analysis of coal combustion by-product disposal practices
TRANSCRIPT
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Civil Engineering ETDs Engineering ETDs
2-1-2012
Analysis of coal combustion by-product disposalpractices in an arid climate : leachate water qualityCheryl Parker
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Cheryl Parker Candidate Department of Civil Engineering Department This thesis is approved, and it is acceptable in quality and form for publication: Approved by the Thesis Committee: Bruce Thomson , Chairperson John Stormont Kara Hart
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ANALYSIS OF COAL COMBUSTION BY-PRODUCT DISPOSAL PRACTICES IN ARID CLIMATES:
LEACHATE WATER QUALITY
by
CHERYL HENDERSON PARKER
BACHERLOR OF SCIENCE IN CIVIL ENGINEERING
THESIS
Submitted in Partial Fulfillment of the Requirements for the Degree of
Master of Science Civil Engineering
The University of New Mexico
Albuquerque, New Mexico
December 2011
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©2011, Cheryl Parker
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DEDICATION
Dedicated to Jed Parker for continually motivating me to become a better person.
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ACKNOWLEDGMENTS
First thanks goes to my spouse and first editor-in-chief, Jed , though a small word of
thanks is not enough for many hours of work and frustration that was editing this thesis, I do
thank you from the bottom of my heart for all you hard work patience. To Chris and Susan
Henderson, my parents, for having the patience to deal with me throughout my younger
years. To Tim and Chris Parker, who gave me immeasurable support over the years. Your
encouragement is greatly appreciated.
I heartily acknowledge Bruce Thomson, my advisor and dissertation chair, for
continuing to encourage me and keeping me on track. His guidance and life lessons will
remain with me as I continue in my career, dog training and motorcycle maintenance.
I also thank my committee members, Dr. John Stormont and Kara Hart for their
valuable recommendations pertaining to this study and assistance in my professional
development. Thanks to Mark Stone for his support through out the research. Gratitude is
extended to the Jim O-Hara, Chuck Thomas, Dave Clark, Monte Anderson for the funding to
pursue this research.
A special thanks to the University of New Mexico Earth and Planetary Science
department, specifically Abdul-Mehdi Ali, Jim Connolly and Mike Spilde for all their
technical assistants.
Thanks to Bill Skeet and Mike Goen from the San Juan Coal Mine and San Juan
Generating Station respectively for helping with information gathering.
Many thanks and best of luck to Ryan Webb and Kirsty Bramlett for their help in
gathering information and their support.
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ANALYSIS OF COAL COMBUSTION BY-PRODUCT DISPOSAL PRACTICES IN ARID CLIMATES:
LEACHATE WATER QUALITY
By
Cheryl Parker
B.S., Civil Engineering, University of Utah, 2008 M.S., Civil Engineering, University of New Mexico, 2011
ABSTRACT Coal combustion by-products (CCBs), produced from a large power plant in New Mexico, have been disposed of in a nearby coal mine since 1973. These CCBs consist of fly ash, bottom ash, and sludge from the flue gas desulfurization process and have elevated concentrations of hazardous constituents. There is concern that disposal of these materials in an unlined surface mine may cause ground and surface water contamination. This research project focused on determining the leachate characteristics from fresh unburied and old buried CCBs, and investigated the geochemical transformations that occur with time. Samples of CCBs ranged in age from less than a year old to over 30 years old. These samples were subjected to batch leaching tests as well leaching in unsaturated column tests. The mineralogy and physical characteristics of the CCBs and spoil were determined by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The analyses found that unburied and buried ash contained elevated concentrations of arsenic and barium relative to spoil material while all other constituents analyzed had similar concentrations to those found in the native soils/spoil. Concentrations of chemical constituents in ash samples varied with sample depth to which suggested geochemical evolution of CCBs as a function of time. These changes are attributed to age, water chemistry, process changes within the power plant and other factors. Of the chemical constituents analyzed, barium and arsenic demonstrated the largest change in concentration over depth. The remaining constituents showed relatively no change over depth and were in trace amounts. As depth of sampling increased, the age of recovered ash was likely to have increased as well. Mineralogical examination found evidence of dissolution of some mineral phases on buried CCBs. Older ash samples showed evidence of secondary mineralization leading to formation of calcite. Dissolution of aluminosilicate minerals was found in unsaturated column leach tests as increasing concentrations of aluminum, silica, lithium and vanadium. Barium showed the highest concentration when leached both with ground and deionized water.
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Although present in underlying groundwater, boron was not present at elevated concentrations in any of the ash sample leachates or column tests.
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TABLE OF CONTENTS DEDICATION ......................................................................................................................... iv ACKNOWLEDGMENTS ........................................................................................................ v ABSTRACT ............................................................................................................................. vi TABLE OF CONTENTS ....................................................................................................... viii LIST OF FIGURES .................................................................................................................. x LIST OF TABLES ................................................................................................................. xiii 1. Introduction ....................................................................................................................... 1 1.1. Coal mining in the United States .................................................................................. 1 1.1.1. Western coal.............................................................................................................. 2 1.2. CCB disposal ................................................................................................................ 4 1.3. Disposal spill ................................................................................................................. 5 1.4. Problem statement ......................................................................................................... 5 2. Background ....................................................................................................................... 7 2.1. Coal Combustion By-Products ..................................................................................... 8 2.1.1. Fly Ash ...................................................................................................................... 8 2.1.2. Bottom Ash ............................................................................................................. 12 2.1.3. Flue Gas Desulfurization Sludge ............................................................................ 13 2.2. Reuse of CCB ............................................................................................................. 14 2.3. Potential environmental impacts ................................................................................. 15 2.3.1. Environmental persistence ...................................................................................... 17 2.4. Regulatory framework ................................................................................................ 17 2.4.1. Federal regulations .................................................................................................. 17 2.4.2. State regulations ...................................................................................................... 18 2.5. San Juan Coal Mine site description ........................................................................... 19 2.5.1. SJCM geology and pathology ................................................................................. 26 2.5.2. Hydrology ............................................................................................................... 34 2.5.2.1. Groundwater ....................................................................................................... 34 2.5.2.2. Surface water ...................................................................................................... 41 2.5.2.3. Recharge ............................................................................................................. 44 2.6. San Juan Coal Mine and San Juan Power Generation Station .................................... 44 3. Methods........................................................................................................................... 46 3.1. Sample collection and preservation ............................................................................ 46 3.1.1. Geoprobe ® sample collection ................................................................................ 47 3.1.2. Sonic drilling sample collection .............................................................................. 49 3.2. Preparation of samples ................................................................................................ 52 3.3. Geochemical analyses ................................................................................................. 53 3.3.1. Acid digest procedure ............................................................................................. 54 3.3.2. Deionized water extraction procedure .................................................................... 54 3.4. Mineralogy .................................................................................................................. 57 3.4.1. Scanning Electron Microscopy ............................................................................... 57 3.4.2. X-Ray Diffraction ................................................................................................... 59 3.5. Column study procedure ............................................................................................. 60 3.5.1. Leaching sequence columns ................................................................................... 64 4. Results & Discussion ...................................................................................................... 65
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4.1. Analytes within SJCM CCBs and Spoil ..................................................................... 65 4.2. Concentration changes with depth .............................................................................. 82 4.3. Leachate variability with time .................................................................................... 92 4.4. Mineralogical evidence of aging of buried CCB materials ...................................... 107 4.4.1. SEM ...................................................................................................................... 107 4.4.2. XRD ...................................................................................................................... 114 4.5. Stratigraphy around CCBs and the relationship with No 8 Coal Seam .................... 123 4.6. Potential Impacts of Leachate from Buried CCBs on groundwater ......................... 123 5. Conclusion .................................................................................................................... 125 5.1. Analytes of concern .................................................................................................. 125 5.2. Specific leachates and sequence ............................................................................... 126 5.3. Evidence of aging in the buried CCBs ...................................................................... 126 5.4. Comparison of results with historical data ................................................................ 127 5.5. Applicability of Kingston, TN spill to SJCM operations ......................................... 128 Appendix ............................................................................................................................... 129 Bibliography ......................................................................................................................... 152
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LIST OF FIGURES Figure 1: An example of the coal powered electricity generating plant
http://www.worldcoal.org/media/jpg/585/174139cgart.jpg ..................................................................... 7 Figure 2 : General location of San Juan Coal Mine seen in yellow ................................................................ 20 Figure 3 : General location of San Juan Coal Mine within the state of New Mexico (Mines and Minerals
Division, New Mexico 2011) ..................................................................................................................... 21 Figure 4: Pinon, Juniper and Underground sections within the permitted area of the SJCM .................... 22 Figure 5 : SJCM overview of current and historical CCB disposal pits (Mines and Minerals Division,
New Mexico 2011) ..................................................................................................................................... 24 Figure 6: NRCS PRISM Map of United States. http://www.wcc.nrcs.usda.gov/images/prism_map.jpg ... 25 Figure 7 : Average annual precipitation at SJCM (Mines and Minerals Division, New Mexico 2011) ..... 26 Figure 8 : MMD Geology classification for SJCM (Mines and Minerals Division, New Mexico 2011) ...... 27 Figure 9 : Geologic formations near the San Juan Coal Mine (Ginn, Perkins, and O’Hayre 2009) ........... 28 Figure 10: Cross Section of Geology at the San Jan Coal Mine from Fruitland Formation to Lewis Shale
(Ginn, Perkins, and O’Hayre 2009) ......................................................................................................... 29 Figure 11 : CCB Disposal map of typical channel construction (Chee 2009) ................................................ 30 Figure 12 : Profile cross section of A-A’ shown in Figure 11 showing typical CCB disposal cover and
location in regards to the pit wall (Chee 2009) ....................................................................................... 31 Figure 13 : Profile cross section of B-B’ and C-C’ shown in Figure 11 showing typical CCB disposal cover
and location in regards to changes in channel location (Chee 2009) .................................................... 32 Figure 14 : MMD vegetation classification map for San Juan Coal Mine (Mines and Minerals Division,
New Mexico 2011) ..................................................................................................................................... 33 Figure 15: SJCM-SM04 site looking back at San Juan Power Generating Station ...................................... 34 Figure 16 : Changes in the TDS concentration in the No 8 Coal Seam wells of G-26 and G3 from 2006 to
2010 (Mines and Minerals Division, New Mexico 2011) ........................................................................ 35 Figure 17: SJCM Map of monitoring wells throughout SJCM (Mines and Minerals Division, New Mexico
2011) ........................................................................................................................................................... 37 Figure 18 : Historical water elevations measured in the alluvial well GL in the Shumway Arroyo from
1979 to 2007 (Norwest 2009) .................................................................................................................... 39 Figure 19 : Calculated potentiometic gradients between alluvial wells GL and GE in the Shumway
Arroyo based of historical data (Norwest 2009) ..................................................................................... 40 Figure 20 : The calculated potentiometic surface at No 8 Coal Seam monitoring well G3 from 1990 to
2009 (Norwest 2009) .................................................................................................................................. 41 Figure 21 : Zoomed view of Figure 5 showing pre-diversion of Westwater Arroyo(Mines and Minerals
Division, New Mexico 2011) ..................................................................................................................... 43 Figure 22:Geoprobe ® coring samples diagram .............................................................................................. 48 Figure 23: Complete SCJM-SM-04 sonic drilling samples ............................................................................. 49 Figure 24: Sonic drilling samples diagram ....................................................................................................... 51 Figure 25: Nine samples before shake test ASTM D3987-06 .......................................................................... 55 Figure 26: ASTM D3987-06 18-hour shake phase ........................................................................................... 56 Figure 27: Nine samples after 18-hour shake sxtraction ASTM D3987-06 ................................................... 57 Figure 28: UNM-EPS SEM Equipment. http://epswww.unm.edu/iom/ebeam/mikesem1.gif ...................... 58 Figure 29: UNM-EPS XRD Equipment. http://epswww.unm.edu/xrd/lab1.jpg ........................................... 59 Figure 30: Eight separate 2 inch ID and 10 inches tall columns ..................................................................... 61 Figure 31: Average distribution of constituents from acid-digested spoil materials .................................... 67 Figure 32: Average distribution of constituents from acid-digested fresh fly ash materials ....................... 67 Figure 33: Average distribution of constituents from acid-digested buried fly ash materials ..................... 68 Figure 34 : Average distribution of constituents from acid-digested fresh bottom ash materials ............... 68 Figure 35 : Average distribution of constituents from acid-digested buried bottom ash materials ............ 69 Figure 36 : Average distribution of constituents from acid-digested fresh FGDS materials ....................... 69 Figure 37 : Average distribution of DI water leachates from fresh CCBs (mass basis) ............................... 70 Figure 38 : Average distribution of DI water leachates from buried CCBs (mass basis) ............................ 71 Figure 39 : Average distribution of DI water leachates from spoil (mass basis) ........................................... 71 Figure 40 : Average extract Sulfate concentration in CCBs and Spoil .......................................................... 73
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Figure 41 : Average total Vanadium concentration in CCBs and Spoil ........................................................ 74 Figure 42: Average extract Nitrite concentration in CCBs and Spoil ............................................................ 74 Figure 43: Average extract Calcium concentrations in CCBs and Spoil ....................................................... 75 Figure 44 : Average total of Barium in spoil, fresh ash and buried ash with significant buried ash
concentrations ........................................................................................................................................... 75 Figure 45 Average total of Lead in spoil, fresh ash and buried ash with significant buried ash
concentrations ........................................................................................................................................... 76 Figure 46 : Average totals iron concentration in CCBs and Spoil ................................................................. 76 Figure 47 : Average total concentration in Arsenic with elevated concentrations in buried CCBs ............ 77 Figure 48 : Average totals Sr concentration in CCBs and Spoil .................................................................... 79 Figure 49 : Average total Magnesium concentration in CCBs and Spoil ...................................................... 80 Figure 50 : Average Extract Nitrate concentration in CCBs and Spoil ......................................................... 80 Figure 51: Average Arsenic concentrations in variety of different aged CCBs and spoil compared to
drinking water standard ........................................................................................................................... 82 Figure 52 : Concentration of Nickel in buried CCB level with sample depth ............................................... 83 Figure 53 : Concentration of Barium and Boron in buried CCB increased with sample depth.................. 84 Figure 54 : Concentration of Iron in buried CCB increased with sample depth .......................................... 85 Figure 55 : Concentration of Strontium in buried CCB decreased with sample depth ............................... 86 Figure 56 : Concentration of Magnesium in buried CCB decreased with sample depth ............................. 87 Figure 57 : Normalized concentrations of CCBs plotted over depth of sample ........................................... 88 Figure 58 : Elements showing concentration increases with depth (normalized concentration) ................. 89 Figure 59 : Elements showing concentration with depth (normalized concentration) ................................. 90 Figure 60 : Elements showing concentration level with depth (normalized concentration) ........................ 90 Figure 61 : Elements showing concentration with depth for anions (normalized concentration) ............... 91 Figure 62 : Changes in Arsenic concentration with depth (normalized concentration) ............................... 92 Figure 63 : Column test concentration changes over time for Na with largest initial concentration .......... 95 Figure 64 : Column test concentration changes over time for Ni with smallest initial concentration ........ 96 Figure 65 : Normalized concentrations of constituents in DI water column leachate of fresh fly ash ........ 97 Figure 66 : Normalized concentrations of constituents in DI water column leachate of fresh fly ash with
Ba, and Sr removed ................................................................................................................................... 98 Figure 67: Normalized concentrations of constituents in DI water column leachate of fresh bottom ash . 99 Figure 68: Normalized concentrations of constituents in DI water column leachate of old buried fly ash
.................................................................................................................................................................. 100 Figure 69: Normalized concentrations of constituents in DI water column leachate of old buried bottom
ash ............................................................................................................................................................. 101 Figure 70: Normalized concentrations of constituents in DI water column leachate of young buried fly
ash ............................................................................................................................................................. 102 Figure 71: Normalized concentrations of constituents in DI water column leachate of spoil .................... 103 Figure 72: Normalized concentrations of constituents in No 8 Coal Seam Water column leachate of fresh
fly ash ....................................................................................................................................................... 104 Figure 73: Normalized concentrations of constituents in No 8 Coal Seam Water column leachate of fresh
fly ash with Al, Li and V not plotted ..................................................................................................... 105 Figure 74: Normalized concentrations of constituents in No 8 Coal Seam Water column leachate of old
buried fly ash ........................................................................................................................................... 106 Figure 75: Normalized concentrations of constituents in No 8 Coal Seam Water column leachate of old
buried fly ash with Ba, Al and Si removed ........................................................................................... 107 Figure 76 : SEM: SE fly ash sample, silicate spheres. Original magnification=400x; Scale
Bar=100μm(Spilde 2011) ........................................................................................................................ 108 Figure 77 : SEM: BSE image fly ash. silicate spheres. Original magnification= 1500x; Scale Bar=20μm
(Spilde 2011) ............................................................................................................................................ 109 Figure 78 : SEM: BSE bottom ash, silica glass spheres and angular material, darker contains
significantly more carbon then silicate sphere. Original magnification =180x; Scale bar =200μm (Spilde 2011) ............................................................................................................................................ 110
Figure 79 : SEM: BSE bottom ash. Glass sphere and silica glass blobs fused to aggregate. Original magnification=1000x; Scale bar=50μm (Spilde 2011) .......................................................................... 111
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Figure 80 : SEM: BSE FGDS Close up of crystal aggregate. Original magnification=430x; Scale bar=100μm (Spilde 2011) ....................................................................................................................... 112
Figure 81 : SEM: BSE Old bottom ash. Broken spheres and growth together. Original magnification=500x;Scale bar=100μm (Spilde 2011) ........................................................................... 113
Figure 82 : SEM: SE old buried fly ash. Fine mesh material on surface and crystal growth. Original magnification=3000x; Scale bar=10μm (Spilde 2011) .......................................................................... 114
Figure 83 : XRD Fresh fly ash diffraction pattern match (Connolly 2011) ................................................. 115 Figure 84 : XRD Fresh bottom ash diffraction pattern match (Connolly 2011) ......................................... 116 Figure 85 : XRD Fresh FGDS diffraction pattern match with gypsum (Connolly 2011) .......................... 117 Figure 86 : XRD old buried fly ash diffraction pattern match (Connolly 2011) ......................................... 118 Figure 87 : XRD old buried bottom diffraction pattern match (Connolly 2011) ........................................ 119 Figure 88 : XRD Spoil diffraction pattern match for clays .......................................................................... 120 Figure 89 : XRD fly ash sample comparison showing calcite peak within buried samples only. .............. 121 Figure 90 : XRD bottom ash diffraction pattern comparison and identification of fly ash sample rather
then bottom ash. (Connolly 2011) .......................................................................................................... 122 Figure 91 : Summary of average total contaminants in CCBs and Spoil for all elements analyzed ......... 129 Figure 92 : Concentration of Al with depth ................................................................................................... 139 Figure 93 : Concentration of V with depth .................................................................................................... 139 Figure 94: Concentration of Li with depth ..................................................................................................... 140 Figure 95: Concentration of K with depth ..................................................................................................... 140 Figure 96: Concentration of Ca with depth.................................................................................................... 141 Figure 97: Concentration of Si with depth ..................................................................................................... 141 Figure 98: Concentration of Cr with depth .................................................................................................... 142 Figure 99: Concentration of anions with depth ............................................................................................. 142 Figure 100 : Concentration of Ag for each column ....................................................................................... 144 Figure 101: Concentration of Al for each column ......................................................................................... 144 Figure 102: Concentration of B for each column ........................................................................................... 145 Figure 103: Concentration of Ba for each column ......................................................................................... 145 Figure 104: Concentration of Ca for each column ........................................................................................ 146 Figure 105: Concentration of K for each column .......................................................................................... 146 Figure 106: Concentration of Cr for each column ......................................................................................... 147 Figure 107: Concentration of Li for each column ......................................................................................... 147 Figure 108: Concentration of Mg for each column ....................................................................................... 148 Figure 109: Concentration of Cu for each column ........................................................................................ 148 Figure 110: Concentration of Mo for each column ....................................................................................... 149 Figure 111: Concentration of Si for each column .......................................................................................... 149 Figure 112: Concentration of Sr for each column ......................................................................................... 150 Figure 113: Concentration of V for each column .......................................................................................... 150 Figure 114: Concentration of Zn for each column ........................................................................................ 151 Figure 115: Concentration of Be, Cd, Co & Pb for each column ................................................................. 151
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LIST OF TABLES
Table 1 : Dissolved trace element concentrations in groundwater, leachate, and leachates attenuated with
No 8 Coal Seam water (Luther, Musslewhite, and Brown 2009) .......................................................... 11 Table 2 : Mean trace element concentrations in Bottom Ash, Fly Ash and Overburden at the SJCM
(Luther, Musslewhite, and Brown 2009) ................................................................................................. 13 Table 3: New Mexico drinking water standards compared to range of water quality (Drinking Water
Bureau 2011),(United States Environmental Protection Agency 2011) ................................................ 16 Table 4 : Specific locations for the sample groups used for each test procedure .......................................... 53 Table 5 :Constituents Limit of Detection (LOD). ............................................................................................ 54 Table 6 : Mineral phases present in each sample classification ...................................................................... 60 Table 7 : No 8 Coal Seam Water Quality for column test and historical data (Mines and Minerals
Division, New Mexico 2011) ..................................................................................................................... 63 Table 8: Historical comparisons of CCB acid and leach tests for specific parameters ................................ 65 Table 9 : Total Chemical composition results from acid digestion ............................................................... 66 Table 10: DI water extraction results for Spoil, Fresh and Buried CCBs ..................................................... 71 Table 11: Two Tailed t-Test for Barium between Spoil vs Ash & Fresh FA vs Old FA ............................... 72 Table 12 : Lab pH, electric conductivity and total dissolved solids concentrations for CCBs and spoil .... 78 Table 13 : Water Quality Results for No 8 Coal Seam Water used for column leach and historical data
compared to typical water quality data .................................................................................................. 94 Table 14 : A comparison of contaminate concentration in CCB column leachate and groundwater from
monitoring well GL ................................................................................................................................. 124 Table 15 : Total acid digest results of each constituents’ concentration for each sample .......................... 130 Table 16: Table 15 Contiuned… Total acid digest results of each constituents’ concentration for each
sample ...................................................................................................................................................... 131 Table 17 : DI Extraction results for spoil, fresh CCBs and buried CCBs ................................................... 131 Table 18 : Two Tail T-Test with Unequal Variance results for each analyte .............................................. 132 Table 19 : Sample table of column leach test results for fresh FA ............................................................... 143
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1. Introduction
1.1. Coal mining in the United States
An estimated 21% of energy consumed worldwide is used by the United States, making it the
largest single consumer of energy in the world. Though the rate of increase in the United
States is not high compared to more rapidly developing nations, an increase of 5.3% in
consumption was observed from 2009 to 2010. In the year 2010 an estimated 85% of U.S.
energy was supplied by fossil fuels such as gas (28%), oil (37%) and coal (20%) (British
Petroleum 2011).
