Proceedings America Society of Mining and Reclamation, 2004 PROPERTIES OF CONSTRUCTED SOILS ALONG FOUR-LANE HIGHWAYS IN WEST VIRGINIA1 Rosa Lee Miller and John C. Sencindiver2 Abstract. Four-lane highways have been constructed in West Virginia since the 1960’s. During the early construction periods of four-lane highways, geologic information was not assessed, nor was the effect of the disturbance of these geologic materials on soil quality established prior to construction activities. Due to the mountainous topography of the Central Appalachian region, the construction of four-lane highways requires large, expansive cut and fill areas that may contain acid or alkaline producing materials. The disturbance and mixing of these materials with the original soil produces “new” soil that differs considerably from the surrounding native soil. In order to evaluate highway substrate conditions and the development processes of these new soils, study areas along sections of highways have been selected for comparison based on differences in age and geologic parent materials. The long-term goal of this research is to improve selective soil handling of earth excavated during highway construction similar to that of mine overburden materials. Cut, fill and on-grade areas within sections of Interstates 68, 79, and 81 and Corridor H (U.S. Route 33 and State Route 55) have been randomly selected as sampling sites. Soil pits located at 10- m increments along transects perpendicular to these four-lane highways have been sampled at 0-10 cm and 10-20 cm depths and described according to USDA methods. Surface samples also were taken near the edge of the highway. Field pH values of all sites ranged from 5 to 8. Preliminary analysis of the data suggests that thin A horizons develop within 1 to 2 years in rapidly weathering surface materials. In these young soils, little development is observed beneath a weakly developed A horizon, commonly creating an A-C1-C2 or A-AC-C horizon sequence. Soils of intermediate ages (9-12 yrs) were similar to young soils, although at some sites a more developed soil profile was occasionally observed (A-Bw-C1-C2). The most developed soil profiles were observed on sites where soils had been constructed 25 to 43 years ago. At these locations, multiple B horizon sequences were common creating A-Bw1-Bw2-C or A-Bw- BC-C horizons. Additional Key Words: Soil quality, soil development, disturbed soils, minesoils, soil genesis. 1 Paper was presented at the 2004 National Meeting of the American Society of Mining and Reclamation and The 25th West Virginia Surface Mine Drainage Task Force, April 18-24, 2004. Published by ASMR, 3134 Montavesta Rd., Lexington, KY 40502. 2 Rosa Lee Miller is a research assistant and John C. Sencindiver is a professor in the Division of Plant and Soil Sciences, West Virginia University, P.O. Box 6108, Morgantown, WV 26506. Proceedings America Society of Mining and Reclamation, 2004 pp 1315-1337 DOI: 10.21000/JASMR04011315 1315 Proceedings America Society of Mining and Reclamation, 2004 Introduction Highway construction disturbs long linear strips that cross a variety of soil and geologic materials. Therefore, soil placement and handling problems are unique. Many completely different micro sites may be generated over short distances. Some areas along highway corridors remain bare of vegetation, even after periods of greater than 25 years have passed since construction. With prior knowledge of these potential problem areas, engineers and planners would be able to develop alternative methods of soil and rock handling. For instance, analysis of soils and geologic materials in advance of highway construction, similar to that required for surface coal mining operations, would assist in the prediction of problem areas for the establishment of vegetation for effective sediment and erosion control. Because soils along highway corridors are disturbed in a similar way as surface coal mining, these two different activities are comparable. Disturbed soils have distinctly different morphological features when compared to contiguous native soils. Disturbed soil properties are the result of various blasting and soil/rock handling and placement procedures employed as well as the consequent natural soil formation functions of time, topography, parent material, biological activity, and climate. These disturbed soils are in theory quite “young” in the sense that time has not fully acted upon them, and they have not yet reached a state of equilibrium with the environment. However, several studies have noted that surface horizonation is evident in as little as three years post disturbance creating an A-C horizon sequence (Ciolkosz et al., 1985; Daniels and Amos, 1981; Shafer, 1980; Sencindiver and Ammons, 2000; Thurman and Sencindiver, 1986). This trend is credited to the acceleration of the soil physical and chemical processes performed by air, water and plant roots acting upon consolidated rock at the surface or near surface of disturbed soils (Sencindiver and Ammons, 