Southeastern Naturalist J. Lanham, J. Sencindiver, and J. Skousen 2015 Vol. 12, Special Issue 7 58 Canaan Valley & Environs 2015 Southeastern Naturalist 14(Special Issue 7):58–64 Characterization of Soil Developing in Reclaimed Upper Freeport Coal Surface Mines Jennifer Lanham1, John Sencindiver1, and Jeff Skousen1,* Abstract - A new highway, called Appalachian Corridor H, will pass through the Beaver Creek watershed in Tucker County, WV. Some of this area has been affected by surface mining of Upper Freeport Coal. The resulting mined lands are currently producing acid mine drainage and have the potential to produce more if disturbed. To document soil development and the effect that disturbance of these mined lands might have on water quality, we evaluated the properties of the soils that will potentially be affected by highway construction. Six sampling sites were located on mine soils and on adjacent undisturbed soils. After describing soil profiles, we sampled each horizon for laboratory analyses. We analyzed the soil samples for pH, electrical conductivity , carbon, nitrogen, sulfur, and acid-base account. Other soil properties like texture, water holding capacity, acidity, cation exchange capacity, and elemental concentrations (Al, Ca, Mg, Na, K, Fe) were determined but not reported herein. Most of the mine soils had weakly developed B horizons and were classified as either entisols or inceptisols. The pH values ranged from 3.2–4.8. Electrical conductivity and total nitrogen were low. Total sulfur was generally low, ranging from 0.1% to 0.17%. However, one mine soil had sulfur values >1% in the lowest horizon. We sampled two overburden rock cores and analyzed them for acid-base account characteristics. These data support the mine soil data, which indicate that acid materials occur in this region and may produce additional acid if unweathered rocks and mine soils are exposed to the atmosphere during road construction. Recommendations for reclamation of the disturbed materials will be developed. Introduction Part of a new highway, called Appalachian Corridor H, will pass through the Blackwater River and Beaver Creek watersheds, Tucker County, WV. Beaver Creek flows adjacent to Rt. 93, northeast of Davis in Tucker County. The Upper Freeport Coal bed dominates areas on the southeastern side of Rt. 93, and the Bakerstown Coal bed dominates the road’s northwestern side. Upper Freeport Coal forms the upper strata of the Allegheny Group of the Pennsylvanian System (West Virginia University 1995). The rocks of this system are sedimentary, with the youngest found at the surface in Tucker County (Losche and Beverage 1967). Much of the Beaver Creek watershed has been extensively surface mined, and parts of it are still being mined. Construction of the new highway will re-disturb areas of the Beaver Creek watershed that were previously mined for Upper Freeport Coal, as well as impact undisturbed materials that have formed over the Upper Freeport Coal and also tend to exhibit acidic properties. Upon exposure to air and water, 1Division of Plant and Soil Sciences, West Virginia University, PO Box 6108, Morgantown, WV 26506. *Corresponding author - jskousen@wvu.edu. Southeastern Naturalist J. Lanham, J. Sencindiver, and J. Skousen 2015 Vol. 12, Special Issue 7 59 the shales found over and under the Upper Freeport Coal, and the coal itself, are expected to produce acid-mine drainage (West Virginia University 1995). Mine soils in the area are currently producing some acid-mine drainage. Redisturbance of the mine soils could potentially exacerbate the area’s acid-mine drainage problems. Characteristization of the Upper Freeport Coal mine soils will provide the WV Division of Highways with crucial data for predicting problems that could result from Corridor H construction. This information could be useful