D.1 Introduction

Appendix D

Leachate Testing Procedures

D.1 Introduction

This appendix provides detailed step-by-step procedures for conducting tests

for evaluation of confined disposal facilities (CDF) leachate. The background,

rationale, and tiered framework for application of these procedures are discussed in

Chapter 6 of the main text of this Upland Testing Manual (UTM). Two test

procedures are included in this appendix:

a. Sequential Batch Leachate Test (SBLT).

b. Pancake Column Leach Test (PCLT).

D.2 Theoretical Basis and Considerations for

Testing

A basic understanding of the theoretical aspects of interphase contaminant

transfer is necessary for informed interpretation of leachate testing results.

Contaminant migration via leachate seepage is a porous-medium contaminant

transport problem (Figure D-1). Leaching is defined as interphase transfer of

contaminants from dredged material solids to the pore water surrounding the

solids and the subsequent transport of these contaminants by pore water seepage.

Interphase mass transfer during dredged material leaching is a complicated

interaction of many elementary processes and factors affecting these processes

(Figure D-2). A complete description of all these processes, factors, and

interactions is not presently possible. Instead, a lumped variable, the distribution

coefficient, is used to describe the distribution of contaminant between aqueous

and solid phases.

D.2.1 Equilibrium Assumption

In order for contaminants to cross the interface between dredged material

solids and water, a difference in chemical potentials must exist. Chemicals

migrate from a region of high chemical potential to a region of low chemical

Appendix D Leachate Testing Procedures