Ohio Journal of Science: Volume 100, Issue 3-4 (June-September, 2000)

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https://kb.osu.edu/handle/1811/22157

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pp. 0
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Ohio's Fractured Environment: Introduction to the Ohio Journal of Science's Special Issue on Fractures in Ohio's Glacial Tills
Weatherington-Rice, Julie; Christy, Ann D.; Forsyth, Jane L. pp. 36-38
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Fractures and Their Distribution in the Tills of Ohio
Brockman, C. Scott; Szabo, John P. pp. 39-55
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Distribution of Soils in Ohio that are Described with Fractured Substratums in Unconsolidated Materials
Tornes, Lawrence A.; Miller, K. Edwin; Gerken, Jonathan C.; Smeck, Neil E. pp. 56-62
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Survey of Fractured Glacial Till Geotechnical Characteristics: Hydraulic Conductivity, Consolidation, and Shear Strength
Allred, Barry J. pp. 63-72
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Characterization Methods for Fractured Glacial Tills
Haefner, Ralph J. pp. 73-87
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Root Growth, Calcite Precipitation, and Gas and Water Movement in Fractures and Macropores: A Review with Field Observations
McMahon, Margaret J.; Christy, Ann D. pp. 88-93
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Field Workshops on Subsurface Fractures in Glacial Till and Their Environmental Implications: An Educational Experience for Professionals and Decision-makers
Christy, Ann D.; Weatherington-Rice, Julie pp. 94-99
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The Use of Test Pits to Investigate Subsurface Fracturing and Glacial Stratigraphy in Tills and Other Unconsolidated Materials
Christy, Ann D.; McFarland, Louis A.; Carey, Duane pp. 100-106
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Properties of the Fractured Glacial Till at the Madison County, Ohio, Field Workshop Pit Site
Fausey, Norman R.; Hall, George F.; Bigham, Jerry M.; Allred, Barry J.; Christy, Ann D. pp. 107-112
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pp. 999
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Back Matter
(2000-06)
Properties of the Fractured Glacial Till at the Madison County, Ohio, Field Workshop Pit Site
(2000-06) Fausey, Norman R.; Hall, George F.; Bigham, Jerry M.; Allred, Barry J.; Christy, Ann D.
Water and contaminants obviously do move through the so-called impermeable glacial tills in Ohio. This study was conducted to illustrate the extensive presence of fractures in the till and to quantify the differences in hydraulic conductivity and physical and chemical properties between the fractureaffected zones and the till matrix. In situ measurements of the saturated hydraulic conductivity were made in small boreholes positioned either in the matrix or intersecting the fractures. Soil samples from both the fracture faces and the matrix were analyzed for particle size distribution, clay mineralogy, calcite, dolomite, and iron content. Hydraulic conductivity measured in boreholes intersecting fractures was 1.25 x 105 cm/sec (0.018 in/hr), one order of magnitude greater than in boreholes in the matrix. Particle size distribution was the same for the fracture faces and the matrix. The fracture faces showed no significant change in total clay content and a slight increase in expandable clay. Calcite content was 62% greater, dolomite content was 6% lower, and iron content was 73% lower on the fracture faces as compared to the matrix. The fractures affected approximately 7% of the soil volume.
The Use of Test Pits to Investigate Subsurface Fracturing and Glacial Stratigraphy in Tills and Other Unconsolidated Materials
(2000-06) Christy, Ann D.; McFarland, Louis A.; Carey, Duane
Joints and fractures, common in Ohio glacial tills, often influence shallow ground water flow paths and rates. Environmental site investigations in glacial till and lacustrine sediments should include determination of the glacial stratigraphy and evaluation of the presence, extent, and density of subsurface fractures. The test pit is one approach to directly assess fracturing and stratigraphy. The design and construction of deep test pits is examined in this research report, which includes an extensive literature review and case studies from three test pit sites in Ohio. A generic design is recommended that may be used for 1-meter, 2-meter, 3-meter, or 4-meter deep test pits. Scaled drawings are included.
Field Workshops on Subsurface Fractures in Glacial Till and Their Environmental Implications: An Educational Experience for Professionals and Decision-makers
(2000-06) Christy, Ann D.; Weatherington-Rice, Julie
This paper documents the history of the Ohio Fracture Flow Working Group and describes their conceptualization, planning, coordination, and implementation of a unique outdoor field workshop on joints and fractures in glacial till held in London, OH, on 28 August 1997. The one-day event was coordinated and staffed by geologists, soil scientists, well drillers, and engineers. More than 175 people were in attendance, representing local, state and federal agencies, colleges and universities, and the private consulting sector. The field day included a morning lecture series of short plenary presentations and four afternoon field demonstration stations. The field stations included geophysics (downhole gammalogs, surface resistivity arrays), hydraulic conductivity testing (slug tests), two drilling rigs (an angle auger rig and a rotosonic rig), and a series of drilling cores that were described by a glacial geologist, two soil scientists, and a geotechnical engineer, demonstrating the different approaches, terminologies, and classifications that each discipline uses. The final field station was a large three-tiered pit approximately 10m x 25m and 3.7m deep that was used to demonstrate soil profiles and how they were formed, their relationship to the underlying glacial till deposits and the associated polygonal fracture patterns, and the difference in hydraulic conductivity between areas of fractures and areas of no fractures. Participant evaluations were very favorable, and plans are being made for future educational work on fractures.
Root Growth, Calcite Precipitation, and Gas and Water Movement in Fractures and Macropores: A Review with Field Observations
(2000-06) McMahon, Margaret J.; Christy, Ann D.
