Browsing by Author "Orndorff, Zenah W."
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- Batch extraction method to estimate total dissolved solids (TDS) release from coal refuse and overburdenCastillo-Meza, Luis E.; Cravotta, Charles A.; Tasker, Travis L.; Warner, Nathaniel R.; Daniels, W. Lee; Orndorff, Zenah W.; Bergstresser, Tim; Douglass, A.; Kimble, George; Streczywilk, Joelle; Barton, Christopher D.; Fulton, Stephanie; Thompson, Aaron; Burgos, William D. (2020-04)A rapid batch extraction method was evaluated to estimate potential for total dissolved solids (TDS) release by 65 samples of rock from coal and gas-bearing strata of the Appalachian Basin in eastern USA. Three different extractant solutions were considered: deionized water (DI), DI equilibrated with 10% CO2 atmosphere (DI thorn CO2), or 30% H2O2 under 10% CO2 (H2O2+CO2). In all extractions, 10 g of pulverized rock (<0.5-mm) were mixed with 20 mL of extractant solution and shaken for 4 h at 50 rpm and 20-22 degrees C. The 65 rock samples were classified as coal (n =3), overburden (n = 17), coal refuse that had weathered in the field (n = 14), unleached coal refuse that had oxidized during indoor storage (n = 20), gas-bearing shale (n = 10), and pyrite (n = 1). Extracts were analyzed for specific conductance (SC), TDS, pH, and major and trace elements, and subsequently speciated to determine ionic contributions to SC. The pH of extractant blanks decreased in the order DI (6.0), DI thorn CO2 (5.1), and H2O2+CO2 (2.6). The DI extractant was effective for mobilizing soluble SO4 and Cl salts. The DI thorn CO2 extractant increased weathering of carbonates and resulted in equivalent or greater TDS than the DI leach of the same material. The H2O2+CO2 extractant increased weathering of sulfides (and carbonates) and resulted in the greatest TDS production and lowest pH values. Of the 65 samples, 19 had leachate chemistry data from previous column experiments and 35 were paired to 10 field sites with leachate chemistry data. When accounting for the water-to-rock ratio, TDS from DI and DI thorn CO2 extractions were correlated to TDS from column experiments while TDS from H2O2+CO2 extractions was not. In contrast to column experiments, field SC was better correlated to SC measured from H2O2+CO2 extractions than DI extractions. The field SC and SC from H2O2+CO2 extractions were statistically indistinguishable for 7 of 9 paired data sets while SC from DI extractions underestimated field SC in 5 of 9 cases. Upscaling comparisons suggest that (1) weathering reactions in the field are more aggressive than DI water or synthetic rainwater extractants used in batch or column tests, and (2) a batch extraction method utilizing 30% H2O2 (which is mildly acidic without CO2 enrichment) could be effective for identifying rocks that will release high amounts of TDS.
- Delineation and management of sulfidic materials in Virginia highway corridorsOrndorff, Zenah W.; Daniels, W. Lee (Virginia Center for Transportation Innovation and Research, 2002-09)Excavation through sulfidic geologic materials during road construction has resulted in acid drainage related problems at numerous discrete locations across Virginia. Barren acidic roadbanks, and acidic runoff and fill seepage clearly cause local environmental problems along Virginia road corridors. Degradation of construction materials may necessitate road repairs, which can be time-consuming, costly, and a nuisance to travelers. These problems can be minimized, and even prevented, by incorporating sulfide hazard analysis into the pre-design stage of highway construction. Evaluating the likelihood of encountering sulfidic materials can decrease exposure of problematic materials. When exposure cannot be avoided, proper characterization of the material allows for immediate application of appropriate remediation procedures. Failure to rigorously identify and remediate acid-forming materials in the road planning and construction process will inevitably lead to the mix of engineering and environmental problems discussed and documented in this report. While the barren and erosive slopes resulting from acidification of cut roadbanks are the most obvious indicator of this problem, the long term emission of acidic drainage from fills is clearly the most serious environmental compliance problem that VDOT will face with sulfidic materials over time. Unfortunately, many of these problems (e.g. acid seepage from fills) do not become obvious for some period of time after the road construction contracts have been closed, leaving the full liability for environmental compliance resting upon VDOT maintenance budgets. Therefore, the true cost of identifying, handling and disposing of potentially acid-forming materials must be rigorously assessed and designed for in the road building process.
