Surface Mining Remediation
Utilizing Vertical Wetlands and Engineered
Soils for the Red River Coal Co.
BSE 4125 Comprehensive Design Project
May 13, 2009
Purpose:
The submission of the final report.
Team Name: Mining R&R
Group: Christian Bongard, Matthew Gloe, and Gil Brown
Advisors:
Dr. Lee Daniels, Dr. Bobby Grisso
Title: Surface Mining Remediation Utilizing Vertical Wetlands and Engineered
Soils for the Red River Coal Co.
Executive Summary: Surface Mining Remediation Utilizing Vertical Wetlands and
Engineered Soils for the Red River Coal Co.
The goal of this project was to create a design to remediate and reclaim a coal waste
pile. These coal waste piles, often referred to as Gob Piles, are piled-up impurities found
in coal seams during the processing stage. These impurities contain acid forming pyrite,
heavy metals and other environmentally damaging compounds. The site that we selected
is a gob pile managed by the Red River Coal Company, located outside of Norton, a
small town inside Wise County. To treat water leaving the coal waste pile, a vertical
flow wetland was designed. The vertical flow wetland has two important functional
parts, a layer of organic matter and biomass that immobilize heavy metals by lowering
oxygen levels and creating reducing conditions, and then a layer of limestone to
neutralize the acidity. The wetland is designed to treat only the baseflow leaving the site,
not the immediate runoff from storm events. Water quickly running off the surface of the
gob pile does not have enough contact time with the site to pick up significant pollutants.
However water that infiltrates into the pile and flows through the subsurface to the base
of the pile will have significant levels of metals and acidity.
With the water leaving the pile now treated, the attention of our project focused on
reclamation of coal waste pile itself. The best way to do this is to create an engineered
soil matrix and then revegetate the site. In order to come up with an innovative design
but still meet our sponsor’s needs, two separate soil matrices were engineered. The first
is a traditional soil mix of a direct lime to provide a pH buffer and then a layer of topsoil
to provide rooting depth and a temperature buffer. While a time tested method, this
method has high costs; covering the entire site with limestone and scraping topsoil from
another site and trucking it over to this site is a costly affair. To reduce our costs and
improve growth rate, our second design calls for an application of lime-stabilized
biosolids to be added to the site. Biosolids can be provided for no cost, by most large
cities. The normal cost of disposing a cities’ biosolids is so high, that cities will pay for
the lime and woodchip additions, as well as transportation costs. Despite its strengths,
the use of biosolids is controversial with the local population, and to avoid the wraith of
the public Red River Coal has elected to not use biosolids to date.
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Upon the closing of the coal waste pile in the next 15-20 years, we believe the
combination of our vertical flow wetland and either designed soil matrix will successfully
remediate and reclaim the site. We hope that the time between today and when the site
closes, public perception improves on the use of biosolids.
Two vertical flow wetlands should be implemented on the site. One will be placed
on the west side of the pile and along the drainage path. The second wetland will be
placed on the south side of the pile. Together, the wetlands will hold 454 m3 of lime to
reduce the acidity of the drainage. Each wetland will be 49.8 m x 7.6 m x 0.6 m.
Two soil matrices were designed for the site. One was developed at the request of
Red River Coal. It is a traditional mix of topsoil and lime. The second is a contemporary
soil matrix that consists of a lime application followed by a biosolids application. It is
recommended that the biosolids should be applied at a rate greater than or equal to 112
Mg ha-1.
For those that could continue this project, there are several aspects of the project that
could be expanded. We chose to design two vertical flow wetlands; however other teams
may find a one, three, or even four wetland system to be better choice. Dependent on the
number of wetlands, locating appropriate locations for these wetlands will result in
several different combinations; ultimately other teams may find a more efficient
arrangement. We choose two different soil matrices to focus on, but there are other
possibilities other teams could explore; these possibilities include, paper mill waste,
cottonseed meal, fruit pomaces (fruit waste from juice process), blood meal
(slaughterhouse waste), seaweed, and many other soil amendments.
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Contents
Executive Summary. ........................................................................................................... 2
Contents .............................................................................................................................. 4
1.0 Introduction ................................................................................................................... 5
2.0 Problem Statement ........................................................................................................ 5
3.0 Connection to Contemporary Issues ............................................................................. 5
4.0 Scope of Work .............................................................................................................. 6
Objectives: ...................................................................................................................... 6
Deliverables: ................................................................................................................... 6
5.0 Design Criteria and Constraints .................................................................................... 6
6.0 Literature Review.......................................................................................................... 6
6.1.1 Wise County........................................................................................................... 6
6.1.2 Terms ..................................................................................................................... 7
6.2.1 Getting Coal Power ................................................................................................ 8
6.2.2Past Problems now being addressed ..................................................................... 10
6.2.3 Red River Coal Company .................................................................................... 11
6.2.4 Red River Coal Current Practices ........................................................................ 13
6.5.1 Passive Treatments............................................................................................... 15
6.5.2 Chemical Treatments ........................................................................................... 18
6.7.1 Environmental Regulations, Clean Water Act ..................................................... 20
6.7.2 Mining Regulations, SMCRA.............................................................................. 21
6.7.3 Mining Regulations, States .................................................................................. 22
6.7.4 Construction Safety, Heavy Machinery and Chemicals ...................................... 22
6.8 The Use of Biosolids as a Soil Amendment .......................................................... 22
7.0 Preliminary/Alternative Designs ................................................................................ 25
7.1 GIS Analysis .......................................................................................................... 26
8.0 Project Design ............................................................................................................. 28
8.1.2 Calculating Limestone Volume ........................................................................... 30
8.1.3 Drainage ............................................................................................................... 32
8.1.4 Basic Construction .............................................................................................. 33
8.1.5 Maintenance ......................................................................................................... 34
9.0 Work Plan/Summary................................................................................................... 36
Project Timeline ............................................................................................................ 36
10.0 Summary and Conclusions ....................................................................................... 39
11.0 Design Reflections .................................................................................................... 40
Resources .......................................................................................................................... 41
Appendix A: Student Skills .............................................................................................. 42
Appendix B: Water Quality Data ...................................................................................... 43
Appendix C: List of Figures ............................................................................................ 44
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Title: Surface Mining Remediation Utilizing Vertical Wetlands
and Engineered Soils for the Red River Coal Co.
1.0 Introduction
Surface mining is an unavoidable reality of today’s world; in order to minimize its
effects, environmental remediation must be conducted. Two of the biggest problems, in
many areas, with surface mining are acid leaching, and the degradation of the soil
structure. These problems, in many instances, leave the landscape barren, and unable to
support significant levels of vegetation. Natural formation of soil can take thousands of
years; in order to speed this process up, as well as reduce the acidity, engineered soils can
be brought into the equation.
Red River Coal Co. in Norton, VA has been mining in the local area since the 1980s,
and has produced a substantial coal waste pile. Their pile is currently active, but plans
need to be instated for its retirement, namely a reclamation plan. They currently treat acid
mine runoff through a series of collection pools and pH neutralization via chemical drips
(NaOH, etc…). The chemical treatment option is not the best long term solution, as it
requires high maintenance and continual costs. A more biologically based approach
would help to restore a more natural balance to the area in a self sustaining manner.
2.0 Problem Statement
During surface mining, waste from coal processing is discarded in large localized
disposal fills. Upon completion of mining, reclamation of these waste piles is much more
challenging than the actual mined area. To remediate and reclaim these sites, a
comprehensive plan and design must be devised and implemented.
3.0 Connection to Contemporary Issues
In order to remediate a coal waste pile to a less polluting and useful landscape within
a human lifetime; a multiple discipline approach is needed. Coal provides 56% of electric
power for the United States overall. This percentage is much higher in certain
Appalachian states. The amount of waste produced from coal mining continues to
increase as long as coal is used as a primary source of energy. A portion of this waste
includes, solid coal impurities, which are gathered into gob piles. Each of these gob piles
can become a major source of water impairments.