According to the British Petroleum (BP) Statistical Review of 2011, the U.S. mined 552.2
million tonnes oil equivalent of coal in 2010 and consumed 524.6 million tonnes oil
equivalent. An oil equivalent tonne is the energy contained in 1,000 kg of oil. The specific
amount of energy released by burning one tonne of crude oil is approximately 42 GJ
(gigajules) One tonne oil equivalent is a measurement on how much energy in GJ is released
from burning coal in relation to burning oil. One tonne of coal equivalent is equal to 29.3 GJ
or 27.8 MBtu (British Petroleum 2011).
Coal in New Mexico was formed during the Carboniferous Period roughly 290 to 360 million
years ago. Solar energy was stored in livings plants and released when said plants died,
however, if the decaying process was interrupted, energy was locked in that matter. These
swamps and peat bogs were then buried through tectonic movements and subjected to high
temperatures and pressures. These factors caused physical and chemical changes in the
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decaying vegetation, transforming it into peat and subsequently into coal (World Coal
Association 2011).
Coal is mined by either underground or surface mining methods. Surface mining is used
when coal seams are located near the surface as it is expensive to excavate large volumes of
soil to reach the seams. Surface mining of coal started around the mid-sixteenth century and
continues today around the world (Montrie 2004).
Increased utilization of coal for electric power generation produces increased masses of coal
generated waste. One of the largest volume contributors of energy-related wastes are Coal
Combustion By-Products (CCBs) (Yeboah and Burns 2011). CCB is a term that refers to the
three main components of the waste generated during the coal burning process: fly ash,
bottom ash, and flue gas desulfurization sludge (FGDS) (Luther, Musslewhite, and Brown
2009). CCBs can be of environmental concern as they contain many of the heavy metals
which were present in the initial coal product. Large volumes of CCB disposal result in the
potential of higher leachate concentrations due to the concentrated volume of waste then
from native soil.
1.1.1. Western coal
Coal use in the arid southwestern U.S. likely began centuries ago when early Spanish settlers
were documented to have used small amounts of coal. Around the year 1861 a significant
use for commercial coal mining in New Mexico was documented when the U.S. Army
opened the Carthage field and mined coal for use at Fort Craig, New Mexico. The annual
coal production in New Mexico was estimated to be one million tons by 1889, but it was not
3
until 1918 that coal production peaked at an estimated use of four million tons, largely
attributed to demand during World War 1. Railroads and factories were large consumers of
coal until trains converted to diesel fuel and factories converted to natural gas, both of which
contributed to a slump in coal production (New Mexico Mining and Minerals Division 2009).
In 1958 an adoption of inexpensive strip mining processes made coal mining more
economical which increased the demand for coal powered electrical plants (New Mexico
Mining and Minerals Division 2009). In New Mexico there is an estimated 25,000 square
miles of underground coal, or an area equal to 20.6% of the total surface area of the state.
The majority of coal being mined in New Mexico is located in the San Juan Basin and the
Grants area, located in northwest and north-central New Mexico, respectively (New Mexico
Mining and Minerals Division 2009).
According to the Mines and Minerals Division of New Mexico (MMD) the age of coal in
New Mexico ranges from the late Cretaceous Age to the Paleocene Age. The majority of the
coal in the San Juan Basin is located in the Fruitland Formation. Coal in New Mexico’s San
Juan Basin is classified as subbituminous A to high volatile bituminous C with an estimated
coal reserve base of 4.65 billion tons, or roughly 1 percent of the national reserves (New
Mexico Mining and Minerals Division 2009).
Bituminous coal is considered a low rank coal which means it contains higher impurities and
higher water content when compared to high rank coal. These impurities result in lower
energy output when the coal is burned (World Coal Association 2011). The burning and
disposal of low ranking coal can be of concern due to their increased concentrations of
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impurities. Impurities in parent coal remain in CCB waste and have a greater potential to
have negative environmental impacts due to higher concentrations when compared to high
rank coal.
1.2. CCB disposal
In the year 2009 an estimated 134,699,700 short tons of CCBs were produced (World Coal
Association 2011). CCBs are typically disposed in surface impoundments, commercial lined
landfills or unlined pits (Yeboah and Burns 2011),(ACAA 2009). In the process of disposing
CCBs in impoundments, water is added to keep the waste in a saturated state so that it can be
gravity fed along trenches and pipes (Yeboah and Burns 2011). In commercial landfills,
CCBs can be left in their original dried state and moistened to limit dust during transport and
be placed in lined pits. These lined pits are designed to prevent environmental degradation
due to leaching. However, not all disposal pits are lined and thus have a higher potential for
leaching heavy metals. To detect the presence of contaminants which could potentially leach
from disposal pits, mining operations will typically place monitoring wells around disposal
sites (Yeboah and Burns 2011).
CCBs in the Western United States are typically disposed in landfills or pits because space is
generally not a concern. Old surface mining pits provide an economical disposal site when
available. Western CCBs are consequently stored in a moist state which inhibits easy
movement of large volumes of CCBs, similar to the berm spill of CCBs into rivers that
happened in Kingston, TN discussed below (EPA).
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1.3. Disposal spill
Improperly disposed CCBs can pose a risk for environmental contamination. This risk was
realized with a catastrophic failure in the Tennessee Valley Authority (TVA) Kingston pit in
Tennessee in December 2008. A breach in the retention pit led to 3.7 million cubic meters of
saturated fly and bottom ash escaping into the Emory River and surrounding area (Ruhl et al.
2010). The site and surrounding area are still undergoing cleaning and monitoring as of 2011
(EPA). Attention from the TVA Kingston spill lead to increased scrutiny of CCBs disposal
practices from environmental groups like the Sierra Club. In a study done in 2009 looking at
the environmental fate of spilled CCBs in the Emory River and its tributaries, Rhul et al.
found that the leachable coal ash contaminants (specifically arsenic (As), selenium (Se),
boron (B), strontium(Sr) and barium (Ba)) are below the EPA drinking water thresholds.
However, Ruhl et al., documented that there are levels contaminants above EPA thresholds in
areas where there is restricted water exchange in the sediment of the river (Ruhl et al. 2010).
1.4. Problem statement
Since the TVA Kingston spill public awareness of CCB disposal has increased. In response
to this increased scrutiny New Mexico Mines and Minerals Division (MMD) in 2010
provided funding to the University of New Mexico (UNM) to conduct studies on CCBs
disposal at the San Juan Mine (SJCM). UNM was asked to address concerns regarding the
potential for leachate transport in the vadose zone.
Other entities were hired to determine if and where any subsurface alluvial flow is occurring
in the SJCM. The concern is where water is coming from and if it is reaching buried CCBs
within SJCM (Norwest 2009). UNM was tasked to determine and evaluate the potential of
6
leachates from the unlined disposal pits and identify possible trace elements. A companion
study to this research is to determine the physical behavior of CCBs and create a transport
model of contaminants through the vadose zone.
This study focused on the SJCM located in the arid climate of New Mexico and the adjacent
San Juan Power Generating Station which stores generated CCBs in a now reclaimed part of
the old, unlined strip mine. The research focused on determining the potential constituents
within CCBs and evaluating the resulting leachate. This was accomplished by comparing the
differences in mineralogical and geochemical make up of freshly generated ash compared to
buried ash from the reclaimed area to determine if the ash was aging. To determine if
constituents were being transported to underlying groundwater chemical markers in the
leachate were identified which would be attributed to the disposed CCBs.
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2. Background
Due to the burning of coal in furnaces at high temperatures, most organic matter is volatized
and the resulting ash is composed of mainly aluminosilicates associated with minerals and
soil present in the coal. Contaminants such as heavy metals (As, B, nickel (Ni), copper (Cu),
Se, molybdenum (Mo), cadmium (Cd), zinc (Zn) and lead (Pb)) that were present in the coal
sometimes remain in ash after combustion. During transport and disposal the CCBs can be
subjected to leaching by rainwater or contact with other substances such as chlorides, sulfates
and organic matter forming complexes with heavy metals (Manskinen, Poykio, and
Nurmesniemi 2011). Figure 1 below demonstrates a common schematic of the coal burning
process which generates electricity (World Coal Association 2011).
Figure 1: An example of the coal powered electricity generating plant http://www.worldcoal.org/media/jpg/585/174139cgart.jpg
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2.1. Coal Combustion By-Products
As previously stated, CCBs are a combination of three types of waste generated during the
coal burning process: fly ash, bottom ash, and flue gas desulfurization sludge (FGDS).
Overall properties of CCBs are dependent mostly on the properties of the parent coal in
addition to the condition during incineration and efficiency of the recapture equipment at the
specific power plant. However, each sub group has unique characteristics which the
following discusses briefly (El-Mogazi, Lisk, and Weinstein 1988).
2.1.1. Fly Ash
Fly ash is a very fine gray powder that is captured from the exhaust gases of furnaces by
electrostatic precipitators and scrubbers (ACAA 2011). Physical features of fly ash include
spherical particles constructed in an amorphous matrix (El-Mogazi, Lisk, and Weinstein
1988). The spherical shape is a result of molten droplets of fused coal material being carried
upward and cooled in a stream of flue gasses (Dudas and Warren 1987). The physical size of
fly ash is typically that of silt, 2 μm to 50 μm (Chang et al. 1979). Typical surface areas
within that size distribution vary from 1.27 to 0.45 m2g-1 with large, porous and carbonaceous
features on the surface (El-Mogazi, Lisk, and Weinstein 1988), (Fisher, Chang, and Brummer
1976).
Fly ash generated from the coal burning process is similar to volcanic ash in that both are
primarily composed of aluminosilicate glass, and during weathering form clay minerals
(Zevenbergen et al. 1999). Major elements within fly ash are, in decreasing abundance silica
(Si), aluminum (Al), oxygen (O), iron (Fe), calcium (Ca), carbon (C), magnesium (Mg),
potassium (K), Na, sulfur (S), titanium (Ti) and manganese (Mn) (Zevenbergen et al. 1999;
9
Dzombak and Morel 1990; El-Mogazi, Lisk, and Weinstein 1988; Dudas and Warren 1987;
Bhangare et al. 2011; Fisher, Chang, and Brummer 1976). Fly has pozzolan properties due
to the high alumina and silica composition which means the fly ash has cementitious
properties when combined with calcium hydroxide (You, UM, and et al. 2009).
The core of fly ash is made up of aluminosilicates which are stable while many of the trace
elements (As, Se, Mo, Cd and Zn) are located in the surface layers which make them more
available for leaching. The hypothesis for why these trace elements are located on the
surface layers is this is a result from particular elements volatized during combustion and
then condensing onto the surface of the ash as the flue gas cools in the stack scrubbers (El-
Mogazi, Lisk, and Weinstein 1988).
Analysis of different types of coal sampled across the United States show western Cretaceous
coal typically has higher pH and increased concentrations of boron, sodium and calcium
when compared with eastern U.S. coal ash. Higher Ca concentrations can contribute to
higher alkalinity within CCBs due to the increased carbonate concentrations (Dudas and
Warren 1987);(Shannon and Fine 1974; James et al. 1982). The solubility characteristics of
the various chemical species within the fly ash are directly effect by the pH (El-Mogazi,
Lisk, and Weinstein 1988), (D. J. Hassett, Hassett, and Brobjorg 1988). To determine a
specific ash’s potential environmental effects leach test must be conducted to identify the
trace constituents and the fly ash’s affect on pH.
10
A leach test consists of adding a specific ratio of water to soil samples for a specific amount
of time. A batch leach tests is a different leach tests that uses a high water ratio to soil ratio
20:1, which are meant to characterize the types of constituents that have the potential to leach
in the presence of water. Other tests with much smaller fractions of water to soil ratios are
used to characterize concentrations of leachate similar to field conditions like column tests
(Bin-Shafique et al. 2006),(Ram et al. 2007).
Experiments demonstrate that different constituents and concentrations leach with different
leach tests. One study found that the range of leaching metals concentration changes in
descending order for each of the following tests: buffer columns, aqueous columns, aqueous
shake, and buffer shake tests (Ram et al. 2007). Recent column leach studies found that
decreasing the pH (ph<4) resulted in higher metal ions (As, B, Cd, Cr, Zn, Pb, Hg and Se)
concentrations in the leachate. This is most likely due to the instability of the mineral phase
of the fly ash as these lower pH ranges (Baba et al. 2008), (Zhao et al. 2006). Previous batch
leach studies results (Table 1) conducted by the SJCM found high concentration of Ba and
fluoride (F) (Luther, Musslewhite, and Brown 2009).
11
Table 1 : Dissolved trace element concentrations in groundwater, leachate, and leachates attenuated with No 8 Coal Seam water (Luther, Musslewhite, and Brown 2009)
Groundwater CCB LeachateParameter mg/L mg/LAluminum <0.05 2.2Arsenic <0.003 <0.003Barium 0.21 0.28Boron <0.009 0.44
Cadmium <0.002 <0.002Chromium <0.001 <0.001
Cobalt <0.006 <0.006Copper <0.001 <0.001Cyanide 0.53 <0.02Fluoride 2.1 2.4
Iron 0.37 2Lead 0.02 0.01
Manganese 0.18 0.16Mercury <0.002 <0.002Nickel 0.004 0.006
Selenium <0.003 <0.003Silver <0.002 0.006Zinc 0.87 0.01
How and what leaches from the fly ash also has to do with the mineralogy of the fly ash. The
dominant morphology of fly ash is amorphous glass matrices identified as glass, mullite-
quartz and magnetic spinel (i.e. magnetite, hematite and ferrite). The magnetic matrix has a
high reactivity and a high potential for carrying and releasing toxic elements such as arsenic,
boron and selenium (El-Mogazi, Lisk, and Weinstein 1988), (Ward and French 2006). A
unique mineralogical aspect of fly ash that is not found in bottom ash is the presence of
hematite (Fe2O3) (Sultana, Das, and et al. 2011; Ward and French 2006; Manskinen, Poykio,
and Nurmesniemi 2011).
12
2.1.2. Bottom Ash
Bottom ash is grey to black angular particles that are porous. It forms in the coal furnaces on
the wall or floor and is too large to be carried up the flue. It is collected through open grates
into ash hoppers at the bottom of the furnaces and later combined with fly ash and FGDS for
disposal (ACAA 2011).
The physical appearance of bottom ash is often angular which consists of a mix of large
particles and fused spheres seen in the fly ash. The size distribution of bottom ash is from
the fine sand to fine gravel (62.5 μm - 75 μm), larger then that found in fly ash (You, UM,
and et al. 2009).
Bottom ash is typically composed of the similar elements ()found in fly ash of Si, Al, Fe, Ca,
C, Mg, K, Na, Si, Zn, and Mn (Table 2) (El-Mogazi, Lisk, and Weinstein 1988; You, UM,
and et al. 2009). Bottom ash typically has a lower Total Organic Carbon (TOC) content and
electrical conductivity then fly ash (Manskinen, Poykio, and Nurmesniemi 2011).
13
Table 2 : Mean trace element concentrations in Bottom Ash, Fly Ash and Overburden at the SJCM (Luther, Musslewhite, and Brown 2009)
Mean Mean MeanBA FA Spoil
Parameter mg/Kg mg/Kg mg/KgAluminum 7079 6062 7428Arsenic 2.76 10.8 2.85Barium 505 758 141Boron 51.1 200 N
Cadmium 0.42 0.45 3.01Chromium 2.68 5.83 5.66
Copper 18.6 12.7 33.4Iron 4648 3471 NALead 8.46 5.52 10.2
Manganese 59.4 80.5 NAMolybdenum 3.44 5.82 NA
Nickel 2.15 1.79 9.1Selenium 0.55 0.58 0.39
Silver <1.0 <1.0 <1.0Zinc 37.7 25.8 73.9
A
Similar to fly ash the dominant morphology of bottom ash is amorphous glass matrices are
identified as glass, mullite-quartz and magnetic spinel (i.e. magnetite, dolomite hematite and
ferrite) (Sultana, Das, and et al. 2011) (Ward and French 2006). Again the magnetic matrix
is high reactivity and has a high potential for carrying and releasing toxic elements within the
bottom ash (El-Mogazi, Lisk, and Weinstein 1988). Dolomite (CaMg(CO3)2) is found only
in bottom ash from a mineralogical stand point (Sultana, Das, and et al. 2011; You, UM, and
et al. 2009).
2.1.3. Flue Gas Desulfurization Sludge
Flue Gas Desulfurization Sludge (FGDS) is the material produced by emissions control
systems (scrubbers) that remove sulfur dioxide (SO2), a key component to acid rain, from
power plant flue gas streams (ACAA 2011). The scrubbers consist of a tower where the flue
gas containing sulfur dioxide is pumped into the lower part. A slurry of water and lime
14
(CaCO3) is then sprayed in a mist at the top of the tower down on the flue gas as it rises. The
results is relatively clean air exits through the top of the tower and a collection of the lime
slurry now composed of calcium sulfite (CaSO3) collects at the bottom of the tower. The
calcium sulfite is often left to further oxides to produce marketable gypsum (CaSO4 2H2O)
as a final product. The end composition of the FGD is dependant on the power plant’s
design, type of equipment used for incineration, composition of the parent coal, composition
of the limestone, forced oxidation and end treatment (i.e length of dewatering) (Baligar et al.
2011). The composition of the produced gypsum is the same chemical makeup as mined
gypsum. A study conducted on 12 different FGDS showed the following results of the
primarily composition of Ca, S, Al, Fe, and Si, an average pH around 9 and electrical
conductivity around 2.3 μS/cm (Baligar et al. 2011).
2.2. Reuse of CCB
In attempts to limit the volume of CCBs buried in landfills alternative means of reusing
CCBs are being developed. Reuse of CCBs has focused on exploiting the specific physical
and chemical properties of the ash.
For instance, fly ash is often used in concrete due to its pozzolanic characteristics discussed
earlier and its ability to resist corrosion (You, UM, and et al. 2009). These characteristics
lead to a longer life span of concrete. Other uses for fly ash include a supplement in feed
stock and in embankments, soil modification/stabilization and road bases. Bottom ash can be
reused as aggregate due to its angular and well-graded size in embankments, road bases and
concrete products. FGDS is a high quality gypsum that is reused in wallboard, cement and
15
geotechnical applications. The agricultural industry also uses gypsum to treat soils and
improve crop performance (ACAA 2011).
2.3. Potential environmental impacts
There are two problems related to disposal of CCBs: 1) physical characteristics that may lead
to catastrophic failure of a CCB disposal facility and 2) chemical characteristics that may
threats to human health and the environment associated with CCB leachates. As previously
stated, the main concern of CCBs as they relate to common disposal practices is that they
retain the heavy, non volatile contaminants of their parent coal. Such components include
silver (Ag), arsenic (As), barium (Ba), cadmium (Cd), chromium (Cr), copper (Cu), iorn (Fe),
mercury (Hg), manganese (Mn), lead (Pb), selenium (Se), strontium (Sr), zinc (Zn), fluorine
(F) and chlorine (Cl). These potential contaminants have demonstrated adverse affects in
exposed populations when released into the environment (Ruhl et al. 2010),(White et al.
1994). The heavy metals of concern in western CCBs are generally arsenic (As), boron (B),
lead (Pb), selenium (Se), cadmium (Cd) and mercury (Hg). These metals are considered
carcinogenic, cause varies health problems, and effect fetal development when consumed
(El-Mogazi, Lisk, and Weinstein 1988). Concentrations in the waters of the U.S. are
regulated by the Environmental Protection Agency (EPA) while the regulation on the
disposal of CCBs is left to individual state regulatory agencies. Typically a batch leach and a
total composition tests are required and in New Mexico both tests are conducted quarterly
(Mines and Minerals Division, New Mexico 2011; Luther, Musslewhite, and Brown 2009).
Table 3 compares the State regulated pollutants for agriculture and domestic drinking water
use to typical ranges for what is considered good and poor water quality of regulated dinking
water.
16
Table 3: New Mexico drinking water standards compared to range of water quality
(Drinking Water Bureau 2011),(United States Environmental Protection Agency 2011)
Parameter Domestic Irrig. Low HighpH 4.85 12.61
Spec cond (uS/cm)TDS 1000 30 69800TOC 0.001 415
K 0PO4 0.001 34.8Ca 4600Mg 0.1 2270Na 0.1 27800H2S 0
Phenols 0.005 0.001 7.8HCO3 0.001 2970CO3 75Cl 250 16700F 1.6 0.1
SO4 600 0.01 52000NO3 10 0.5 180Al 5 0.5 31As 0.1 0.05 2.41B 0.75 0.005 10Ba 1 0.001 51.6Cd 0.01 5E-05 0.5Cr 0.05 0.001 0.5Cu 1 0.0001 8.7Co 0.05 0.0003 0.3Fe 1 0.001 72.3Pb 0.05 0.0001 2.82Mn 0.2 0.0005 12.4Hg 0.002 0.0001 0.06Mo 0.001 0.07Ni 0.02 0.001 0.2Se 0.05 0.001 15.4Ag 0.05 5E-05 0.5V 0U 5 1E-05Zn 10 0.001 5.98
Ra-226 0 579
NM Groundwater Standards
Water Quality Data
.001 286
.2 386
54
.0001 2150
17
2.3.1. Environmental persistence
Trace contaminants in CCBs are commonly alkali metals, alkaline earth metals, transition
metals and metalloids. These compounds are generally charged with very high melting
points and are reactive with water. These characteristics allow for the analytes to either
remain in a solid form during the combustion of the coal or to vaporize during combustion
and then condense onto the surfaces layers of the fly ash as the flue gas cools. Either way
results in metals being associated with the CCBs and have the potential to leach when water
is introduced to the ash. Once analytes are dissolved in water they can be transported to
living creatures where they can cause varies health problems (Ruhl et al. 2010). For example
a study on selenium toxicity in aquatic systems found that in matrices contaminated with
selenium were slow to recover (Hamilton 2004).
2.4. Regulatory framework
The energy industry is regulated at both the Federal and State level. The coal industry must
meet requirements to obtain permits to mine while the coal powered plants must meet the
Environmental Protection Agency’s regulations on emissions.
