Acid Mine Drainage Sources Research Articles

Spatial variations in the fate and transport of metals in a mining-influenced stream, North Fork Clear Creek, Colorado

North Fork Clear Creek (NFCC) receives acid-mine drainage (AMD) from multiple abandoned mines in the Clear Creek Watershed. Point sources of AMD originate in the Black Hawk/Central City region of the stream. Water chemistry also is influenced by several non-point sources of AMD, and a wastewater treatment plant (WWTP). In-stream conditions immediately downstream from point-source inputs result in a visual and rapid precipitation of hydrous iron oxides (HFO). Hydrous manganese oxides (HMO) are seen to coat rocks further downstream during some seasons. Synoptic spatial sampling was used to assess the fate and transport of Cu, Fe, Mn, and Zn during different years and hydrological seasons. Visual-MINTEQ was used to compare observed and model-calculated percentage particulate Cu and Zn as influenced by sorption to both HFO and HMO and aqueous complexation with dissolved organic carbon (DOC). Over distance, Cu and Fe were transported predominantly in the particulate phase, Mn in the dissolved phase, and Zn was intermediate in its distribution, with generally about 50% being in each phase. Under higher flows, a larger fraction of the total metals was present in the dissolved phase, along with a lower total suspended sediment (TSS) concentration. This is consistent with the source of TSS being predominantly in-stream precipitation of metals, which might be kinetically limited under higher flows. Modeling results most closely represented observed percentage particulate Cu under lower flows; a strong seasonal trend was not evident for Zn. Model over-predictions of percentage particulate Cu suggest non-equilibrium with sorbent phases or that something in addition to DOC was keeping a portion of the Cu in solution; under-predictions for Zn suggest an additional sorbent. Differences between observed and modeled particulate varied significantly between sites and seasons; ranging from 1 to 54% for Cu and 1 to 34% for Zn overall.

Hydrochemical characteristics and seasonal influence on the pollution by acid mine drainage in the Odiel river Basin (SW Spain)

The Odiel river Basin is heavily affected by acid mine drainage (AMD) from the sulphide mining areas in the Iberian Pyrite Belt (IPB). A thorough study has been conducted along this fluvial system, monitoring the seasonal influence on the pollution level and its hydrochemical characteristics. From 2002 to 2006, surface water samples were collected at 91 different points throughout the Odiel river Basin and analyzed by field and laboratory methods for dissolved metals and metalloids. Acid mine drainage affects 37% of the length of the drainage network, which shows a great diversity of geochemical conditions as well as significant variations through the hydrological year. Unaffected streams show different water types depending on the lithological substrate and the marine aerosol influence. Mean concentrations in the contaminated streams are very high: 231 mg/L of Fe, 135 mg/L of Al, 56 mg/L of Zn, 16 mg/L of Cu, etc. Four types of contaminated streams were recognized based on hydrochemical and physicochemical characteristics. There are important seasonal variations depending on the precipitation regimen, level of pollution and proximity to the AMD sources. In the more contaminated samples the M/Fe ratio (M = metals other than Fe) decreases during the summer season. Slightly contaminated samples show an inverse evolution as this ratio increases in spring and summer due to substantial Fe precipitation. A recomparison of contaminant loads suggests that the Odiel river Basin (including the Tinto river) accounts for 15% of the global gross flux of dissolved Zn and 3% of the global gross flux of dissolved Cu transported by rivers into the ocean.

Effect of pH, ionic strength, dissolved organic carbon, time, and particle size on metals release from mine drainage impacted streambed sediments

