Phytoreclamation of Dredged Material: A Working Group Summary

Technical Note DOER-C9

November 1999

Phytoreclamation of Dredged Material:

A Working Group Summary

PURPOSE: The purpose of this technical note is to summarize the discussions and conclu-

sions of the Phytoreclamation Working Group meeting held at the U.S. Army Engineer

Research and Development Center (ERDC), Waterways Experiment Station (WES), Vicksburg,

MS, March 16-18, 1999. The meeting was held as part of the Dredging Operations Environmental

Research Program, Vegetation Management Work Unit.

BACKGROUND: Dredged material, in simple terms, is nothing more than displaced topsoil that

enters and eventually is removed from navigable waterways. Although contaminant discharges into

waterways over time have resulted in contamination of bottom sediment, only a small percentage

of dredged material is contaminated by definition. Once sediment is removed from a waterway by

dredging, it must be placed outside the navigation channel. One alternative to open water discharge

is confined upland placement. In many areas where dredging is frequent and space for confined

disposal facilities (CDF) is at a premium, the cost for confined upland placement is rising or this

alternative is not available. One solution is to utilize dredged material as a soil resource offsite,

reducing the need for construction of additional CDFs. For contaminated dredged material that

was, has been, or will be determined suitable for upland placement in a CDF, the next logical step

is to make it suitable for reuse offsite as a soil material by reducing contaminant concentrations to

within regulatory compliance concentrations.

The Vegetation Management Work Unit is part of the Contaminated Sediments Focus Area of the

Dredging Operations and Environmental Research (DOER) Program. The focus of the work unit

is to determine vegetation management alternatives that enhance cleanup and reuse and/or minimize

adverse effects of contaminants in upland CDFs. One task in the work unit includes phytoreclama-

tion, the use of plants to reduce contaminant concentrations in dredged material. Phytoreclamation

of dredged material has not previously been considered as a cleanup alternative, and little informa-

tion on application to dredged material is available. Previous efforts in other areas of dredged

material research relied on focussed discussion of a problem and consensus by a working group of

peers. The working group approach resulted in the successful completion of research on contami-

nant mobility in plants and animals at the Blackrock Harbor, Connecticut, CDF, under the Field

Verification Program. Therefore, the same approach was enlisted to evaluate phytoreclamation.

PHYTORECLAMATION WORKING GROUP: A list of potential participants was assembled

from personal knowledge and previous interactions at professional meetings relating to phytorecla-

mation. Selections of participants were made to ensure the working group would have a broad

knowledge base and ability to interact constructively. The participants of the working group and

their affiliation are provided in Table 1. The participants were invited by WES and were selected

based on their professional experience and interest in phytoreclamation vested in sound, scientific

judgment. The newly formed Phytoreclamation Working Group met at WES on March 18-20, 1999.

The purpose of the meeting was to discuss the issues relating to phytoreclamation of contaminants