AbstractThe 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 GoalsThis 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 AcidificationChristian 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. 20162. "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.