Masters Theses

Date of Award

12-1988

Degree Type

Thesis

Degree Name

Master of Science

Major

Plant, Soil and Environmental Sciences

Major Professor

John T. Ammons

Committee Members

John E. Foss, John G. Graveel, Mike Timpson

Abstract

The landform and soil development study was completed on the proposed Low-Level Waste Disposal, Development and Demonstration project (LLWDDD) site in Bear Creek Valley, Oak Ridge, Tennessee. The objectives of the study were to complete a detailed soil characterization of major soils on the Cambrian aged Conasauga Group, and apply the information to gain an understanding of soil and landform stability. Eight pits (nine soil profiles) were excavated, described, and sampled on major soil mapping units of the upper Pumpkin Valley Shale, Rogersville Shale, Maryville Limestone, and Nolichucky Shale geologic formations. Samples were prepared and analyzed for soil physical, chemical, and mineralogical characterization. Six of the nine soil profiles are residual. Five of the six residual soil profiles are classified as Ruptic-Ultic Dystrochrepts. The remaining residual soil profile, being very severely eroded, is a Typic Udorthent. One colluvial, one colluvial over alluvial, and one alluvial soil profile are classified as Typic Hapludults.

Chemical analyses indicated that the soils were moderately acid, had cation exchange values ranging from 10 To 30 cmol(+) kg-1, and had base saturation values less than 30 percent. Magnesium was the predominant exchangeable ion found in residual soils. In highly developed soils, iron and manganese had translocated through the solum into the underlying saprolite. Most residual soils were shallow to saprolite, as a result of geologic and anthropogenically accelerated erosion. This resulted in soils with low to moderate available water holding capacity, low infiltration capacities, and high runoff rates. All soils contained clays that had low liquid and plastic limits, and low activities (shrink-swell potential). Mineralogy of saprolites was dominated by illite. Kaolinite was present in high amounts in soils and saprolites of the upper Pumpkin Valley shale. Hydroxyinterlayered vermiculite was present in high amounts in soils formed from the upper Pumpkin Valley Shale. Kaolinite and hydroxyinterlayered vermiculite was found in moderate to trace amounts in other soils on the LLWDDD site.

Soil transect studies on the lower Pumpkin Valley Shale indicated that slope and permeability of soil and saprolite were factors influencing weathering and soil development. Soils on slopes greater than 45 percent seldom developed Bt horizons. Glauconitic sandstones were found to be more permeable than shales, and produced thicker soils. Because shales and sandstones alternated on the lower Pumpkin Valley Shale, soil depth to saprolite varied greatly over short distances. Broader spur ridges promoted greater soil development, contained thicker layers of colluvium, and decreased the erosion potential. Topographic reversal and alluvial accumulation revealed past climatic effects upon these soils. Of the major soils found on the LLWDDD site, soils formed on the upper Pumpkin Valley Shale were most developed, followed by soils formed on the Nolichucky Shale, Maryville Limestone, and Rogersville Shale. Permeability, slope gradient, and presence or absence of limestones were the major factors which influenced weathering and soil development of the Conasauga Group.

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