- Developing Field and Lab Predictors of Appalachian Surface Coal Mine Spoil Leachate GeochemistryJohnson, Daniel K.; Daniels, W. Lee; Orndorff, Zenah W.; Ross, L. Clay; Klopf, Sara K. (Virginia Tech. Powell River Project, 2015)
- Evaluation of Sulfidic Materials in Virginia Highway CorridorsOrndorff, Zenah W. (Virginia Tech, 2001-09-10)Road construction through sulfidic materials in Virginia has resulted in localized acid rock drainage (ARD) that threatens water quality, fill stability, integrity of building materials, and vegetation management. The objectives of this study were: i) to develop a state-wide sulfide hazard rating map based on characterization of the geologic formations associated with acid roadcuts, ii) to estimate depth to sulfidic sediments in the Coastal Plain based on landscape relationships, and iii) to evaluate potential acidity testing procedures on diverse materials. Geologic formations associated with acid roadcuts were characterized by potential peroxide acidity (PPA) and S content, and grouped into four categories. Listed in order of increasing severity, these formations included: the Tabb Formation (Coastal Plain), the Lynchburg Group of the Ashe Formation (Blue Ridge), the Chesapeake Group and Lower Tertiary deposits (Coastal Plain), the Millboro shale, Marcellus shale, Chatanooga shale and Needmore Formation (Valley and Ridge), and the Quantico Formation (Piedmont). Evaluation of landscape parameters near Richmond, Virginia, indicated that the likelihood of encountering sulfidic materials within a given depth at a specific location was related to elevation and mapped soil types. Elevation and soil map units were assigned to risk classes to indicate the likelihood of encountering sulfides within a depth of 9 m. Comparison of PPA and S content for 296 diverse samples indicated that S may serve as a screening tool to evaluate materials without carbonates. Comparison of PPA and conventional Acid-Base Accounting (ABA) for 14 diverse samples indicated that PPA and ABA were highly correlated, with PPA yielding 0.60 to 0.95X the amount of acidity as ABA. Potential acidity by Soxhlet extraction and PPA were equivalent for 3 of 4 diverse samples. Average acidity and metal contents of leachate from Soxhlet extractors were correlated with acidity and metals of road drainage. Sulfide hazard analysis should be an essential step in the pre-design phase of highway construction and other earth-disturbing activities.
- Locating and Identifying Low TDS Strata in Appalachian Soil-Overburden SequencesJohnson, Daniel K.; Daniels, W. Lee; Orndorff, Zenah W. (Virginia Tech. Powell River Project, 2014)Release of total dissolved solids (TDS) from Appalachian coal mine spoils to headwater streams has emerged as a significant concern for the coal mining industry, its regulatory agencies, and non-governmental organizations. The overall objective of this project is to develop a new set of techniques to reliably predict the amount, ionic composition, and temporal pattern of TDS release from a range of spoil and overlying soil materials from regional coal surface mines. This project was initiated in 2010 with sole support from Powell River Project. Between 2011 and 2013, we received significant parallel funding for this program from the Appalachian Research Initiative for Environmental Science (ARIES) to support our collaboration with the University of Kentucky and West Virginia University to broaden the scope to the central Appalachian region while continuing to focus on SW Virginia in more detail. Therefore, we are utilizing Powell River Project (PRP) funds to focus specifically on the determination of TDS release potentials of soil-saprolite-hard rock sequences in SW Virginia and adjacent counties in eastern Kentucky and southern West Virginia. This information will better allow operators to determine the thickness and availability of low TDS forming strata for use in new and innovative mining and reclamation plans designed to limit TDS release to local streams.
- Long-Term Mine Soil Weathering and TDS ReleaseOrndorff, Zenah W.; Daniels, W. Lee; Beck, Mike; Eick, Matthew J.; Zipper, Carl E. (Virginia Tech. Powell River Project, 2011)The Surface Mining Control and Reclamation Act (SMCRA) of 1977 contained a number of contentious provisions including return to original contour (AOC), long-term liability bonding periods, and return to “equal or better” post-mining land use conditions. However, one of the more interesting provisions was SMCRA’s allowance for use of pre-selected overburden materials as topsoil substitutes when (A) the native A+E horizon materials are less than 6 inches thick, and (B) the physical and chemical properties of the proposed substitute spoil materials are deemed suitable for such use. Since native topsoil layers throughout the Appalachian coalfields are usually less than six inches thick, and removing them from steep slopes is difficult and expensive, the vast majority of coal mined lands in the region have employed topsoil substitutes. One of the unintended secondary effects of this practice has been the intentional selection and placement of topsoil substitute materials derived from deeper unweathered strata that are higher in pH and extractable nutrients than near-surface weathered strata. As discussed later, many of these otherwise suitable topsoil substitutes are also generate significant ionic loads to runoff and leaching waters as they weather over time.