Recent research on the presence and dynamic nature of fractures and soil macropores has generated interest in their impact on root growth in minimally disturbed soils due to no-till or reduced tillage farming practices. The balance of water, air, and nutrients in the subsurface is, in part, determined by the structure and type of macropores. Biological systems can create and expand the network of biopores, or change the biogeochemistry within a given fracture or biopore. In the field, roots have been observed to grow preferentially through fractures. At a demonstration test pit at The Ohio State University (OSU) Molly Caren Agricultural Research Center in London, OH, networks of roots were exposed within fractures at 1.0 to 2.0 m in depth. A streambank on the OSU Waterman Agricultural and Natural Resources Laboratory in Columbus, OH, provided a natural exposure of fractures and roots preferentially growing in these fractures at depths of 1.0 to 1.5 m. A deeply incised streamcut in Batavia, OH, revealed live roots growing (at a depth of 15 to 20 m) within pre-Illinoian glacial till fractures. Microbial action upon living roots and in the degradation of dead root material can lead to calcite precipitation and infilling of fractures and other macropores. Earthworm burrowing can redistribute nutrients to the deeper subsurface, facilitating root growth at greater depths. During construction of the small test pit located near Tremont City, OH, a live earthworm was observed within a fracture at a depth of approximately 3.0 m.
Characterization Methods for Fractured Glacial Tills
(2000-06) Haefner, Ralph J.
This paper provides a literature review of methods successfully employed to characterize finegrained and fractured or unfractured glacial deposits. Descriptions and examples are given for four major categories of characterization methods: physical, hydraulic, chemical, and indirect. Characterization methods have evolved significantly within the past ten years; however, there still exists uncertainty about the reliability of individual characterization methods applied to till deposits. Therefore, a combination of methods is best, the choice of which depends on the objectives of the work. Sampling methods, sampling scales, and reporting methods are extremely important and should be considered when interpreting and comparing results between sites. Recognition of these issues is necessary to ensure that decisions regarding the transport of fluids in fractured tills are not based on the assumption that poorly permeable tills are always an inhibitor of subsurface flow.
Survey of Fractured Glacial Till Geotechnical Characteristics: Hydraulic Conductivity, Consolidation, and Shear Strength
(2000-06) Allred, Barry J.
A literature survey was conducted and fracture influences on engineering behavior of glacial till are summarized, specifically with regard to saturated hydraulic conductivity, consolidation potential, and shear strength. Saturated hydraulic conductivity is increased by fractures, in some cases by two or more orders of magnitude. This in turn results in larger values for the coefficient of consolidation, cv, governing the rate of consolidation. A larger cv corresponds to faster settlement. Modest increases in total settlement occur only if fractures are open. Fractures also have the overall effect of reducing shear strength. Upon removal of surface material by excavation or erosion, stress release and water infiltration lead to further decreases in shear strength. This strength loss process, called softening, is due mostly to a decrease in effective cohesion and usually takes years to complete. Once failure occurs, there is another substantial drop in shear strength to a residual value. This residual strength is a result of realignment of particles along the failure plane during shear, which decreases the effective angle of internal friction. The fracture impact magnitude on glacial till saturated hydraulic conductivity, consolidation potential, and shear strength is determined largely by aperture and spacing characteristics. As the number and/or size of fractures increase, changes in these geotechnical properties become more pronounced.
Distribution of Soils in Ohio that are Described with Fractured Substratums in Unconsolidated Materials
(2000-06) Tornes, Lawrence A.; Miller, K. Edwin; Gerken, Jonathan C.; Smeck, Neil E.
Soil scientists, who systematically made soil surveys of Ohio, compiled the first comprehensive inventory of fractures in unconsolidated parent materials, or C horizons, of soils. Fractures have been documented in the C horizon of 95 soil series extending across 55 Ohio counties. A variety of terms were used to describe these nearly vertical fractures in otherwise massive materials. By convention, structural units are considered a product of soil-forming processes and the use of structural unit terminology has been limited to the solum consisting of O, A, E, and B master horizons and transitional horizons like AB, BE and BC horizons. Thus, terms used to describe soil structure have not been applied to the C horizon, even though the faces of prismatic structural units in the lower part of the B horizon commonly show continuity with fractures in the C horizon. Fractures have been identified in unconsolidated soil parent materials with textures of loam, silt loam, clay loam, silty clay loam, silty clay and clay. Clay films and carbonate coatings on fracture planes in the C horizon of soils indicate that water moves into and through these fractures. Fractures in the C horizon of soils also affect air movement and plant root extension into C horizons.
Fractures and Their Distribution in the Tills of Ohio
(2000-06) Brockman, C. Scott; Szabo, John P.
Fractures in till may be horizontal, parallel high- to low-angle, or polygonal (when viewed on a horizontal surface). They have been attributed to several geologic processes, the most important of which are desiccation, freeze-thaw, glaciotectonics, and lodgement till deposition. A literature review, a field study, and core examinations have identified many areas in Ohio where fractures are relatively common. All types of fractures are present within the state, but the depths, relative abundance of types, and their concentrations differ among physiographic regions.
Ohio's Fractured Environment: Introduction to the Ohio Journal of Science's Special Issue on Fractures in Ohio's Glacial Tills
(2000-06) Weatherington-Rice, Julie; Christy, Ann D.; Forsyth, Jane L.
This paper describes the importance of subsurface fractures in Ohio glacial tills and provides a historical perspective on fracture research and educational efforts in Ohio. It also serves as an introduction to and overview of this special issue of The Ohio Journal of Science.
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(2000-06)

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