Document Type

Thesis - University Access Only

Award Date

1995

Degree Name

Master of Science (MS)

Department / School

Civil Engineering

First Advisor

Vernon R. Schaefer

Abstract

Vast areas of eastern South Dakota are underlain by thick deposits of clay-rich glacial till. From ground surface to a variable depth between 20 and 40 feet, the clayey till is highly fractured and oxidized. These fractures have been shown to govern the infiltration and the flow of water within the weathered zone. At a site west of Sioux Falls, small-diameter, in situ laboratory samples were recovered at depths varying from eighteen to seventy-five feet using three-inch-diameter Shelby tubes. Shelby tube sections provided intergranular hydraulic conductivity values ranging from 4xl0"9 emfs to 4xl0"8 emfs, while results from corresponding field slug tests, accounting for both intergranular and fracture flow, varied from 4x10-9 emfs to 1x10-5 cm/s. Conductivities for the unweathered zone, determined by both the laboratory and field methods, were less than 1x10-7 cm/s. Large-diameter in situ block samples were retrieved to produce hydraulic conductivity results that correspond with those from field methods. Results from the 12-inch-diameter samples ranged from 5x10-8 cm/s to 6x10-5 cm/s, very similar to values from the well tests. The 12-inch samples, as opposed to Shelby sections, better represent the hydraulic conductivity of the deposit and may be used in place of conventional field methods.

Library of Congress Subject Headings

Soil permeability
Hydraulic fracturing
Drift -- South Dakota

Format

application/pdf

Publisher

South Dakota State University

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Rights Statement

In Copyright