for determining the exact route of the proposed road, the preventative measures needed to protect the area from a detrimental increase in acid mine drainage, and the amendments needed to reclaim disturbed sites. Methods and Materials The research area is comprised of three major areas along ridge tops that were disturbed by mining of the Upper Freeport Coal bed. These three sites are located on the southeastern side of Rt. 93, about 5 km (3.0 mi) northeast of Davis, WV (Davis Quadrangle topographic map [USGS 1995]). On each disturbed study site, we excavated two soil pits to >100 cm (40 in) deep and described the soil profiles according to standard soil survey techniques (Soil Survey Staff 1996). Within the research area, we labeled the southwestern-most spoil pile as site 1, the northeastern-most spoil pile was site 3, and site 2 was located between sites 1 and 3. We took bulk samples from each described horizon. The samples were delivered to laboratories in the Division of Plant and Soil Sciences at West Virginia University, where they were prepared for analyses by air drying and sieving to less than 2 mm. We analyzed each mine soil sample for pH, electrical conductivity, acid-base accounting, total carbon, total nitrogen, and total sulfur. We measured pH on 1:1 soil:water samples (method 81c, Soil Survey Staff 1996), electrical conductivity with a 1:2 soil:water ratio, and total carbon, nitrogen, and sulfur by using a LECO CNS 2000 analyzer. We determined the acid-base account of the mine soils by using the procedure outlined in Skousen et al. (1997). The acid-base account consists of three important values: (1) the maximum potential acidity (MPA) is the maximum amount of sulfuric acid that can be produced from the oxidation of sulfur in the coal and overburden (Skousen et al. 2001); (2) the neutralization potential (NP) is a measure of the amount of neutralizing materials within the soil, coal, and overburden; and (3) the net neutralization potential (NNP) is determined by subtracting the MPA from the NP. All values are expressed in tons of CaCO3/1000 tons of material. A negative NNP value indicates potential acid-producing material, whereas a positive number indicates potentially acid-neutralizing material (Skousen et al. 1987, 2001). In order for material to produce a significant amount of acidic drainage, its NNP value must be less than -5 tons CaCO3/1000 tons. The acid-base account procedure can also help to identify alkaline materials. In order for a material layer to be considered alkaline and thus useful for neutralizing surrounding Southeastern Naturalist J. Lanham, J. Sencindiver, and J. Skousen 2015 Vol. 12, Special Issue 7 60 acidic layers, it must have a NNP value of >15 tons CaCO3/1000 tons (Skousen et al. 1987). Rock cores were drilled and sampled by a private consulting firm. Of the 12 cores drilled along the proposed route, we chose four within the vicinity of the soil pits for discussion in this paper. Cores R-1-3 and R-1-5 were taken from site 1 and Cores R-1-9 and R-1-10 were on site 2. No cores were sampled for acid-base accounting on site 3. Acid-base accounts of these core samples should complement the mine soil data and thereby provide more information because the cores reached to the depth of the actual road construction. Results and Discussion All of the soils described featured distinguishable A horizons, which ranged in thickness from 3 to 8 cm (1.2–3.2 in; Table 1). Five of the profiles had Bw horizons, i.e., weakly developed B horizons. The thickness of these horizons ranged from 7 to 91 cm (2.8–36.4 in). At site 2, the BC horizon at pit 3 was located below a Bw horizon. Every soil had a C horizon described. The combined thickness of the C horizons ranged from 71 cm to ≥161 cm (28.4 in to ≥64.4 i n). The colors of the soils varied from black (N 2.5/0) and gray (10YR 5/1) to yellowish brown (10YR 5/4). Structure in the A horizons was weak or moderate granular, or weak sub-angular blocky. The B horizons had weak or moderate subangular blocky structure. All of the C horizons were massive. The A horizons had loam or silt loam textures, and the B horizons had silty clay loam, silt loam, or clay loam textures. The C horizons were described as having silty clay loam, silt loam, clay loam, sandy loam, or clay textures. Table 1. Chemical properties of Upper Freeport mine soils. Site/pit Horizon Depth (cm) EC (ds/m) % C % N Site 1, pit 1 A 10 0.02 2.5 0.02 B 35 0.01 1.3 0.01 C ≥190 0.04 1.4 less than 0.00 Site 1, pit 2 A 8 0.09 6.9 0.02 B 99 0.11 6.4 0.01 C ≥250 0.14 5.7 0.01 Site 2, pit 1 A 5 0.04 5.6 less than 0.00 B 12 0.03 3.4 less than 0.00 C ≥141 0.02 5.5 0.02 Site 2, pit 3 A 5 0.04 3.8 less than 0.00 B 49 0.06 3.5 less than 0.00 C ≥120 0.16 25.5 0.26 Site 3, pit 1 A 9 0.02 7.7 0.02 C ≥170 0.05 6.5 0.01 Site 3, pit 2 A 11 0.01 4.5 less than 0.00 B 34 0.02 2.6 less than 0.00 C ≥118 0.02 2.6 less than 0.00 Southeastern Naturalist J. Lanham, J. Sencindiver, and J. Skousen 2015 Vol. 12, Special Issue 7 61 The presence of the A and B horizons in these mine soils is evidence of soil development. Mine soils with little or no development would not have contained a B horizon. One of our soil profiles did not have a B horizon, which suggests that it may be younger than the others, or that it had not been affected as much by the factors of soil formation. Chemical properties of the mine soils did not vary widely (Table 1). For purposes of presenting and analyzing data, all subordinate horizons and transition horizons beginning with A, such as AC, have been combined for each soil profile and are shown as horizon A. Likewise, all subordinate B horizons, the Bw and BC horizons, were combined and are shown as the B horizon for each soil, as have those of the C horizons. Electrical conductivity, which indicates salt content, was 0.01 to 0.09 dS/m in the A horizons, between 0.01 and 0.11 dS/m in the B horizons, and from 0.02 to 0.16 dS/m in the C horizons. These fairly low values suggest that the salts created from active acid-sulfate weathering have been leached to lower depths. Johnson and Skousen (1995) showed that Upper Freeport abandoned mine soils had EC values of 0.1 to 0.5 dS/m in upper and lower horizons. The A horizons had total carbon contents ranging from 2.5 to 7.7%. Total carbon values in the B horizons were 1.3–6.4%, and those of the C horizons ranged from 1.4 to 25.5%. Site 1-pit 2 and site 3-pit 1 had generally higher carbon levels than the other soils. We attribute this to the presence of carbolithic material, i.e., high-carbon rock and coal fragments within the profile. A noticeably high total carbon of 25% was found in the C horizon of site 2-pit 3. When the profile was described, the C horizon was very dark gray to black, indicating a horizon of concentrated carbolithic coal-like material. It was unlike any other horizon described within the profiles sampled in this project. Nitrogen content in the mine soils ranged from 0.00 (below detectable limits) to 0.02% in the A horizons, from below detectable limits to 0.01% in the B horizons, and from below detectable limits to 0.26% in the C horizons. The nitrogen values of all horizons were remarkably similar, except for the C horizon of site 2-pit 3. This was the same dark colored horizon where we had found a high total carbon content. All of the mine soils were generally acidic, with pH values of less than 5 (Table 2). The pH of the A horizons ranged from 3.4 to 4.6, B horizon pH varied between 3.2–4.9, and pH values of the C horizons were 3.3–4.8. These low pH values suggest that the mine soils tested have the potential to produce small amounts of acid mine drainage. Due to the nature of Upper Freeport