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4.0 Scope of Work
1.
2.
3.
4.
1.
2.
3.
4.
Objectives:
Choose the future land use of the coal waste pile
Knowing the future land use, the appropriate soil cover layer will be designed.
Utilize GPS, GIS, and site investigations to find the best location for a vertical
flow wetland system.
Design a vertical flow wetland system specifically to treat acid mine drainage
from the coal waste pile
Deliverables:
Coal waste pile reclamation plan
Design for an engineered soil
Vertical wetland system design
Economic analyses of the designs compared to conventional alternatives
5.0 Design Criteria and Constraints
Criteria and constraints were determined on our second site visit on December 17,
2008. We will be obtaining exact soil and water chemistry data. Our vertical flow
wetland system design will be constrained by heavy metal content, pH levels, flow rate,
and concentration of dissolved oxygen in the influent acid mine drainage. The design of
the engineered soil will be constrained by pH versus depth requirements, water holding
capabilities, compaction, public perception, and budget.
6.0 Literature Review
The following section is a collaboration of background information concerning acid
mine drainage treatment and mined land reclamation. Background history of our site is
also included, along with information on the coal industry, mining techniques, and
associated issues.
6.1 Site Description
6.1.1 Wise County
The area of Wise County was open to settlement in 1768 (Henson, 2006). The
county’s coal resources were not widely exploited until the railroad system was
established in the county in 1886 (Henson, 2006). Since then, Wise County has been
mined extensively. During its coal mining history, a series of mining boom towns would
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become established and then be deserted based on the cycles of the available coal. Sadly,
this region had dramatic social shifts as mines would open and close, bringing in an
influx of workers and then massive unemployment when they would close. This created
dangerous circumstances for the new immigrants to the area.
During the shift from deep mining to surface mining, whole towns shut down due
to the fact that surface mining needed fewer workers. However, the county has settled to
a new equilibrium and the population has been steadily rising to its current population of
41,710 in 2002 (Henson, 2006). There are six towns in Wise County, ranging between
1,000 and 5,000 residents each (Henson, 2006). To bring more jobs to the area, besides
just mining, the county now has a Technology Center, a satellite campus of UVA, and a
community college. Despite increased job opportunities from new industries attracted by
these schools, the unemployment is well above the national average at 4.3% in 2004 and
is most likely currently even higher due to the economic slowdown (Henson, 2006).
Increased environmental regulations have significantly improved the quality of
the land reclaimed by the mining industry. Despite these improvements, significant
environmental challenges arise from the historic mine sites in Wise County that were
poorly reclaimed or abandoned.
6.1.2 Terms
Remediation - Taking action to reduce, isolate, or remove contamination from an
environment with the goal of preventing exposure to people or animals.
Restoration- return to its original or usable functioning state.
Reclaim – return of seriously disturbed land surfaces to an improved and stable land use.
Gob Pile – The common name for coal waste pile. Before coal is sold, to increase its
value, low quality coal or impurities are separated and gathered in to a pile. This pile
concentrates potential contaminants to one location, making its management easier than if
it was widely dispersed.
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Compaction– In every gob pile, compaction of the waste material is needed to stabilize
the material. This is executed by heavy machinery making multiple passes across the top
of the material to compact the waste. Compaction is important for safety, but may cause
problems during the revegetation process. The compaction may cause problems with
rooting depth.
6.2 Coal Industry
6.2.1 Getting Coal Power
Coal provides a massive amount of power for the United States and the world.
The United States has numerous reserves of coal. There are only two methods to remove
coal from these reserves. One method is to physically dig down beneath the earth to the
coal and extract it, this is called subsurface mining. The other method is done by
removing everything on top of the coal and then removing the coal, this is called surface
mining. Both techniques have their advantages and disadvantages, including the
controversial issues surrounding them. Arguably, the most controversial of these
techniques is a type of surface mining called mountain top removal (MTR), as shown in
figure 1. The vast majority of mountaintop removal sites are located in the Appalachia
coal mining region, specifically eastern Kentucky, southern West Virginia, western
Virginia and some sections of eastern Tennessee. Combined, these regions cover
approximately 4.8 million hectares (12 million acres) of land which are estimated to
contain 2.59 x 1013 kilograms (28.5 billion tons) of coal. While some underground
mining is still active in these areas, surface mining is a growing trend. The average
surface mine has between a 14/1 to 20/1 ratios of overburden to coal. The removal of the
estimated 2.59 x 1013 kilograms (28.5 billion tons) of coal will require a large acreage of
land to be remediated (Valigra-2006).
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Mountain top removal takes place in 5 basic steps
1. Layers of rock and dirt above the coal seam are blasted and removed.
2. The overburden (rocks and dirt) is dumped into adjacent valleys.
3. The seams of coal are removed, and the spoils within the seam are placed into a
separate pile.
4. Regrading begins as coal removal continues.
5. Once all the coal is removed final grading takes place and the area is revegetated.
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Figure 1. Basics of Mountain top removal (EPA Factsheet-2008)
The coal mining industry prefers MTR and other extensive surface mining
techniques, because they can often recover up to 90% of the coal of the mine. A
traditional underground mine normally only recovers 45 to 50 percent (Valigra 2006).
Besides the more efficient removal of the coal, MTR is less labor intensive than
underground mining, and requires less than half as many workers per ton of coal
removed.
Once the coal is collected, it is brought to a processing plant. To increase its
quality, low-grade coal and impurities are separated from the main coal at the processing
plant. It is common for the waste to be gathered into one pile near the processing plant.
This pile is referred to as many names including; gob pile, waste pile and coal refuse pile.
This pile concentrates potential contaminants to one location, making its management
easier than if it was widely dispersed. The remaining high quality coal is then loaded
onto train cars and sent across the country.
6.2.2 Past Problems now being addressed
Increased regulation, through Surface Mining Control and Reclamation Act
(SMCRA), has significantly improved the quality of the land remediated by the mining
industry. Despite these improvements, significant environmental challenges arise from
historic sites that were poorly remediated long ago.
When unregulated sites were remediated, coal companies often used unsound
methods that caused numerous problems, one of which is that the soil was overly
compacted, which hindered tree growth. On this compacted soil, fast growing grasses
were often seeded after regrading to reduce erosion; however, this thick cover out
competed trees, hindering forest growth. Modern techniques for remediated sites have
reduced compaction, allowing for deeper root penetration. Modern seeding techniques
spread the seeds thinner along the slope, so that natural succession by trees can take place
faster. Fertilizers and lime can be added to remediated soils to dramatically improve their
productivity. One potential additive is biosolids.
Cities around the state and nation produce large volumes of human sludge. This
substance is the byproduct of all of our digestive system, and is loaded with organic
material and nutrients. Currently these biosolids are burnt, dumped in landfills, applied
to agricultural areas, and a few mining sites. The costs of disposal of these biosolids are
10
so high, that cities are willing to mix the biosolids with lime to raise the pH and ship
them nearly anywhere. This situation would effectively make the cost of applying
biosolids to our site near zero. Besides the economic incentive of using biosolids,
biosolids have a quicker growth time, promote a higher vegetative cover, require less
fertilizer, and would prevent another mountaintop to have its topsoil scraped off. A mix
of biosolids, sawdust and lime can dramatically reduce the number of years it takes for
sustainable grazing or forestry to develop.
6.2.3 Red River Coal Company
Red River Coal Company began as Greater Wise, Inc. in 1971 by Bill Humphreys
(Red River). Since becoming Red River Coal Co. it has established itself as one of the
largest family-owned and operated coal producers in the country. Its current owners are
Danny Humphreys, Doug Humphreys and Mike Thomas. Red River operates surface and
deep mines in Wise County. All of their mines are located to the Northwest of Norton,
VA on the border of Virginia and Kentucky. The company produces approximately 2.27
billion kilograms (2.5 million tons) of coal per year (Red River). The company has one
preparation plant that can load clean coal at a rate of 3.6 million kilograms per hour
(4,000 tons per hour) (Red River). The preparation plant loads the coal into a 130-car
unit train that is operated on the Norfolk-Southern Railway (Red River). Under the
current lease, the Red River Coal Company has more than 27.2 billion kilograms (30
million tons) of coal reserves (Red River). The company is one of the leading postmining reclamation operations. It has reclaimed more than 1.6 square kilometers (4,000
acres) of land over the last 30 years (Red River). Figure 2 shows the location of Red
River Coal Company’s mine site in relation to Norton, VA. Figure 3 displays an aerial
image of the coal companies’ coal waste pile and several treatment ponds.
