Reduction of Contaminant Releases in Surface Runoff Water

Technical Note DOER-C3

May 1999

phytoreclamation goals. The plant bioassay procedure requires growing the plants to

maturity, generally 45 to 90 days, and chemical analysis for the contaminants of concern.

Reduction of Contaminant Releases in Surface Runoff Water. Rainfall on unpro-

tected dredged material can result in the release of both soluble and insoluble (bound-to-soil

particles) contaminants in the surface water runoff. Phytoreclamation through stabilization

of the soil surface can reduce the entrainment of sediment into runoff and bound contami-

nants, while immobilization (chemical and/or physical fixation) will reduce the soluble

contaminants. Although there are no specific tests described for upland plants, tests similar

to those described by Best et al. (1997a,b,c) for aquatic and wetland plants may be useful in

screening upland plants for reduction of soluble contaminants in surface water runoff. Tests

using the WES rainfall simulator/lysimeter system (RSLS) can quantify the effectiveness of

the selected phytoreclamation process in reducing contaminant movement in surface runoff

water. The RSLS has the ability to predict surface runoff water quality from dredged material

and other soil materials under various conditions (slope, amendments, vegetation type and

condition) and treatment scenarios. Recent unpublished tests at WES (Price, Larson, and

Neumann, in preparation) quantified the effectiveness of soil amendments and vegetation in

reducing suspended solids and RDX and TNT concentrations in surface runoff from an

explosives-contaminated soil. A procedure using the RSLS is currently being developed to

evaluate the fate of contaminants in upland/wetland ecosystems, such as an upland CPF and

wetland discharge/mixing zones, and can quantify the effectiveness of a phytoreclamation

technique in similar situations.

SUMMARY AND CONCLUSIONS: The purpose of this technical note is to describe a develop-

ing framework for evaluating the suitability of dredged material for phytoreclamation using

currently available testing protocols. Phytoreclamation of dredged material is an attractive treat-

ment alternative that at present has little research support to implement without testing on a

case-by-case basis. As research in this area continues, the framework will evolve with the

development of simple screening-type tests.

The approaches described in this technical note will assist in determining the feasibility of using

phytoreclamation for cleanup or stabilization of contaminated dredged material in order to minimize

risks to the environment and to make the material available for beneficial uses. Once a phytorecla-

mation approach has been determined, implementation and management strategies must be devel-

oped to ensure success. The use of phytoreclamation can result in significant cost savings compared

with other treatment or stabilization techniques. However, failure to conduct adequate testing and

relying on generalities may result in failure of the phytoreclamation effort and/or adverse effects

and unacceptable risks to human and environmental concerns.

A number of test procedures and guides from CE reports are cited in this technical note. Subsequent

technical notes will follow describing these test procedures in detail.