Acid-mine drainage (AMD) input to a stream typically results in the stream having a reduced pH, increased concentrations of metals and salts, and decreased biological productivity. Removal and/or treatment of these AMD sources is desired to return the impacted stream(s) to initial conditions, or at least to conditions suitable for restoration of the aquatic ecosystem. Some expected changes in the water chemistry of the stream following removal of AMD input include an increase in pH, a decrease in ionic strength, and an increase in dissolved organic carbon (DOC) concentrations from increased biological activity in the absence of toxic metals concentrations. These changes in water chemistry may cause the existing contaminated bed sediments to become a source of metals to the stream water. Streambed sediments, collected from North Fork Clear Creek (NFCC), Colorado, currently impacted by AMD, were assessed for the effects of pH, ionic strength, DOC concentration, time, and particle size on metals release using a factorial design. The design included two levels for each chemical parameter (ionic strength = 40 and 80% lower than ambient; pH = 6 and 8; and DOC = 1 and 3 mg/l higher than ambient), ten sampling times (from zero to 48 h), and two size fractions of sediments (63 μm ≤ x < 2 mm and <63 μm). Greater concentrations of metals were released from the smaller sized sediments compared with the larger, with the exception of Cu. A mild acid digestion (0.6 M HCl) evaluated the amount of each metal that could be removed easily from each of the sediment size fractions. Release of all metals over all time points, treatments, and from both sediment sizes was less than 1% of the extractable concentrations, with the exception of Mn, which ranged from 4 to 7% from the smaller sized sediment. Greater percentages of the 0.6 M HCl-extractable concentrations of Cu, Fe, and Zn were released from the larger sized sediment, while this was true for release of Cd and Mn from the smaller sized sediment. Thus, at least for Cd and Mn, the observed higher concentrations released from the smaller sized sediment with each treatment solution is not simply a function of these particles having higher concentrations available for release, but that these metals also are more readily released from the smaller sediment particles versus the larger. DOC concentration strongly influenced the release of Cu; ionic strength strongly influenced the release of Cd, Mn, and Zn; and interaction effects were observed with the release of Cu, Mn, and Zn from the larger size fraction and with the release of Zn from the smaller size fraction. Overall, results suggest that the expected changes in water chemistry following removal/treatment of the AMD sources would result in a release of metals from the existing sediments, with a greater effect on the release of Cu and Fe, than on the release of Cd, Mn, and Zn.

English

Acid mine drainage (AMD) is a major environmental consequence of mining activity. This is a recurring problem around the world, and especially in some specific areas of United States, including Pennsylvania. Remediation of AMD has three requirements: pH neutralization, reduction of sulfate concentrations, and removal of dissolved metals. The aim of this study was to evaluate the sustainable waste material, crab-shell-chitin, as a multifunctional substrate for AMD remediation. The performance of chitin was evaluated under different raw water characteristics (comparative sites test), and compared with lactate and spent mushroom compost (comparative substrates test). Sacrificial, duplicate microcosms were prepared in serum bottles containing AMD water, sediment (microbial source), and the evaluated substrate. For the comparative sites test, three microcosm sets were prepared using AMD water from three different sites within central Pennsylvania, and all were treated with crab-shell-chitin. For the comparative substrates test, the AMD source was held constant and the substrate varied between crab-shell-chitin, sodium lactate, and spent mushroom compost. Microcosms were incubated in the dark, at room temperature, and under anoxic conditions for up to 50 days. Crab-shell-chitin (ChitoRem™ SC-20) increased the pH from pH 3.0 - 3.5 to near neutral in 2 - 3 days. Increases in pH were much faster in the microcosms containing chitin than with the other substrates. In microcosms containing chitin, steady alkalinity generation and acidity removal were observed at average rates of 35 and - 27 mg CaCO3/L-d, respectively. The activity of SO4 2- reducing bacteria was evident after 7 - 9 days of incubation, with reduction rates of 11.9 - 17.8 mg SO4 2- /L-d. Similar changes in alkalinity, acidity, and SO4 2- were also observed in lactate- containing microcosms, but they only started after 27 days. No alkalinity generation or sulfate reduction activity was observed in bottles containing spent mushroom compost. Aluminum and Fe removal was observed with all substrates, but it was much faster with chitin. Chitin was the only substrate able to partially remove manganese (>73%). The results of this study indicate that crab-shell-chitin is a promising material to be used as a substrate or amendment for AMD remediation. Its slowly fermentable nature makes it a suitable electron donor source to support the activity of sulfate reducing bacteria. In addition, the rapid release of its built-in carbonate minerals effectively neutralize acidic waters and facilitate the precipitation of dissolved metals.