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Figure 2. Red River Coal Mine Location
Figure 3 Aerial image showing the coal waste pile and treatment ponds
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6.2.4 Red River Coal Current Practices
Currently, Red River Coal treats their acid mine drainage through a number of
processes. They spend between $100 and $1,000 a month on a sodium hydroxide drip to
neutralize acid to treat the acid drainage produced by their gob pile, which is
approximately 41 hectares (100 acres). This is used in conjunction with numerous settling
ponds to allow for heavy metal removal. The wide range in costs is due to the fact that in
most months, a high percentage of runoff from the site is pumped back into the
processing plant, mixed into a slurry and then pumped back up to the top of the pile. This
water recycling program causes a vast majority of contaminated water to evaporate or be
reused by the system. Therefore only a small amount of water leaves the system, causing
a small cost of treatment. If there is a break in production at the processing plant, then
more water may leave the system and increase the costs. Our design, however, is for a
time that the processing plant is completely shut down and a majority of rainfall onto the
system will need to be treated.
Existing reclamation practices for the refuse pile involve direct liming of the coal
waste. This serves as an acid buffer for plants. Without this, plant roots would be acid
burned and killed. In addition, 0.15-0.2 m (6-8 in) of soil is added over the limed refuse.
This serves two purposes. The first is as a rooting layer for plants, and the second is as a
thermal buffer. Without the soil as a thermal buffer, the dark coal waste heats up during
the summer months and burns any vegetation currently growing on the slope.
6.3 Future Landuses
The primary objective of reclaiming a coal refuse pile is to control erosion and
provide wildlife habitat. Grass land is the most common post-mining landuse because it
is easier to establish compared to forest and other post-mining land uses. Research is
being conducted to try to fully understand how to establish forests on waste piles.
Rooting depth is the largest obstacle faced when trying to establish woody species on
coal waste piles. As the roots approach the acid buffer, the root tips are burned and
inhibit plant growth. Red River Coal Co. plans to establish grass land on their waste pile.
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6.4 AMD Sources and Background Information
Acid mine drainage (AMD) is defined as a low pH leachate formed by the
oxidation of sulfide materials (Nyavor, 1995). The sulfuric material that produces the
AMD is known as pyrite (FeS2). These materials are usually found in coal waste piles,
also named gob piles, which are formed from the coal processing wastes. Gob piles that
contain fine (<0.60 mm) processing wastes are considered acid producing by the Federal
Office of Surface mining (Gray, 2000). Once oxidized, pyrite produces an acidic
leachate. Pyrite can become oxidized if it is exposed to oxygen and water. The chemical
oxidation of pyrite can be seen in Equation 1.
4FeS2 + 13O2 + 2H2O → 4FeSO4 + 2H2SO4 + 2SO2
(1)
The oxidation process can be catalyzed by bacterial organisms. The oxidation of the
sulfides produces acid, which in turn causes heavy metals to leach from the soil solution.
If precipitation falls, the acidic water containing the heavy metals will leach into
surrounding waters (ground water and surface water). Figure 4 displays an example of
current AMD at the Red River coal mine in Wise County.
Figure 4. Acid mine drainage in Wise County.
6.5 AMD Treatment
The following two sections explore two different ways acid mine drainage can be
treated. A generic term for describing the systems used to treat acid mine drainage
14
problems is RAPS, or “Reducing and Alkalinity-Producing Systems”. AMD can be
treated by a direct chemical application to the drainage or by routing the drainage through
a series of passive systems. A combination of the two different ways is also an option.
Chemical treatment of AMD is a straightforward approach that has been proven to work
in almost every situation, although it can be expensive and include a long term treatment
liability (Skousen, 2008). On the contrary, the passive system approach can only be
executed in certain situations, but utilizes natural processes to treat the AMD without
requiring long term maintenance.
6.5.1 Passive Treatments
There are numerous passive treatment systems utilized in the treatment of AMD.
The most widely used systems are open limestone channels (OLC), vertical flow
wetlands (VFW), anaerobic wetlands (AnW), aerobic wetlands (AW), limestone leach
beds (LSB), alkalinity producing systems (APS) and anoxic limestone drains (ALD)
(Ziemkiewicz, 2003). These systems can be seen in Figure 5.
Figure 5. A diagram of different types of passive treatments (Skousen, 2008)
Each system has limitations, so different situations require a different system. A
selection flowchart to determine which system is best for a specific scenario is shown in
Figure 6. Aerobic wetlands may require dredging due to the large amount of metals that
precipitate out as the drainage flows through the system. Anaerobic wetlands do not
promote the precipitation of metals, so a settling pond may need to be implemented
15
before the drainage reaches the system. Both AW and AnW are adapted to and can
handle relatively low pH drainage. Anoxic limestone drains require low metal content.
Figure 6. Flowchart for selecting passive treatment systems. (Skousen, 2008)
The passive systems that are being studied most heavily are the various wetland
systems. Each type of wetland has advantages for varying water conditions, to include
pH, dissolved oxygen amounts, and metal concentrations (Ziemkiewicz et al., 2003).
Aerobic wetlands are best suited for treating AMD in situations where pH ranges from
4.5-6.3, and has iron concentrations of Fe<70 mg/L, Mn<17 mg/L, and Al<30 mg/L
(Ziemkiewicz et al., 2003). If these criteria are met, and the wetland is designed for
sufficient flocculation and residence time, metal oxidation and hydrolysis occurs,
allowing metals to precipitate out and the pH to be stabilized.
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Anaerobic wetlands contain an array of organic-rich substrates, which allow for
reducing conditions to develop, as well as containing limestone for acid neutralization.
Similarly to aerobic wetlands, anaerobic systems must have significant residence time
allowing the treatment of large amounts of water.
In traditional vertical flow wetlands (VFW), influent acidic water first flows
downward through an organic matter layer. Here, iron and other metals precipitate out in
the reducing conditions and remain in the soil as sulfides or organic complexes. Next, the
water flows through a limestone layer. In this medium, the acidity is buffered through the
alkalinity induced by dissolution of the limestone gravel. This water then flows out
through an under drain. In order to prevent the buildup of metal flocculants inside the
wetland, frequent flushing will keep it clear and operating smoothly (Ziemkiewicz et al.,
2003).
Not only does a VFW neutralize acid through limestone dissolution, shown in
equations 2 and 3, but by promoting reducing conditions which can occur in organic
matter. These conditions aid in reducing sulfates, which also generates alkalinity. This
process is shown in Equation 4.
2H+ + CO32-  H2O + CO2
H++ HCO3-  H2O + CO2
2 CH2O = SO42- →H2S + 2 HCO3 -
(2)
(3)
(4)
Generally, a layer of limestone 0.6-1.2 m thick is placed on the bottom of an
excavated area, followed by perforated pipes in the lower area of the limestone (Watzlaf,
2003). Organic material is then placed 0.15-0.61 m thick on top of everything (Watzlaf,
2003). This promotes sulfate reducing bacteria to grow. This system avoids clogging
from ferric iron armoring the limestone due to the reducing conditions. This system also
shows resistance to clogging from aluminum hydroxide flocculants, thanks to the larger
cross sectional area and higher head pressures present.