2.4.1. Federal regulations
The Surface Mining Control and Reclamation Act of 1977 (SMCRA) created the Office of
Surface Mining Reclamation and Enforcement (OSM) in the Department of the Interior.
SMCRA provides authority to OSM to oversee the implementation of and provide Federal
funding for State regulatory programs that have been approved by the Secretary of the
Interior as meeting the minimum standards specified by SMCRA (New Mexico Mining and
Minerals Division 2009). SMCRA requires that areas mined must be reclaimed and regarded
18
close to the original contour with minimal disturbance to the hydrologic balance at the mine
site and associated off-site areas (U.S. Congress 1977).
2.4.2. State regulations
OSM regulates the coal areas that are mostly under Native American owned land while
MMD regulates the mines on the remainder of the state (New Mexico Mining and Minerals
Division 2009). The New Mexico MMD Program regulates eight (8) inspectable units:
Chevron Mining Inc., Ancho York Canyon Surface, York Canyon Underground, and
McKinley mines; BHP Billiton’s San Juan Coal Company La Plata mine and San Juan
underground; Peabody Natural Resources’ Lee Ranch and El Segundo surface mines. Only
the San Juan underground mine, Lee Ranch and El Segundo are currently producing coal.
The six remaining mines under MMD jurisdiction are reclaimed and just awaiting final bond
release (New Mexico Mining and Minerals Division 2009).
Coal production in New Mexico has varied over the last several years with an all time peak
in 2001. Production has declined 1.971 million short tons from 2006-2008 with the closure
of the McKinley Mine (New Mexico Mining and Minerals Division 2009).
MMD has a Coal Mine Reclamation Program that sets guidelines and benchmarks to
reclaimed areas disturbed by coal mining. The criteria to be classified “reclaimed” are strict
to ensure minimal after effects due to the mining operations. Contours must be reconstructed
to fit the original elevations while surface water must be drained off the area in a timely
manor to limit infiltration. For example, San Juan Coal Compnay’s La Plata mine took six
years of geomorphic design and construction to fully reclaim. Once a mine has met all final
19
reclamation criteria it can then appeal for bond release. Geomorphic reclamation projects are
ongoing as of 2011 at the McKinley and San Juan coal mines (New Mexico Mining and
Minerals Division 2009).
2.5. San Juan Coal Mine site description
The San Juan Coal Mine (SJCM) is located near Farmington, New Mexico in the northwest
part of the state. Figure 1 shows the general location of the SJCM in regards to the United
States. New Mexico is the state highlighted in teal and the location of the mine within the
state is boxed in yellow. The SJCM began operation in 1972 and has coal reserves on site
estimated to last another 25 years.
20
Figure 2 : General location of San Juan Coal Mine seen in yellow
21
The yellow box is an approximate of the SJCM location and the exact boundary location s of
the mine is shown in Figure 3 with the boundaries shown in red.
Figure 3 : General location of San Juan Coal Mine within the state of New Mexico (Mines and Minerals Division, New Mexico 2011)
22
The SJCM permitted area is seen in as the red hashed area in Figure 3 and is the area where
the MMD has permitted for coal mining purposes. The permitted area is broken up into three
general sections within this paper to refer to different general locations. These sections can
be seen in Figure 4 with each color designating a different general area. The dotted red and
blue line show the boundary of the worked area and the permitted area respectively. The
Pinon pit is the area shown in light blue and is located in the northwest section of the mine.
The Pinon pit has several ponds and topsoil stockpiles within the area. The Juniper pit area is
seen in pink and is located in the southwestern part of the SJCM. The Juniper pit has the
Shumway Diversion running along the western side as well as the reclaimed area that was
focused upon within this research. The underground mining area is highlighted in green and
is where active underground mining and support structures are in place.
Figure 4: Pinon, Juniper and Underground sections within the permitted area of the SJCM The brown area is where several sections overlap and near the active CCB dumping site.
23
An aerial photograph is presented in Figure 5. It shows in purple show the backfill area
where active CCB disposal is taking place in the Pinon area in the northwest as well as
historical CCB disposal pits the Juniper pit area (Mines and Minerals Division, New Mexico
2011).
24
Figure 5 : SJCM overview of current and historical CCB disposal pits (Mines and Minerals Division, New Mexico 2011)
25
Dates of when disposal pits were closed can be linked to the age of the ash at the top of the
pit, however, the date cannot be correlated to anything much below the first few inches. This
is because the SCJM had several pits open at any given point in time and where the ash on
any given day was disposed of had to do with several factors such as diesel prices, which
haul roads were being used, etc.
The SJCM receives a mean annual precipitation of 9 inches, as seen in Figure 6 and Figure 7
with the SJCM location at the black arrow and red hash area respectively, with most of the
precipitation during the monsoon months from July to October (NRCS and University of
Oregon PRISM 2000).
Figure 6: NRCS PRISM Map of United States.
http://www.wcc.nrcs.usda.gov/images/prism_map.jpg
26
Figure 7 : Average annual precipitation at SJCM (Mines and Minerals Division, New Mexico 2011)
Climate is defined by a NOAA (National Oceanic and Atmospheric Administration) as the
ratio between the average annual precipitation over the annual pan evaporation. Farmington,
NM is the nearest pan evaporation site and from 1978 to 2005 have an average of 66.81
inches (Anon.). The climate ratio for Farmington, NM is then 0.13 in/in which according to
NOAA is classified as an arid climate (Anon.).
2.5.1. SJCM geology and pathology
The SJCM is geographically located on the western edge of the San Juan Structural Basin
with the geologic strata slanted towards the east. The classification of the MMD for the
SJCM can be seen in Figure 8 (Mines and Minerals Division, New Mexico 2011). The
geologic formations consist cretaceous period Pictured Cliffs Sandstone, Fruitland
27
Formation, Kirtland Formation and unconsolidated alluvial deposits (Mines and Minerals
Division, New Mexico 2011).
Figure 8 : MMD Geology classification for SJCM (Mines and Minerals Division, New Mexico 2011) A sandstone classification of the cretaceous geology of the area can be seen in Figure 9 with
the mine centered over Kirtland shale.
28
Figure 9 : Geologic formations near the San Juan Coal Mine (Ginn, Perkins, and O’Hayre 2009)
29
A cross section of the typical geology throughout the permitted area can be seen in Figure 10
with Fruitland Formation nearest the surface, which contains the coal layers that are
overlying Pictured Cliffs Sandstone.
Figure 10: Cross Section of Geology at the San Jan Coal Mine from Fruitland Formation to Lewis Shale (Ginn, Perkins, and O’Hayre 2009) Figure 11 show the plan view of what a typical CCB disposal pit my look like in regards to
proximity channels that lace throughout the permitted area. Dotted areas show location of
ash in Figure 11 through Figure 13. State regulations mandate that a minimum of 6 feet of
cover spoil will always be on top of the disposal pits and this can clearly be seen in the
typical profiles shown in Figure 12 and Figure 13 (Chee 2009). Figure 12 shows a typical
30
cross section of how spoil and CCB disposal pits are located under an alluvial channel.
Figure 13 shows typical cross sections of spoil arrangement along the surface of the land.
Figure 11 : CCB Disposal map of typical channel construction (Chee 2009)
31
Figure 12 : Profile cross section of A-A’ shown in Figure 11 showing typical CCB disposal cover and location in regards to the pit wall (Chee 2009)
32
Figure 13 : Profile cross section of B-B’ and C-C’ shown in Figure 11 showing typical CCB disposal cover and location in regards to changes in channel location (Chee 2009)
33
The vegetation, which must be planted as part of the reclamation criteria must match
surround species, which as seen in Figure 14 below in the MMD map is classified as great
basin desert scrub.
Figure 14 : MMD vegetation classification map for San Juan Coal Mine (Mines and Minerals Division, New Mexico 2011)
A visual image of the SJCM can be seen in Figure 15 showing the desert scrub and arid
climate. The picture was taken facing north at a the sonic drilling sample site with the white
moisture clouds on the left coming from the power generating plant on site. Figure 15 also
shows the general landscape of the reclaimed area in the SJCM and is representative of the
overall area outside mine property.
34
Figure 15: SJCM-SM04 site looking back at San Juan Power Generating Station
2.5.2. Hydrology The site poses unique hydrologic properties as its southern boarder meets the San Juan River
and the exact groundwater flows through the PC and Lewis shale under the SJCM are
unknown. As part of the permitting process the SJCM submitted a reclamation plan to
protect the hydrologic balance of the area. The purpose the reclamation plan is to assure
protection of the surface and groundwater quality by monitoring mine water inflows,
minimizing surface runoff and sedimentation into streams. Groundwater is present due to
perched aquifers, location of the groundwater table within the area, leakage from water pipe
used by SJCM and PNM, a native river, arroyos and storm water runoff (Ginn, Perkins, and
O’Hayre 2009).
2.5.2.1. Groundwater Within the permitted area of the SJCM, seen as the blue dotted line in Figure 4, there are no
existing springs or domestic/wildlife/livestock wells (Ginn, Perkins, and O’Hayre 2009). As
of 2011 the SJCM actively diverts surface water around Pinon area and pumps groundwater
from the formation to dewater the underground mine (Norwest 2009). Groundwater
pumping from the mine ranged from 12 to 20 acre feet/ month with an average of 15 acre
feet/month from January 2006 to February 2009 (Ginn, Perkins, and O’Hayre 2009).
35
Monitoring wells have been installed in any area where water has been identified during coal
exploration as seen in Figure 17. Monitoring wells in the Picture Cliff Sandstone (PCS) are
labeled GA and monitoring wells placed within the Shumway are labeled GE and GL
respectively. G26 and G3 are the current monitoring wells with water in them from the No 8
coal seam water (Ginn, Perkins, and O’Hayre 2009). Ranges in the concentrations of
analytes along the No 8 Coal Seam can be seen in Figure 16 showing the changes in TDS
over time at well G26 and well G3.
G3 & G26 Well Water Lab TDS Concentration Changes Over Time
0
1000
2000
3000
4000
5000
6000
3/29/10 9/23/09 9/17/08 3/11/08 3/30/07 9/29/06
Date of Sample
Con
cent
ratio
n (m
g/L)
G-26 G-3
Figure 16 : Changes in the TDS concentration in the No 8 Coal Seam wells of G-26 and G3 from 2006 to 2010 (Mines and Minerals Division, New Mexico 2011)
There are 4 classified aquifers within the permitted area the Pictured Cliffs Sandstone (PCS),
Fruitland Formation coal Unit No 8 coal seam, Fruitland Formation coal Unit No 9 coal
seam, and the Westwater-Shumway Arroyo alluvial (Luther, Musslewhite, and Brown 2009).
Figure 17 shows an overview of the SJCM with different colored dots representing different
kinds of monitoring wells (Mines and Minerals Division, New Mexico 2011). The blue,
36
purple, orange and red dots show the location of the most recent monitoring wells drilled in
summer 2011. Green dots represent existing or Legacy wells.
37
Figure 17: SJCM Map of monitoring wells throughout SJCM (Mines and Minerals Division, New Mexico 2011)
38
Within the permitted area of the SJCM the PCS is on average 120 feet thick with a one to
two degree tilt to the east southeast. PCS secondary permeability controls seepage due to
small fracturing caused by a close proximity to fault areas but groundwater is essentially not
existent due to a low permeability, poor water quality and low production rates. The
groundwater is classified as sodium-bicarbonate-chloride and contains elevated
concentrations of S, F, SO4. In 1979 a test concluded the PCS had a transmissivity of 1.12 ft2
day-1 and hydraulic conductivity of 0.03 ft dy-1.(Luther, Musslewhite, and Brown 2009).
No 9 coal seam located a perched water table roughly 100 ft above the No 8 coal seam, but
due to the No 9 coal seam thinning abruptly the amount of water was determined to be
negligible as it can percolate away (Luther, Musslewhite, and Brown 2009).
The No 8 coal seam is a potential recharge source due to outcrops of the coal seam that
intersect with intermittent stream channels within the SJCM. No 8 coal seam flows east with
flow gradients of 0.001 to 0.011 ft/ft. Transmissivity tests on the aquifer conclude an
extremely low transmissivity of 0.183 ft2 day-1 and hydraulic conductivity of 0.005 ft dy-1.
The water quality of No 8 coal seam is classified as sodium-sulfate-bicarbonate type and
considered poor quality with high concentrations of chloride and calcium. No 8 Coal seam
water quality does vary through out the SJCM. For example the total dissolved solids ranges
from 3,645 mg/ L to 18,560 mg/L and pH ranges from 8.5 to 12.6 (Luther, Musslewhite, and
Brown 2009).
39
The water elevations collected from GL wells in the Shumway Arroyo since 1979 have been
declining as seen in Figure 18. The points shown in Figure 18 some scatter in earlier years
most likely due to in accurate or inconsistent measuring tools (Norwest 2009).
Figure 18 : Historical water elevations measured in the alluvial well GL in the Shumway Arroyo from 1979 to 2007 (Norwest 2009) Similar measurements were collected at GE wells and followed a similar trend. This leaded
to the conclusion that the alluvial water table between the wells is flat with little to no
groundwater flow along the Shumway Arroyo just east of the Westwater Arroyo (Norwest
2009).
The well data from GE and GL was then compiled to estimate the potentiometic gradient
between them (Figure 19) (Norwest 2009). When values in the figure are positive it is
indicative of a gradient from GL to GE and visa versa. With the overall average percent
40
changes of-0.04% it can be verified that the gradient between wells GE and GL is relatively
flat with the overall grained from well GE to GL (Norwest 2009).
Figure 19 : Calculated potentiometic gradients between alluvial wells GL and GE in the Shumway Arroyo based of historical data (Norwest 2009)
As previously mentions, G3 is one of the monitoring wells for the No 8 Coal Seam aquifer.
The G3 well data was plotted to determine the draw down and recovery of mining in the
Pinon Pit. Figure 20 shows that the initial draw down can be clearly seen and then some
slight recovery once mining completed, most likely due to some saturation next to the
highwall (Norwest 2009). It also shows an estimated original water elevation of 5325 ft and
roughly where the water table is expected to return when site dewatering stops.
41
Figure 20 : The calculated potentiometic surface at No 8 Coal Seam monitoring well G3 from 1990 to 2009 (Norwest 2009) Water that is captured by the pumps, an average of 6.3 acre feet/month from 2006 to 2009, is
discharge to detention ponds and is combined with surface water to be used for mine and
power plant operations. The SJCM uses water in operation of coal mining, for reclamation,
dust suppression, within mine ventilation systems and cooling purposes. Surplus water is
pumped back to the surface to keep the mining area safe as coal dust underground can
instantaneously combust if not moistened. For example on average 21% of the surface water
diverted was reused in operations from 2006 to 2009 (Ginn, Perkins, and O’Hayre 2009).
The SJCM reclamation permit accounts for procedures of closing and sealing underground
portions of the mine as well as covering and revegetate surface mine spoils.
2.5.2.2. Surface water
Due to arid climate most standing water in the area is exposed to high evaporation and
infrequent rain events. Storm water is accounted for in the permitting process with uniform
42
gradients throughout the permitted area seen in hashed red in Figure 7 to maintain even sheet
flow to detention ponds used to retain the water until it evaporates. Storm water that collects
in the Juniper pit is stored in a retaining pond to evaporate. The mine took into account the
estimated discharge of storm events and designed the reclamation area with slopes and
valleys to reduce remove water from the area quickly to reduce infiltration with minimal
erosion (Ginn, Perkins, and O’Hayre 2009).
Hydrologically the SCJM also has two arroyos, the Shumway and Westwater, within the
permitted SJCM area as well as the southern border of the SJCM bound by the San Juan
River. The arroyos are currently diverted around the pits, preventing ephemeral flows from
entering the mine site during active mining (Norwest 2009). Figure 21 below shows the pre-
diversion location of the Westwater arroyo in pale blue running through the Juniper pit area
while the pale pink line shows the current diversion location (Mines and Minerals Division,
New Mexico 2011).
43
Figure 21 : Zoomed view of Figure 5 showing pre-diversion of Westwater Arroyo(Mines and Minerals Division, New Mexico 2011) The Shumway and Westwater are commonly known jointly as the Shumway Diversion and is
the only channel that has a connected biological community reliant on water being present
within the SJCM permitted area. The Shumway Diversion stream valleys consist of
quaternary alluvial waters which are characterized as sodium-bicarbonate type. It is
considered poor water quality as it exceeds NM drinking water standards (Luther,
Musslewhite, and Brown 2009).
The SJCM diverts water from the San Juan River for various mine and power plant
operations such as cooling. From January 2006 to February 2009 an average of 36.5 acre-
feet/month of water was diverted and used for SJCM operations (Ginn, Perkins, and O’Hayre
2009).
44
2.5.2.3.Recharge The SJCM has estimated coal reserves for at least 25 more years so active pumping within
the permitted area will continue until at least around 2036 (Ginn, Perkins, and O’Hayre
2009),(Luther, Musslewhite, and Brown 2009). The SJCM permit required a model study to
estimate groundwater recharge and the resulting study concluded that the potential recharge
scenario is by the return of the groundwater along the No 8 Coal seam and underling Pictured
Cliffs Sandstone and/or through ephemeral stream flow along the alluvial channels along the
arroyos. The exact model parameters and results can be found in San Juan Reclamation
Hydrologic Balance 907 Permit 04-01 Appendix 907.B (Ginn, Perkins, and O’Hayre 2009).
2.6. San Juan Coal Mine and San Juan Power Generation Station
Areas that were mined previously were filled with spoil and CCBs, approximately 3% of
total volume used in backfill, to the approximate original contours and then backfilled with
spoil at least 6 to 10 feet thick. Areas of disposal can be seen in green of Figure 5 in a map
published by the SJCM. The pale purple areas show the areas where the ground has been
disturbed due to mining. The red dotted line draws the boundary of the SJCM property while
the blue dotted line draws the boundary of the permitted area (Luther, Musslewhite, and
Brown 2009).
Yearly approximately 7 million short tons of coal are produced from the SJCM resulting in
2.7 million short tons of CCBs generated by the power plant. Most of the waste generated
was then used as fill material in the old surface mined areas where the MMD permitted
burial. The typical ratio of CCBs generated at the power plant yearly is around 70% fly ash,
15% bottom ash and 15% FGDS (Luther, Musslewhite, and Brown 2009).
45
The CCBs are hauled to the excavated areas and placed in discontinuous pockets and layers
where they are surrounded for the most part with low permeability native soil backfill
materials to limit exposure to water.
46
3. Methods Samples of varying ages were collected from buried pits across the reclaimed area and
compared to each other as well as to representative samples collected from the adjacent
power generation station that were not buried, as control samples, to determine the
physiochemical characteristics of CCBs.
The New Mexico MMD has all the historical records of the quarterly ash samples available
from when the SJCM originally opened to present day. This data base was used to verify that
small samples collected from the power plant and out of the disposal pits are representative.
Ash data from present until 1995 was compared for all the constituents and no significant
difference in between the ash samples was found. This allows us to apply the conclusion
from the samples tested within this research and apply them to the all the buried CCB
disposal pits with certainly.
3.1. Sample collection and preservation
Fresh samples collected from the power plant were collected in the same protocol as the
MMD quarterly samples. Fly ash was collected once per week from each of the four fly ash
collector units at the unloader site of each ash bin. Bottom ash was collected twice per
month from each of the 3 units where the collection hoppers dump into the transport trucks.
FGDS was collected once per week in one liter grabs sampled off the conveyer. Each of the
weekly samples are then combined for a representative sample for the 3 months for each fly
ash unit, each bottom ash unit and the FGDS (Chee 2009).
47
Core samples were collected in rigid clear plastic pipe during Geoprobe sampling or double
bagged in gallon plastic bags from the ultrasonic drilling program. Samples were stored in a
cooler at 4 ºC and transported to the UNM Albuquerque campus where they were stored in a
refrigerator at 4 ºC prior to analysis. Samples were prepared according to part 2540 Solids
Procedures in Standard Methods (Eaton et al. 2005).
3.1.1. Geoprobe ® sample collection
Drilling was utilized to collect buried CCB samples from the SJCM. From Sept 13th, 2010 to
Sept 17th, 2010 the US Geological Survey (USGS) collected core samples using a
Geoprobe® 540UD with an operations crew to collect samples at the Yucca Ramp and
Juniper Pit storage locations as seen in Figure 5.
Sites were selected to maximize recovery of CCB sample by drilling in areas where CCB
material was known to have been disposed. Jim O’Hara, from the New Mexico Mining and
Minerals Division (MMD), assisted in identifying location of the core sampling. Samples
were collected from each of 8 sites. Direct push collection was favorable since samples
collected in this method maintain representative in-situ conditions. Two inch diameter cores
were collected in plastic. The direct push method can not break/drill through large rocks
which resulted in refusal at depths ranging from 10ft to 20ft. However, coring at the Yucca
Ramp did produce some CCB around 25 ft depth. Figure 22 shows the soil profile of each of
the 8 sites sampled (New Mexico Mining and Minerals Division 2009). The horizontal red
lines indicate the depth of core material that was subsequently analyzed for their physical and
chemical properties.
48
surface SJM YR1-01
9/13
10ft below
30ft below
20ft below
40ft below
SJM YR1-01D 9/14
SJM YR2-01 9/14
SJM YP1-01 9/15
SJM WYP1-01 9/16
SJM WYP1-02 9/16
SJM JP-01 9/17
SJM JP-02 9/17
LegendTop soil Spoil Spoil/top soil mix Ash Clay/spoil (intermittent) Ash/spoil (intermittent)
18” 12
”
12”
15”
16”
24”
1.5’
9’
13’
27’
31’
40’
26’
14’
28’
11’
8’
16’
19’
23’
21.5
’
19’
21’
Sample locations selected for testing Physical & Chemical properties
Abbreviation: SJM – San Juan Mine YR1 – Yucca Ramp 1 YR2 – Yucca Ramp 2 YP1 – Yucca Pit 1 WYP1 – West Yucca Pit 1 JP – Juniper Pit
Figure 22:Geoprobe ® coring samples diagram
49
3.1.2. Sonic drilling sample collection
A second set of samples was conducted during a coring and monitoring well installation
program in summer of 2011. This drilling program produced samples from the Juniper Pit
(JP) area as shown in Figure 4. Sonic drilling was employed because of its speed, the fact
that water or drilling mud is not needed, and it produces a continuous sequence of core
material. Drilling occurred from April 28, 2011 to May 1, 2011. Sonic drilling samples were
collected solely for geochemical analysis. This process pulverizes the core material which
limits their value for physical measurements. A total of seven locations were drilled. The
first was the in the Juniper Pit Surface Material 04 (SJCM- SM-04). A picture of the
complete core removed from SJCM-SM-04 is presented in Figure 24 and is discussed below.