Water management for acid mine drainage control at the polymetallic Zn–Pb–(Ag–Bi–Cu) deposit Cerro de Pasco, Peru

The geochemical and mineralogical study of the Quiulacocha tailings impoundment has shown that the hydrological connection of the three studied mine-waste systems at Cerro de Pasco (Pyrite-rich waste-rock dump Excelsior, old tailings impoundment Quiulacocha, and the active tailings impoundment Ocroyoc) is a critical concern for effective acid mine drainage (AMD) control and mine-waste management. The Quiulacocha tailings covered 114 ha, comprising 79 Mt of tailings, which contained ∼ 50 wt.% pyrite, and are located at 4340 m altitude in a tropical puna climate with about 1025 mm/a rainfall and 988 mm/a of evaporation. The tailings were partially overlain by the Excelsior waste-rock dump, which contains about 26,400,000 m 3 of waste rocks that cover 94 ha and contained ∼ 60 wt.% of pyrite, which origin from a massive pyrite-quartz replacement body. Therefore, these two mine-waste deposits had a direct hydrological connection, resulting in the export of AMD produced at Excelsior towards Quiulacocha. In the Quiulacocha impoundment there are two different types of tailings recognized, that interact with the AMD from Excelsior: 1) Zn–Pb-rich tailings and 2) Cu–As-rich tailings. During the sampling, the Zn–Pb-rich part of Quiulacocha was not producing important excesses of AMD from the oxidation zone, since the pH increased to near neutral values at 1 m depth. The underlying tailings were still able to neutralize the acidity produced in the oxidation zone through sulfide oxidation by the carbonates (mainly dolomite and siderite) contained in the Zn–Pb mineral assemblage. The main source of AMD in this mine-waste system is the Excelsior waste-rock dump. Its acid seepage infiltrates into Quiulacocha forming a Fe–Zn–Pb plume with a pH 5.5–6.1 and containing up to 7440 mg/L Fe, 627 mg/L Zn, and 1.22 mg/L Pb. The plume was detected at 10–13 m depth in the stratigraphy of Quiulacocha tailings. Additionally, the AMD seepage outcropping at the base of the Excelsior waste-rock dump was channeled on the tailings surface into the Quiulacocha pond (pH 2.3), which covered the Cu–As-rich tailings. Infiltration of this Fe(III)-rich AMD increased tailings oxidation in the southwestern part of the impoundment, and subsequently liberated arsenic by enargite oxidation. Additionally, the AMD collected in the Quiulacocha pond was pumped into the active Ocroyoc tailings impoundment, where sulfide oxidation was strongly enhanced by the input of dissolved Fe(III). Therefore, the AMD management and a hydrological separation of the different mine-waste systems could be a first step to prevent further extension of the AMD problem in order to prevent increased sulfide oxidation by Fe(III)-rich solutions.

Hydrochemical variations and contaminant load in the Río Tinto (Spain) during flood events

The aim of this work is to study the hydrochemical variations during flood events in the Rio Tinto, SW Spain. Three separate rainfall/flood events were monitored in October 2004 following the dry season. In general, concentrations markedly increased following the first event (Fe from 99 to 1130 mg/L; Q(max) = 0.78 m(3)/s) while dissolved loads peaked in the second event (Fe = 7.5 kg/s, Cu = 0.83 kg/s, Zn = 0.82 kg/s; Q(max) = 77 m(3)/s) and discharge in the third event (Q(max) = 127 m(3)/s). This pattern reflects a progressive depletion of metals and sulphate stored in the dry summer as soluble evaporitic salt minerals and concentrated pore fluids, with dilution by freshwater becoming increasingly dominant as the month progressed. Variations in relative concentrations were attributed to oxyhydroxysulphate Fe precipitation, to relative changes in the sources of acid mine drainage (e.g. salt minerals, mine tunnels, spoil heaps etc.) and to differences in the rainfall distributions along the catchment. The contaminant load carried by the river during October 2004 was enormous, totalling some 770 t of Fe, 420 t of Al, 100 t of Cu, 100 t of Zn and 71 t of Mn. This represents the largest recorded example of this flush-out process in an acid mine drainage setting. Approximately 1000 times more water and 1408 200 times more dissolved elements were carried by the river during October 2004 than during the dry, low-flow conditions of September 2004, highlighting the key role of flood Events in the annual pollutant transport budget of semi-arid and and systems and the need to monitor these events in detail in order to accurately quantify pollutant transport. (c) 2007 Elsevier B.V. All rights reserved.

