SUMMARY OF QUESTIONS AND RESPONSES (cont.)

ERDC TN-DOER-T4

December 2001

bucket so fast, and this is the bucket I want you to use," the responsible dredging contractors will

avoid that job. So, you will normally get the services of the local mom and pop organization that

is more than willing to rent bodies to operate a particular piece of dredge. Unfortunately, the small,

inexperienced contractors do not understand the complexities of dealing with a sensitive environ-

mental dredging contract. The panel member concluded his remarks with "just take the history."

Session Moderator: So is this an education process?

Panel Response: Environmental dredging is such a changing field that the regulatory staffs who

deal with a number of different kinds of partners must be educated by the engineering firms and

dredging contractors. So, yes, the answer to the moderator's question is that this is truly an education

process.

Audience Response: One participant went so far as to advise that the panel members temper their

comments to qualify the circumstances where design-and-build type contracting may be appropriate.

The example of projects like the Fox River pilot study that had to be completed within 90 days was

cited as one that involved just digging and hauling the material to a landfill. However, the example

of a remediation project that needed a confined disposal facility (CDF) requiring a formal design

for the CDF would not be very compatible with the fast-track, design-construct process. So, the

audience member cautioned the panel and others about obtaining the services of design-and-build

firms by just using a performance-based contract that can present significant difficulty and problems

for the more technically complex and challenging projects.

Session Moderator: Can the dredging industry meet strict excavation goals based on mass removal

and/or residual concentration at the end point of excavation?

Panel Response: Clearly most of the projects have been designed to dredge to a target depth based

on the concentration at some depth. And then after the fact, the question is Can you dig to or can

you meet the residual concentration goals? It is very difficult to remove the last gram or a few

centimeters on the surface that is highly mobile material. So, as far as defining success, one needs

to know where you are starting from in terms of what you use to evaluate the dredging contractor's

performance. The specification needs to be tied to a target elevation as an end point as opposed to

some final superficial material concentration. The fact is clear that anybody who is going to bid

the contract for a certain amount of money per subsequent number of passes needed will get paid

for each one of those passes. The panel member did not think this was a very practical way to do

the job and suggested that we needed to come to grips with this whole idea of residue on the surface

because it is hard to define and is mobile. Several fishery studies have shown that there may be a

timeline where there are higher concentrations of contaminants immediately after the dredging

operation before the concentrations begin to decrease. He concluded that one should have good

physical and chemical characterization of the superficial material before starting to dredge. Then

the result would be that you are not dealing with superficial material after the fact and confounding

the result by not knowing the baseline conditions of the superficial material.

Another observation was that there is no success during any remedial dredging if only the residual

surface material is targeted unless there is good source control. It is impossible to get that last little

bit until you've taken care of the sources. So, the rhetorical question asked by the panel member