Coal, we expected to find low pH values. This expectation is supported by Johnson and Skousen (1995), who found similar pH values (pH = 3.5–5.2) in Upper Freeport Coal mine soils. The total percent sulfur of the soils did not vary widely, showing the same trend as carbon and nitrogen. Total sulfur was 0.02–0.17% in the A horizons, 0.02–0.15% in the B horizons, and 0.02–0.64% in the C horizons. The highest sulfur level occurred in the C horizon of site 2-pit 3. The sulfur content of samples from site 1-pit 2 was also generally higher than the other samples but Southeastern Naturalist J. Lanham, J. Sencindiver, and J. Skousen 2015 Vol. 12, Special Issue 7 62 lower than the C horizon sulfur content at site 2-pit 3. As with carbon content, these high values can also be attributed to the presence of carbolithic material. The MPA, which is calculated by multiplying percent S by 31.25, ranged from 0.63 to 20.00 tons CaCO3/1000 tons, the NP was 1.54–11.57 tons CaCO3/1000 tons, and the NNP was -18.46 to 10.95 tons CaCO3/1000 tons. Two horizons yielded negative NNP values—the B horizon of site 1-pit 2 and the C horizon of site 2-pit 3. The B horizon of site 1-pit 2 had an NPP value of -0.68; this layer also had a low pH and a relatively high EC (Table 1). C horizons at site 2-pit 3 exhibited an NNP of -18.46. Due to its high sulfur content and very low pH, this layer clearly has the potential to produce significant acid-mine drainage if it were Table 2. Acid-Base Account of Upper Freeport mine soils. MPA = maximum potential acidity, NP = neutralization potential, NNP = net neutralization potential Site/Pit Horizon Depth (cm) pH % S MPA NP NNP Site 1, pit 1 A 10 4.3 0.02 0.63 9.95 9.33 B 35 4.9 0.02 0.63 11.57 10.95 C ≥190 4.2 0.02 0.63 6.94 6.32 Site 1, pit 2 A 8 3.4 0.17 5.31 6.48 1.17 B 99 3.3 0.15 4.69 4.01 -0.68 C ≥250 3.2 0.13 4.06 6.71 2.65 Site 2, pit 1 A 5 3.9 0.05 1.56 5.09 3.53 B 12 4.0 0.03 0.94 5.56 4.62 C ≥141 4.3 0.05 1.56 6.85 5.29 Site 2, pit 3 A 5 3.8 0.07 2.19 6.48 4.29 B 49 3.9 0.09 2.81 4.01 1.20 C ≥120 3.0 0.64 20.00 1.54 -18.46 Site 3, pit 1 A 9 4.5 0.07 2.19 9.03 6.84 C ≥170 4.0 0.07 2.19 9.41 7.23 Site 3, pit 2 A 11 4.2 0.05 1.56 9.26 7.70 B 34 4.6 0.04 1.25 6.48 5.23 C ≥118 4.7 0.03 0.94 3.09 2.15 Table 3. Acid-Base Account of core samples. MPA = maximum potential acidity, NP = neutralization potential, NNP = net neutralization potential Core Depth (cm) pH %S MPA NP NNP R-1-3 305 4.5 0.08 2.50 1.84 -0.66 610 4.6 0.17 5.31 2.44 -2.87 R-1-5 396 4.7 0.02 0.64 0.26 -0.38 549 4.6 0.05 1.56 0.91 -0.65 853 4.8 0.01 0.31 0.81 0.50 R-1-9 213 5.0 0.15 4.69 0.69 -4.00 518 5.1 0.16 5.00 3.63 -1.37 923 5.5 0.64 20.00 6.28 -13.72 1128 5.8 0.52 16.25 8.13 -8.12 R-1-10 274 3.3 0.37 11.56 0.18 -11.38 579 4.5 0.21 6.56 4.00 -2.56 Southeastern Naturalist J. Lanham, J. Sencindiver, and J. Skousen 2015 Vol. 12, Special Issue 7 63 to be disturbed and exposed to the atmosphere. Most of the major horizons were found to have positive NNP values, but all were less than 11 tons CaCO3/1000 tons. We found no alkaline layers among the mine soils, therefore no acid-neutralizing materials are available. The acid-base accounting data of the core samples (Table 3) provided even better insights into the potential for acid production in the mine soils. The pH values (3.3–5.8) indicate that the samples were acidic. The MPA values from the core samples were 0.64–20.00 tons/1000 tons. NP values of the samples ranged from 0.18 to 8.13 tons/1000 tons. The NNP values ranged from -13.72 to 0.50. All but one of the layers had a negative NNP value. Three of the layers were identified as significant acid producers because they had NNP values less than -5 tons/1000 tons. The third layer from core R-1-5 had a positive NNP value of 0.50 tons CaCO3/1000 tons, however this was not high enough to identify the layer as