2000). Seventeen of 29 pedons described in Pennsylvania minesoils, aged 1 to 29 years had AC or Bw subsurface horizons (Ciolkosz et al., 1985). Haering et al. (1993) observed Bw horizons in minesoils constructed from coal overburden strata consisting of siltstone, but in material containing more than 25% sandstone, only A, AC and C horizons were evident. The importance of soil texture to chemical and physical properties, such as nutrient and water behavior is well documented. Sobek et al. (1978) observed that minesoil properties were closer to their parent material properties than natural soils were to their parent material properties. The texture of soils disturbed by mining 1316 Proceedings America Society of Mining and Reclamation, 2004 operations and road construction is directly related to the geologic materials disturbed and may be sandy, if derived of sandstone, or silty, if derived of siltstone. Successful reclamation along highways is dependent upon a thorough knowledge of the individual soil and site properties that must be stabilized and a prediction of how the soils will behave over time (Booze-Daniels et al., 2000). Soils on cut areas will be thinner than the native soils; therefore, vegetation will have a smaller volume of soil from which to absorb water and nutrients. Soils on fill areas may be thicker than soils on cut and on-grade areas, so effective plant rooting should not be restricted by unbroken parent material or underlying rock. Compacted zones may perch water tables during wet weather conditions causing saturation and anaerobic conditions within the rooting zone. In a study of older mine soils (5-20 years old) at the Powell River Project watershed in southwest Virginia, compaction was the most significant soil factor limiting successful long-term revegetation (Daniels and Zipper, 1997). Severely compacted mine soils, especially those with less than 60 cm of effective rooting depth, cannot hold enough plant available water to sustain plant communities through extended periods of drought (Daniels and Zipper, 1997). Current interest by the West Virginia Division of Highways (DOH) in the use of native plant species for site stabilization has led to a parallel study of the anthropogenic substrates. This study seeks to evaluate existing soil conditions along highway corridors and develop new methods to enhance soil quality on highway cut, fill and on-grade areas. The first objective was to evaluate and compare soil properties on highway cut, fill and on-grade sites located adjacent to Interstate Highways 68, 79 and 81 in West Virginia. The ongoing construction of Corridor H along U.S. Route 33 and State Route 55 presents a unique opportunity to study development of soils affected by highway construction over time. Therefore, the second objective was to evaluate soil development on five fill areas adjacent to Corridor H, and to compare soil properties to age and geology. Methods and Materials Procedures for Selecting Sampling Sites Sampling sites were selected along Interstate Highways 68, 79, and 81, and Corridor H (U.S. Route 33 and State Route 55) in West Virginia. Before field work began, the following criteria were established for selecting highway sampling sites: 1317 Proceedings America Society of Mining and Reclamation, 2004 1. Slope steepness should be no more than 70%. 2. Cut and fill areas must extend at least 20 m perpendicular to the highway from the point at which vegetation begins (described as the site boundary) to allow for 10-m and 20-m sampling points (on-grade areas must extend at least 10 m). 3. Bridges, culverts or any other type of drainage structure should not interrupt transects. 4. There must be ample parking space at the site for safety of the workers. Highways were first subdivided based on gross geologic differences. It was determined that geology for the entire length of Interstate 68 was uniform. Interstate 79 was originally divided into two sections, but fieldwork indicated that soils were similar between the two sections. Therefore, only the northern section was included in this paper. For Interstate 81, two geologic sections were originally identified. The longer section was predominantly limestone whereas a shorter section on the northern end consisted mostly of shale. However, no acceptable sampling sites were identified within the shale section. Therefore, only the limestone section was evaluated. Each highway was visually surveyed, for all cut, fill and on-grade sites apparently meeting the criteria described above. Potential sites were listed according to type and were randomized using Microsoft Excel spreadsheet with RAND and RANK functions. Sampling sites were selected by visiting the first site on each randomized list. If the site met the selection criteria, then the site was chosen for sampling. If the site did not meet all of the selection criteria, then the next site on the list was visited. This selection process continued until one fill, one cut and one on-grade site in each section met all the selection criteria.