Figure 23: Complete SCJM-SM-04 sonic drilling samples
50
The depth at which samples were collected is loosely correlated to its age, as information on
date and elevation of disposal is not available. Relatively young fly ash (FA) material from
shallow depths were collected at the first layer of ash located ten feet below the surface. The
core was consistently uniform fly ash for the next 100 feet and no deeper samples were
collected. At 109.5 feet below the surface, samples were collected from a layer that was six
inches thick of what appeared to be bottom ash (BA) due to the presence of smelter slag
chunks and grainier ash material. A sample was collected at 120 feet depth, a 4 inch layer
that appeared to be FGDS, based on its higher moisture content and grainer appearance. This
layer turned out be fly ash (FA) based on SEM and XRD analyses. At 124 ft, drilling
encountered dry FA and samples were collected at the bottom layer that rested on PCS at 125
ft below the surface. The well screen and casing was then set to serve as a monitoring well.
The second site for sonic drilling was the SJCM KPC 03 (SJCM-KPC-03) site, on the edge
of reclaimed area. Material at this site mainly consisted of PCS, with a small section
between 34 and 41 feet of what appeared to be a mix of ash and sandstone due to a finer
powder. However, these samples were deemed unusable for geochemical purposes due to the
high fraction of sandstone which would make data interpretation difficult. A total of 10
samples were collected during the sonic drilling program. Figure 24 shows the complete soil
profiles of each of the drill holes and the location of sample collection points.
51
Figure 24: Sonic drilling samples diagram
52
3.2. Preparation of samples
From the total 24 samples that were collected (9 samples from the Geoprobe drilling
samples, 7 samples from the Sonic drilling samples and 8 samples of fresh ash collected from
the power generating station) 16 were selected for geochemical analysis.
Thirteen of the 16 samples were determined to be representative of the buried CCBs and 3
samples of the fresh CCBs from the power generating station were analyzed as control
samples. The recovered samples consisted of spoil/top cover from Yucca Ramp, CCB from
Yucca Ramp 01, Juniper Pit 01, Surface Material 04 and KPC 03. The samples from the
power station consisted of fly ash collected from furnace #1, bottom ash from furnace units 1
& 2 and FGDS.
As previously stated, in the actual disposal of the CCBs all three waste products were often
combined into a single truck load. However, the fresh samples were collected separately
using procedure similar to those established by MMD as previously stated.
The samples were classified as fly ash (FA), bottom ash (BA), and FGDS with three sub
groups within each classification: fresh (unburied CCB), young (CCB from the reclaimed
pits near the surface) and old (CCB from the reclaimed pits near bedrock).
The mass and overall appearance was noted of all samples. The samples were oven dried at
105 °C for 24 hours with their mass and appearance recorded again. Samples that contained
larger material were then crushed in a mortar and pestle to shatter box size. Approximately
53
15 grams were then sent to the University of New Mexico’s Earth and Planetary Science
Analytical Geochemistry Laboratory (UNM-EPS-AGL) for a suite of geochemical analysis
tests.
3.3. Geochemical analyses
Geochemical analyses were conducted to determine the total chemical composition of each
of the CCB samples. Analysis also assists in determining what constituents would be
expected to occur in leachates. Testing was done following procedures comparable to the
EPA Method 200.2 and ASTM D3987-06 Shake Extraction of Solid Waste with Water
respectively. Table 4 shows each classification and site location for the samples.
Table 4 : Specific locations for the sample groups used for each test procedure
Type Name Type Name Type Name Type Name Type NameSpoil YR1-01-01T YFA SM4-01-01B Spoil YR1-01-01T Fresh NE-FA-01 Fresh NE-FA-01Spoil YR1-01-01B YFA SM4-02-01B Spoil YR1-01-01B Fresh NE-BA-01 Fresh NE-BA-01Spoil YR1-01-02B OFA SM4-03-01B Spoil YR1-01-02B Fresh NE-FGD-01 Spoil YR1-01-01TSpoil YR1-01-03B OBA SM4-04-01B Spoil YR1-01-03B Spoil YR1-01-01T OBA SM4-04-01BYFA YR1-01-05B OFA SM4-05-01B YFA YR1-01-05B OBA SM4-04-01B OFA SM4-06-01BYFA YR1-01-06B OFA SM4-06-01B YFA YR1-01-06B OFA SM4-05-01B YFA JP4-01-01BSpoil JP1-01-01B Mix KPC3-01-01B Spoil JP1-01-01B OFA SM4-06-01B Fresh* NE-FA-01Spoil JP1-01-03B Mix KPC3-02-01B Spoil JP1-01-03B YFA JP4-01-01B OFA SM4-05-01BSpoil JP1-01-08B Fresh NE-FA-01 Spoil JP1-01-08B Spoil JP1-01-03BSpoil WPR1-01-01B Fresh NE-BA-01 Fresh NE-FA-01
Fresh NE-FGD-01 Fresh NE-BA-01KEY Fresh NE-FGD-01
Fresh OBA SM4-04-01BSpoil OFA SM4-05-01BYFA OFA SM4-06-01BOFA Spoil KPC3-01-01BOBA
Column Test8 Samples
*=No 8 Coal Seam Water Used
CCBs Sample Classification and Location
10 Samples 11 Samples 10 Samples16 SamplesAcid Dig./DI Extract XRD/SEMSonic CollectionGeoprobe
Old Bottom Ash
Fresh unburied Top SpoilYoung Fly AshOld Fly Ash
54
3.3.1. Acid digest procedure
An analysis using a comparable test to the EPA Method 200.2 acid digest test involving and
acid digestion with nitric and hydrochloric acids was preformed to determine elemental
composition of 16 of the CCB samples (Table 4). This test was employed to compare
composition of fresh vs. buried and spoil vs. CCBs. Samples were dried and then grinded.
Acids were added while the samples was heated at 95°C. The samples were analyzed for the
contaminants listed in Table 3 on a Perkin-Elmer Optima 5300 DV Inductively Coupled
Plasma-Atomic Emission Spectrometer (ICP-AES). The specific limit of detection for each
of the elements is listed Table 5 :Constituents Limit of Detection (LOD). Table 5 with most
about 0.3 mg/L except arsenic and aluminum with 0.25 and 0.14 mg/L respectively.
Table 5 :Constituents Limit of Detection (LOD).
ElementMDL (mg/L)
Ag 0.065Al 0.14As 0.25B 0.024Be 0.0035Cd 0.0135Co 0.035Cr 0.0355Cu 0.027Fe 0.031Mo 0.0395Ni 0.075Pb 0.21Se 0.375V 0.032Zn 0.1
3.3.2. Deionized water extraction procedure
Deionized water extraction was performed on 16 (Table 4) of the collected samples to
determine the leachable concentrations of following anions: Fluoride (F), Chloride (Cl),
55
Nitrite (NO2), Bromide (Br), Nitrate (NO3), Phosphate (PO4) calcium (Ca), potassium (K),
magnesium (Mg), sodium (Na) and Sulfate (SO4). The purpose of the test was to determine
the difference in concentrations of said anions between old, young, and fresh CCB.
Concurrent with the ASTM D3987-06 Shake Extraction of Solid Waste with Water method,
two grams from each of the sixteen samples were added to 40 mL of deionized water for a
1:20 ratio. A photo of the filled vials is presented in Figure 25.
Figure 25: Nine samples before shake test ASTM D3987-06
The vials were then fitted onto a rotation wheel, as seen in Figure 26, to agitate the samples
for 18.5 hours at 30 rotations per minute, per ASTM D3987-06.
56
Figure 26: ASTM D3987-06 18-hour shake phase
Upon conclusion of the mixing phase the samples were placed in a centrifuge for two
minutes each to settle out larger particles. The centrifuge supernatant was then filtered using
0.47 μm membrane filer made by Glenman Sciences. Filtered samples were analyzed by the
UNM-EPS-Analytical Geochemistry Laboratory by ion chromatography using a Dionex DX
500 Ion Chromatograph (IC) to determine anions in the aqueous samples.
57
Figure 27: Nine samples after 18-hour shake sxtraction ASTM D3987-06
3.4. Mineralogy
Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD) analysis was employed
to determine the morphological characteristics and mineralogy of the CCB samples and to
look for signs of aging. The intent was to compare the fresh CCB samples to the buried
samples collected in the field for differences in physical and mineralogical compositions. Of
particular interest were changes in the samples from amorphous structures to more
crystalline-clay structures and the appearance of secondary mineral phases sush as
carbonates, hydroxides or sulfates.
3.4.1. Scanning Electron Microscopy
Ten samples were selected for analysis in the SEM (Figure 28): spoil from Juniper Pit 01 and
Yucca Ramp 01, young fly ash from Yucca Ramp 01, old fly ash from Juniper Pit 04, old
58
bottom ash from Juniper Pit 04, fresh fly ash from furnace unit 1, fresh bottom ash from
furnace units 1 & 2 and fresh FGDS, see Table 4 for location of samples.
Figure 28: UNM-EPS SEM Equipment. http://epswww.unm.edu/iom/ebeam/mikesem1.gif
The samples were analyzed at UNM-EPS Institute of Meteoritics using a JEOL JSM5800LV
variable pressure scanning electron microscope equipped with an Oxford Instruments Energy
Dispersive X-ray Spectrometer (EDX) and an Oxford X-ray analyzer (Spilde 2011). Samples
were analyzed with both secondary electron (SE) imaging that renders sample’s surface
topographical information, and backscattered electron (BSE) imaging that scales higher and
lower atomic number materials brighter and darker respectively. All samples were coated in
an EmiTech K950 vacuum evaporator with gold-palladium alloy prior to analysis and
examined at an accelerating voltage of 20 kV and a beam current of 0.4 nA (Spilde 2011).
59
3.4.2. X-Ray Diffraction
Samples, listed in Table 4, were analyzed at UNM-EPS XRD Laboratory on a Scintag PAD
V Diffractometer/Goniometer with a Scintillation detector. Datascan software (Materials
Data, Inc.) for diffractometer automation and data collection, Jade Software (Version 9.1,
also from MDI) which can access the complete IDCC Powder diffraction filed database was
used to assist in data analysis and interpretation. Some of the samples required a significant
amount of grinding to create homogeneous specimens for XRD analysis. For the first runs a
standard sample run conditions was 5-65 deg 2-theta, in a continuous scan mode at 1/2
deg/min (for total run time of 2 hr per sample) and a standard slit configuration (2-4-1-
0.3mm) was also used (Connolly 2011).
Figure 29: UNM-EPS XRD Equipment. http://epswww.unm.edu/xrd/lab1.jpg
60
The major mineral phases identified in the coal fly ash are included: quartz, mullite, glass,
and minor phases of anorthite and hematite (Table 6) (You, UM, and et al. 2009)(Sultana,
Das, and et al. 2011)(Ward and French 2006) The other minor phases that may be present
vary depending on the mineralogical variations in the specific coal burned to produce the ash
(Ward and French 2006). These samples were run using Plexiglas sample holders that give a
notable amorphous background "hump" in the 10-20 deg 2-theta range; in many of these
samples there was substantial background noise in the 20-35 deg 2-theta range overprinting
the sample background which was indicative of significant amorphous constituents(s) in the
specimens run. These results are consistent with the glassy constituents which were found in
coal fly and bottom ash (Connolly 2011).
Table 6 : Mineral phases present in each sample classification
Fly Ash Quartz Mullite HematiteBottom Ash Mullite Quartz Calcite Feldspar AnorthiteFGDS Gypsum Quartz
Major Phases Minor PhasesClassification
of Sample
3.5. Column study procedure
The intent of the column study was to simulate the effects of rain water or natural
groundwater infiltrating through buried CCBs and identify the sequence of leachates to
establish a unique map of trace elements with regard to time.
Columns were constructed from clear acrylic Excelon R - 4000 Transparent Rigid pipe. Two
inch ID pipe was used. Each column was 10 inches long and was fitted with clear acrylic 1
61
inch thick caps that contained an O-ring and ½ inch drilled holes through each cap for
fittings. Jaco - Kynar®, nylon, and polypropylene tube and hose connector fittings were
used to connect hosing to the columns to Erlenmeyer flasks as seen in Figure 30. The entire
assembly was mounted on a 24 inch by 35 inch masonite board for stability.
Figure 30: Eight separate 2 inch ID and 10 inches tall columns
Eight representative samples were selected which consisted of fly ash (two fresh, one young,
two old), bottom ash (one each fresh and old) and spoil material. Water collected from the
number 8 coal seam at SJCM was applied to the second samples of the fresh and buried fly
ash.
62
The chemical composition of the No 8 Coal Seam water provide by BHP Billiton was
compared to historical information gathered by MMD from the G-26 and G-3 well at the
SJCM and the results are shown in Table 7.
63
Table 7 : No 8 Coal Seam Water Quality for column test and historical data (Mines and Minerals Division, New Mexico 2011)
Parameter Column Water Low HighpH 7.9 8.7
Spec cond (uS/cm) 5160 7280TDS 3190 4850TOC 4.4 50
K 4.4 3.5PO4 0.06 0.46Ca 14.27 7.9 20Mg 5.2 2.5 8Na 1959 1090 1650H2S 0.22 171
PhenolsHCO3 760 1720CO3 1 220Cl 58 520F 1.9
SO4 580 3000NO3 0.02 2Al -0.047 0.1 0.1As -0.043 0.0005 0.005B 1.6 0.8Ba 0.013 0.0179 0.2671Cd -0.039 0.00005 0.001Cr -0.033 0.001 0.095Cu 0 0.0001 2.4Co -0.038 0.01 0.0161Fe -0.063 0.03 0.08Pb -0.053 0.0001 0.01Mn -0.034 0.005 0.023Hg 0.002 0.002Mo -0.022 0.005 0.005Ni -0.044Se -0.107 0.005 0.025Ag 0.043V -0.009 0.0005 0.1U 0.00001 0.001Zn -0.054 0.007 0.16
Ra-226 0.2
4.9
4
1.4
3 1
*Analysis of No. 8 Coal Seam Water Used in Column Studies
No 8 Coal Seam Since 2005
No. 8 Coal Seam*
64
No. 8 Coal Seam water was used to simulate the effect of inflow to the buried waste from the
surrounding aquifer that will occur after underground mining was completed. DI water was
applied to the other 6 columns to simulate the effect of rainwater infiltrating through the
buried CCBs.
3.5.1. Leaching sequence columns
Specific physical characteristics of material recovered from fresh and buried CCB areas such
as Yucca Ramp and Juniper Pit were determined at UNM graduate student Ryan Webb in a
companion study. The columns were packed to the approximate density and porosity of
buried CCBs in the mine. Columns were compacted to 64.2 lb/ft3 and pore volume was
estimated to be 34.3 mL. The volume of fluid was added daily over a time frame of 30-37
days. Leachate samples were collected every 2 days producing a total of 12 to 16 samples,
each representing 2 pore volumes of sample. These samples were analyzed by UNM-EPS
Geochemical Laboratory for the contaminants listed on the drinking water standards in Table
3.
65
4. Results & Discussion
A number of studies have been run on the CCBs at the SJCM as part of the mine’s quarterly
testing requirements of the MMD (Table 8). The results of these tests are similar to the
results observed in the column study. Slight differences in MMD quarterly reports compared
to the UNM column studies may be due to difference in CCB samples, analytical methods
and leaching procedures.
Table 8: Historical comparisons of CCB acid and leach tests for specific parameters
Sample ID Method pH Arsenic Boron BariumStudy s.u. mg/Kg mg/Kg mg/Kg mg/Kg mg/L
Intermountain Laboratories, Inc.January-98 Unit 2 FA SM 311 4B, 601 0A/200 .7, 20 0.9 11.92 0.160 230 360 720 <0.2
Intermountain Laboratories, Inc.May-02 Unit 2 FA SM 311 4B, 601 0A/200 .7, 20 0.9 12 0.110 250 470 900 <1
Current StudyApril-11 Unit 2 FA Comparable EPA 200.2 11.64 0.185 340 1934 656 0.56
MagnesiumParameters
4.1. Analytes within SJCM CCBs and Spoil
Results of the column leach tests for the different types of CCBs and spoil material are
summarized in Table 9, Table 10 and Table 19.
Previous studies have found that CCBs are primarily made up of aluminosilicate with other
trace elements (World Coal Association 2011; El-Mogazi, Lisk, and Weinstein 1988;
Manskinen, Poykio, and Nurmesniemi 2011; A. C. Chang et al. 1979; James et al. 1982). Fly
ash and bottom ash results show a high fraction of aluminum, silica, calcium and iron. These
results were consisten with results previously submitted to MMD which found that coal from
66
the Fruitland formation is mostly made up of the same elements (Luther, Musslewhite, and
Brown 2009). Table 9 shows an example of the results collected from acid digestion (See a
full version of the Table 9 in the Appendix).
Table 9 : Total Chemical composition results from acid digestion
Sample(mg/Kg)Analyte Name
min max ave max err min err min max ave max err min err min max ave max err min err
Ag
Al 19327 29838 24417 5422 5090 43650 43650 43650 0 0 32327 39540 36003 3536 3676
As 0.091 0.091 0.091 0.000 0.000 0.062 0.185 0.124 0.062 0.062 0.110 0.236 0.185 0.051 0.075
B 3355 5639 4266 1373 910 338 342 340 2 2 525 3145 1275 1870 749Ba 1403 2238 1802 437 398 223 1561 892 669 669 1422 2534 1934 600 512BeCa 743 5839 3610 2228 2867 7669 8186 7928 258 258 4500 6269 5692 577 1192CdCo 5 13 9 4 4 7 9 8 1 1 5 12 8 4 2Cr 15 25 19 5 4 14 17 15 1 1 13 17 14 3 1Cu 12 43 22 21 11 31 37 34 3 3 30 39 35 4 5Fe 17383 22562 19440 3122 2058 20804 20941 20873 68 68 19798 22908 21529 1379 1731K 3714 11370 8318 3051 4604 3564 3962 3763 199 199 2171 3815 3069 746 897Li 70 606 357 249 287 730 774 752 22 22 442 601 545 56 103
Mg 180 929 450 479 271 492 656 574 82 82 340 484 392 92 52Mn 125 357 233 124 108 115 119 117 2 2 122 169 137 32 15MoNa 8381 17216 13710 3505 5329 8535 8945 8740 205 205 7016 9437 8400 1037 1384Ni 7 14 10 4 3 6 7 7 1 1 6 9 7 2 1Pb 3 24 10 14 7 12 13 12 0 0 7 19 13 6 6SeSi 90463 220434 150222 70212 59759 56692 82234 69463 12771 12771 68352 163049 111161 51888 42810
Sr 32 110 57 53 25 82 124 103 21 21 89 110 100 10 11
V 37 67 50 17 13 41 51 46 5 5 42 60 48 12 6Zn 43 73 53 20 10 39 99 69 30 30 22 40 30 10 9
Fresh BuriedSpoil
Table 9 results are consistent with previous reports that western U.S. coal contains elevated
levels of calcium and iron (Manskinen, Poykio, and Nurmesniemi 2011). Silicon is the most
abundant analyte, as expected since silica is a major constituent of most dirt/clay earthen
materials. It is usually present in the form of glass (SiO2) due to the high temperatures in the
combustion furnaces where the coal is burned. Sodium and Barium are the most abundant
trace elements in the fresh CCBs. Below Figure 31 and Figure 33 show a summary of the
overall composition of representative spoil and fresh and buried fly ash from the results in
Table 9.
67
Spoil
1%9%
4%
6%66%
2%2%10%
AlB
BaCaFe
KNa
Si
Figure 31: Average distribution of constituents from acid-digested spoil materials
Fresh FA
28.04%
44.63%0.22%
5.62% 13.41%5.09%
0.57%
Al
B
Ba
Ca
Fe
K
Na
Si
Figure 32: Average distribution of constituents from acid-digested fresh fly ash materials
68
Buried FA19.04%
58.80%
1.02%
3.01%
11.39%
1.62%
4.44%
0.67%
Al
B
Ba
Ca
Fe
K
Na
Si
`
Figure 33: Average distribution of constituents from acid-digested buried fly ash materials
Fresh BA
26%
5%
5%
49%
0%1%
12%2%
AlBBaCaFeKNaSi
Figure 34 : Average distribution of constituents from acid-digested fresh bottom ash materials
69
Buried BA
19%
3%
4%
60%
2%
11%
1%0%
AlBBaCaFeKNaSi
Figure 35 : Average distribution of constituents from acid-digested buried bottom ash materials
Fresh FGDS
8%1%
10%
74%
2%0%
1%4%
AlBBaCaFeKNaSi
Figure 36 : Average distribution of constituents from acid-digested fresh FGDS materials Figure 32 and Figure 33 demonstrate the higher levels of Al and Fe than in spoil samples.
These figures also show that the trace elements such as Na, Ba and Ca all have higher
concentrations in the buried fly ash then the fresh fly ash. These higher concentrations are
likely the result due to leaching from the buried CCBs. Figure 34 and Figure 35 show the
composition differences of bottom ash. The changes in the constituents concentrations is
70
relatively small and bottom ash has a similar percentile composition to that of fly ash.
Figure 36 shows the percent composition of fresh FGDS which has large percent silica like
fly ash and bottom ash. Boron concentrations are 2% in the FGDS and higher then those
seen in fly ash and bottom ash at less then 1%.
DI water extraction tests were used to help identify parameters of concern that have the
potential to leach. Studies conducted for the mine have found that common leachate from
CCBs exhibit high concentrations of Ca, SO4 and Na (Luther, Musslewhite, and Brown
2009). The results were verified with the higher concentrations in leachates from fresh
CCBs (Figure 37) and (Figure 38) for buried CCBs. Figure 39 shows what would be
expected leachate of sodium saturated smectitic clays with sulfate and carbonate salts
present.
