Introduction - trel02-380010

Introduction

Background

Confined disposal facilities (CDFs) have historically been used for disposal

of both clean and contaminated dredged material from navigational dredging

projects where open-water disposal was not permitted. Many CDFs are nearing

capacity. Removal of uncontaminated materials from the CDFs is a viable option

for extending the life of these facilities. This approach carries the additional

benefit of producing a marketable product for beneficial uses, which can

potentially help to offset the cost of processing. Use of CDFs as rehandling

facilities, with long-term storage for only the most contaminated sediments, is

being investigated by the U.S. Army Engineer Research and Development Center

(ERDC), in partnership with the U.S. Army Engineer District, Detroit, the Great

Lakes National Program Office (GLNPO) of the U.S. Environmental Protection

Agency (USEPA), and local port authorities.

The feasibility of physical separation as a volume reduction method has been

demonstrated at Saginaw Bay (USEPA 1994), the Erie Pier CDF, Duluth/

Superior Harbor (Olin and Bowman 1996) and Fort Myers, Florida (Granat

1998). Despite successful demonstrations at these locations and continued

interest in the technology, physical separation has not yet been implemented as a

standard operational practice, with the exception of the Erie Pier CDF. In part,

this is due to the lack of internal expertise regarding physical separation and

feasibility determinations, the cost of feasibility evaluations, and equipment

availability.

A guidance document addressing principles of physical separation as they

apply to soils and sediments, and identifying standard equipment, selection

criteria, and potential sources was completed (USEPA 1999b). Technical notes

addressing recovery of materials from CDFs were also completed under the

Dredging Operations and Environmental Research (DOER) program (Olin-Estes

and Palermo 2000a,b; Olin-Estes 2000). Work is ongoing at ERDC, funded

under the DOER program, to develop bench-scale methods for economical

preliminary feasibility evaluations. While bench-scale testing is a necessary first

step, the limited volume of material that can be tested with these procedures

cannot provide information regarding the potential heterogeneities of large

quantities of material. Industry practice is to follow bench-scale testing with

evaluation of an intermediate volume of material using a representative unit

operation, such as a hydrocyclone. If these results are promising, a preliminary

Chapter 1 Introduction