Evaluation of Dredged Material for Phytoreclamation Suitability

Technical Note DOER-C3

May 1999

Evaluation of Dredged Material for

Phytoreclamation Suitability

PURPOSE: This technical note serves primarily to describe an approach to evaluating the

phytoreclamation alternative for dredged material treatment. This approach falls under the treat-

ment block described as part of a framework for testing and evaluation of dredged material for

beneficial uses in Technical Note DOER-C2 (U.S. Army Engineer Waterways Experiment Station

(WES) 1998a). This technical note expands the framework to include a phased approach to

determine the suitability of a contaminated dredged material for plant-mediated reclamation

(phytoreclamation), sometimes termed phytoremediation.

BACKGROUND: In the course of completing its mission of maintaining and improving naviga-

tion in waters of the United States, the U.S. Army Corps of Engineers (CE) must annually manage

over 300 million cubic meters of dredged material. Five to ten percent of this material is not suitable

for unrestricted open-water placement, and increased opposition to open-water placement is

beginning to limit this option where any adverse biological effects are possible. Another option for

management of dredged material is placement in confined placement facilities (CPF). However,

this is quickly becoming a difficult option, since most CPFs are at or approaching design capacity

and locations for new CPFs are hard to find. As a result, other means of handling dredged material

are needed. Potential uses of dredged material include landfill cover, recreational, industrial

brownfield area development, wildlife habitat, manufactured soil for commercial use, etc. In the

case of contaminated dredged material, remediation or reduction of contaminant concentrations

may be required prior to its ultimate use. Phytoreclamation offers a potentially effective and

affordable means of decontamination. However, at present, it is difficult to determine with certainty

if it is a viable alternative for treatment of contaminated dredged material without conducting a

number of evaluations.

INTRODUCTION: Phytoreclamation or phytoremediation can be defined by three basic processes

(Cunningham and Lee 1995):

Plant extraction is the removal of contaminants from a soil material or water through plant

uptake and bioconcentration with possible volatilization by plant respiration and transpiration

(Figure 1).

Degradation is the metabolism and/or degradation by plant processes or plant-associated

enzymes, bacteria, and other microflora (Figure 2).

Stabilization and containment is the in situ immobilization of contaminants by virtue of

reducing soil erosion and minimizing uptake of particular contaminants (Figure 3).

Phytoreclamation of contaminated soils has been applied to industrial sites by commercial entities

with documented success. It is fast becoming acceptable to the public and in most cases is less

expensive than traditional treatment technologies such as incineration, bioslurry composting, etc.