers economic, environmental and social factors. The use of geographic information system (GIS) tools may aid in this approach by allowing for spatial analyses of various resources (e.g. mineral values, water resources, community infrastructure) and identification of potential areas of conflict between these factors. By GIS analysis of the on-the-ground issues related to sustainability, the key parameters to be considered in decision-making were identified. This type of analysis is crucial not only for regulatory compliance, but also to ensure that the operation has obtained the ‘social licence’ to mine. To demonstrate this approach, a case study was conducted on a mountaintop coal mining operation in central Appalachia. High-conflict areas were found to be primarily concentrated near streams and residential developments through the use of GIS. The case study suggests that use of this approach could have allowed for better communications and planning. The controversies surrounding permitting at the site, including litigation, could have also been avoided. Adoption of such a process could assist in the transition to a new regulatory framework that promotes and is based on sustainable development principles.

Interactive effects of water quality, physical habitat, and watershed anthropogenic activities on stream ecosystem health

Ecological degradation of streams remains a major environmental concern worldwide. While stream restoration has received considerable attention, mitigation efforts focused on the improvement of physical habitat have not proven completely effective. Several small-scale studies have emphasized that effective restoration strategies require a more holistic understanding of the variables at play, although the generalization of the findings based on the small-scale studies remains unclear. Using a comprehensive statewide stream monitoring database from West Virginia (WV), a detailed landscape dataset, and a machine learning algorithm, this study explores the interactive impacts of water quality and physical habitat on stream ecosystem health as indicated by benthic macroinvertebrate scores. Given the long history of energy extraction in this region (i.e., coal mining and oil/gas production), investigation of energy extraction influences is highlighted. Our results demonstrate that a combination of good habitat and low specific conductance is generally associated with favorable benthic macroinvertebrate scores, whereas poor habitat combined with water quality conditions typically indicative of high ionic strength are associated with impaired stream status. In addition, streams impacted by both energy extraction and residential development had a higher percentage of impairment compared to those impacted predominantly by energy extraction or residential development alone. While water quality played a more important role in the ecosystem health of streams impacted primarily by energy extraction activities, habitat seems to be more influential in streams impacted by residential development. Together, these findings emphasize that stream restoration strategies should consider interactive effects of multiple environmental stressors tailored to specific sites or site types - as opposed to considering a single stressor or multiple stressors separately.

Tracking the downstream impacts of inadequate sanitation in central Appalachia

Poor sanitation in rural infrastructure is often associated with high levels of fecal contamination in adjacent surface waters, which presents a community health risk. Although microbial source tracking techniques have been widely applied to identify primary remediation needs in urban and/or recreational waters, use of human-specific markers has been more limited in rural watersheds. This study quantified the human source tracking marker Bacteroides-HF183, along with more general fecal indicators (i.e. culturable Escherichia coli and a molecular Enterococcus marker), in two Appalachian streams above and below known discharges of untreated household waste. Although E. coli and Enterococcus were consistently recovered in samples collected from both streams, Bacteroides-HF183 was only detected sporadically in one stream. Multiple linear regression analysis demonstrated a positive correlation between the concentration of E. coli and the proximity and number of known waste discharge points upstream; this correlation was not significant with respect to Bacteroides-HF183, likely due to the low number of quantifiable samples. These findings suggest that, while the application of more advanced source targeting strategies can be useful in confirming the influence of substandard sanitation on surface waters to justify infrastructure improvements, they may be of limited use without concurrent traditional monitoring targets and on-the-ground sanitation surveys.