Traditional horizontal wetlands often have varying treatment efficiencies;
however vertical flow wetlands have higher efficiencies (Demchak, 2008). They are also
more cost effective than chemical treatments over extended periods of time. Building a
vertical wetland is a one-time cost that can provide effective treatment for decades, rather
17
than paying for a chemical treatment monthly for that same time period (Demchak,
2008). The only downfall to these vertical flow systems is that there may be needs for a
final chemical treatment and additional chemical additions during the winter months, all
depending on the situation.
6.5.2 Chemical Treatments
As mentioned above chemical (active) treatment is a straightforward process. It
requires the introduction of a alkaline chemical to the AMD to reduce the acidity of the
drainage. The most common chemical application is to directly drip a neutralizing agent
into the AMD. There are numerous chemicals used in the industry, with sodium
hydroxide (NaOH) being the most common. Other common chemicals in use are calcium
hydroxide, calcium carbonate, calcium oxide, anhydrous ammonia and sodium carbonate
(soda ash). The AMD at the Wise County mine is currently treated with NaOH. There
are many advantages in treating AMD with chemicals, but there are also several
disadvantages. The largest disadvantage is the need for a preliminary treatment/settling
basin. If a settling basin is not being used then the chemical treatment does a poor job of
removing the metal contaminants in AMD compared to passive treatments. Other
problems include the cost of the chemicals and the man hours needed to operate/monitor
the chemical application.
One way to treat AMD from a chemical standpoint, other than direct
neutralization, is to prevent the oxidation of pyrite in the first place. This requires less
manpower and reduces the need for long term treatment systems. Phosphating or
phosphate coating the waste material is one way to prevent the formation of pyrite that is
being studied (Nyavor, 1995). This means that an acidic phosphate solution could be
used to reduce pyrite oxidation by coating the pyrite surface with a complex phosphate
coating. Research, in a lab setting, has shown that the pyrite oxidation can be reduced by
adding the phosphate coating (Nyavor, 1995). It was found that the phosphate creates an
iron phosphate coating on the pyrite molecules, which prevents the oxidants from
reaching the pyrite matrix (Nyavor, 1995). Since the oxidants cannot reach the pyrite
matrix, it causes the rate of oxidation to decrease. This process has yet to be proven to
work at an actual operating gob pile scale.
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6.6 Coal Refuse Reclamation
Coal mining operations not only have to reclaim mined lands, they must also
reclaim the areas in which the deposit their post-treatment coal waste. In most situations,
the coal refuse areas, also known as gob piles, are constructed as large valley fills in the
head waters of the watersheds in the region (Daniels and Stewart, 2000). These refuse
disposal areas, like all mining, are regulated by the state in which the gob pile is located.
The most important regulation is the five year bond liability period (Daniels and Stewart,
2000). The five year bond liability period is a regulation that requires that the reclaimed
gob pile must show substantial evidence that it can support long term vegetation. The
regulation states that the gob pile must be reclaimed and then no augmentations may be
made for the next five years. If substantial vegetation remains after five years, then the
bond monies will be released. Due to the fact that coal mine operations have a significant
amount of money tied up in these bonds, coal refuse reclamation is one of the most
studied aspects of coal mining. The problem with gob pile reclamation is that it requires
numerous inputs to work in unison, which makes it one of the most difficult aspects of
coal mining.
Coal refuse is under such strict regulations due to the fact that, if left untreated, it
has the potential to cause numerous hazards. These potential hazards include, water
contamination, sedimentation in surrounding watershed, damage from landslides, and
spontaneous combustion (Daniels and Stewart, 2000). Water contamination could be
caused by acid leachate originating from the gob pile. Barren refuse could contribute to
sedimentation in nearby watersheds. Vegetative cover is essential in reducing
sedimentation problems. The potential of landslides comes from the fact that most gob
piles have steep faces. Correct construction of gob piles, specifically the compaction
aspect of the construction, is important in reducing the land stability hazard. Since most
gob piles have some amount of pyritic material, pyrite oxidation is going to occur. As
mentioned earlier, pyrite oxidation is an exothermic reaction, so if conditions are right the
gob pile could actually spontaneously combust. All of the above mentioned hazards must
be considered when a coal company is constructing their coal waste pile.
Once the gob piles are fully constructed (no more waste is being added) the first
step is to establish vegetation. The establishment of vegetation reduces erosion of the
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gob pile. Many characteristics of typical coal refuse in Virginia make it difficult to
establish vegetation. The main problems with coal refuse is that it is highly variable, low
in pH, high in potential acidity and low in fertility (Daniels and Stewart, 2000). Once the
refuse is constructed into a gob pile other constraints come into play. The piles
themselves usually have steep slopes, produce acid leachate and seepage, are highly
compacted, have shallow rooting depth, and have high surface temperatures (Daniels and
Stewart, 2000). They also lack the ability, in most situations, to retain necessary
moisture. To counteract the abovementioned constraints, an integrated approach is
needed. The approach used must be based on a thorough understanding of the refuse and
gob pile site in question (Daniels and Stewart, 2000).
The revegetation process begins during the final grading of the gob pile. It is
suggested that the final 0.5 m of the gob pile be left uncompacted as much as possible
(Daniels and Stewart, 2000). Once the final grading is complete, the most common
approach is to add a liming agent, if needed, directly to the gob pile first. It has been
found that incorporating the liming agent into the coal waste provides the best results in
most situations (Daniels and Stewart, 2000). In some situations, when the net acidity of
the gob pile is greater than 50 Mg ha-1, a topsoil addition is needed (Daniels and Stewart,
2000). After lime is added, fertilizers should be added. Then, depending on what type of
vegetation is going to be established (annual or perennial), seeding should be done.
Gob piles with high net acidity require a topsoil cover. Numerous materials have
been researched as potential topsoil covers. Materials that have been found to be
potential covers are, but not limited to, crushed overburden, sand, locally harvested
topsoil, biosolids, mulch, and sawdust.
Overall, gob pile reclamation is a very complex process that requires many
different aspects to work in unison. The reclamation of gob piles is one of the most
important aspects to coal mining, due to the environmental concerns and the fact that the
mining companies have a lot of money occupied in bonds related to the reclamation of
the waste piles.
6.7 Safety, Regulatory, and Environmental Concerns
6.7.1 Environmental Regulations, Clean Water Act
20
Mining operations are regulated under the Clean Water Act (CWA), including
discharges of pollutants to streams from valley fills (CWA Section 402) and the valley
fill itself where the rock and dirt is placed in streams and wetlands (CWA Section 404).
The Clean Water Act section 404 permit program, regulates the dredge or fill
material of navigable waters, including wetlands. The Clean Water Act’s jurisdiction
over valley fills mining operations is obvious. If any streams or wetlands are covered up
by overburden, the mine must first receive a permit. This is a lengthy process that needs
to have a management and remediation plan. Often requiring twice as much area of
wetlands to be constructed, to replace what is lost.
The Clean Water Act, section 402, regulates all pollutants discharged from a point
source into the “waters of the United States.” All runoff leaving a mine site is subject to
section 402 of the clean water act. This requires the mining company to file a permit for
the discharge leaving the site; historically the mining industry is in the process of
switching from concentration standards to mass loading standards. This is a much more
complicated system but should reduce the overall mass that enters the waterways. (EPA
Factsheet-2008)
6.7.2 Mining Regulations, SMCRA
The Surface Mining Control and Reclamation Act of 1977 (SMCRA) is the set of
federal laws (PL 95-87) that regulates environmental effects of coal mining in the United
States. It contains two programs, one which regulates active coal mines, and one for
reclaiming abandoned mine lands. This act grew due to concern of environmental effects
of strip mining for coal, and is considered the main regulatory law for coal surface
mining.
The main section of SMCRA that needs to be considered in the design process
falls under Title V, “Control of the Environmental Impacts of Surface Coal Mining”.
Within Title V there are numerous sub sections which will need to be specifically heeded.
These include sections: 508 (Reclamation plan requirements), 515 (Environmental
protection performance standards), and 517 (Inspections and monitoring).
Section 508 is specifically important, because it lays out what must be included in
a reclamation design plan in order to be permitted. Requirements include detailed
21
descriptions of measures taken to ensure protection of water quality, water rights of users,
and the quantity of water on and off site.