A quantitative estimation of the factors affecting pH changes using simple geochemical data from acid mine drainage

The behavior of heavy metals in acid mine drainage (AMD) is mainly controlled by pH values. Therefore, a quantitative estimation of factors affecting pH values in AMD is very important in predicting the behavior of those metals. Many different factors cause pH changes in streams affected by AMD and we quantitatively estimated those factors by making simple equations from geochemical data collected from the Dalsung mine. In a stream from that mine, the pH values decrease as the stream flows downstream from the AMD source, which is different from normal streams affected by AMD. The stream shows low pH ranges (4.04–5.96), high electrical conductivity (1,407–1,664 μS/cm), and sulfate concentration (680–854 ppm). Most ion concentrations decrease or do not show noticeable changes mainly due to dilution. The change of the iron content is most significant, even though the concentration of iron is relatively low compared with other ions. The iron concentration (13.4 ppm) becomes almost 0 ppm due to precipitation. Schwertmannite is the dominant precipitated phase downstream and whitish basaluminite is observed in the upstream. From our pH estimation, precipitation is the most important process lowering pH values from 5.96 to 4.04. The dilution factor was calculated by the concentration changes in sulfate ions. Dilution increases pH values, but compared with the precipitation factor, the contribution of the dilution factor to pH is relatively small. Alkalinity is the main factor that buffers hydrogen, which is released by precipitation. The redox changes, which were calculated from the pH and Eh values, also affect pH at each sampling site. The trend of estimated pH changes is almost identical to the observed ones, but the values are slightly different. Some errors are expected mainly due to the uncertainty in the observed Eh values and the chemistry of the added water for dilution.

Enhancement of bacterial iron and sulfate respiration for in situ bioremediation of acid mine drainage sites: a case study

The prevention of acid mine drainage (AMD) in situ is more attractive than down-gradient treatment alternatives that do not involve source control. AMD source control can be achieved by shifting the microbial activity in the sulfidic rock from pyrite oxidation to anaerobic heterotrophic activity. This is achieved by adding biodegradable organic carbon amendments to the sulfidic rock. This technique was applied to an abandoned coal mine pool in Pennsylvania. The pool had a pH of 3.0 to 3.5. Following treatment, near-neutral pH and decreased effluent heavy metal concentrations were achieved. In situ bioremediation by the enhancement of bacterial iron and sulfate reduction is a promising technology for AMD prevention.

English

Intensive mining and processing of silver, lead, tin and zinc ores have occurred in various locations within and around the city of Potosi, Bolivia since 1545. Surface and subsurface waters, stream sediments and soils are contaminated with various heavy metals. Acid mine drainage and processing plant effluent are primary contaminants in the headwaters of the economically vital, yet highly impacted, Rio Pilcomayo watershed. Previous studies have documented downstream heavy metal contamination. The acid mine drainage sources documented in this study help to link downstream pollution to primary origins. Selected acid mine drainage sources, from both operating and abandoned mines contributing to local streams, contained total metal concentrations of 0.284- 977 mg/L Al, 0.03-191 mg/L As, 0.025-50.68 mg/L Cd, 0.03-161 mg/L Cu, 0.15- 7,320 mg/L Fe, 0.3-438 mg/L Mn, 0.03-15.0 mg/L Pb and 1.46-11,760 mg/L Zn, with pH and specific conductance ranging from 2.46-6.39 and 893-19,070 μS/cm, respectively. Data were gathered during the dry season with flows ranging from nil to 4.59 L/s. Metals concentrations and pH values in all mine drainage sources sampled are several orders of magnitude above compliance with Bolivian environmental law.