Fresh
2.17%0.58%
42.99%46.55%
3.75%2.38%0.13%
1.43%FClNO2BrNO3PO4SO4CaKMg Na
Figure 37 : Average distribution of DI water leachates from fresh CCBs (mass basis)
71
Buried
6.99%
0.48%0.03%
0.02%
0.13%11.73%
80.39%
0.23%FClNO2BrNO3PO4SO4CaKMg Na
Figure 38 : Average distribution of DI water leachates from buried CCBs (mass basis)
Spoil
95.21%
2.19%0.20%
0.42%
0.01%0.17%
0.16%1.64%FClNO2BrNO3PO4SO4CaKMg Na
Figure 39 : Average distribution of DI water leachates from spoil (mass basis)
The complete results of the DI water extraction test can be seen in Table 10 for selected
constituents with a full data set available in the Appendix .
Table 10: DI water extraction results for Spoil, Fresh and Buried CCBs
72
Sample(mg/Kg) YR1-01-01T YR1-01-01B JP1-01-08B NE_FA_01 NE_BA_01 NE_FGD_01 YR1-01-06B JP4_04_01BAnalyte Name
01T 01B 08B FA BA FGDS 06B 4
F 1.10 1.55 1.25 14.0 1.54 158 58.3 7.07Cl 2.99 11.7 106.1 34.5 40.9 1154 319 11.2
NO2 0.4562 18.2 0.0817 3.22 0.324 0.831 39.7 1.22
4.1.1. Parameters with elevated concentrations within each group
Two Tailed T-Tests with unequal variances were run on the results of each analyte to
determine those with a significant difference between fresh FA, buried FA and spoil samples.
The null hypothesis assumed that results were from the sample group and a hypothesized
mean difference of zero. Table 11 shows the results of the T-Test for barium. The left
column compares spoil and combined fresh and old FA and BA. The right column,
highlighted in yellow, compares fresh FA against old FA.
Table 11: Two Tailed t-Test for Barium between Spoil vs Ash & Fresh FA vs Old FA
Spoil AshMean 1801.559417 1933.886525Variance 67535.72636 209255.5732Observations 8 4Hypothesized Mean Difference 0df 4t Stat -0.536852201P(T<=t) one-tail 0.309919447t Critical one-tail 2.131846782P(T<=t) two-tail 0.619838893t Critical two-tail 2.776445105
Ba
With a T-critical for two tails greater than the T-statistic the null hypothesis was rejected and
samples are considered to be from two separate populations. Similar T-Tests were then run
73
on each of the analytes to determine elevated concentrations of spoil vs CCBs and fresh fly
ash vs old fly ash.
Spoil samples contained elevated concentrations of sulfate (SO4) and vanadium (V)
compared to fresh and old FA and BA samples. CCB samples contained elevated
concentration of nitrite (NO2), calcium leach (Cal), barium (Ba), lead (Pb), iron (Fe) and
arsenic (As). These results are displayed in Figure 40 through Figure 47.
Average Sulfate Extract in Samples
0
10000
20000
30000
40000
50000
60000
70000
SO4
Analyte
Tota
l Con
cent
ratio
n (m
g/K
g)
Spoil Fresh Ash Buried Ash
Figure 40 : Average extract Sulfate concentration in CCBs and Spoil
74
Average Total Vanadium in CCBs and Spoil
0
10
20
30
40
50
60
70
80
V
Element
Tota
l Con
cent
ratio
n (m
g/K
g)
Spoil Fresh Ash Buried Ash
Figure 41 : Average total Vanadium concentration in CCBs and Spoil
Average Nitrite Extract in Samples
00.20.40.60.8
11.21.41.61.8
2
NO2
Analyte
Tota
l Con
cent
ratio
n (m
g/Kg
)
Spoil Fresh Ash Buried Ash
Figure 42: Average extract Nitrite concentration in CCBs and Spoil
75
Average Calcium Extract in Samples
0
200
400
600
800
1000
1200
Ca 317.933
Analyte
Tota
l Con
cent
ratio
n (m
g/Kg
)
Spoil Fresh Ash Buried Ash
Figure 43: Average extract Calcium concentrations in CCBs and Spoil
Average Total Barium in CCBs and Spoil
0
500
1000
1500
2000
2500
3000
Ba
Element
Tota
l Con
cent
ratio
n (m
g/K
g)
Spoil Fresh Ash Buried Ash
Figure 44 : Average total of Barium in spoil, fresh ash and buried ash with significant buried ash concentrations
76
Average Total Contaminant in CCBs and Spoil
0
5
10
15
20
25
Pb
Element
Tota
l Con
cent
ratio
n (m
g/K
g)Spoil Fresh Ash Buried Ash
Figure 45 Average total of Lead in spoil, fresh ash and buried ash with significant buried ash concentrations
Average Total Iron in CCBs and Spoil
0
5000
10000
15000
20000
25000
Fe
Element
Tota
l Con
cent
ratio
n (m
g/K
g)
Spoil Fresh Ash Buried Ash
Figure 46 : Average totals iron concentration in CCBs and Spoil
77
Average Total Arsenic in CCBs and Spoil
0.00
0.05
0.10
0.15
0.20
0.25
As
Element
Tota
l Con
cent
ratio
n (m
g/K
g) Spoil Fresh Ash Buried Ash
Figure 47 : Average total concentration in Arsenic with elevated concentrations in buried CCBs The elevated concentrations of Fe, Pb, As and Ba within buried ash as opposed to fresh ash is
believed to be due to the reactivity of the ash materials with water. A low pH range of 7 to
12 in the CCBs, as seen in Table 12 leaves carbonate is most prevalent in their least hydrated
forms within the CCB leachate. This means that many constituents will remain dissolved
within solution.
78
Table 12 : Lab pH, electric conductivity and total dissolved solids concentrations for CCBs and spoil
pH EC µS/cm TDS (mg/l)
Spoil YR1-01-01T 7.92 229 115
Spoil YR1-01-01B 8.59 1342 672
Spoil YR1-01-02B 8.32 1839 919
Spoil YR1-01-03B 10.51 772 387
Ash/Spoil YR1-01-05B 9.60 819.0 410
Spoil JP-01-01B 8.52 1377 689
Spoil JP-01-03B 7.86 1745 875
Spoil JP-01-08B 8.30 2400 1200
Ash/Rock KPC3_01_01B 8.56 1626 815
Young Ash YR1-01-06B 10.58 617 309
Old Ash SM4-04-01B 10.17 566 280
Old FGDS SM4-05-01B 10.44 718 358
Old Ash SM4-06-01B 10.68 651 314
Fresh Fly Ash NE_FA_01 11.64 3640 1730
Fresh Bottom A
pH EC µS/cm TDS (mg/l)
s NE_BA_01 9.44 242 122
Fresh FGDS NE_FGD_01 7.71 3250 1640
Sample ID
Sample ID
Ba has the highest concentrations in the buried ash by far as seen in Figure 44 most likely
due to the high mobility of ba in water. Water is present in the CCBs at disposal to prevent
dust and this water likely lead to small amounts of barium leaching from the upper levels of
the disposal pit into the lower levels and accumulating there.
79
The spoil, or native soil, used as cover for the CCB pits contained high concentrations of
vanadium (V) and sulfate (SO42-). These constituents are characteristic of soils in the area
(Figure 40 and Figure 41).
Analytes’ concentrations between fresh CCB samples were compared against buried CCB
samples to determine elevated concentrations in each group. Fresh CCB samples showed
elevated concentration of NO2, nitrate (NO3), CaL, magnesium (Mg) and strontium (Sr).
These results can be seen in Figure 42, Figure 43, Figure 48,Figure 49 and Figure 50 . These
analytes occur naturally within coal as trace elements, for example NO2 commonly forms
bonds with the alkyl group to which coal belongs.
Average Total Strontium in CCBs and Spoil
0
20
40
60
80
100
120
140
Sr
Element
Tota
l Con
cent
ratio
n (m
g/K
g)
Spoil Fresh Ash Buried Ash
Figure 48 : Average totals Sr concentration in CCBs and Spoil
80
Average Total Calcium in CCBs and Spoil
0100
200300
400500600
700800
9001000
Mg
Element
Tota
l Con
cent
ratio
n (m
g/K
g)
Spoil Fresh Ash Buried Ash
Figure 49 : Average total Magnesium concentration in CCBs and Spoil
Average Extract in Samples
0
10
20
30
40
50
60
70
NO3Analyte
Tota
l Con
cent
ratio
n (m
g/Kg
)
Spoil Fresh Ash Buried Ash
Figure 50 : Average Extract Nitrate concentration in CCBs and Spoil
Buried CCB samples showed high concentrations of Ba, Pb, Fe and As compared to fresh
CCB samples. These results can be seen in Figure 44 through Figure 47.
81
While there is a statistical difference between the spoil, fresh, and old CCBs, it is not
possible to identify any of these as the source term for the leachate composition. This is
because the concentrations of the constituents can not be traced back to the CCBs or spoil
specifically as the overall concentrations between CCBs and spoil are relatively similar. For
example, if nitrite is detected within the groundwater beneath the buried waste, it is not
possible to determine if is the results of leachate through the spoil, buried waste, or
infiltration from No. 8 Coal Seam water.
Arsenic concentrations are higher within the CCBs as well as the spoil compared to EPA
primarily drinking water standards of 10 ug/L. Figure 51 shows the different total
concentration of arsenic present in the spoil, fresh fly ash, fresh bottom ash, old fly ash, old
bottom ash, and young fly ash. Fly ash has around double the concentration of arsenic then
bottom ash and buried samples concentrations increase compared to the control fresh
samples. Arsenic is a mobile metal as it dissolves and is transported in water easily which is
likely why old and young buried ash have the increased concentrations.
82
Figure 51: Average Arsenic concentrations in variety of different aged CCBs and spoil compared to drinking water standard
4.2. Concentration changes with depth
The following results focused on determining how concentrations changed with depth of the
CCBs and to identify possible leachate sequences for a recharge scenario. Acid digestion
results of buried ash materials were used. The total concentrations for each constituent for
the fresh fly ash and old fly ash samples taken from SM04 were plotted against depth.
As previously stated exact ages can not ascribed to the buried CCBs. However, it is known
that age increases with depth.
Buried CCBs demonstrated an increasing concentration trend with Ba and Na while the
remaining constituents remained fairly constant with the initial concentrations.
83
Total concentrations spiked up at the end which is most likely due to changes in air pollution
control equipment at the power plant in response to new discharge regulations. This deep ash
is presumably older than the EPA’s regulations on discharge, allowing for the increased
capture or release of each parameter respectively, as seen in Figure 52 through Figure 54.
0
1
2
3
4
5
6
7
8
0 20 40 60 80 100 120 140
Depth (feet)
Con
cent
ratio
n (m
g/K
g)
Ni
Figure 52 : Concentration of Nickel in buried CCB level with sample depth
Ni concentrations remained fairly constant over depth but showed a slight trend downward as
depth increased. This downward trend is most likely due to Ni leaching from the buried
CCBs due to the water present at burial.
84
Analytes with Increasing Concentrations
0
500
1000
1500
2000
2500
3000
0 20 40 60 80 100 120 140
Depth (feet)
Conc
entr
atio
n (m
g/Kg
)B Ba
Figure 53 : Concentration of Barium and Boron in buried CCB increased with sample
depth
Ba concentrations spiked upward after burial and continued to slowly increase. This is most
likely due to mineral dissolution within the CCBs. While B present in the CCBs remained
fairly constant with a slight upward trend.
Fe concentrations increased with depth then leveled off before dropping at the greatest depth.
The high concentrations at moderate depth my be due to mineral dissolution within the CCBs
while the drop at the end is most likely due to changes in air pollution control equipment at
the power plant allowing for higher concentrations within the ash to remain behind.
85
Analytes with Decreasing Concentrations
19500
20000
20500
21000
21500
22000
22500
23000
23500
0 20 40 60 80 100 120 140
Depth (feet)
Con
cent
ratio
n (m
g/K
g)
Fe
Figure 54 : Concentration of Iron in buried CCB increased with sample depth
Sr and Mg declined from initial fresh concentrations, but quickly leveled off after the 10 foot
reading which can be seen in Figure 55 and Figure 56
Sr is a naturally occurring element with chemsity similar to Ca and it is highly reactive and
soluble (Patnaik 2002). Samples collected with the direct push method maintained in-situ
conditions and lab analysis determined an in-situ moisture content of 20% (Ryan Webb et al.
2012). This is likely why the concentration dropped once buried as the analyte would
dissolve into any moisture within the buried samples and would then leach.
86
0
20
40
60
80
100
120
140
0 20 40 60 80 100 120 14
Depth (feet)
Con
cent
ratio
n (m
g/K
g)
0
Sr
Figure 55 : Concentration of Strontium in buried CCB decreased with sample depth
Mg is also a naturally occurring element and it is soluble in water (Patnaik 2002). The in-situ
moisture measured from the direct push method samples are likely the result of Mg leaching
out within the moisture of the sample itself, hence the immediate decline in concentration.
87
0
100
200
300
400
500
600
700
0 20 40 60 80 100 120 140
Depth (feet)
Con
cent
ratio
n (m
g/K
g)Mg
Figure 56 : Concentration of Magnesium in buried CCB decreased with sample depth
The overall changes in constituent concentration with depth shows that the type of coal,
incineration process, air pollution treatment equipment used at the plant have a measureable
effect on end concentrations of analytes within the ash. This is expected and supported by
previous reports which states that, aside from the parent coal’s original concentrations of
analytes, a major factor affecting end ash concentrations is the incineration and recapture
process (El-Mogazi, Lisk, and Weinstein 1988).
Concentrations were normalized against the concentration of the fresh FA and presented on a
single graph to show the relationship between concentration and depth for all the analytes
(Figure 57). Normalizing the data is important to be able to compare the different
88
constituents against each other and draw the relationship between depth and overall changes
in concentration.
Changes in Concentration of CCBs as Depth Increases
0
2
4
6
8
10
12
0 20 40 60 80 100 120 140
Depth (ft)
Nor
mal
ized
Con
cent
ratio
n (C
/Co) Ba
As
Figure 57 : Normalized concentrations of CCBs plotted over depth of sample
Figure 57 shows that the largest change in concentration with depth was an increase in Ba
and As concentrations. The majority of the other constituents followed a similar trend to As
which did not show any change in concentration with increased depth and were removed in
the above figure but a complete graphic including all analyzed constituents can be seen in the
appendix. Barium and As do have an elevated concentrations within CCBs compared to the
spoil and do have a significant difference in concentration of buried as compared to fresh ash.
Figure 57 also shows that the majority of the constituents are present in trace amounts. The
increase in concentrations of barium and arsenic are likely the results of water in the ash at
89
disposal leaching draining to lower levels resulting in higher concentrations as depth
increases. However, because arsenic is already present in the groundwater above EPA MCLs
it does not make a ideal trace parameter to identify CCBs (seeFigure 51).
Other constituents also showed increasing (Figure 58), level (Figure 60) and decreasing
concentration trends (Figure 59) just not on the same scale of Ba. Anions were also analyzed
and sulfate and sodium were the only constituents increased with depth (Figure 61). It
should be noted that the decrease/increase on the last data point can be misleading for
reasons discussed above which involve the coal burning process.
Changes in Concentration of CCBs as Depth Increases
0
0.5
1
1.5
2
2.5
3
3.5
0 20 40 60 80 100 120 140
Depth (ft)
Norm
aliz
ed C
once
ntra
tion
(C/C
o)
BCoCrNiSi
Figure 58 : Elements showing concentration increases with depth (normalized concentration)
90
Changes in Concentration of CCBs as Depth Increases
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
0 20 40 60 80 100 120 1Depth (ft)
Norm
aliz
ed C
once
ntra
tion
(C/C
o)
40
AlCdFeMgMoSeAs
Figure 59 : Elements showing concentration with depth (normalized concentration)
Changes in Concentration of CCBs as Depth Increases
0
0.2
0.4
0.6
0.8
1
1.2
0 20 40 60 80 100 120 140
Depth (ft)
Norm
aliz
ed C
once
ntra
tion
(C/C
o)
CaKLiSrV
Figure 60 : Elements showing concentration level with depth (normalized concentration)
91
Changes in Concentration of CCBs as Depth Increases
0
0.5
1
1.5
2
2.5
0 20 40 60 80 100 120 140
Depth (ft)
Norm
aliz
ed C
once
ntra
tion
(C/C
o)
FClNO2NO3SO4CaL
Figure 61 : Elements showing concentration with depth for anions (normalized concentration) The arsenic CCB samples concentrations were also plotted against the corresponding sample
depth which displays a general increasing trend as depth increases as seen in Figure 62.
92
Changes in Arsenic in CCBs as Depth Increases
00.20.40.60.8
11.21.41.61.8
2
0 50 100Depth (ft)
Nor
mal
ized
Con
cent
ratio
n (C
/Co)
150
Figure 62 : Changes in Arsenic concentration with depth (normalized concentration)
Increasing concentrations after burial may be the result of leachates from material at shallow
depths migrating to underlying materials. Similarly, immediate decreases after burial are
likely the result of the 20% in-situ water content leaching the available element away. The
unvarying concentration at middle depths is most likely due to minimal changes in the CCB
condition between these depths.
4.3. Leachate variability with time
Column leach tests were utilized to simulate rain water percolating through complete layers
of fly ash, bottom ash and spoil to determine the sequence of analytes within the leachate
from each material and to monitor how concentrations changed over time. DI water was
used in 6 of the 8 columns to simulate rain water while No 8 Coal Seam water was used on 2
93
of the columns to simulate inflow to the mine from groundwater. Table 13 shows the
historical average and range of water quality from the No 8 Coal Seam water and as
previously stated when compared to typical water quality parameters, seen in the far column,
shows the No 8 Coal Seam water is of poor quality. The columns consisted of each
subgroup (FA, BA and spoil) and results show how previous buried samples compare to
fresh samples.
94
Table 13 : Water Quality Results for No 8 Coal Seam Water used for column leach and historical data compared to typical water quality data
Parameter Low High Average Low HighpH 7.9 8.7 8.143333 4.85 12.61
Spec cond (uS/cm) 5160 7280 5900TDS 3190 4850 4141 30 69800TOC 4.4 50 13.9 0.001 415
K 3.5 4.9 4.04 0.001 286PO4 0.06 0.46 0.168 0.001 34.8Ca 7.9 20 13.88 4600Mg 2.5 8 4.93 0.1 2270Na 1090 1650 1371 0.1 27800H2S 0.22 171 83.19125 0.2 386
Phenols 0.001 7.8HCO3 760 1720 1248 0.001 2970CO3 1 220 61 75Cl 58 520 217.4 16700F 1.9 4 2.333333 0.1 54
SO4 580 3000 1948 0.01 52000NO3 0.02 2 0.295 0.5 180Al 0.1 0.1 0.1 0.5 31As 0.0005 0.005 0.00318 0.05 2.41B 0.8 1.4 1.09 0.005 10Ba 0.0179 0.2671 0.104256 0.001 51.6Cd 0.00005 0.001 0.000441 0.00005 0.5Cr 0.001 0.095 0.023 0.001 0.5Cu 0.0001 2.4 0.26542 0.0001 8.7Co 0.01 0.0161 0.01122 0.00028 0.3Fe 0.03 0.08 0.048889 0.001 72.3Pb 0.0001 0.01 0.00432 0.0001 2.82Mn 0.005 0.023 0.009778 0.0005 12.4Hg 0.002 0.002 0.002 0.0001 0.06Mo 0.005 0.005 0.005 0.001 0.07Ni 0.001 0.2Se 0.005 0.025 0.0512 0.001 15.4Ag 0.00005 0.5V 0.0005 0.1 0.04499 0.0001 2U 0.00001 0.001 0.000444 0.00001 150Zn 0.007 0.16 0.05204 0.001 5.98
Ra-226 0.23 1 0.5925 0 579
Water Quality DataNo 8 Coal Seam Since 2005
The column tests varied from the DI Water Extraction in the ratio of water to soil mass. The
DI water extraction test use at mass of water-to-mass of soil ratio of 20 while the ratio used
95
in the columns tests was 0.14. Others report that low water-to-soil ratio can be representative
when samples are corrected for water content (Bin-Shafique et al. 2006)(Ram et al. 2007).
Initial constituent concentrations in the column tests varied widely, as seen in Figure 63 and
Figure 64, ranging from 2270 mg/Kg for Na in old buried bottom ash material to 0.18 mg/Kg
for Ni in spoil material. Due to very low concentrations, leachate results for Ag, Be, Pb, Zn,
Mg, Cu, Mn, Ni, Co, Cd and Fe are not reported here. Results for these constituents are
contained in the Appendix.
Sodium Leachate Concentration
0
500
1000
1500
2000
2500
7/26/11 7/31/11 8/5/11 8/10/11 8/15/11 8/20/11 8/25/11 8/30/11 9/4/11
Time
Conc
entr
atio
n (m
g/Kg
)
Fresh Fly AshFresh Bottom AshOld Buried Fly AshOld Buried Bottom AshYoung Buried AshSpoilFresh Fly Ash No 8 WaterOld Fly Ash No 8 WaterNo 8 Coal H2O
Figure 63 : Column test concentration changes over time for Na with largest initial concentration
96
Nickel Leachate Concentration
0.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
0.16
0.18
0.20
7/26/11 7/31/11 8/5/11 8/10/11 8/15/11 8/20/11 8/25/11 8/30/11 9/4/11
Time
Con
cent
ratio
n (m
g/Kg
)
Fresh Fly AshFresh Bottom AshOld Buried Fly AshOld Buried Bottom AshYoung Buried AshSpoilFresh Fly Ash No 8 WaterOld Fly Ash No 8 WaterNo 8 Coal H2O
Figure 64 : Column test concentration changes over time for Ni with smallest initial concentration To facilitated graphical display constituent concentrations of the leachates were normalized
by plotting the ratio C/Cinitial where Cinitial was the concentration in the first pore volume of
water passing through the column (Figure 65 through Figure 75).
DI water leachate through the fresh fly ash sample percolated with DI water took 6 days to
before breakthrough and samples were collected over 37 days. This was the only sample in
which precipitates appeared in the collection vial. 18 days after the initial water was added,
what appeared to be white amorphous aluminum precipitation, consistently appeared in the
samples collected for 8 days and then disappeared. Results show that Ba had the highest
concentration and it was one of the constituents to leach first with Sr which then slowly
declined with time. Ca, Li and Al all appeared after 6 days but did not appear at the same
levels of Ba (Figure 65).