6.7.3 Mining Regulations, States
The Clean Water Act, while having authority to regulate the previous two
sections, in practice it has delegated that authority to the individual states. Each state is
given the option to have its coal mining regulated by the Federal government, or enact
their own standards that are at least as strict as the Office of Surface Mines (OSM) and
then regulate themselves. Most states, including Virginia, have chosen to regulate
themselves. In Virginia the agency is the Department of Mines, Minerals and Energy
(DMME). In this way all of the Clean Water Act and SMCRA rules have to be followed,
but the states ensure their own compliance.
6.7.4 Construction Safety, Heavy Machinery and Chemicals
The reclamation of coal waste piles can be dangerous due to need of numerous
earth moving pieces of equipment. The fact that the equipment is not only driven on flat
land but also on steep, sometimes unstable, slopes makes safety more important. OSHA
publishes a standard for all earth moving equipment. It states general equipment safety
and it details practices that should be followed in unique circumstances that can be
encountered. The standard is Material Handling Equipment. – 1926.602. The equipment
safety factors need to be considered to not only protect employees of the mine but to also
ensure that the Red River Coal company does not encounter any fines or law suits due to
safety issues.
During the reclamation of the waste pile a lot of liming material will be needed.
There are liming regulations that need to be followed. Most of these regulations are
implemented by the Commonwealth of Virginia. The Virginia Agricultural Liming
Materials Act (3.1-126) is where these regulations can be found. Although the
application of the lime is not in an agricultural setting these regulations must be
considered because the liming materials being used are agricultural limes.
6.8 The Use of Biosolids as a Soil Amendment
Gob pile reclamation can be improved by using biosolids. As mentioned early,
some of the pressing issues with the gob pile material are that it is usually compacted,
low in pH, low in fertility, has a low water holding capacity, and is low in organic matter.
Biosolids can decrease the negative affects the latter four conditions impose. An obstacle
22
that must be overcome when applying biosolids is gaining the acceptance of nearby
community members. In the past, public complaints have halted several biosolids
application projects. The application of biosolids on the Red River Coal Company’s gob
pile has been highly opposed by the public, this is the reason the company does not use
biosolids as a soil amendment. The public perceives that biosolids will cause health
problems along with water quality problems; although no study has ever shown that an
EPA regulated biosolid application has caused detrimental effects to humans.
The three most common concerns from the public are increased pathogen
transmittal, ground and surface water contamination due to nitrate (NO3), and the
deposition of heavy metals into the food chain. Biosolids pretreatment techniques can be
used to almost eliminate any pathogens in the biosolids. Aerobic and anaerobic
digestion, along with lime stabilization and composting are some of the most common
pretreatment techniques used to reduce levels of pathogenic bacteria in biosolids. To
combat nitrate leaching, the C/N of the material must be increased to a ratio of 20:1 or
higher (Daniels et. al, 2000). The high C/N ratio will cause the nitrogen from the
biosolids to become immobilized and unable to leach out of the coal waste. One common
way to increase the C/N ratio is to mix wood chips with the biosolids. To decrease the
affects of the heavy metals in biosolids one must maintain a pH of 5.5 or higher in the
amended soil (Daniels et. al, 2000).
There have been three major studies done dealing with biosolids applications.
One was done in the state of Pennsylvania on a burned recontoured bank. The
Pennsylvania was the first to use a mine reclamation specific biosolids. It was called
mine mix. This mix is a 1:1 by volume mixture of composted sludge cake with wood
chips and anaerobically digested dewatered sludge cake (Daniels et al., 2000). The study
showed that the mine mix could be effectively used on surface mined areas and on coal
waste piles. It showed that forage production levels and pH levels were higher when
using the mine mix. It was found that the mine mix increased the organic carbon and
total nitrogen levels. The application of the mine mix did not affect the nitrate levels in
the nearby ground and surface waters. The monitoring program also showed that the
biosolids application didn’t increase the heavy metal levels in animals above the tolerant
23
levels. The study concluded that the optimum application rate of the mine mix was
approximately 134 Mg ha-1 (Daniels et. al, 2000).
Another study was done in the Chicago area. This study used sludge cake as a
soil amendment. The study applied biosolids every year instead of just one large
application as in Pennsylvania. With the annual application of the biosolids there was a
problem with heavy metal levels in the plants and animals in the application area. The
third study was done by Virginia Tech on the Powell River Project Research Area in
Wise County, Virginia.
The study conducted by Virginia Tech is the most relevant to this project because
it was done in the same county as this project is focused on. The study included some
small research plots and large research plots (70 ha). Sludge cake was used as the
biosolid on the small research plots and Philadelphia mine mix was used on the large
research plots. Although the study was implemented on overburden it is applicable to the
gob pile because the pH levels are generally similar in this area. The study observed the
yield of tall fescue and pine trees. Water quality was monitored throughout the study. It
was concluded that applications of dewatered sludge cake should be greater than or equal
to 80 Mg ha-1 and the application of wood waste/biosolids product should be greater than
or equal to 112 Mg ha-1 (Daniels et. al, 2000). An application greater than 112 Mg ha-1
can be used if long term pH control is addressed. The heavy applications would be
mainly used on coal waste material. The study also concluded that areas with a pH lower
than 6 should be limed before the biosolids application (Daniels et. al, 2000). The study
also suggests that the biosolids should not be applied within 5 m of drainage areas, wet
spots, or outslopes (Daniels et. al, 2000). The biosolids material should be incorporated
to a depth of at least 10 to 15 cm (Daniels et. al, 2000). Heavy metal and NO3 levels
should be monitored extensively before and after biosolids application.
All three studies show that biosolids application can be very effective in areas
where the public approves of the application. The biosolids can improve vegetation
growth and soil quality. The studies show that biosolids can be used as an effective long
term soil amendment. Techniques that decrease NO3 leaching and heavy metal
deposition have been determined and can be implemented easily. Pathogen transmittal
will not be a problem as long as the correct pretreatment and correct application is
24
conducted. Biosolids is a viable choice of soil amendment as long as the public approves
of the application.
7.0 Preliminary/Alternative Designs
In order to treat acid mine drainage, there are numerous designs that can be
utilized. The six designs, shown in Figure 5, are the major treatment systems being
utilized in the mining industry today. To appropriately assess which design fits the Red
River Coal Company’s coal waste pile best, the exact chemistry of the influent needs to
be determined. The decision matrix shown in Figure 7 shows the preliminary system
selection based solely on current research. These numeric values are subject to change
once the exact influent chemistry is determined. Currently a vertical flow wetland system
is the best option for the site.
A decision matrix was not developed for the engineered soil, because only two
options were feasible, a traditional soil matrix and a contemporary soil matrix which
utilizes biosolids. The traditional option is currently utilized by Red River Coal
Company and the contemporary matrix was designed for potential future implementation.
25
Horizontal
Flow
Wetland
Vertical
Flow
Wetland
Anoxic
Limestone
Drains
Alkalinity
Producing
System
Open
Limestone
Channel
Limestone
Pond
Chemical
Treatment
Active
Treatments
Passive Treatments
Initial
Costs
Annual
Costs
Physical
Constraints
Area
Required
Years
Effective
Acid
Removal
Metal
Removal
% Possible
3
1
4
4
3
3
8
8
9
3
7
9
4
1
3
5
2
4
3
3
8
3
8
5
7
6
6
8
8
9
9
8
7
7
1
8
9
7
8
8
9
9
8
8
4
6
4
4
4
58.6
70.0
48.6
62.9
57.1
51.4
55.7
Figure 7. Decision Matrix used to determine passive treatment system
7.1 GIS Analysis
An initial analysis of the site was conducted using ArcGIS. This analysis was to
create an overall suitability map for locating our wetlands. Elevation data, as well as road
and building location data layers were utilized. Constraints were defined as shown in
Figure 8, and the overall GIS methodology is shown in Figure 9.
