Date of Award

Spring 1993

Document Type

Thesis

Degree Name

Master of Science in Environmental Engineering - (M.S.)

Department

Civil and Environmental Engineering

First Advisor

John R. Schuring

Second Advisor

Paul C. Chan

Third Advisor

Hsin Neng Hsieh

Abstract

The purpose of this thesis was to study the anticipated benefits of integrating pneumatic fracturing with in situ bioremediation. Since pneumatic fracturing increases subsurface air flow in low permeability formations, it has the potential to overcome many of the major limiting factors of microbial growth and activity. A new innovation called pneumatic bio-injection can further enhance in situ bioremediation by efficiently dispersing biological solutions, including microorganisms, into a formation.

Bench scale experiments were conducted to examine the ability of microorganisms to survive the pressures and stresses associated with pneumatic injection. Tests conducted at pressures ranging from 60 to 500 psi showed consistent survivability under varied conditions. In fact, many tests showed an increase in microbial growth following pressurization, which was found to be a result of the superior dispersion produced by the injection system. Full scale tests indicated that the prototype pneumatic bio-injection system will disperse a finely-textured mist into the fracture network at flow rates up to 4.5 GPM.

A full field pilot demonstration was implemented for an industrial site underlain by petroleum contaminated clayey silt. The characterization and preparation phases are described including the initial pneumatic fracturing activities. Subsurface permeabilites increased 35 times as result of fracturing, and mass removal through vapor extraction for the target contaminants increased 50 to 75 times.

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