97
Fresh Fly Ash with DI Water
0
2
4
6
8
10
12
14
16
Time (days)
Nor
mal
ized
Con
cent
ratio
n (C
/Co)
Al 396.153 B 249.772 Ba 455.403
Ca 317.933 K 766.490 Li 610.362
Mo 202.031 Na 589.592 Se 196.026
Si 251.611 Sr 421.552 V 310.230
Figure 65 : Normalized concentrations of constituents in DI water column leachate of fresh fly ash
From Figure 66 shows Ca and Li concentration spikes initially then remain fairly constant
thereafter. B, Na, K, Mo, Na and Se all showed leaching behavior expected of readily
soluble constituents that asymptotically approached zero. Al and Si showed a curve
matching that of slow mineral dissolution where concentrations spiked after 20 day and
slowly decreased. Mineral dissolution of aluminosilicates results in higher Al concentration
than Si as reported by others (Dudas and Warren 1987).
98
Fresh Fly Ash with DI Water
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
Time (days)
Nor
mal
ized
Con
cent
ratio
n (C
/Co)
Al 396.153B 249.772Ca 317.933K 766.490Li 610.362Mo 202.031Na 589.592Se 196.026Si 251.611V 310.230
Figure 66 : Normalized concentrations of constituents in DI water column leachate of fresh fly ash with Ba, and Sr removed
The column of fresh bottom ash leached with DI water took 5 days to breakthrough with
water added to the column daily for 37 days. The results shown in Figure 67 show that the
majority of the elements follow a rapid leaching curve which, on average, lasted for 12 days
before approaching zero. Li and Al had a slight peak in concentration initially, but not on the
scale of concentration seen in fresh fly ash (Figure 65). After 14 days V concentrations
begin to spike before slowing dropping which was similar to dissolution of the fly ash
particles (Figure 65).
99
Fresh Bottom Ash with DI Water
0
1
2
3
4
5
6
7
8
Time (days)
Norm
aliz
ed C
once
ntra
tion
(C/C
o)
Al 396.153 B 249.772 Ba 455.403
Ca 317.933 K 766.490 Li 610.362
Mo 202.031 Na 589.592 Se 196.026
Si 251.611 Sr 421.552 V 310.230
Figure 67: Normalized concentrations of constituents in DI water column leachate of fresh bottom ash The column containing old buried fly ash leached with DI water took 6 days to break through
and water was added daily and samples collected for another 31 days. Li was the only
element that showed a dramatic change in concentration relative to the other analytes (Figure
68). The majority of analytes followed an asymptotic leaching trend except Ca, V and B.
These constituents remained constant throughout the 37 day period however, they were
present in lower concentrations (1.5 C/Co) than those found in fresh fly ash (2 C/Co) . This
implies less weathering or mineral dissolution within the old fly ash than fresh fly ash over
the same the time period measured.
100
Old Fly Ash with DI Water
0
1
2
3
4
5
6
Time (days)
Norm
aliz
ed C
once
ntra
tion
(C/C
o)Al 396.153 B 249.772 Ba 455.403
Ca 317.933 K 766.490 Li 610.362
Mo 202.031 Na 589.592 Se 196.026
Si 251.611 Sr 421.552 V 310.230
Figure 68: Normalized concentrations of constituents in DI water column leachate of old buried fly ash The column containing old buried bottom ash and leached with DI water took 7 days to
breakthrough and samples collected 31 more days. Results are similar to Figure 68 which
displayed old fly ash, rather than the fresh bottom ash sample, with the majority of the
elements following a characteristic asymptotically declining leach profile and largest leach
concentration from Li. The highest Li concentration was found in the old buried bottom ash,
leached with DI water. The concentrations were twice those found in old fly ash and
approximately six times larger than those leached from fresh bottom ash material.
Vanadium, which leached to a large extent within the fresh bottom ash, showed a slowly
increasing trend. Aluminum and Si showed a dissolution trend similar to other columns but at
their highest concentration, approximately three times higher than previous concentrations
seen in fresh bottom ash (Figure 67).
101
Old Bottom Ash with DI Water
0
2
4
6
8
10
12
Time (days)
Norm
aliz
ed C
once
ntra
tion
(C/C
o)Al 396.153 B 249.772 Ba 455.403
Ca 317.933 K 766.490 Li 610.362
Mo 202.031 Na 589.592 Se 196.026
Si 251.611 Sr 421.552 V 310.230
Figure 69: Normalized concentrations of constituents in DI water column leachate of old buried bottom ash
The column of young leached with DI water took 6 days to breakthrough and water and
sample collected for another 31 days. The trends displayed in Figure 70 are similar to
previous fly ash column trends in Figure 68 and Figure 65 with most the elements showing
asymptotic decreasing leach profiles. Aluminum, Si, Li and V showed increasing trends of
concentration representative of CCB dissolution with Al concentrations found similar to
those in old bottom ash. The third Si data point is uncharacteristic of the trend and is
believed to be an analytical error.
102
Young Fly Ash with DI Water
0
1
2
3
4
5
6
7
8
9
10
Time (days)
Norm
aliz
ed C
once
ntra
tion
(C/C
o)Al 396.153 B 249.772 Ba 455.403
Ca 317.933 K 766.490 Li 610.362
Mo 202.031 Na 589.592 Se 196.026
Si 251.611 Sr 421.552 V 310.230
Figure 70: Normalized concentrations of constituents in DI water column leachate of young buried fly ash
The spoil column was leached with DI water for 37 days. It took 14 days to breakthrough
and no more than 10 mL were ever collected every two days although 34.3 mL added daily
for the first three days. By the fourth day the head space above the spoil material was
completely full of water as the water leached through at a much slower rate then the CCBs.
Water was added until the head space above the spoil material was filled and then daily
addition of water was discontinued except to keep the head space full. A total volume of
1,269 mL was passed through the columns containing CCBs over 37 days while the spoil
column only passed a total volume of 267.2 mL over 37 days. Clay in the spoil material
(Figure 71) results in a very low saturated hydraulic conductivity estimated at 10-6 cm/sec
which prevented flow of water through the column. Boron had the highest concentration in
the spoil percolated with DI water than all the other CCB columns. Boron also leached first
but after 2 days its concentration declined. Molybdenum was the next constituent to leach
103
and took 12 days to decline and only showed up in trace amounts in other CCB columns.
The rest of the constituents showed characteristic asymptotic leach curves with Li remaining
fairly constant. Leachate concentration of Al, Si and Li did not increase with time from the
spoil material in contract to the other leach columns.
Spoil with DI Water
0
1
2
3
4
5
6
Time (days)
Nor
mal
ized
Con
cent
ratio
n (C
/Co)
Al 396.153 B 249.772 Ba 455.403
Ca 317.933 K 766.490 Li 610.362
Mo 202.031 Na 589.592 Se 196.026
Si 251.611 Sr 421.552 V 310.230
Figure 71: Normalized concentrations of constituents in DI water column leachate of spoil
A column of fresh fly ash was leached with No 8 Coal Seam water for 30 days. It took 7
days to breakthrough. Many constituents such as Se, Mo and Ba showed an expected
decreasing concentration trend. Al concentrations in Figure 72 increased similar to young fly
ash leached with DI water (Figure 70). Al, Li and Si all showed clear increasing trends
representative of mineral dissolution with increasing concentrations with time increased.
Vanadium had the higher concentrations in fresh fly ash percolated with No 8 Coal Seam
water than the other columns and shows an increasing trend with time.
104
Fresh Fly Ash with No8 Coal Seam Water
0
2
4
6
8
10
12
Time (days)
Norm
aliz
ed C
once
ntra
tion
(C/C
o)Al 396.153 B 249.772 Ba 455.403
Ca 317.933 K 766.490 Li 610.362
Mo 202.031 Na 589.592 Se 196.026
Si 251.611 Sr 421.552 V 310.230
Figure 72: Normalized concentrations of constituents in No 8 Coal Seam Water column leachate of fresh fly ash
By not plotting Al, Li, V and Si the asymptotic leach trend of minerals can be seen in Figure
73. Sr and Na show a relatively consistent concentration over time while Se and Mo
concentrations decrease quickly. The concentrations for these constituents, however, are
small (less then 1%) to begin with and relatively small changes over time ( less then 1%)
making them of little importance.
105
Fresh Fly Ash with No8 Coal Seam Water
0
0.2
0.4
0.6
0.8
1
1.2
Time (days)
Nor
mal
ized
Con
cent
ratio
n (C
/Co)
B 249.772Ba 455.403Ca 317.933K 766.490Mo 202.031Na 589.592Se 196.026Sr 421.552
Figure 73: Normalized concentrations of constituents in No 8 Coal Seam Water column leachate of fresh fly ash with Al, Li and V not plotted The column of old FA that was leached with No 8 Coal Seam water lasted for 30 days. It
took 7 days before breakthrough and shows very similar trends to fly ash leached with DI
water. Barium had the highest normalized leach concentration of all the columns and took 18
days to completely leach out. Al and Si concentrations increased with time when leached
with No. 8 Coal Seam water implying dissolution of aluminosilicate minerals.
106
Old Fly Ash with No8 Coal Seam Water
0
5
10
15
20
25
30
35
40
45
50
Time (days)
Nor
mal
ized
Con
cent
ratio
n (C
/Co)
Al 396.153 B 249.772 Ba 455.403
Ca 317.933 K 766.490 Li 610.362
Mo 202.031 Na 589.592 Se 196.026
Si 251.611 Sr 421.552 V 310.230
Figure 74: Normalized concentrations of constituents in No 8 Coal Seam Water column leachate of old buried fly ash
Removing Ba, Al and Si, from the plots facilitates examination of the leaching behavior of
the other constituents ( Figure 75). Li increases with time which is consistent with
appearance due to mineral dissolution trend while the remaining constituents show an
asymptotically decreasing leach behavior. Sr results were not available for the first 3 data
points.
107
Old Fly Ash with No8 Coal Seam Water
0
0.2
0.4
0.6
0.8
1
1.2
7/31/11
8/5/11
8/10/11
8/15/11
8/20/11
8/25/11
8/30/11
Time (month/day/year)
Norm
aliz
ed C
once
ntra
tion
(C/C
o)B 249.772 Ca 317.933
K 766.490 Li 610.362
Mo 202.031 Na 589.592
Se 196.026 Sr 421.552
V 310.230
Figure 75: Normalized concentrations of constituents in No 8 Coal Seam Water column leachate of old buried fly ash with Ba, Al and Si removed
Observed trends in Figure 75 demonstrate the consistency of the results. Such trends can be
seen throughout all the data with minimal jumps in concentrations such as that seen in Figure
75 on the 9th data point of Li.
4.4. Mineralogical evidence of aging of buried CCB materials
Fresh CCB samples were compared to buried samples collected in the field for differences in
physical and mineralogical compositions. SEM images showed evidence of aging and lath-
like crystal growth. XRD results showed changes in the samples from amorphous structure
to more crystalline clay structure along with formation of secondary elements.
4.4.1. SEM
CCB samples were made up of mostly spheres with only a few other irregular or elongated
features. The spheres ranged in size from 100 μm to 50 nm. The spheres were made up of
108
mostly Si (10-28 weight%), Al (5-23 weight %) and oxygen with variable trace amounts of
Na, Mg, S, P, K, Ca, Ti and Fe. Images were collected using two detectors Secondary
electron imaging and Backscattered electron imaging. A secondary electron imaging (SE) is
an image which provides topographical information. Backscattered electron imaging (BSE)
is an image which provides spatial chemical information with the brighter material having
the higher the atomic number and visa versa (Spilde 2011). Figure 76 and Figure 77 show the
range of size and clumping of the silica spheres.
Figure 76 : SEM: SE fly ash sample, silicate spheres. Original magnification=400x; Scale Bar=100μm(Spilde 2011)
109
Figure 77 : SEM: BSE image fly ash. silicate spheres. Original magnification= 1500x; Scale Bar=20μm (Spilde 2011)
BA samples contained rough and irregular grains along with spheres. The samples had a
similar chemical composition of primarily Si and Al with trace amounts of Na, Mg, K, Ca, Ti
and Fe similar to the fly ash. One difference was higher levels of carbon which were
measured up to 45 weight % more in bottom ash then in the fly ash. An example of this can
be seen in Figure 78. Bottom ash samples also showed evidence of the spheres fusing
together as seen in Figure 79 (Spilde 2011).
110
Figure 78 : SEM: BSE bottom ash, silica glass spheres and angular material, darker contains significantly more carbon then silicate sphere. Original magnification =180x; Scale bar =200μm (Spilde 2011)
111
Figure 79 : SEM: BSE bottom ash. Glass sphere and silica glass blobs fused to aggregate. Original magnification=1000x; Scale bar=50μm (Spilde 2011)
FGDS samples, as expected, consisted primarily of calcium sulfate crystals. The crystals
were subhedral to euhedral and showed a monoclinic crystal habit that is common in
gypsum. Figure 80 is a BSE image of the uniform gypsum that makes up FGDS (Spilde
2011).
112
Figure 80 : SEM: BSE FGDS Close up of crystal aggregate. Original magnification=430x; Scale bar=100μm (Spilde 2011)
Old ash samples show similar composition and the presence of spheres as in fresh samples.
However, the older samples showed significant alteration and degradation with more
fracturing of spheres, irregular blobs and fine material meshing the spheres together. In
addition, a mesh between spheres of lath-like crystals was observed as seen in Figure 82
made up of Si, Al and Ca while the composition of the mesh could not be verified (Spilde
2011).
113
Figure 81 : SEM: BSE Old bottom ash. Broken spheres and growth together. Original magnification=500x;Scale bar=100μm (Spilde 2011)
114
Figure 82 : SEM: SE old buried fly ash. Fine mesh material on surface and crystal growth. Original magnification=3000x; Scale bar=10μm (Spilde 2011)
4.4.2. XRD
Previous studies of CCBs characterized by XRD reported that the primary composition is
quartz, mullite and glass with minor phases of cristobalite, magnetitie, maghemite and
hematite. The minor phases present depend on the mineralogical variation within the parent
coal and should be mostly amorphous constituents (You, UM, and et al. 2009; You, UM, and
et al. 2009; Sultana, Das, and et al. 2011; Ward and French 2006; Connolly 2011).
Fresh fly ash samples resulted in matches of composition of quartz (SiO2) and mullite
(Al6Si2O13) (Table 6). The X-ray diffraction pattern also displayed a substantial background
peak indicating significant amorphous constituents, which with manual comparison matched
115
data patterns of hematite (Fe2O3) (Connolly 2011). Figure 83 shows the diffraction pattern
match for fresh fly ash.
Figure 83 : XRD Fresh fly ash diffraction pattern match (Connolly 2011) The diffraction pattern of fresh bottom ash displayed matches for mullite and quartz as the
dominant phases. There is a defined amorphous peak; however it is not as distinctive as in
the fly ash implying that the amount of amorphous components may be smaller. There were
two peaks that were consistent with the presence of Calcite (CaCO3) and Feldspar (Albite
NaAlSi3O8), this can be seen in Figure 84.
116
Figure 84 : XRD Fresh bottom ash diffraction pattern match (Connolly 2011)
The FGDS diffraction pattern indicated the presence of gypsum with a well defined
crystalline structure. Trace amounts of calcite and quartz were also found and can be seen in
(Figure 85) (Connolly 2011).
117
Figure 85 : XRD Fresh FGDS diffraction pattern match with gypsum (Connolly 2011)
Old fly ash samples showed a diffraction pattern similar to the fresh fly ash samples with the
clear presence of quartz and mullite. The old fly ash contains more crystalline structure
shown by the smaller amorphous. A clear calcite peak is present that was not in the fresh fly
ash diffraction pattern. A peak at 9.07 degrees has possible matches of aluminum phosphate,
ferrierite, clintonite and paragonite but can not be positively identified with given XRD
resolution. The match diffraction pattern can be seen in Figure 86 (Connolly 2011).
118
Figure 86 : XRD old buried fly ash diffraction pattern match (Connolly 2011)
The diffraction pattern of Old bottom ash was similar to the fresh bottom ash pattern in
indicating the presence of mullite and quartz with calcite and feldspar peaks. The intensity
peaks of quartz are lower than in the fresh bottom ash samples. Figure 87 show the match of
old bottom ash with these constituents (Connolly 2011).
119
Figure 87 : XRD old buried bottom diffraction pattern match (Connolly 2011) A spoil sample showed characteristics of a clay material with quartz and nontronite (an iron-
rich clay) with other various clay phases. These phases can be seen in the diffraction pattern
in Figure 88 (Connolly 2011).
120
Figure 88 : XRD Spoil diffraction pattern match for clays
Fly ash diffraction patterns were compared in Figure 89. The black line is fresh fly ash that
has never been buried and shows a similar fly ash pattern established above. The red line is
buried fly ash sample from SM04 collected 10 feet below the surface and shows a fly ash
diffraction pattern with the addition of a calcite peak. The final maroon line is from SM04
collected 125 below the surface and shows a fly ash diffraction patter with a calcite peak. A
clear resemblance can be seen in the overall pattern indicating mullite and quartz
constituents. The buried samples, seen in red and maroon, show a peak indicating the
presence of calcite. The oldest samples, plotted in maroon, display a series of small low
angle peaks which is an indication of clay minerals that are not present in the younger sample
seen in red. According to the XRD analyst it implies there is some diagenetic process
121
resulting in the formation of secondary calcite and development of clays by alteration of the
ash (Connolly 2011).
Figure 89 : XRD fly ash sample comparison showing calcite peak within buried samples only.
Diffraction patterns for aged bottom ash samples of different ages are compared in Figure 90.
The black pattern is that of the fresh ash and shows the bottom ash characteristic feldspar and
calcite peak. The red line is from the SM04 sample collected 120 feet below the surface that
when collected was coarse and showed physical characteristics (color and granulation)
expected of bottom ash. The maroon line is the diffraction pattern of bottom ash collected
from the SM04 site 109 feet below the surface and appeared to be bottom ash. The
diffraction patterns reveal that what was believed to be bottom ash was simply fly ash as it
122
lacks the feldspar and calcite peak characteristic of bottom ash. The older bottom ash shows
a less prominent peak of quartz then the fresh sample and non clay peaks were sited
(Connolly 2011).
Figure 90 : XRD bottom ash diffraction pattern comparison and identification of fly ash sample rather then bottom ash. (Connolly 2011)
The results show that there was evidence, at least in the fly ash, of aging and the ash
mineralogy changing from a glassy amorphous phase to a more clay/crystalline structure.
The presence of calcite in the fly ash as a secondary phase is also sited as aging as it would
not survive the furnace temperatures and verified with the SEM lath-like crystals.
123
4.5. Stratigraphy around CCBs and the relationship with No 8 Coal Seam
Results from the column leach study demonstrate that specific constituent concentrations
depend largely upon the characteristics of the water which will interact with buried CCBs in
the future. The stratigraphy surrounding buried CCB pits depend on the pits location as CCB
were used to fill low spots historically (Ginn, Perkins, and O’Hayre 2009). CCB pits are
known to be either surrounded by spoil material entirely or along the tops and sides by spoil
material, with PCS enclosing along the bottoms (Ginn, Perkins, and O’Hayre 2009). It is
inferred then, that CCBs should leach similar to the columns percolated with No 8 Coal Seam
water. The column leached with No 8 Coal Seam water showe higher mineral dissolution
and higher Ba concentrations.
4.6. Potential Impacts of Leachate from Buried CCBs on groundwater To determine the potential of CCB leachate to contaminate underlying SJCM groundwater,
the maximum concentration of each constituents found in the column leach tests was
compared to the corresponding concentration of the same constituents in the underlying
groundwater obtained from monitoring well “GL” (see Figure 17). Monitoring well GL was
chosen as representative of underlying groundwater as it is the nearest monitoring well to the
disposal pit ash where buried CCB samples were collected. Constituents which
demonstrated a higher concentration in CCB leach as opposed to water from monitoring well
GL were identified as potential contaminants. Levels of Al, B, Ba, Ca, Li, Mo, Si, Sr and V
were higher in the CCB leachate compared to groundwater. Table 14 shows a sample of
these results with potential contaminant constituents highlighted in blue.
124
Table 14 : A comparison of contaminate concentration in CCB column leachate and groundwater from monitoring well GL
Parameter(mg/kg) FFA FBA OFA OBA YFA Spoil FFA OFA
Al 0.005 1.503 0.273 0.315 1.55 5.667 0.031 2.064 3.273B 1.13 2.146 67.64 29.6 33.51 33.26 7.406 40.26 11.34
Ba 0.1 6.42 0.067 0.058 0.053 0.052 0.154 0.057 4.32Ca 508 436.6 665.2 605.7 454.2 591.2 317.5 403.4 472.7Se 0.0105 0.125 0.244 0.182 0.088 0.078 1.934 0.191 0.935Si 10.25 0.768 6.334 8.093 4.316 2.256 8.766 1.97 27.12V 0.1 0.026 0.147 0.24 0.141 0.136 -0.024 0.757 0.49
High CCB Leach
DI WATER Recharge GWRecharge
GWColumn Tests
The column study contained herein demonstrated that constituents B, Ca, Mo and Sr will
follow an asymptotic leach. As such it is assumed that concentrations of these constituents
will quickly decline in-situ, while in the presence of No 8 Coal Seam water. (Figure 105).
Al, Li, Si, and V are elements associated with mineral dissolution and will likely increase
over time as the CCBs disassociate as seen in Figure 111.
Until mine dewatering ceases, it is assumed that the groundwater level will not return to its
original piezometric surface. When the water table is allowed to return the likely scenario of
surface water infiltrating the spoil is very unlikely. This is due to the very low hydraulic
conductivity of the spoil material (10-6 cm/sec). This suggests that once buried, leachate
from CCBs would not reach underlying groundwater for over several hundred years due to
surface water infiltration. Similarly, groundwater will not infiltrate CCB pits from below for
over several hundred years.
125
5. Conclusion
5.1. Analytes of concern
Barium and arsenic were established as the primary SJCM and MMD analytes of concern
because of their relatively high concentration in leachates from CCBs in most ash analyses
collected since 1972. Results presented here also indentify barium and arsenic as the
constituents of principal concentration from CCBs (Luther, Musslewhite, and Brown
2009)(Mines and Minerals Division, New Mexico 2011). This study found that barium and
arsenic concentrations increase with depth in CCB disposal pits.
Selenium and boron, which have been reported in similar studies regarding CCBs as having
elevated concentrations were surprisingly not found at high concentrations in SJCM ash
(Zhao et al. 2006; Yuan 2009; Baba et al. 2008; Bhangare et al. 2011). In addition, these
constituent concentrations did not approach drinking water MCLs in any of the CCB or spoil
samples.
