TABLE OF CONTENTS Paul C. Johnson
Department of Civil and Environmental Engineering
Arizona State University
Tempe, Arizona
This chapter focuses on in situ treatment systems designed to eliminate or minimize the impacts of hazardous chemicals on groundwater quality. This chapter builds on the principles introduced in Chapter 4. First, typical soil and groundwater contamination scenarios of interest are introduced. Then a discussion of general remediation design principles and strategies follows. Finally, the design, monitoring, and refinement of selected in situ remediation technologies is presented. These include both conventional and developing technologies, and include containment, reaction barrier, active remediation, and passive remediation systems.
The design of in situ treatment systems for groundwater contamination is uniquely different from the design of above-ground treatment and hydraulic conveyance systems. The subsurface is an environment that is difficult to describe precisely; it is naturally heterogeneous and, due to practical constraints, characterization data are generally limited. Thus, treatment systems must be designed under conditions of great uncertainty usually the amount of chemical spilled is unknown, the timing of the release is unknown, and the system into which the spill occurred is poorly characterized. For this reason, the design of in situ treatment systems relies heavily on
conceptual models,
screening-level calculations,
empiricism, heuristics, and experience, and
monitoring and refinement of the design.
A conceptual model is a realization of how the subsurface might look and how contaminants might move, based on the available data. Often, there...