English

The Sugar Creek Watershed is located north of Huntsville in northcentral Missouri. Water quality in Sugar Creek has been affected by acid mine drainage (AMD) generated by underground mining and coal refuse disposal before the Surface Mining Control and Reclamation Act of 1977 and has been listed on Missouri’s 303d list as an impaired stream. To support the state of Missouri’s development of a Total Maximum Daily Load (TMDL) assessment and remediation efforts, the Office of Surface Mining (OSM), Mid-Continent Region in cooperation with the U. S. Geological Survey (USGS), Missouri Water Science Center Kansas City Office has completed a technical evaluation and economic and logistical feasibility study for the AMD affected waterway. Utilizing a water-quality assessment completed in 2005 by the USGS, the OSM study proposes the construction of passive treatment facilities for three major AMD sources identified by the USGS in the watershed. Site-specific remediation costs are determined for each site using OSM’s Technical Innovation and Professional Services software AMDTreat. The proposed treatment systems utilize state-of-the-art passive treatment technology, including anaerobic bioreactors and vertical flow wetlands. Treatment of the discharges from two of the AMD sources add alkaline effluent from public waste-water treatment facilities for neutralizing acidity, dilution of the AMD, and addition of nutrients into the proposed wetland treatment systems. This study will be used to develop costs and a plan for the remediation of the Sugar Creek discharges and can serve as a guide in TMDL assessments in Missouri and other coal mining areas. Additional

English

The Quiulacocha tailings cover 114 ha, comprising 79 Mt of tailings, which contain ~ 50 wt% pyrite. The tailings are located at 4340 m altitude in a tropical puna climate with about 1025 mm/a rainfall. The tailings are partially overlain by the Excelsior waste-rock dump, which contains about 26,400,000 m 3 of waste rocks that cover 94 ha and contain ~60 wt% of pyrite. In the Quiulacocha impoundment there are two different types of tailings recognized: 1.) Zn-Pb-rich tailings and 2.) Cu-rich tailings. During the sampling campaign, the Zn-Pb-rich part of Quiulacocha was not producing important excesses of acid mine drainage (AMD) from the oxidation zone, where pH is increased to near neutral values at 1 m depth. The underlying tailings were able to neutralize the acidity produced in the oxidation zone through sulfide oxidation by the underlying carbonates (dolomite and siderite). The main source of AMD in this mine-waste system is from the Excelsior waste-rock dump. Its acid seepage infiltrates into Quiulacocha forming a Fe-Zn-Pb plume with a pH 5.5 - 6.1 and containing up to 7440 mg/L Fe, 627 mg/L Zn, and 1.22 mg/L Pb. The plume was detected between 10 m to 13 m depth in the stratigraphy of Quiulacocha tailings. Additionally, the AMD seepage from the base of the Excelsior waste-rock dump is channeled on the tailings surface to the pond of Quiulacocha (pH 2.3), which covers Cu-rich tailings. Infiltration of this Fe(III)-rich AMD increases oxidation of tailings in the southwestern part of the impoundment and subsequently liberates As by enargite oxidation. Additionally, the AMD collected in the Quiulacocha pond was pumped into the active Ocroyoc tailings impoundment, where sulfide oxidation was strongly enhanced by the input of dissolved Fe(III). Therefore, a hydrological separation of the different mine-waste systems might be a first step to prevent further extension of the AMD problem.

