Date of Award

4-2020

Degree Name

Master of Science

Department

Geological and Environmental Sciences

First Advisor

Dr. Matt Reeves

Second Advisor

Dr. Duane Hampton

Third Advisor

Dr. Dan Cassidy

Keywords

Hydrogeology, slug tests, hydraulic conductivity, aquifer testing methods, scale effect

Access Setting

Masters Thesis-Open Access

Abstract

Variations in hydraulic conductivity (K) between larger scale aquifer tests and smaller scale slug tests, and within individual aquifer tests, have been linked to method bias and aquifer heterogeneity. The impacts of varying slug sizes on K, which represents K dependence on a smaller scale, is not as well understood. To examine the relationship between K and slug size, a series of slug tests with a range of initial displacements were performed in three intermediate to high K, unconfined aquifers encompassing homogeneous, mildly heterogeneous, and moderate to highly heterogeneous conditions. Slug test estimated K values at Asylum Lake are compared to K values derived from a 28-hour aquifer pumping test to examine for method bias. A statistically significant increase in hydraulic conductivity with decreasing scale, or in this case slug size, was only found at the Grand Rapids site and is likely related to turbulent energy loss in the porous media surrounding the well screen for the largest slugs. Additionally, a series of multi-well pneumatic slug tests were performed at Asylum Lake in hopes of obtaining reliable storage parameters comparable to an aquifer pumping test and testing the effect of slug size on storage parameters. Results indicate that multi-well tests can produce reliable Ss estimates representative of the aquifer. Lastly, guidelines were developed for performing pneumatic slug testing in the field using a newly designed pneumatic slug unit.

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