Hazardous Waste Site Soil Remediation

Theory and Application of Innovative Technologies

David J. Wilson

• Editore: CRC Press
• Anno: 2017
• ISBN:
  9781351441407
• Edizione: 1
• Argomento: Biowissenschaften
• Categoria: Umweltwissenschaft

Introduces the most up-to-date techniques for soil remediation, including chemical fixation/stabilization, soil vapor extraction, thermally enhanced vapor stripping, biodegradation, and air spargingwritten in a style accessible to nonspecialists. Desc4ibes the ex shu technique of thermal desorption of soil contaminants-a low-cost aftemative to incineration for the removal of organics.

1

CONTAMINANT TRANSPORT AND BEHAVIOR IN THE SUBSURFACE

James H. Clarke

ECKENFELDER INC.
Nashville, Tennessee

Danny D. Reible

Louisiana State University
Baton Rouge, Louisiana
and University of Sydney
Sydney, Australia

Robert D. Mutch, Jr.

ECKENFELDER INC.
Mahwah, New Jersey

INTRODUCTION

An understanding not only of the nature of soil contamination for a given site, but also of the equilibrium and mass transport processes that govern the potential migration of particular chemicals, is a critical first step in any successful soil contamination evaluation and remediation effort. In the following sections of this chapter, information is presented concerning the important physical and chemical properties of the contaminants and the subsurface environment, together with a practical and applied discussion of potential migration pathways, upper limits of contamination based on equilibrium assumptions, and fundamental mass transport processes that govern the fate of a chemical in the subsurface.

Initially, the focus is on the development of a conceptual and predictive model based on the nature of contamination, the actual geological complexity of the subsurface, and the mass transport processes themselves, which is unquestionably oversimplified. Nevertheless, this approach results in an increased understanding of the equilibrium limits and the transport processes, which is most useful as a basis for further evaluation. Often, the assumption of uniform and homogeneous site conditions can enable the use of mathematical models that yield analytical, closed-form solutions that may be reliable within an order of magnitude. This is, in many cases, sufficient for further evaluations. Should more precise estimates be needed, the additional complexity, concerning both the contamination and the subsurface conditions, will typically dictate the need for the use of dynamic numerical models that require an extensive amount of data for reliable calibration and verification. Our objective is not to take the analysis to this level in this treatment, but rather, to focus on providing a good understanding of the contaminant migration pathways that can occur, the definition of pertinent equilibrium states and potential upper limits of contamination, and those steady-state mass transport analyses that can be used to generate predictive estimates most easily. The major focus is on the transport and behavior of organic compounds of low water solubility.

NATURE OF THE SUBSURFACE ENVIRONMENT

Although a comprehensive presentation of groundwater hydrogeology is beyond the scope of this book, there is merit in reviewing some of the fundamental principles of subsurface geology and groundwater movement. These principles are then expanded in subsequent sections of the chapter concerning contaminant migration. Several excellent books are available as resources in fundamental quantitative hydrogeology (Davis and DeWiest, 1966; Freeze and Cherry, 1979; Cedergren, 1977).

It is useful to think in terms of a hierarchy of evaluations concerning the movement of chemicals in the subsurface. Initially, one needs a good understanding of subsurface geology and the movement of water within the subsurface. This can be obtained through the performance of fairly fundamental hydrogeological investigations designed to map the subsurface geology in the vicinity of the chemical release. Typically, soil borings are performed to nee...