Criteria
Must lie within 15.5 m (50
feet) of flow path
Must have slope < 38%
Dataset
Attribute
Topography
Elevation
Topography
Elevation
Building Locations,
Roads, Power Lines,
Train Tracks
Primary, Secondary
and Tertiary Roads
Area must not conflict with
existing structures
Land Use / Cover
Must be within 183 m (200
yd) of a maintained road
Roads
Figure 8. GIS Criteria
26
Figure 9. GIS Methodology Flowchart
A 15.5 m buffer (approx. 50 ft.) around the flow network is used to make sure that
the wetland is be constructed as close as possible to the existing flow, which would
reduce construction costs. The 183 m buffer around the roads was needed to make sure
the wetland is easy to access for maintenance in the future. Once the buffers were
established and all of the constraints were met, all of the layers were intersected to yield a
final suitability map, Figure 10. The highlighted areas on this map show all the potential
locations which meet all of the defined criteria for the wetlands.
27
Figure 10. Final Suitability Map
8.0 Project Design
The final design will consist of two vertical flow wetland systems and an
engineered cover soil. One of the vertical flow wetlands will be located below the
existing treatment pond (south west of the gob pile), and the second will be located below
the pond on the southern side of the pile. Figure 11 displays the preliminary possible
locations of the VFW, with the primary and tertiary locations ultimately being chosen.
The primary location will allow any sediment laden runoff to enter the pond and settle
out before entering the wetland system. This will keep the wetland relatively free of
sediment and reduce maintenance costs and frequency. The tertiary location ensures the
acidic flow produced on the eastern side of the gob pile will be treated.
In addition to treating the acid mine drainage, an engineered soil will be
developed in order to reclaim the gob pile. Initially, direct liming of the coal waste will
28
be conducted in order to serve as an acid (pH) buffer. Afterwards, an engineered soil
matrix will be added at a depth yet to be determined. This matrix will include organic and
inorganic materials, including, but not limited too, crushed overburden, sand, locally
harvested topsoil, bio-solids, mulch, and sawdust.
Secondary
Location
Primary
Location
Tertiary
Location
Figure 11. Aerial image displaying the
\ three possible locations for the VFW
8.1 Vertical Flow Wetland Design
Vertical flow wetland systems rapidly neutralize acid due to their active mixing of
acid mine drainage with limestone (Zipper and Jage, 2009). Within these systems, a few
factors affect the dissolution of limestone, namely residence time and pH. In the first few
hours of contact, limestone dissolves more readily within the acid mine drainage.
However, as time progresses, more dissolved calcium is present and the dissolution rate
slows. In addition, limestone dissolves more rapidly in lower pH conditions than higher.
29
Thus, the first step in designing the wetland is determining the limestone volume.
Appendix B shows the present water quality data, which is used in the design
calculations.
8.1.1 The Organic Layer
This uppermost layer within the wetland system is one of the most critical and
vulnerable layers. It provides residence for sulfate-reducing bacteria, as well as removing
dissolved oxygen and providing reducing conditions to prevent limestone armoring
(Zipper and Jage, 2009). Key components of this layer are its temperature and
permeability. Oxygen removal is directly related to water temperature and acid mine
drainage residence time within the organic matter. With this in mind, the organic layer
must be designed with adequate size to remain effective throughout cold winter months.
The organic layer can consist of a variety of materials or mix of materials
including composted manure, spent mushroom compost, decomposed wood mulch, or
other mixtures of composted materials (Zipper and Jage, 2009). Organic layer depths
ranging from 12-18 inches (30.5-45.75cm) are generally adequate for most systems. If
this depth is increased, permeability issues may arise as the matter decomposes. If this
layer is too shallow the system may short circuit and allow oxygenated water to reach the
limestone (Zipper and Jage, 2009). When installing, this layer needs to be well mixed,
evenly distributed, and uncompacted.
8.1.2 Calculating Limestone Volume
The system needs to be designed to produce alkalinity adequate of offsetting nonMn acidity (Zipper and Jage, 2009), with additional alkalinity as a safety margin. In this
case, a margin of 100 mg/L of alkalinity will be used as such safety margin. Non-Mn
acidity can be calculated as shown in equation 5.
Non-Mn Acidity = Acidity – 1.818 * Mn
(5)
where,
Acidity = Acidity (mg/L as CaCO3) of the design influent water quality
Mn = Manganese concentration (mg/L) of the design influent water quality
Non-Mn Acidity = acidity derived from Al, Fe, H+ and other ions (mg/L as CaCO3)
30
The residence time of a system can be estimated after the alkalinity design right
has been determined. This is accomplished using equation 6. Figure 12 shows alkalinity
generation as predicted by equation 6.
Alknet = 99.3 * log 10(tr) + 0.76 * Fe + 0.23 * Non-Mn Acidity - 58.02
(6)
where,
Alknet = net alkalinity to be generated (mg/L as CaCO3)
Fe = total iron concentration (mg/L) of the design influent water quality
Non-Mn Acidity = non-manganese acidity (mg/L as CaCO3 - see equation 5)
tr = average residence time in the limestone layer (hours)
Figure 12. Alkalinity generation as predicted by equation 6
This residence time calculated from equation 6 gives an estimated time in which
acid mine drainage must be present in the limestone layer in order to produce adequate
alkalinity. To translate this to size the system, residence time is converted into a
limestone layer volume (Vls) in cubic feet. To convert Vls to cubic meters, multiply the
calculated number from equation 7 by 0.028. This is shown in equation 7.
31
Vls = 8.02 Q tr
Vv
(7)
Where,
Q = influent flow (gallons per minute)
tr = residence time in limestone (hours)
Vv = bulk void volume of limestone expressed as a decimal (e.g., 50% = 0.5)
Vls (m3) = Vls x 0.028
These equations are intended for use with systems utilizing high-calcium
limestone ranging from 0.1-0.15 inches (Zipper and Jage, 2009). This limestone is more
readily dissolved as compared to limestone containing more Mn. The residence time
calculated from equation 6 needs to be adjusted in order to account for aging of the
system and thus overall loss of limestone. Thus, additional limestone (Vls+) must be
factored into the design. Equation 8 calculates this.
Vls+ = 0.044 Q C T
x
(8)
Where,
Q = influent flow (GPM)
C = predicted net alkalinity generation (mg/L)
T = design life (years)
x = CaCO3 content of limestone, expressed as a decimal (e.g., 90% = 0.9)
Vls+ (m3) = Vls+ x 0.028
Typically a limestone layer is designed for a 20-25 year lifetime (Zipper and Jage,
2009). In addition, dolomitic limestone should be avoided for construction, as highcalcium limestone is much more soluble.
8.1.3 Drainage
Below the organic and limestone layer, an underdrain is located to allow for
treated water to escape. This shall be constructed from perforated Polyvinylchloride
piping, with its diameter based on the design flow. Drain diameters of 15.24 cm (6
inches) should be avoided as precipitated metals and sediment accumulation to cause
blockage. Hole diameters should be 2.54 cm (1 inch), this ensures they will not be
blocked by precipitants (Zipper and Jage, 2009). Traditional drain layouts consist of a ‘T’
32
or ‘Y’ shape, usually located within the lower 30.5 cm (12 inches) of the limestone layer,
see figure 13. However, the drains need to be designed to fully utilize all of the limestone
within the wetland. The drains also need to be joined to an elevated standpipe in order to
maintain a constant water head above the organic layer (Zipper and Jage, 2009).
Figure 13. Typical drainage layouts for a vertical flow wetland system
In order to help maintain maximum efficiency of the wetland, a flushing system
should be utilized. A valve located below the standpipe should be opened allowing for
water drawdown of the system. This allows any metal accumulation accumulating in the
limestone to be flushed. In addition, a settling pond should be located following the
vertical flow wetland system. This allows for oxygenation of the water, as well as metal
precipitation and additional pH adjustment (Zipper and Jage, 2009).
