1. Abstract
The mining industry produces a multitude of
environmental problems through the practice of strip
mining. The acidification of surface and ground water,
even after reclamation, is an example of such
environmental problems. Because acidic water and
neutral water look the same to the untrained eye, this
issue is often overlooked without doing proper soil,
groundwater, and surface water testing and sampling.
The objective of the study was to determine the
source or cause of the acid mine seep. This study took
place in a recently reclaimed area of an undisclosed
mining company’s coal mine in east Texas. We
concluded that the upper most ground water bearing
unit was comprised of an unconfined aquifer
dominated by a loamy sand soil that appeared to be
oxidized that resulted in acid formation.
Introduction and Objectives
Coal mines are notorious for being environmentally
harsh (3), and through the process of strip mining
environmental problems such as acid seeps can occur.
Acid seeps are the product of ground and surface
water acidification (1). A seep is caused when
downward traveling groundwater confronts an
impermeable layer like clay and is forced to move
horizontally through the path of least resistance using
the force of hydrostatic pressure, similar to an artesian
well (2). Since water travels downhill, our sampling
protocol was to obtain samples along the route of
ground and surface water to the point of the seep.
Methods
For each core sample we performed five different tests
(pH (Figure 7), specific conductivity (µS/cm), color,
texture, trace elements (Figure 6), and Sulfate presence
(Figure 5). To do these tests we used a YSI multiprobe,
Munsell Color Chart, USDA Texture Chart, X-Ray
Fluorescence(XRF) Meter, and a Barium Chloride solution
to determine the soil characteristics, respectively.
Soil was further divided into 0.5 ft. subsamples derived
from the two foot core intervals (8) that had the lowest
pH, with one additional sample being obtained at a
depth interval just above the largest pH drop. A total of
five subsamples were obtained from each borehole.
Samples were then frozen at -20°C and will be analyzed
for metals and anions. A smaller portion of these
samples were subsampled for iron and sulfur oxidizing
bacteria and analyzed using the Most Probable Number
method. Results from this analysis are still pending.
Relationship to Career Goals
This was a hands-on experience and training that an
undergraduate student typically does not obtain
even in most internships. In a practical fashion I
learned how to collect environmental data using
proper protocol. I was fortunate because my mentor
has approximately ten years of environmental
consulting experience. Working in the field with an
experienced individual also gave me the
opportunity to experience how data is interpreted,
what conclusions can be made, and how to apply
what is learned from the data to address a real-
world problem.
Results
Conclusion
Literature Cited
I thank Jason Paul for giving me the opportunity to
assist him in his research, and giving me this
irreplaceable experience. Sponsors for high impact
experiences for BESC and the BESC poster
symposium include the Department of Plant
Pathology and Microbiology, the College of
Agriculture and Life Sciences, the Office of the
Provost and Executive Vice President for Academic
Affairs.
Coal Mine Ground Water Acidification
Christian Eubanks1, Jason Paul2 and Paul Schwab2
Bioenvironmental Sciences1 and Department of Soil and Crop Sciences2
Texas A&M University
During the mining process the soil was turned
from the bottom to the top. In doing so oxidized
soil is now at the bottom which provided an
oxygen source for further oxidation of soil
components. Soil that was reduced is now at the
top which is closer to the atmosphere enabling it
to become oxidized. This provides an overall oxic
environment which promotes oxidation of iron
sulfides and other acid forming minerals by soil
microorganisms. This will be confirmed through
chemistry and soil analysis.
Acid seepage from reclaimed coal mines in Texas
is a major issue for which research to prevent its
occurrence post-mining has been rarely
conducted. By using a variety of testing
techniques we were able to characterize the
overburden, which is required in order to
understand how to prevent acid seepage.
Depth pH SO4(Y/N) SC
0-2 5.12 N 18.7
2-4 4.74 N 23.6
4-6 4.97 N 21
6-8 4.17 N 49.9
8-10 3.53 N 82
10-12 3.27 N 156.2
12-14 3.7 N 83
14-16 3.78 N 78
Fig. 3
Fig. 4 Fig. 6
Fig. 5 Fig. 7
Table 1: Sample of information recorded in field journal
Fig. 1 and 2. Fig 1. Holding tank for reclaimed water from coal mine. Fig 2. Primary acid seep at work site.
Fig. 1 Fig. 2
A total of 15 boreholes were used to install monitor
wells based on their distance and difference in
elevation. At each well location, a drilling team bored
to a determined depth using a drill rig (Figure 4) to
obtain core samples in two foot intervals. At each
borehole, drilling total depth targeted the water
elevation of the nearest lake, to which it would be
hydrogeologically connected.
Fig. 8. Example of a two foot sample
Fig. 4. Testing for sulfate. Fig. 5. Testing for trace elements. Fig. 6. Testing for pH
and SC. Fig. 7. Recording data in field journal
Fig. 3. Drilling rig used to bore wells
Acknowledgements
1. Texasmpa.org. N. p., 2016. Web. 6 Oct. 2016
2. "Artesian Well". Encyclopedia Britannica. N. p., 2016.
Web. 6 Oct. 2016.
3. "About Coal Mining Impacts". Greenpeace International.
N. p., 2016. Web. 6 Oct. 2016.