- Phosphorus adsorption on sandy mine tailings: a comparison of treatments with fertilizers, wood ash, and compostOrndorff, Zenah W. (Virginia Tech, 1995)Approximately 378 million metric tons of soil in the Upper Coastal Plain of Virginia and North Carolina may be processed during proposed titanium mining.. This area is prime agricultural land, and with proper management productivity can be maintained with treated mine tailings. Since P is usually a limiting plant nutrient, proper P fertilization is essential for continued agricultural productivity. Seven different soil systems including unamended tailings (UT), a series of 5 treatments with fertilizers, wood ash, and increasing rates of compost (treatments 1, 3, 6, 8, and 9), and natural soil (NS) were evaluated and compared with regards to P status. Comparisons were based on standard Langmuir adsorption isotherms, Mehlich III extractable-P, and selected chemical and physical properties including pH, cation exchange capacity, compost rate, and specific surface area. Phosphorus adsorption decreased in the order UT, 1, 3, 6, 8, 9, and NS. Decrease in P adsorption was due primarily to increasing organic matter which both physically blocks P adsorption sites, and competes for these sites. Previous addition of large amounts of P fertilizer caused a decrease in P adsorption by occupying some adsorption sites. Wood ash increased pH, which decreased anion exchange capacity and thereby decreased P adsorption. Treatment 9 (12% compost) most closely resembled the natural soil in terms of P status. Agriculturally, economically, and environmentally, the tailings may be suitably managed with high compost rates, an initial heavy application of P fertilizer, and lighter yearly supplements of P fertilizer.
- Predicting TDS Release from SW Virginia Soil-Overburden SequencesJohnson, Daniel K.; Orndorff, Zenah W.; Daniels, W. Lee (Virginia Tech. Powell River Project, 2012)Release of total dissolved solids (TDS) from Appalachian coal mine spoils to headwater streams has emerged as a significant concern for the coal mining industry, its regulatory agencies, and non‐governmental organizations. The overall objective of this project is to develop a new set of techniques to reliably predict the amount, ionic composition, and temporal pattern of TDS release from a range of spoil and overlying soil materials from regional coal surface mines. This project was initiated in 2010 with sole support from Powell River Project. In 2011/2012 we received significant parallel funding for this program from the Appalachian Research Initiative for Environmental Science (ARIES) to support our collaboration with the University of Kentucky and West Virginia University to broaden the scope to the central Appalachian region while continuing to focus on SW Virginia in more detail. Therefore, we are utilizing Powell River Project (PRP) funds to focus specifically on the determination of TDS release potentials of soilsaprolite‐hard rock sequences in SW Virginia. This information will better allow operators to determine the thickness and availability of low TDS forming strata for use in new and innovative mining and reclamation plans designed to limit TDS release to local streams.
- Predicting TDS Release from SW Virginia Soil-Overburden SequencesJohnson, Daniel K.; Daniels, W. Lee; Orndorff, Zenah W. (Virginia Tech. Powell River Project, 2013)Release of total dissolved solids (TDS) from Appalachian coal mine spoils to headwater streams has emerged as a significant concern for the coal mining industry, its regulatory agencies, and non-governmental organizations. The overall objective of this project is to develop a new set of techniques to reliably predict the amount, ionic composition, and temporal pattern of TDS release from a range of spoil and overlying soil materials from regional coal surface mines. This project was initiated in 2010 with sole support from Powell River Project. Between 2011 and 2013, we received significant parallel funding for this program from the Appalachian Research Initiative for Environmental Science (ARIES) to support our collaboration with the University of Kentucky and West Virginia University to broaden the scope to the central Appalachian region while continuing to focus on SW Virginia in more detail. Therefore, we are utilizing Powell River Project (PRP) funds to focus specifically on the determination of TDS release potentials of soil-saprolite-hard rock sequences in SW Virginia and adjacent counties in eastern Kentucky and southern West Virginia. This information will better allow operators to determine the thickness and availability of low TDS forming strata for use in new and innovative mining and reclamation plans designed to limit TDS release to local streams.