BIOLOGICAL SOURCE TREATMENT OF ACID MINE DRAINAGE

Acid mine drainage (AMD) originates from mining operations with oxidation of metal sulfides. The oxidizing process releases protons and generates acidity. A biological source treatment (BST) technique has been developed to address AMD at its source. The BST technique utilizes sulfate-reducing bacteria (SRB) and substrate amendments to establish an intracellular and/or extracellular biogeochemical formation on the surface of metal sulfide, shielding them from being oxidized. SRB transfer electrons from organic substrates to sulfate and form sulfide. This process consumes protons and raises pH, while dissolved metals are precipitated with sulfide. Laboratory studies have shown that effluent/solids from wastewater treatment plants contain adequate populations of SRB as the inoculum for BST applications. In laboratory studies, the pH of AMD samples increased from 7.0 and stabilized in the neutral pH range for more than 20 months with one treatment. A field pilot study of the BST technique was conducted at a reclaimed coal mine in central Tennessee. Results to date indicate a significant increase in pH in the testing area, stabilizing in the pH range from 6.0 to 7.0, from the initial acidic readings. Decreases in sulfate and increases in sulfide concentrations confirm valid sulfate-reducing activity. Electromagnetic surveys were conducted in the field pilot test to identify AMD source and assist in monitoring the performance. Data from both the laboratory and field studies demonstrate that BST process is an innovative technology that can be applied in suitable sites and offer a cost-effective and long-term treatment of AMD.

Using airborne thermal infrared imagery and helicopter EM conductivity to locate mine pools and discharges in the Kettle Creek watershed, north-central Pennsylvania

The Kettle Creek watershed contains 50–100-year-old surface and underground coal mines that are a continuing source of acid mine drainage (AMD). To characterize the mining-altered hydrology of this watershed, an airborne reconnaissance was conducted in 2002 using airborne thermal infrared imagery (TIR) and helicopter-mounted electromagnetic (HEM) surveys. TIR uses the temperature differential between surface water and groundwater to locate areas where groundwater emerges at the surface. TIR anomalies located in the survey included seeps and springs, as well as mine discharges. In a follow-up ground investigation, hand-held GPS units were used to locate 103 of the TIR anomalies. Of the sites investigated, 26 correlated with known mine discharges, whereas 27 were previously unknown. Seven known mine discharges previously obscured from TIR imagery were documented. HEM surveys were used to delineate the groundwater table and also to locate mine pools, mine discharges, and groundwater recharge zones. These surveys located 12 source regions and flow paths for acidic, metal-containing (conductive) mine drainage; areas containing acid-generating mine spoil; and areas of groundwater recharge and discharge, as well as identifying potential mine discharges previously obscured from TIR imagery by nondeciduous vegetation. Follow-up ground-based electromagnetic surveys verified the results of the HEM survey. Our study suggests that airborne reconnaissance can make the remediation of large watersheds more efficient by focusing expensive ground surveys on small target areas.

Geochemical and Stable Isotope Evidence for Precipitation and Groundwater Sourcing of Recharge at the Green Valley Site, Vigo County, Indiana

We examined the recharge sources of acid mine drainage (AMD) seeps that form at the toe of the coal refuse (gob) pile at a site in Indiana, using traditional geochemistry and oxygen isotopes. AMD from this site has impacted local waterways, and reducing the volume of AMD is a priority. Our observations indicate that there are two main sources of recharge. The first is relatively dilute, isotopically homogenous, geochemically-reducing groundwater that flows up through pre-mining karst-like features beneath the gob pile due to localized, precipitation-induced, hydraulic head. This produces a perched water table above the regional water table. The second source of recharge is oxidizing and isotopically variable meteoric precipitation that percolates through the permeable capping material; a partially buried and abandoned railroad grade may also channel meteoric waters into the pile. During periods of low precipitation, oxygenated pore moisture in the unsaturated zone facilitates AMD generation. During periods of elevated precipitation, these metal-rich pore fluids are flushed through the system by isotopically variable, oxygenated, metal-poor meteoric waters. Each source contributes subequal but variable amounts of recharge waters. The hydraulic conductivity and permeability of the gob pile, as calculated by isotopic lag, is consistent with values for silty to clean unconsolidated sand.