acid-neutralizing. NNP values indicate that there is no acid-neutralizing material within these samples, and that the area’s mine soils could produce acid runoff. Therefore, the mine soil data and core data show very similar results. Conclusions Although the soils in this study are very young, they are showing some signs of development and genesis, such as horizonization, structure, and color changes within the profiles. Five of the six profiles had Bw horizons, an indicator of mine soil genesis. All of the layers sampled in our profiles showed active acid-sulfate weathering, suggesting that the sulfur associated with the Upper Freeport Coal and nearby rock layers had reacted to form acidic soils. Acid-base account data supported this interpretation. The acid-base account data from the core samples indicated that the mine soils could continue to produce acid upon re-disturbance. Exposure of potentially acid-producing materials that are currently buried will certainly cause future problems. While some of the horizons have the potential to produce acid, that potential would be much greater from horizons disturbed below the current weathered zone. The core samples were drilled to depths much deeper than the depths excavated for the soil profiles. Therefore, their acid-base account data were more representative of what could happen when the road is constructed. These samples show a slightly higher possibility of acid production than did the mine soils, mainly because many of the layers in the cores were not as weathered as the mine soil horizons. To prevent acidic degradation to the Beaver Creek watershed, acid neutralization along Corridor H’s proposed route must be accomplished by limestone application because neutralizing materials are unavailable on s ite. Acknowledgments The authors appreciate the WV Division of Highways and WV Agricultural and Forestry Experiment Station for funding, and to everyone that helped in both field and laboratory. Southeastern Naturalist J. Lanham, J. Sencindiver, and J. Skousen 2015 Vol. 12, Special Issue 7 64 Literature Cited Johnson, C.D., and J.G. Skousen. 1995. Minesoil properties of 15 abandoned mine land sites in West Virginia. Journal of Environmental Quality 24:635–643. Losche, C.K., and W.W. Beverage. 1967. Soil survey of Tucker County and part of northern Randolph County, West Virginia. USDA Soil Conservation Service. US Government Printing Office, Washington, DC. Skousen, J.G., J.C. Sencindiver, and R.M. Smith. 1987. A review of procedures for surface mining and reclamation in areas with acid-producing materials. National Research Center for Coal and Energy, National Mine Land Reclamation Center. Morgantown, WV. 39 pp. Skousen, J., J. Renton, H. Brown, P. Evans, B. Leavitt, K. Brady, L. Cohen, and P. Ziemkiewicz. 1997. Neutralization potential of overburden samples containing siderite. Journal of Environmental Quality 26:673–681. Skousen, J., J. Simmons, and P. Ziemkiewicz. 2001. The use of acid-base accounting to predict post-mining drainage quality on West Virginia surface mines. Pp. 437–447. In Proceedings of the 18th American Society for Surface Mining and Reclamation National Meeting. 3–7 June 2001, Albuquerque, NM. Soil Survey Staff. 1996. Soil Survey laboratory methods manual. Soil Survey Investigations Report No. 42, Version 3.0. National Soil Survey Center, Lincoln, NE. Available online at http://soils.usda.gov/technical/lmm/. Accessed 14 November 2011. US Geological Survey. 1995. Davis 7.5’ Quadrangle map. Available online at http://nationalmap. gov/viewer.html. Accessed 3 July 2013. West Virginia University. 1995. Corridor H/Blackwater River restoration. Unpublished report submitted to the West Virginia High Technology Consortium, WVHTC-F- S95- 1011. Available from West Virginia National Research Center for Coal and Energy, Morgantown, WV. 96 pp.