There is no significant difference in constituent concentrations between CCBs and spoil
material. For example, in Figure 54, an average iron concentration of 20872 mg/kg was
observed in the CCBs which not statistically different from the average concentration of iron
in the spoil material of 19440 mg/kg. Further, the mass of spoil in the backfill area is orders
of magnitude larger than the mass of ash (except in the immediate vicinity of ash disposal
areas). Therefore, it is not possible to determine the relative contributions of iron to
underlying groundwater.
126
The concentrations of all constituents associated with the CCBs are not high enough to result
in exceedance of groundwater standards for any parameters except for potential barium and
arsenic.
5.2. Specific leachates and sequence
Most of the constituents in CCBs decreased, in concentration, exponentially with time when
exposed to deionized water or No. 8 Coal Seam groundwater. Constituents typically
disappeared within 14 days of initial percolation. Barium was an exception as its highest
concentration was observed 16 days after initial percolation with DI and No 8 Coal Seam
water.
Also aluminum and silicon concentrations spiked 28 days after the initial percolation which
was evidence of aluminosilicate mineral dissolution occurring in all CCB samples. Samples
leached with DI water showed a slower dissolution rate than those with No 8 Coal Seam
water. Overall, the highest aluminum and silicate concentrations were observed when buried
old CCB samples were leached with No 8 Coal Seam water. Higher ionic strength, present
within the coal seam water likely resulted in a higher activity and thus higher dissolution of
constituents.
5.3. Evidence of aging in the buried CCBs SEM analysis of buried CCBs showed signs of dissolution when compared to fresh CCB
samples with rounded edges and fractures of glassy fly ash particles. There was also
evidence of calcite, a secondary mineral, having formed in the buried ash. XRD analysis
127
verified the presence of calcite within the buried CCB samples as well as the oldest samples
having showed higher crystalline structure than that of young buried CCBs.
The spoil material was classified as sodium saturated smectitic clays with a secondary
accumulation of sulfate and carbonate salts which swelled when water was introduced. As a
result, the hydraulic conductivity of the spoil was shown to be very low (10-6 cm/s). This
was observed when only 267 ml of a total 1269 ml amount of water added infiltrated through
the unsaturated spoil columns. These results suggest that very little water will infiltrate
through the spoil cover and reach the buried ash in the future.
5.4. Comparison of results with historical data
Minor differences were observed between historical results and those from this study. The
observed difference is believed to be due to the varying composition of the coal as mining
progressed. The varying composition in coal with depth of disposal can be attributed to
differences in air pollution control equipment over the 40 years the power plant has been in
operation, as well as differences analysis procedures. The majority of the tested CCB
samples were collected from the Juniper Pit area and represent the potential of leachate in the
event that groundwater enters that pit. The No 8 Coal Seam water is believed to be
representative of the groundwater that will eventually fill the mine when mine dewatering
stops. Potentiometric maps suggest that the No 8 Coal Seam water will penetrate the side of
the Juniper Pits due to alluvial flows.
128
5.5. Applicability of Kingston, TN spill to SJCM operations
It should be noted that the spill scenario which played out at the Tennessee Valley Authority
(TVA) Kingston, TN coal power plant, mentioned previously, is unlikely to take place at the
SJCM for a number of reasons. The TVA plant added water to their CCB waste to transport
it along flumes to the ash detention ponds. SJCM uses haul trunks which are sprayed with
water to inhibit particles from being blown away during transport. TVA stored CCBs in
man-made berms, above surrounding ground level while SJCM places their CCBs in the old
open pit mine, below ground level. The TVA spill led to the contamination of surrounding
while CCBs at SJCM would only be able to contaminate groundwater due to below ground
storage, surrounding hydrology and lack of lined disposal pits. However, due to the low
hydraulic conductivity of the surrounding soils and spoil cover, the infiltration rate of
groundwater when it is allowed to return will be very slow, and thus take several hundred
years to infiltrate the CCB pits. In conclusion the summation of these differences eliminates
the possibility of a spill, similar to that of the TVA plant from occurring at SJCM.
129
Appendix
Figure 91 : Summary of average total contaminants in CCBs and Spoil for all elements analyzed
Average Total Contaminants in CCBs and Spoil
0
20
40
60
80
100
120
Co Cr Cu Ni Pb Sr V Zn
Element
Tota
l Con
cent
ratio
n (m
g/K
g) Spoil Fresh Ash Buried Ash
Average Water Extract
0
5000
10000
15000
20000
25000
30000
F Cl NO2 Br NO3 PO4 SO4 Ca K Mg Na
Parameter
Sam
ple
conc
entr
atio
n(m
g/Kg
)
Spoil Fresh Ash Buried Ash
Table 15 : Total acid digest results of each constituents’ concentration for each sample
Total Chemical Analysis
Sample(mg/Kg) YR1-01-01T YR1-01-01B YR1-01-02B YR1-01-03B YR1-01-05B NE_FA_01 NE_BA_01 NE_FGD_01 YR1-01-06B JP4_04_01B JP4_05_01B JP4_06_01BAnalyte Name 01T 01B 02B 03B 05B FA BA FGDS 06B 01B 01B 01B
Ag - - - - - - - - - - - -
Al 26670 21573 28072 26233 29838 43650 7521 35077 32327 37069 39540
As 0.091 0.185 0.062 0.236 0.110 0.208
B 4276 4038 3528 3355 4308 342 338 2075 3145 525 598 830Ba 2238 1805 1690 1403 1862 223 1561 118 1859 1422 1921 2534BeCa 5839 3994 2615 743 3266 7669 8186 1486 4500 6195 5804 6269CdCo 5 11 11 13 12 9 7 0 12 7 6 5Cr 15 18 25 22 21 17 14 1 17 13 13 14Cu 12 19 27 39 43 37 31 4 39 30 33 37Fe 17672 20941 22562 20941 20804 525 20577 22908 22833 19798
University of New Mexico-Earth and Planetary Department-Dr Abdul-Mehdi S. Ali
130
131
Table 16: Table 15 Contiuned… Total acid digest results of each constituents’ concentration for each sample
Sample(mg/Kg) YR1-01-01T YR1-01-01B YR1-01-02B YR1-01-03B YR1-01-05B NE_FA_01 NE_BA_01 NE_FGD_01 YR1-01-06B SM4-04-01B SM4-05-01B SM4-06-01BAnalyte Name 01T 01B 02B 03B 05B 06B 01B 01B 01B
K
FA BA FGDS
11370 8901 9001 3714 3749 3962 3564 3833 3109 2171 3180 3815Li 606 364 265 70 325 730 774 167 442 583 554 601
Mg 929 402 736 180 232 656 492 1246 484 353 340 391Mn 226 357 204 125 153 119 115 48 122 129 169 127MoNa 13335 15304 12687 8381 11398 8535 8945 9640 8400 7016 8748 9437Ni 7 12 14 11 11 7 6 2 9 7 7 6Pb 3 6 4 21 24 12 13 2 16 7 10 19SeSi 189432 128863 117982 90463 124502 56692 82234 74900 93365 68352 119880 163049
Sr 81 43 32 34 110 124 82 10 110 89 96 103
V 38 48 67 66 64 51 41 12 60 42 42 46Zn 43 62 73 52 49 39 99 40 22 25 34
Ash Sample
Spoil or Spoil/Ash mix
New Ash Sample Table 17 : DI Extraction results for spoil, fresh CCBs and buried CCBs Sample(mg/Kg) YR1-01-01T YR1-01-01B JP1-01-08B NE_FA_01 NE_BA_01 NE_FGD_01 YR1-01-06B JP4_04_01B JP4_05_01B JP4_06_01B KPC3_01_01BAnalyte Name
01T 01B 08B FA BA FGDS 06B 4 5 6 1
F 1.10 1.55 1.25 14.0 1.54 158 58.3 7.07 5.79 5.95 15.7Cl 2.99 11.7 106.1 34.5 40.9 1154 319 11.2 361 15.1 147
NO2 0.4562 18.2 0.0817 3.22 0.324 0.831 39.7 1.22 0.732 0.838 0.692Br 0.0413 - 0.1495 57.3 0.380 6.06 - - 0.643 - -
NO3 34.7 - 37.2 90.2 3.55 73.8 193.4 2.66 3.88 4.25 15.1PO4 0.2607 - - - - 14.6 - - 2.33 - 1.90SO4 9.22 50357 8934 1034 380 20824 22730 2191 2386 2044 7521
132
Table 18 : Two Tail T-Test with Unequal Variance results for each analyte
Spoil Ash Fresh FA BA Old AshMean 24416.75 36003.19843 Mean 43650.39841 36003.1984Variance 14382619.36 9338552.483 Variance #DIV/0! 9338552.48Observations 8 4 Observations 1 4Hypothesized Mean Difference 0 Hypothesized Mean Difference 0df 7 df 0t Stat -5.699617516 t Stat 5.004868385P(T<=t) one-tail 0.000367821 P(T<=t) one-tail #NUM!t Critical one-tail 1.894578604 t Critical one-tail #NUM!P(T<=t) two-tail 0.000735641 P(T<=t) two-tail #NUM!t Critical two-tail 2.364624251 t Critical two-tail #NUM!
Spoil Ash Fresh FA BA Old AshMean 3735.240879 780.3452828 Mean 340.0149402 651.046858Variance 2062941.779 83770.62695 Variance 5.239252155 25347.4448Observations 8 4 Observations 2 3Hypothesized Mean Difference 0 Hypothesized Mean Difference 0df 8 df 2t Stat 5.596128421 t Stat -3.38322731P(T<=t) one-tail 0.000256278 P(T<=t) one-tail 0.038681403t Critical one-tail 1.859548033 t Critical one-tail 2.91998558P(T<=t) two-tail 0.000512555 P(T<=t) two-tail 0.077362806t Critical two-tail 2.306004133 t Critical two-tail 4.30265273
Spoil Ash Fresh FA BA Old AshMean 1801.559417 1933.886525 Mean 891.7455179 1933.88652Variance 67535.72636 209255.5732 Variance 894819.5096 209255.573Observations 8 4 Observations 2 4Hypothesized Mean Difference 0 Hypothesized Mean Difference 0df 4 df 1t Stat -0.536852201 t Stat -1.474217405P(T<=t) one-tail 0.309919447 P(T<=t) one-tail 0.189722584t Critical one-tail 2.131846782 t Critical one-tail 6.313751514P(T<=t) two-tail 0.619838893 P(T<=t) two-tail 0.379445167t Critical two-tail 2.776445105 t Critical two-tail 12.70620473
Spoil Ash Fresh FA BA Old AshMean 3610.374068 322.0454137 Mean 613.4926701 322.045414Variance 2534739.695 1005.529765 Variance 511739.5773 1005.52976Observations 8 3 Observations 2 3Hypothesized Mean Difference 0 Hypothesized Mean Difference 0df 7 df 1t Stat 5.838804529 t Stat 0.575792761P(T<=t) one-tail 0.000318907 P(T<=t) one-tail 0.333705412t Critical one-tail 1.894578604 t Critical one-tail 6.313751514P(T<=t) two-tail 0.000637815 P(T<=t) two-tail 0.667410824t Critical two-tail 2.364624251 t Critical two-tail 12.70620473
B
Al
Ba
Ca
KeySame population Difference Differenc
fresh Ash vs Old Ash Spoil vs Ash
133
Spoil Ash Fresh FA BA Old AshMean 9.323341356 12.82161337 Mean 8.229581673 12.8216134Variance 8.815719925 0.592659776 Variance 1.230449219 0.59265978Observations 8 4 Observations 2 4Hypothesized Mean Difference 0 Hypothesized Mean Difference 0df 9 df 2t Stat -3.128787 t Stat -5.255714565P(T<=t) one-tail 0.006072707 P(T<=t) one-tail 0.017173987t Critical one-tail 1.833112923 t Critical one-tail 2.91998558P(T<=t) two-tail 0.012145413 P(T<=t) two-tail 0.034347974t Critical two-tail 2.262157158 t Critical two-tail 4.30265273
Spoil Ash Fresh FA BA Old AshMean 19.35696099 33.38245461 Mean 15.21414343 33.3824546Variance 9.89424299 11.20377568 Variance 3.751180537 11.2037757Observations 8 3 Observations 2 3Hypothesized Mean Difference 0 Hypothesized Mean Difference 0df 3 df 3t Stat -6.290425341 t Stat -7.670542461P(T<=t) one-tail 0.004057284 P(T<=t) one-tail 0.002301486t Critical one-tail 2.353363435 t Critical one-tail 2.353363435P(T<=t) two-tail 0.008114569 P(T<=t) two-tail 0.004602971t Critical two-tail 3.182446305 t Critical two-tail 3.182446305
Spoil Ash Fresh FA BA Old AshMean 22.3378482 361.5715185 Mean 34.22559761 361.571518Variance 160.5263223 712.0898783 Variance 21.11852639 712.089878Observations 8 3 Observations 2 3Hypothesized Mean Difference 0 Hypothesized Mean Difference 0df 2 df 2
t Stat -21.14317217 t Stat -20.78973306P(T<=t) one-tail 0.001114745 P(T<=t) one-tail 0.001152838t Critical one-tail 2.91998558 t Critical one-tail 2.91998558P(T<=t) two-tail 0.00222949 P(T<=t) two-tail 0.002305675t Critical two-tail 4.30265273 t Critical two-tail 4.30265273
Spoil Ash Fresh FA BA Old AshMean 20966.75 21529.17183 Mean 20872.75896 21529.1718Variance 14173349.64 2502383.746 Variance 9377.951342 2502383.75Observations 8 4 Observations 2 4Hypothesized Mean Difference 0 Hypothesized Mean Difference 0df 10 df 3t Stat -0.363248791 t Stat -0.826815534P(T<=t) one-tail 0.361990102 P(T<=t) one-tail 0.234483404t Critical one-tail 1.812461102 t Critical one-tail 2.353363435P(T<=t) two-tail 0.723980205 P(T<=t) two-tail 0.468966808t Critical two-tail 2.228138842 t Critical two-tail 3.182446305
Cr
Co
Cu
Fe
KeySame population Difference Differenc
fresh Ash vs Old Ash Spoil vs Ash
134
Spoil Ash Fresh FA BA Old AshMean 8318.5 3068.782514 Mean 3762.761454 3068.78251Variance 8910530.857 458689.9614 Variance 79116.00144 458689.961Observations 8 4 Observations 2 4Hypothesized Mean Difference 0 Hypothesized Mean Difference 0df 8 df 4t Stat 4.736421277 t Stat 1.767100178P(T<=t) one-tail 0.000735357 P(T<=t) one-tail 0.075976343t Critical one-tail 1.859548033 t Critical one-tail 2.131846782P(T<=t) two-tail 0.001470714 P(T<=t) two-tail 0.151952686t Critical two-tail 2.306004133 t Critical two-tail 2.776445105
Spoil Ash Fresh FA BA Old AshMean 356.7988083 544.691138 Mean 751.6807769 544.691138Variance 27206.72228 5095.814288 Variance 976.7407586 5095.81429Observations 8 4 Observations 2 4Hypothesized Mean Difference 0 Hypothesized Mean Difference 0df 10 df 4t Stat -2.748070176 t Stat 4.930667708P(T<=t) one-tail 0.010273092 P(T<=t) one-tail 0.003934543t Critical one-tail 1.812461102 t Critical one-tail 2.131846782P(T<=t) two-tail 0.020546185 P(T<=t) two-tail 0.007869085t Critical two-tail 2.228138842 t Critical two-tail 2.776445105
Spoil Ash Fresh FA BA Old AshMean 450.3823435 141.5457866 Mean 573.5806773 141.545787Variance 66940.83888 551.5075954 Variance 13463.35896 551.507595Observations 8 3 Observations 2 3Hypothesized Mean Difference 0 Hypothesized Mean Difference 0df 7 df 1t Stat 3.339712309 t Stat 5.195251144P(T<=t) one-tail 0.006212281 P(T<=t) one-tail 0.060529107t Critical one-tail 1.894578604 t Critical one-tail 6.313751514P(T<=t) two-tail 0.012424562 P(T<=t) two-tail 0.121058214t Critical two-tail 2.364624251 t Critical two-tail 12.70620473
Spoil Ash Fresh FA BA Old AshMean 233.3968237 136.7010894 Mean 116.8949203 136.701089Variance 5506.668582 461.5560918 Variance 9.065146287 461.556092Observations 8 4 Observations 2 4Hypothesized Mean Difference 0 Hypothesized Mean Difference 0df 9 df 3t Stat 3.410784075 t Stat -1.808638548P(T<=t) one-tail 0.003870001 P(T<=t) one-tail 0.084109715t Critical one-tail 1.833112923 t Critical one-tail 2.353363435P(T<=t) two-tail 0.007740002 P(T<=t) two-tail 0.16821943t Critical two-tail 2.262157158 t Critical two-tail 3.182446305
Mg
K
Mn
Li
KeySame population Difference Differenc
fresh Ash vs Old Ash Spoil vs Ash
135
Spoil Ash Fresh FA BA Old AshMean 13710.125 8400.141249 Mean 8740.039841 8400.14125Variance 8236934.125 1037742.367 Variance 84401.56208 1037742.37Observations 8 4 Observations 2 4Hypothesized Mean Difference 0 Hypothesized Mean Difference 0df 10 df 4t Stat 4.676898162 t Stat 0.618881513P(T<=t) one-tail 0.000435807 P(T<=t) one-tail 0.284749585t Critical one-tail 1.812461102 t Critical one-tail 2.131846782P(T<=t) two-tail 0.000871615 P(T<=t) two-tail 0.56949917t Critical two-tail 2.228138842 t Critical two-tail 2.776445105
Spoil Ash Fresh FA BA Old AshMean 10.2332948 7.29310064 Mean 6.56125498 7.29310064Variance 5.023220732 2.015523815 Variance 1.007238476 2.01552382Observations 8 4 Observations 2 4Hypothesized Mean Difference 0 Hypothesized Mean Difference 0df 9 df 3t Stat 2.763721791 t Stat -0.72911651P(T<=t) one-tail 0.01098899 P(T<=t) one-tail 0.259348337t Critical one-tail 1.833112923 t Critical one-tail 2.353363435P(T<=t) two-tail 0.021977979 P(T<=t) two-tail 0.518696673t Critical two-tail 2.262157158 t Critical two-tail 3.182446305
Spoil Ash Fresh FA BA Old AshMean 9.668619584 12.67054521 Mean 12.32569721 12.6705452Variance 63.93225421 32.01919569 Variance 0.060762924 32.0191957Observations 8 4 Observations 2 4Hypothesized Mean Difference 0 Hypothesized Mean Difference 0df 8 df 3t Stat -0.750567476 t Stat -0.121654982P(T<=t) one-tail 0.237203998 P(T<=t) one-tail 0.455431806t Critical one-tail 1.859548033 t Critical one-tail 2.353363435P(T<=t) two-tail 0.474407996 P(T<=t) two-tail 0.910863613t Critical two-tail 2.306004133 t Critical two-tail 3.182446305
Spoil Ash Fresh FA BA Old AshMean 150222.25 111161.4039 Mean 69462.7739 111161.404Variance 1852969844 1639240112 Variance 326186248.1 1639240112Observations 8 4 Observations 2 4Hypothesized Mean Difference 0 Hypothesized Mean Difference 0df 6 df 4t Stat 1.542291929 t Stat -1.742132493P(T<=t) one-tail 0.086971331 P(T<=t) one-tail 0.07822382t Critical one-tail 1.943180274 t Critical one-tail 2.131846782P(T<=t) two-tail 0.173942662 P(T<=t) two-tail 0.156447641t Critical two-tail 2.446911846 t Critical two-tail 2.776445105
Ni
Si
Na
Pb
KeySame population Difference Differenc
fresh Ash vs Old Ash Spoil vs Ash
136
Spoil Ash Fresh FA BA Old AshMean 56.73755338 43.45786428 Mean 103.0876494 43.4578643Variance 711.941911 6.506932525 Variance 891.7318773 6.50693253Observations 8 3 Observations 2 3Hypothesized Mean Difference 0 Hypothesized Mean Difference 0df 7 df 1t Stat 1.390854375 t Stat 2.81713276P(T<=t) one-tail 0.103439704 P(T<=t) one-tail 0.108574327t Critical one-tail 1.894578604 t Critical one-tail 6.313751514P(T<=t) two-tail 0.206879408 P(T<=t) two-tail 0.217148654t Critical two-tail 2.364624251 t Critical two-tail 12.70620473
Spoil Ash Fresh FA BA Old AshMean 49.80503031 47.51636043 Mean 46.06573705 47.5163604Variance 183.4827225 70.22351927 Variance 42.4410426 70.2235193Observations 8 4 Observations 2 4Hypothesized Mean Difference 0 Hypothesized Mean Difference 0df 9 df 3t Stat 0.359668763 t Stat -0.232954403P(T<=t) one-tail 0.363694866 P(T<=t) one-tail 0.415393049t Critical one-tail 1.833112923 t Critical one-tail 2.353363435P(T<=t) two-tail 0.727389732 P(T<=t) two-tail 0.830786098t Critical two-tail 2.262157158 t Critical two-tail 3.182446305
Spoil Mostly Ash Fresh FA BA Old AshMean 53.17499072 30.41923468 Mean 68.7749004 30.4192347Variance 90.03522841 71.34007934 Variance 1815.57138 71.3400793Observations 8 4 Observations 2 4Hypothesized Mean Difference 0 Hypothesized Mean Difference 0df 7 df 1t Stat 4.219137827 t Stat 1.260703602P(T<=t) one-tail 0.001970408 P(T<=t) one-tail 0.213454041t Critical one-tail 1.894578604 t Critical one-tail 6.313751514P(T<=t) two-tail 0.003940816 P(T<=t) two-tail 0.426908081t Critical two-tail 2.364624251 t Critical two-tail 12.70620473
V
Sr
Zn
Spoil Ash Old AshMean 24200.06 2206.817854 Mean 706.7224 2206.81785Variance 7.43E+08 29422.31954 Variance 213741.5 29422.3195Observations 6 3 Observations 2 3Hypothesized Mean Difference 0 Hypothesized Mean Difference 0df 5 df 1t Stat 1.975784 t Stat -4.391613P(T<=t) one-tail 0.052572 P(T<=t) one-tail 0.071266t Critical one-tail 2.015048 t Critical one-tail 6.313752P(T<=t) two-tail 0.105143 P(T<=t) two-tail 0.142532t Critical two-tail 2.570582 t Critical two-tail 12.7062
SO4Fresh FA BA
KeySame population Difference Differenc
fresh Ash vs Old Ash Spoil vs Ash
137
Spoil Ash Old AshMean 0.260709 2.329461488 Mean 14.64605 2.32946149Variance #DIV/0! #DIV/0! Variance #DIV/0! #DIV/0!Observations 1 1 Observations 1 1Hypothesized Mean Difference 0 Hypothesized Mean Difference 0df 0 df 0t Stat -2.5E+161 t Stat 1.5E+162P(T<=t) one-tail #NUM! P(T<=t) one-tail #NUM!t Critical one-tail #NUM! t Critical one-tail #NUM!P(T<=t) two-tail #NUM! P(T<=t) two-tail #NUM!t Critical two-tail #NUM! t Critical two-tail #NUM!
