BENEFICIAL USES OF DREDGED MATERIAL

Technical Note DOER-C2

May 1999

While habitats will develop from placement of dredged material into disposal sites, the enhancement

and development of high-quality habitats require the utilization of sound management strategies.

Dredged material is an under utilized resource that can be used in a beneficial manner once

appropriate physical, engineering, chemical, or biological properties are determined. Over 2,000

man-made islands have been created in the Great Lakes and coastal and riverine areas by the U.S.

Army Corps of Engineers. These islands, along with additional ones, can provide nesting areas,

protection from terrestrial predators, and the seclusion from humans needed by migratory or colonial

nesting waterbirds and threatened or endangered species (e.g., pelicans, spoonbills, gulls, herons,

terns). Additional beneficial uses in aquatic environments include habitat creation (reefs, tidal flats,

sea grass meadows), erosion control (underwater berms made of geotextile tubes filled with dredged

material, beach and shoreline nourishment), and construction (dikes). Dredged material can be

used to augment decreasing wetland resources including freshwater and saltwater marshes, biofil-

ters for landfill leachate, constructed wetlands for wastewater treatment, or fill for sloughs in riverine

areas or denuded reservoir banks. There are a vast number of beneficial uses in upland areas

including construction of roads or airport runways, landscaping (manufactured soil products), parks

and recreational area development, cemetery development, and others. All products made from

dredged material will have to meet the performance specifications established for existing material

and will have to be cost competitive, available in a timely manner, and tested for performance.

A phased approach to testing should be employed in determining suitability for beneficial uses. It

may not be necessary to conduct all of the characterization tests. An evaluation procedure for

beneficial uses of dredged material is shown in Flowcharts 3-1 and 3-4 of the USACE/USEPA

Technical Framework (USACE/USEPA 1992). First, the beneficial use needs and/or opportunities

should be determined for the specific location. Next, an evaluation of the physical suitability of

material for the proposed uses needs to be conducted using appropriate characterization tests for

determining the physical and engineering properties in Table 1. If the physical properties do not

meet desired specifications, processing the dredged material by addition of available materials such

as spent lime, fly ash, or kiln dust should be considered. Many times the dredged material can be

conditioned to meet desired specifications. Next, the logistical and management requirements are

considered. The evaluation of environmental suitability is then considered. If there is reason to

believe the dredged material is contaminated, either the chemical or biological or both charac-

terization tests should be conducted. A modified version of the framework for testing and evaluating

for beneficial use applications is presented in Figure 1. If the results of the chemical/biological

screening tests indicate the potential for adverse impacts, the dredged material should be treated

and then retested for adverse impacts. If adverse impacts are no longer indicated, or if there is no

reason to believe the dredged material is contaminated, the beneficial uses can be realized, and the

evaluation of socioeconomic, technical, management, and other environmental considerations,

either as an Environmental Assessment or an Environmental Impact Statement, is conducted as

shown in Flowchart 3-1 of the USACE/USEPA (1992) technical framework. If adverse impacts

are still indicated, the dredged material should not be used for beneficial purposes.

SUMMARY: Dredged material can be a valuable resource with numerous potential beneficial uses.

Although dredged material is analyzed prior to placement into CPFs, many physical, chemical, and

biological processes can continue to occur depending on the prevailing environmental conditions

(e.g., precipitation, temperature, biogeochemical factors) around the CPP. The results obtained