Acid neutralization within limestone sand reactors receiving coal mine drainage

Pulsed bed treatment of acid mine drainage (AMD) uses CO2 to accelerate limestone dissolution and intermittent fluidization to abrade and carry away metal hydrolysis products. Tests conducted with a prototype of 60L/min capacity showed effective removal of H+ acidity over the range 196–584mg/L (CaCO3) while concurrently generating surplus acid neutralization capacity. Effluent alkalinity (mg/L CaCO3) rose with increases in CO2 (DC, mg/L) according to the model Alkalinity=31.22+2.97(DC)0.5, where DC was varied from 11–726mg/L. Altering fluidization and contraction periods from 30s/30s to 10s/50s did not influence alkalinity but did increase energy dissipation and bed expansion ratios. Field trials with three AMD sources demonstrated the process is capable of raising AMD pH above that required for hydrolysis and precipitation of Fe3+ and Al3+ but not Fe2+ and Mn2+. Numerical modeling showed CO2 requirements are reduced as AMD acidity increases and when DC is recycled from system effluent.

English

In 1995, the U.S. Office of Surface Mining (OSM) and the National Mine Land Reclamation Center (NMLRC) joined with the Interstate Mining Compact Commission, the National Mining Association, academia, and other Federal agencies to form the Acid Drainage Technology Initiative (ADTI). The ADTI partnership seeks to identify, evaluate and develop best science based practices to prevent new acid mine drainage sources and eliminate existing sources. The ADTI partnership developed a management structure to oversee the program and developed action plans to address key technical areas. The ADTI organization consists of a coal mining sector, a metal mining sector and a secretariat, overseen by an Operations Committee. The coal mining sector of ADTI is divided into a prediction working group and an avoidance and remediation working group to implement and coordinate the research strategy. This paper summarizes the results of the coal mining sector efforts since the completion of the avoidance and remediation, and prediction handbooks in 1998 and 2000, respectively, and the status of current activities. The activities have included field verification of acid drainage predictions using acid-base accounting, monitoring and follow up evaluation of acid mine drainage passive and in-situ treatment systems, developing standardized kinetic testing protocols, flooded underground mine pools, and issues related to elevated selenium in streams associated with surface mines.

Acid Drainage Technology Initiative: Continuing Progress in Coal Related Topics

In 1995, the U.S. Office of Surface Mining (OSM) and the National Mine Land Reclamation Center (NMLRC) joined with the Interstate Mining Compact Commission, the National Mining Association, academia, and other Federal agencies to form the Acid Drainage Technology Initiative (ADTI). The ADTI partnership seeks to identify, evaluate and develop "best science" based practices to prevent new acid mine drainage sources and eliminate existing sources. The ADTI partnership developed a management structure to oversee the program and developed action plans to address key technical areas. The ADTI organization consists of a coal mining sector, a metal mining sector and a secretariat, overseen by an Operations Committee. The coal mining sector of ADTI is divided into a prediction working group and an avoidance and remediation working group to implement and coordinate the research strategy. This paper summarizes the results of the coal mining sector efforts since the completion of the avoidance and remediation, and prediction handbooks in 1998 and 2000, respectively, and the status of current activities. The activities have included field verification of acid drainage predictions using acid-base accounting, monitoring and follow up evaluation of acid mine drainage passive and in-situ treatment systems, developing standardized kinetic testing protocols, flooded underground mine pools, and issues related to elevated selenium in streams associated with surface mines.

Effects of AMD Pollutant Loading on Streams in the Hazleton PA Area

A baseline water quality study of streams impacted by acid mine drainage (AMD) within the Hazleton, PA area was undertaken to determine sources of acidity, aluminum, iron, manganese, and sulfate with the long-term objective of development of regional abatement strategies. Sample site locations were identified for the Black Creek, Little Nescopeck and Nescopeck Creek watersheds, consisting of main-stem locations and tributaries both upstream and downstream of suspected AMD sources. Flow measurements were conducted at each sample location to calculate mass loadings of AMD contaminants. Data will be used to prepare Total Maximum Daily Load (TMDL) reports to determine the required percent removals of acidity and total Al, Fe, and Mn in order to comply with PA water quality standards. Discharge from the Jeddo Tunnel was found to be the largest source of AMD contamination in the Little Nescopeck and Nescopeck Creek watersheds, with an average pH of 4.30 and contributing average mass loadings exceeding 7750 kg/day (17,000 lb/day) of acidity, 1350 kg/day (2900 lb/day) Al, 390 kg/day (860 lb/day) Fe, and 630 kg/day (1350 lb/day) Mn to the Little Nescopeck Creek based on two sampling expeditions. Discharge from the Jeddo Tunnel was compared to historic water quality data for this source, demonstrating improvement in water quality over time. Discharge from the Gowen Mine was the major source of AMD contamination to Black Creek, which also flows into Nescopeck Creek. This discharge had pH less than 4.0 and contributed average mass loadings of 4820 kg/day (10,600 lb/day) of acidity, 715 kg/day (1575 lb/day) Al, and 480 kg/day (1050 lb/day) Mn to Black Creek based on four rounds of sampling and flow measurement. AMD from Jeddo Tunnel and Gowen Mine are among the largest sources of pollutants in the Middle Susquehanna River system. Continued monitoring and field sampling of the streams and discharges within the study area is recommended so that seasonal variations in water quality and flow can be determined in order to evaluate AMD abatement strategies.