Spoil Ash Old AshMean 41.00437 3.594458847 Mean 55.86292 3.59445885Variance 294.7244 0.693602621 Variance 2120.298 0.69360262Observations 7 3 Observations 3 3Hypothesized Mean Difference 0 Hypothesized Mean Difference 0df 6 df 2t Stat 5.749611 t Stat 1.965762P(T<=t) one-tail 0.000602 P(T<=t) one-tail 0.094122t Critical one-tail 1.94318 t Critical one-tail 2.919986P(T<=t) two-tail 0.001205 P(T<=t) two-tail 0.188244t Critical two-tail 2.446912 t Critical two-tail 4.302653
Spoil Ash Old AshMean 0.121629 0.643405745 Mean 57.3304 0.64340575Variance 0.001412 #DIV/0! Variance #DIV/0! #DIV/0!Observations 3 1 Observations 1 1Hypothesized Mean Difference 0 Hypothesized Mean Difference 0df 0 df 0t Stat -24.04749 t Stat 6.8E+162P(T<=t) one-tail #NUM! P(T<=t) one-tail #NUM!t Critical one-tail #NUM! t Critical one-tail #NUM!P(T<=t) two-tail #NUM! P(T<=t) two-tail #NUM!t Critical two-tail #NUM! t Critical two-tail #NUM!
Spoil Ash Old AshMean 3.445419 0.930378056 Mean 1.774349 0.93037806Variance 39.00347 0.066278757 Variance 4.206534 0.06627876Observations 8 3 Observations 2 3Hypothesized Mean Difference 0 Hypothesized Mean Difference 0df 7 df 1t Stat 1.136466 t Stat 0.57891P(T<=t) one-tail 0.146583 P(T<=t) one-tail 0.332961t Critical one-tail 1.894579 t Critical one-tail 6.313752P(T<=t) two-tail 0.293166 P(T<=t) two-tail 0.665922t Critical two-tail 2.364624 t Critical two-tail 12.7062
Fresh FA BA
Fresh FA BA
Fresh FA BA
NO3
Br
NO2
PO4Fresh FA BA
KeySame population Difference Differenc
fresh Ash vs Old Ash Spoil vs Ash
138
Spoil Ash Old AshMean 39.65169 13.12699686 Mean 37.69506 13.1269969Variance 1241.318 7.797665802 Variance 20.47203 7.7976658Observations 8 2 Observations 2 2Hypothesized Mean Difference 0 Hypothesized Mean Difference 0df 7 df 2t Stat 2.103124 t Stat 6.534694P(T<=t) one-tail 0.036766 P(T<=t) one-tail 0.011313t Critical one-tail 1.894579 t Critical one-tail 2.919986P(T<=t) two-tail 0.073531 P(T<=t) two-tail 0.022626t Critical two-tail 2.364624 t Critical two-tail 4.302653
Spoil Ash Old AshMean 2.900712 6.268830056 Mean 7.753711 6.26883006Variance 9.952562 0.483521916 Variance 77.28937 0.48352192Observations 8 3 Observations 2 3Hypothesized Mean Difference 0 Hypothesized Mean Difference 0df 8 df 1
t Stat -2.841263 t Stat 0.238365P(T<=t) one-tail 0.010885 P(T<=t) one-tail 0.425516t Critical one-tail 1.859548 t Critical one-tail 6.313752P(T<=t) two-tail 0.02177 P(T<=t) two-tail 0.851032t Critical two-tail 2.306004 t Critical two-tail 12.7062
Spoil Ash Fresh FA BA Old AshMean 421.0638 322.0454137 Mean 613.4927 322.045414Variance 118618.5 1005.529765 Variance 511739.6 1005.52976Observations 8 3 Observations 2 3Hypothesized Mean Difference 0 Hypothesized Mean Difference 0df 7 df 1t Stat 0.804138 t Stat 0.575793P(T<=t) one-tail 0.223881 P(T<=t) one-tail 0.333705t Critical one-tail 1.894579 t Critical one-tail 6.313752P(T<=t) two-tail 0.447761 P(T<=t) two-tail 0.667411t Critical two-tail 2.364624 t Critical two-tail 12.7062
Spoil Ash Fresh FA BA Old AshMean 561.9 229.2394948 Mean 41.22828 229.239495Variance 112236.5 13117.51116 Variance 243.779 13117.5112Observations 7 4 Observations 2 4Hypothesized Mean Difference 0 Hypothesized Mean Difference 0df 8 df 3t Stat 2.393727 t Stat -3.223765P(T<=t) one-tail 0.021801 P(T<=t) one-tail 0.024223t Critical one-tail 1.859548 t Critical one-tail 2.353363P(T<=t) two-tail 0.043602 P(T<=t) two-tail 0.048445t Critical two-tail 2.306004 t Critical two-tail 3.182446
Cl- high varience in spoilFresh FA BA
Fresh FA BA
Ca-WE
Na- WE
F
KeySame population Difference Differenc
fresh Ash vs Old Ash Spoil vs Ash
139
Analytes with Increasing Concentrations
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
50000
0 20 40 60 80 100 120 140
Depth (feet)
Con
cent
ratio
n (m
g/K
g)Al
Figure 92 : Concentration of Al with depth
Analytes with Increasing Concentrations
0
10
20
30
40
50
60
0 20 40 60 80 100 120 140
Depth (feet)
Con
cent
ratio
n (m
g/K
g)
V
Figure 93 : Concentration of V with depth
140
Analytes with Increasing Concentrations
0
100
200
300
400
500
600
700
800
0 20 40 60 80 100 120 140
Depth (feet)
Con
cent
ratio
n (m
g/K
g)Li
Figure 94: Concentration of Li with depth
Analytes with Increasing Concentrations
0
500
1000
1500
2000
2500
3000
3500
4000
4500
0 20 40 60 80 100 120 140Depth (feet)
Conc
entr
atio
n (m
g/Kg
)
K
Figure 95: Concentration of K with depth
141
Analytes with Increasing Concentrations
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
0 20 40 60 80 100 120 140
Depth (feet)
Con
cent
ratio
n (m
g/K
g)Ca
Figure 96: Concentration of Ca with depth
Analytes with Increasing Concentrations
0
20000
40000
60000
80000
100000
120000
140000
160000
180000
0 20 40 60 80 100 120 140
Depth (feet)
Con
cent
ratio
n (m
g/K
g)
Si
Figure 97: Concentration of Si with depth
142
Analytes with Increasing Concentrations
0
2
4
6
8
10
12
14
16
18
0 20 40 60 80 100 120 140
Depth (feet)
Conc
entr
atio
n (m
g/Kg
)Cr
Figure 98: Concentration of Cr with depth
Increasing Leachate Concentrations with Depth
0.0
500.0
1000.0
1500.0
2000.0
2500.0
3000.0
0 20 40 60 80 100 120 140
Depth (Feet)
Con
cent
ratio
n (m
g/K
g)
F Cl NO2 NO3 SO4 Ca Na
Figure 99: Concentration of anions with depth
143
Table 19 : Sample table of column leach test results for fresh FA Column
1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 1.14 1.15 1.16
8/1/11 8/4/11 8/6/11 8/8/11 8/10/11 8/12/11 8/14/11 8/16/11 8/18/11 8/20/11 8/22/11 8/24/11 8/26/11 8/28/11 8/30/11 9/1/11
Ag 338.289 ‐0.022 ‐0.026 ‐0.024 ‐0.023 ‐0.022 ‐0.02 ‐0.021 ‐0.02 ‐0.02 0.028 0.028 0.028 0.027 0.026 0.028 0.027
Al 396.153 0.657 0.464 0.342 0.259 0.369 0.518 0.582 1.503 1.398 0.957 1.229 1.285 1.251 1.299 1.375 0.909
As 188.979 ‐0.02 ‐0.036 ‐0.036 ‐0.035 ‐0.034 ‐0.033 ‐0.035 ‐0.037 ‐0.035 ‐0.051 ‐0.048 ‐0.058 ‐0.056 ‐0.056 ‐0.054 ‐0.057
B 249.772 0.584 0.439 2.146 0.273 0.273 0.247 0.231 0.052 0.031 0.219 0.294 0.121 0.173 0.109 0.147 0.18
Ba 455.403
0.475 4.759 5.948 6.42 6.178 5.919 6.137 5.662 5.044 4.817 4.418 3.75 3.454 3.107 2.883 2.632
Be 313.107
‐0.075 ‐0.075 ‐0.075 ‐0.075 ‐0.075 ‐0.075 ‐0.075 ‐0.075 ‐0.075 ‐0.073 ‐0.073 ‐0.073 ‐0.073 ‐0.073 ‐0.073 ‐0.073
Ca 317.933
109.3 310.3 395.1 419.9 420.2 388 400.6 410 436.6 422.7 397.8 390.1 392.3 377.3 366.4 342.3
Cd 228.802 ‐0.039 ‐0.039 ‐0.039 ‐0.039 ‐0.039 ‐0.04 ‐0.039 ‐0.039 ‐0.039 ‐0.04 ‐0.04 ‐0.04 ‐0.04 ‐0.04 ‐0.04 ‐0.04
Co 228.616
‐0.041 ‐0.04 ‐0.04 ‐0.04 ‐0.04 ‐0.04 ‐0.04 ‐0.04 ‐0.04 ‐0.04 ‐0.04 ‐0.04 ‐0.04 ‐0.04 ‐0.04 ‐0.04
Cr 267.716 0.114 ‐0.027 ‐0.031 ‐0.031 ‐0.032 ‐0.033 ‐0.033 ‐0.034 ‐0.034 ‐0.035 ‐0.035 ‐0.035 ‐0.036 ‐0.035 ‐0.036 ‐0.035
Cu 324.752
0.006 0.001 0.001 0.001 0 0.001 0.001 0.002 0.001 0 ‐0.001 0 0 ‐0.001 0 0
Fe 259.939
‐0.06 ‐0.062 ‐0.061 ‐0.062 ‐0.061 ‐0.062 ‐0.062 ‐0.062 ‐0.062 ‐0.063 ‐0.063 ‐0.063 ‐0.063 ‐0.062 ‐0.062 ‐0.063
K 766.490 75 28.47 17.83 14.21 12.6 11.04 11.3 11.01 9.984 9.344 9.087 8.914 7.937 7.275 7.034 7.023
Li 610.362 ‐91.47 11.2 31.09 35.75 36.28 37.63 40.05 41.63 42.08 45.8 44 42.06 42.51 41.63 40.63 37.06
Mg 280.271 ‐0.286 ‐0.281 ‐0.276 ‐0.278 ‐0.278 ‐0.279 ‐0.279 ‐0.28 ‐0.28 ‐0.305 ‐0.305 ‐0.302 ‐0.299 ‐0.303 ‐0.301 ‐0.294
Mn 257.610 ‐0.041 ‐0.041 ‐0.041 ‐0.041 ‐0.041 ‐0.041 ‐0.041 ‐0.041 ‐0.041 ‐0.04 ‐0.04 ‐0.04 ‐0.04 ‐0.04 ‐0.04 ‐0.04
Mo 202.031 2.956 0.22 0.117 0.099 0.08 0.073 0.08 0.084 0.076 0.101 0.107 0.108 0.108 0.108 0.114 0.111
Na 589.592 1539 237.2 84.62 61.91 52.86 45.85 44.52 41 36.58 36.68 33.21 31.11 27.76 24.21 22.18 21.56
Ni 231.604
‐0.059 ‐0.046 ‐0.046 ‐0.046 ‐0.046 ‐0.046 ‐0.046 ‐0.047 ‐0.047 ‐0.05 ‐0.049 ‐0.05 ‐0.05 ‐0.05 ‐0.05 ‐0.05
Pb 220.353 ‐0.048 ‐0.046 ‐0.047 ‐0.047 ‐0.047 ‐0.047 ‐0.045 ‐0.045 ‐0.045 ‐0.057 ‐0.058 ‐0.057 ‐0.056 ‐0.057 ‐0.058 ‐0.058
Se 196.026 0.125 ‐0.09 ‐0.103 ‐0.106 ‐0.102 ‐0.103 ‐0.099 ‐0.097 ‐0.102 ‐0.097 ‐0.103 ‐0.099 ‐0.104 ‐0.106 ‐0.095 ‐0.097
Si 251.611 0.762 ‐0.086 ‐0.207 ‐0.054 ‐0.146 ‐0.102 0.038 0.174 0.132 0.433 0.411 0.571 0.686 0.604 0.733 0.768
Sr 421.552 4.9 40.4 28.9 18 11.39 8.087 7.017 5.846 4.944 4.544 3.99 3.599 3.336 3.004 2.769 2.627
V 310.230 ‐0.065 ‐0.063 ‐0.062 ‐0.072 ‐0.074 ‐0.068 ‐0.049 ‐0.051 ‐0.054 0.019 0.012 0.011 0.014 0.008 0.026 0.015
Zn 213.857
‐0.041 ‐0.045 ‐0.034 ‐0.034 ‐0.033 ‐0.039 ‐0.042 ‐0.041 ‐0.041 ‐0.039 ‐0.027 ‐0.031 ‐0.041 ‐0.029 ‐0.041 0.035
1 ‐ Fresh Fly Ash ‐ NE‐FA‐01Sample
(mg/Kg)
Analyte Name
144
Ag Leachate Concentration
0.00
0.05
0.10
0.15
0.20
0.25
0.30
7/26/11 7/31/11 8/5/11 8/10/11 8/15/11 8/20/11 8/25/11 8/30/11 9/4/11
Time
Con
cent
ratio
n (m
g/kg
)Fresh Fly AshFresh Bottom AshOld Buried Fly AshOld Buried Bottom AshYoung Buried AshSpoilFresh Fly Ash No 8 WaterOld Fly Ash No 8 WaterNo 8 Coal H2O
Figure 100 : Concentration of Ag for each column
Al Leachate Concentration
0
1
2
3
4
5
6
7/26/11 7/31/11 8/5/11 8/10/11 8/15/11 8/20/11 8/25/11 8/30/11 9/4/11
Time
Con
cent
ratio
n (m
g/kg
)
Fresh Fly AshFresh Bottom AshOld Buried Fly AshOld Buried Bottom AshYoung Buried AshSpoilFresh Fly Ash No 8 WaterOld Fly Ash No 8 WaterNo 8 Coal H2O
Figure 101: Concentration of Al for each column
145
Boron Leachate Concentration
0
5
10
15
20
25
30
35
40
45
7/26/11 7/31/11 8/5/11 8/10/11 8/15/11 8/20/11 8/25/11 8/30/11 9/4/11
Time
Conc
entr
atio
n (m
g/kg
)
Fresh Fly AshOld Buried Fly AshFresh Fly Ash No 8 WaterOld Fly Ash No 8 WaterNo 8 Coal H2O
Figure 102: Concentration of B for each column
Barium Leachate Concentration
0
1
2
3
4
5
6
7
7/26/11 7/31/11 8/5/11 8/10/11 8/15/11 8/20/11 8/25/11 8/30/11 9/4/11
Time
Con
cent
ratio
n (m
g/kg
)
Fresh Fly AshFresh Bottom AshOld Buried Fly AshOld Buried Bottom AshYoung Buried AshSpoilFresh Fly Ash No 8 WaterOld Fly Ash No 8 WaterNo 8 Coal H2O
Figure 103: Concentration of Ba for each column
146
Calcium Leachate Concentration
0
100
200
300
400
500
600
700
7/26/11 7/31/11 8/5/11 8/10/11 8/15/11 8/20/11 8/25/11 8/30/11 9/4/11
Time
Conc
entr
atio
n (m
g/Kg
)
Fresh Fly AshFresh Bottom AshOld Buried Fly AshOld Buried Bottom AshYoung Buried AshSpoilFresh Fly Ash No 8 WaterOld Fly Ash No 8 WaterNo 8 Coal H2O
Figure 104: Concentration of Ca for each column
Potassium Leachate Concentration
-20
0
20
40
60
80
100
120
140
160
180
200
7/26/11 7/31/11 8/5/11 8/10/11 8/15/11 8/20/11 8/25/11 8/30/11 9/4/11
Time
Conc
entra
tion
(mg/
Kg)
Fresh Fly AshFresh Bottom AshOld Buried Fly AshOld Buried Bottom AshYoung Buried AshSpoilFresh Fly Ash No 8 WaterOld Fly Ash No 8 WaterNo 8 Coal H2O
Figure 105: Concentration of K for each column
147
Cr Leachate Concentration
0.0
0.2
0.4
0.6
0.8
1.0
1.2
7/26/11 7/31/11 8/5/11 8/10/11 8/15/11 8/20/11 8/25/11 8/30/11 9/4/11
Time
Con
cent
ratio
n (m
g/K
g)
Fresh Fly AshFresh Bottom AshOld Buried Fly AshOld Buried Bottom AshYoung Buried AshSpoilFresh Fly Ash No 8 WaterOld Fly Ash No 8 WaterNo 8 Coal H2O
Figure 106: Concentration of Cr for each column
Lithium Leachate Concentration
0
10
20
30
40
50
60
70
7/26/11 7/31/11 8/5/11 8/10/11 8/15/11 8/20/11 8/25/11 8/30/11 9/4/11
Time
Conc
entra
tion
(mg/
Kg)
Fresh Fly AshFresh Bottom AshOld Buried Fly AshOld Buried Bottom AshYoung Buried AshSpoilFresh Fly Ash No 8 WaterOld Fly Ash No 8 WaterNo 8 Coal H2O
Figure 107: Concentration of Li for each column
148
Magnesium Leachate Concentration
-100
0
100
200
300
400
500
600
7/26/11 7/31/11 8/5/11 8/10/11 8/15/11 8/20/11 8/25/11 8/30/11 9/4/11
Time
Conc
entra
tion
(mg/
Kg)
Fresh Fly AshFresh Bottom AshOld Buried Fly AshOld Buried Bottom AshYoung Buried AshSpoilFresh Fly Ash No 8 WaterOld Fly Ash No 8 WaterNo 8 Coal H2O
Figure 108: Concentration of Mg for each column
Cu Leachate Concentration
0.0
0.1
0.1
0.2
0.2
0.3
0.3
0.4
0.4
7/26/11 7/31/11 8/5/11 8/10/11 8/15/11 8/20/11 8/25/11 8/30/11 9/4/11
Time
Conc
entra
tion
(mg/
Kg)
Fresh Fly AshFresh Bottom AshOld Buried Fly AshOld Buried Bottom AshYoung Buried AshSpoilFresh Fly Ash No 8 WaterOld Fly Ash No 8 WaterNo 8 Coal H2O
Figure 109: Concentration of Cu for each column
149
Mo Leachate Concentration
0
2
4
6
8
10
12
7/26/11 7/31/11 8/5/11 8/10/11 8/15/11 8/20/11 8/25/11 8/30/11 9/4/11
Time
Con
cent
ratio
n (m
g/K
g)
Fresh Fly AshFresh Bottom AshOld Buried Fly AshOld Buried Bottom AshYoung Buried AshSpoilFresh Fly Ash No 8 WaterOld Fly Ash No 8 WaterNo 8 Coal H2O
Figure 110: Concentration of Mo for each column
Silica Leachate Concentration
0
5
10
15
20
25
30
7/26/11 7/31/11 8/5/11 8/10/11 8/15/11 8/20/11 8/25/11 8/30/11 9/4/11
Time
Conc
entra
tion
(mg/
Kg)
Fresh Fly AshFresh Bottom AshOld Buried Fly AshOld Buried Bottom AshYoung Buried AshSpoilFresh Fly Ash No 8 WaterOld Fly Ash No 8 WaterNo 8 Coal H2O
Figure 111: Concentration of Si for each column
150
Strontium Leachate Concentration
0
5
10
15
20
25
30
35
40
45
7/26/11 7/31/11 8/5/11 8/10/11 8/15/11 8/20/11 8/25/11 8/30/11 9/4/11
Time
Con
cent
ratio
n (m
g/Kg
)Fresh Fly AshFresh Bottom AshOld Buried Fly AshOld Buried Bottom AshYoung Buried AshSpoilFresh Fly Ash No 8 WaterOld Fly Ash No 8 WaterNo 8 Coal H2O
Figure 112: Concentration of Sr for each column
Vanadium Leachate Concentration
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
7/26/11 7/31/11 8/5/11 8/10/11 8/15/11 8/20/11 8/25/11 8/30/11 9/4/11
Time
Con
cent
ratio
n (m
g/Kg
)
Fresh Fly AshFresh Bottom AshOld Buried Fly AshOld Buried Bottom AshYoung Buried AshSpoilFresh Fly Ash No 8 WaterOld Fly Ash No 8 WaterNo 8 Coal H2O
Figure 113: Concentration of V for each column
151
Zinc Leachate Concentration
0.0
0.0
0.0
0.1
0.1
0.1
0.1
0.1
7/26/11 7/31/11 8/5/11 8/10/11 8/15/11 8/20/11 8/25/11 8/30/11 9/4/11
Time
Conc
entra
tion
(mg/
Kg)
Fresh Fly AshFresh Bottom AshOld Buried Fly AshOld Buried Bottom AshYoung Buried AshSpoilFresh Fly Ash No 8 WaterOld Fly Ash No 8 WaterNo 8 Coal H2O
Figure 114: Concentration of Zn for each column
Be, Cd, Co & Pb Leachate Concentration
0.000
0.100
0.200
0.300
0.400
0.500
0.600
0.700
0.800
0.900
1.000
7/26/11 7/31/11 8/5/11 8/10/11 8/15/11 8/20/11 8/25/11 8/30/11 9/4/11
Time
Con
cent
ratio
n (m
g/kg
)
Fresh Fly AshFresh Bottom AshOld Buried Fly AshOld Buried Bottom AshYoung Buried AshSpoilFresh Fly Ash No 8 WaterOld Fly Ash No 8 WaterNo 8 Coal H2O
Figure 115: Concentration of Be, Cd, Co & Pb for each column
152
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