8.1.4 Basic Construction
The vertical flow wetland system requires a basin to be excavated, and lined with
an impermeable layer of clay or plastic, preventing acid mine drainage seepage.
Embankments should have 2:1 interior slopes and 3:1 exterior slopes with 2.43-3.04 m
top widths (8-10 ft) (Zipper and Jage, 2009). An additional minimum of 30.5 cm (12
inches) of freeboard above designed high water to an emergency spillway should be
allocated to preserve system integrity (Zipper and Jage, 2009). Figure 14 displays a
schematic of the vertical flow wetland system dimensions.
33
Figure 14. Cross sectional schematic of a vertical flow wetland system
8.1.5 Maintenance
Throughout operation, organic matter and limestone are consumed by the wetland
system, and thus leads to reduced performance. In the event of renewal, the system must
be drained, organic layer removed, and then either replace or add additional limestone to
the system. In the event the drainage system is suffering from high deposits of metals, it
may need replacing as well. Preventively, the system should be drained monthly,
however, varying levels of Al and Fe may dictate more frequent flashings (Zipper and
Jage, 2009).
8.1.6 Final Wetland Design
The final limestone volume needed to treat the acid drainage from the gob pile
was found to be 454 m3. The limestone layer in each wetland will be 49.8 m x 7.6 m x
0.6 m. The design drawing of one wetland is shown in figure 15. This size corresponds
to a wetland designed to last 20 years with an influent flow rate of 190 L/min (10 in of
rainfall over the gob pile), and an alkalinity production safety margin of 60 mg/L.
34
Figure 15: A cross sectional view of one of the two vertical flow wetlands
8.2 Engineered Soil Design
To design the most innovative senior design possible, but still have a design that
would be suitable for our sponsor company, we have proposed a two soil matrix design.
The first one is a traditional mix of a directing liming, to provide a pH buffer, and then a
layer of topsoil to provide a rooting layer and temperature buffer. The depth of direct
liming is determined by the soil chemistry and is not meant to neutralize the gob pile’s
acidity but just to provide a buffer for plants to be able to grow in the upper topsoil layer.
The layer of topsoil is supplied by scraping it off a second site and is truck and applied to
the gob pile. Normally, the topsoil layer will be approximately 0.3 m (1 foot) to provide
an adequate rooting depth. This commonly used soil matrix is only being proposed
because our main design, the application of lime-stabilized biosolids is publicly
troublesome.
For the gob pile, biosolids should be applied at a rate of 112 Mg ha-1. Once
applied, the biosolids should be incorporated to a depth of 10-15 cm. Since the pH of the
35
acid drainage produced by the gob pile is less than 6, a layer of lime should be applied
before the biosolids. It is also recommended that the biosolids application should not be
within 5 m of drainage areas, wet spots or outslopes. Table 1 demonstrates how biosolids
are more economical than the traditional methods.
Treatment
Material Application Seeding+Fertilizer Area Covered Total
($/Mg) (Mg/ha)
($/ha)
(ha)
Cost ($)
Lime-Stabilized
Biosolids / Wood
Waste
0
112
600
40.5
24,300
Traditional (Lime)
55.1
33.6
600
40.5
99,280
Figure 16. Cost differences of traditional versus contemporary soil matrices
Sadly the economic benefits are not enough to turn public opinion on the topic,
and to avoid public outcry Red River Coal does not wish to apply biosolids to the site.
We are including both of our designs with the hope that in the 15-20 years that the gob
pile will be closed, that maybe public perception will soften and the environmental and
economic advantages will persuade Red River Coal to give it a try.
9.0 Work Plan/Summary

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Oct 3
Oct 9
Oct 10
Oct 23
Nov 7
Nov 13







Nov 20
Dec 2
Dec 5
Dec 10
Dec 16
Dec 17
Dec-Jan
Project Timeline
Field trip to a site that showcases different remediation techniques
Revision of Cover Page and Scope of Work
1-Project Notebook
Cover Page, Scope of Work, and Resources
2-Project Notebook
Cover Page, Scope of Work, Resources, Safety, Regulatory, and
Environmental Considerations and Work Plan
3-Project Notebook
Oral presentations and discussion
4-Project Notebook
Classes End
Revised Final Report
Second Site Trip, collection of GIS and AutoCAD data
Research on final design and engineered soil
36












Feb 10
Feb 13
Feb 13-16
Feb 16
March 2
March 7
March 23
April
April
April 20
May 7
May 13
Make corrections to Final Report
Meet with Lee Daniels and get estimated Gob pile runoff values
Add to data and latest calculations to the Mid-Term Project Report
Mid-Term Project Report due
Revised Work Plan due
Finish Calculations and have final wetland design and soil matrix
Oral presentations and discussion
Finish Auto Cad design
Final Design Presentation to Red River Coal Company
Draft of the Final Report
Individual Oral Exam
Final Report
During the course of the fall semester, our project has experienced significant
progress. Starting from the initial pitch, which developed group interest, research began
on mining remediation and reclamation. On October 3rd, the group went on a field trip
with Dr. W. Lee Daniels to the Red River Coal Company. There, Dr. Daniels stated that
remediating overburden piles has been thoroughly researched and is no longer a
significant challenge. Instead, it is the gob piles that present the most serious challenge
for engineers to remediate. From this point on, the group has focused on remediating and
reclaiming a coal waste pile. During the following weeks, the group did extensive
research and added to the literature review. During this time, multiple designs were
evaluated and a final design was chosen through a design matrix (Figure7). Nearing the
end of the fall semester, the group presented the design to classmates and facility of the
Biological Systems Engineering Department of Virginia Tech on December 2, 2008. The
group submitted a final report on December 16, 2008.
Immediately after the submission of the mid term final report, Mining R&R made
a second site visit to the Red River Coal Company. During the trip, water samples were
collected from holding ponds around the gob pile, as well as samples directly from the
coal refuse slurry that is being pumped into the gob pile. During the second trip, Mining
R&R meet with the senior engineer of the Engineering consulting firm advising Red
River Coal Co. During that meeting we discussed the constraints and options of both
acid treatment and the engineered soil of the gob pile. During this trip the group learned
a lot about the operations of the processing plant; particularly of its current water
recycling procedure. Currently little to no water treatment is taking place, despite the low
37
pH running off the site. This is due to the fact that a majority of water coming off the site
is gathered in ponds and remixed with more impurities and pumped back into the gob
pile. This effectively creates a closed system that reduces pollution and costs, however
when the site eventually closes this pumping system will be halted. The site is expected
to be closed within the next ten years. Our design is intended to go into use when the site
halts its operations.
Since the water currently leaving the site is not a good indicator of water quality
that would naturally leave the site following the processing plant closing, Mining R&R
was forced to seek outside information. The team advisor, Lee Daniels, is very
knowledgeable of this gob pile and in early work ran experiments to determine the likely
runoff leaving the gob pile. It is with these estimated values that we designed our
wetlands. The group utilized the water treatment plan from the fall semester, which was
a vertical flow wetland. For the engineered soil matrix, it was decided that two separate
designs will be created. One incorporates biosolids from processed human waste, and the
second is a more traditional mix. While the biosolids soil matrix will be a more
innovative and cost effective design; Red River Coal notified the group that the public
attitude towards that solution remains negative and they will like to avoid that.
Respecting the wishes of Red River Coal, a conventional engineered soil design was
provided, but for their future consideration the main soil matrix design with bio-solids
will also be delivered.
In conclusion, Mining R&R remains optimistic about this project, and will be able
to deliver an innovative and realistic design to Red River Coal Company. We look
forward to presenting our final product to Red River Coal Company at the conclusion of
the academic year.
38
Figure 17. Gantt Chart for fall and spring semester work
10.0 Summary and Conclusions
Red River Coal Company will be closing their mining operations in Wise County,
Virginia within the next 20 years. After mining has ceased, their coal waste pile must be
reclaimed and the drainage from the pile must continue to be treated. To resolve these
issues, a vertical flow wetland can be utilized to treat the acid drainage and an engineered
soil matrix can be designed to reclaim the pile.