Solute Transport at Low Flow in an Acid Stream in Appalachian Ohio

The spatial variability in chemical composition of water and sediments along Snow Fork, a stream draining 70 km2 of southeastern Ohio, was investigated under low-flow conditions. The stream is affected by acid mine drainage (AMD) beginning atEssex Mine, an abandoned mine opening, and extending 23 km downstream to the confluence with Monday Creek. Volumetric discharge and changes in stream water and sediment metalconcentrations were examined to identify chemical interactionsand processes controlling the transport and fate of metalcontaminants. The stream loses water to the groundwater system insome sections. The water loss probably occurs through fracturesconnecting the stream to underlying underground coal mines. Massbalance (loading) and mineral saturation index calculations wereused to identify metal sources and sinks. Dissolved metal loadingincreases downstream along the length of Snow Fork, despite theprecipitation of metals as hydroxides in the streambed,indicating multiple groundwater sources of AMD along the flowpath. Relatively high dissolved metal concentrations and lowsediment metal concentrations occur where the pH is low,indicating that local sediment-water interaction dominates masstransfer between sediments and water. Calculated mineralsaturation indexes indicate that aluminum and iron hydroxidesprecipitate in some stream segments and dissolve in others. X-raydiffractograms of sediments show two distinct mineral groups.Amorphous or weakly crystalline minerals dominate one group foundnear the stream headwaters near the underground mine. Crystallinemineral phases dominate the sediments downstream. Thesediffractograms contain the primary peaks for quartz, kaoliniteand illite all of which constitute the local sandstones, shalesor underclay. Peaks of amorphous phases of iron and manganese,if present, are obscured. The implications of these findings arethat the transport of metals in sediments may be as important asdissolved metal transport in estimating the overall stream load,particularly if downstream sources of AMD may remobilize metalsfrom soluble precipitates.

Evaluation of Airborne Thermal Infrared Imagery for Locating Mine Drainage Sites in the Lower Kettle Creek and Cooks Run Basins, Pennsylvania, USA

High-resolution airborne thermal infrared (TIR) imagery data were collected over 90.6 km2 (35 mi2) of remote and rugged terrain in the Kettle Creek and Cooks Run Basins, tributaries of the West Branch of the Susquehanna River in north-central Pennsylvania. The purpose of this investigation was to evaluate the effectiveness of TIR for identifying sources of acid mine drainage (AMD) associated with abandoned coal mines. Coal mining from the late 1800s resulted in many AMD sources from abandoned mines in the area. However, very little detailed mine information was available, particularly on the source locations of AMD sites. Potential AMD sources were extracted from airborne TIR data employing custom image processing algorithms and GIS data analysis. Based on field reconnaissance of 103 TIR anomalies, 53 sites (51%) were classified as AMD. The AMD sources had low pH (<4) and elevated concentrations of iron and aluminum. Of the 53 sites, approximately 26 sites could be correlated with sites previously documented as AMD. The other 27 mine discharges identified in the TIR data were previously undocumented. This paper presents a summary of the procedures used to process the TIR data and extract potential mine drainage sites, methods used for field reconnaissance and verification of TIR data, and a brief summary of water-quality data.