Electronic Theses and Dissertations

Date of Award

1-1-2013

Document Type

Dissertation

Degree Name

M.S. in Engineering Science

Department

Geology and Geological Engineering

First Advisor

Joel S. Kuszmaul

Second Advisor

Adnan Aydin

Third Advisor

Robert M. Holt

Abstract

This research considers discontinuities mapped by Waste Control Specialists LLC to support the site conditions and performance analysis of the Compact Waste Disposal Facility and the Federal Waste Disposal Facility excavations constructed near Andrews, Texas. Discontinuities observed in excavation walls contain a limited number of discontinuities showed evidence of previous fluid movement. While no networks of such discontinuities were observed in the field, the potential for such networks may exist. This research is significant in understanding the performance of these waste facilities by modeling multiple realizations of possible fracture configurations in three-dimensional spatial models of the type of discontinuities observed in the field. The results show the low-angle discontinuities vastly outnumber the near-vertical discontinuities and most hydraulically significant discontinuities are shown with near-vertical orientation. Relatively few hydraulically significant discontinuities were observed across all mapped faces within the set of low-angle discontinuities. Furthermore, the proportion of vertical to horizontal discontinuities decreases with decreasing grain size, and most Genetic units had discontinuities in the upper half of a Genetic unit that were roughly horizontal and very few showed evidence of hydraulic significance. Three-dimensional models were created of the discontinuities in each of the geologic lagers surrounding both facilities using DFNModeler. These models were created using a statistical representation of the hydraulically significant discontinuities observed in each of the geologic units observed in the mapped areas of both facilities. In general, the variation in discontinuity properties do not show significant trends beyond the consistency with the geologic characteristics of each bed or layer, supporting a bedded but otherwise statistically consistent spatial model of the units. The model results showed a mean of maximum fracture network volume or compartment hull volume of 95.72 m3 and 188.59 m3 for the CWF and FWF, respectively. The maximum effective diameter or one-dimensional span of such hulls is small (3.57 m to 6.82 m) relative to the height of width of the excavation walls. The largest proportion of compartment hulls had a volume smaller than 8 m3 and a few hulls were larger than 18 m3. There is no evidence found in models of either the CWF or FWF that there is any credible potential for fluid flow within possible networks of discontinuities within these units in either the vertical direction or horizontal direction.

Concentration/Emphasis

Emphasis: Geological Engineering

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