It was decided that two vertical flow wetlands should be implemented on the site.
One will be placed on the west side of the pile and along the drainage path. The second
wetland will be placed on the south side of the pile. Together, the wetlands will hold 454
m3 of lime to reduce the acidity of the drainage. Each wetland will be 49.8 m x 7.6 m x
0.6 m.
Two soil matrices were designed for the site. One was done at the request of Red
River Coal. It is a traditional mix of topsoil and lime. The second is a contemporary soil
matrix that consists of a lime application followed by a biosolids application. It is
39
recommended that the biosolids should be applied at a rate greater than or equal to 112
Mg ha-1.
The final design can be implemented as soon as mining operations have ceased at
the site. The design was produced to reduce long term maintenance and ensure
compliance with SMCRA environmental regulation.
11.0 Design Reflections
Throughout the past year, our team has had a successful and meaningful design
experience. We initially struggled to find a project idea, after debating between a few
options, but ultimately decided on the mining problem. This turned out to be an excellent
and challenging choice.
We quickly learned that having a very knowledgeable and active advisor made
the overall experience much more enjoyable. We entered our project relatively ignorant
to many aspects of mining and reclamation, and through interactions with our advisor,
field trips, and personal research we have ended our experience much more educated. As
a team we had excellent chemistry and worked well together. Work was often completed
as a group, or divided up evenly without protest. One aspect we came to value was
communication. Even when a member was completing a task individually, more often
than not they were on the internet or telephone communicating with other team members,
asking for suggestions or checking results.
In retrospect, if we were to change anything about our project, it would have been
to work more closely with Red River Coal and state agencies. This may have lent itself to
a more detailed project overall, and provided us with more resources.
40
Resources
1. Daniels, W. Lee, and Barry R. Stewart. 2000. Reclamation of Appalachian Coal
Refuse Disposal Areas. In Reclamation of Drastically Disturbed Lands, 433-459.
Madison, Wisconsin: Madison, Wisconsin USA Publishers.
2. Daniels, W. Lee, Kathryn C. Haering, and Sam E. Feagley. 2000. Reclaiming
Mined Lands with Biosolids, Manures, and Papermill Sludge. In Reclamation of
Drastically Disturbed Lands, 615-644.
3. Demchak, J., J. Skousen, and T. Morrow. “Treatment of Acid Mine Drainage by
Four Vertical Flow Wetlands in Pennsylvania.” West Virginia University
Extension Service. Accessed 20 October 2008.
http://www.wvu.edu/~agexten/landrec/treatment.htm
4. EPA, Fact Sheet. 2008 Mid-Atlantic Mountaintop Mining. Accessed 11
November 2008. http://www.epa.gov/Region3/mtntop/
5. Gray, B., and J.R. Nawrot. 2000. Principles and Practices of Tailings
Reclamation: Coal Refuse. In Reclamation of Drastically Disturbed Lands, 461488. Madison, Wisconsin: Madison, Wisconsin USA Publishers.
6. Gryme, C. “The Role of Coal in Southwest Virgnia” Virginia Places. Accessed
20 October 2008 <http://www.virginiaplaces.org/geology/coalshape.html
7. Henson, Edward. “About Wise County” Wise County Government, 2006.
Accessed 20 October 2008 http://www.wisecounty.org/about_wise_county.html
http://www.wisecounty.org/wise_history.html
8. Nyavor, K., and N. O. Egiebor. 1995. Control of pyrite oxidation by phosphate
coating. The Science of the Total Environment. 162(2-3): 225-227.
9. Red River Coal Company website. Accessed 30 November 2008.
http://www.redrivercoal.com/index.htm
10. Skousen, J. “Overview of Passive Systems for Treating Acid Mine Drainage.”
West Virginia University Extension Service. Accessed 11 November 2008.
http://www.wvu.edu/~agexten/landrec/passtrt/passtrt.htm
11. Valigra, Lori. “Mountaintop Mining Raises Debate in Coal County” National
Geographic News. January 13, 2006.
http://news.nationalgeographic.com/news/2006/01/0113_060113_mountain_mine
_2.html
12. Watzlaf, G, R., K. T. Schroeder, R. L.P. Kleinmann, C. L. Kairies, and R. W.
Nairn. 2003. The Passive Treatment of Coal Mine Drainage. NETL, US Dept. of
Energy.
13. Ziemkiewicz, P.F., J.G. Skousen, and J. Simmons. 2003. Long-Term Performance
of Passive Acid Mine Drainage Treatment Systems. Mine Water and the
Environment 22: 118-129.
14. Zipper, C., C. Jage. “Passive Treatment of Acid-Mine Drainage with Vertical
Flow Systems” Virginia Tech Cooperative Extension Services. Accessed 12
February 2009. http://www.ext.vt.edu/pubs/mines/460-133/460-133.html#L6.
41
Appendix A: Student Skills
Qualifications: Land and Water Resource engineering, Reclamation and Soil
Sciences background
Estimated commitment:
3-5 hours a week
Skills Needed
 Teamwork and communication skills
 Technical writing
 Knowledge of general surface mining operations
 Geographic Information Systems experience
 Knowledge of engineered soils
 Wetland Design
 Soil/Water Geochemistry
 Knowledge of mining and engineering economics
42
Appendix B: Water Quality Data
Data reported as mg/L (unless otherwise noted) in solution. The "<" indicates
concentrations less than the detection limit. Standard Methods used taken from SM 20th
Ed. (unless otherwise noted). Data was processed by water quality lab of Virginia Tech.
The samples were collected on the mine site.
Analyte
Method
Det. Limit
GR 1
GR 2
GR 3
GR 4
GR 5
GR 6
GR 7
pHu
SM 4500H+B
0.1 pHu
DO
Iron
Manganese
Aluminum
Hach 8166
0.3mg/L
SM 3120 B
0.009 mg/L
SM 3120 B
0.003
SM 3120 B
0.006
8.04
7.33
7.35
7.69
7.4
5.08
7.47
3.4
7.9
8.1
7.7
7
7.2
6.6
246.85
3.22
3.439
0.718
0.469
0.019
0.455
11.95
15.367
15.35
7.864
7.905
15.045
2.9
58.43
0.062
0.069
0.161
0.066
7.073
4.689
GR1: Slurry
GR2: Tertiary Location, Above Final Pond 1
GR3: Tertiary Location, Above Final Pond 2
GR4: Primary Location 1
GR5: Primary Location 2
GR6: Secondary Location, Lower Ditch
GR7: Secondary Location, Upper Ditch
43
Appendix C: List of Figures
Figure
Page
Figure 1. Basics of Mountain top removal (EPA Factsheet-2008) ................................. 10
Figure 2. Red River Coal Mine Location.......................................................................... 12
Figure 3 Aerial image showing the coal waste pile and treatment ponds ........................ 12
Figure 4. Acid mine drainage in Wise County. ............................................................... 14
Figure 5. A diagram of different types of passive treatments (Skousen, 2008)............... 15
Figure 6. Flowchart for selecting passive treatment systems. (Skousen, 2008) .............. 16
Figure 7. Decision Matrix used to determine passive treatment system.......................... 26
Figure 8. GIS Criteria ...................................................................................................... 26
Figure 9. GIS Methodology Flowchart ............................................................................ 27
Figure 10. Final Suitability Map ...................................................................................... 28
Figure 11. Aerial image displaying the three possible locations for the VFW ................ 29
Figure 12. Alkalinity generation as predicted by equation 6 ........................................... 31
Figure 13. Typical drainage layouts for a vertical flow wetland system ......................... 33
Figure 14. Cross sectional schematic of a vertical flow wetland system......................... 34
Figure 15: A cross sectional view of one of the two vertical flow wetlands ................... 35
Figure 16. Cost differences of traditional versus contemporary soil matrices ................ 36
Figure 17. Gantt Chart for fall and spring semester work ............................................... 39
44