Figure 4. Scenario 3, processing incoming material and material removed from CDF

ERDC TN-DOER-C27

July 2002

In the first scenario, volume reduction of incoming material (Figure 2), expansion of the CDF is

deferred relative to the baseline condition depicted in Figure 1. This is indicated here by a downward

arrow for raising the berms of the existing CDF. Revenues from the sale of BU material produced

by processing incoming materials are represented by the upward arrow at the time of dredging and

processing. This revenue is assumed to be realized with every dredging and processing event for

purposes of illustration, but is not guaranteed. Regulatory restrictions on use of the material, public

acceptance, and market demand will determine whether the material will be revenue producing.

Comparing the base condition (Figure 1) to scenario 2 (Figure 3), the processing of material removed

from the CDF also postpones the need to expand the capacity of the CDF. In this example, the need

for a new facility is completely eliminated during the period of analysis. Revenues from the sale

of BU material produced by processing previously placed materials are represented in Figure 3 by

the upward arrow at the time of the excavation and processing. The relative rates of material

processing and maintenance dredging will determine how far into the future the need for additional

capacity is postponed.

Figure 4 represents the third scenario, in which incoming material is separated and in-place material

is processed to recover usable material. In this conceptual example, both the expansion of the

existing CDF and the construction of a new CDF are eliminated for the period of analysis. The

downward arrows are longer than in the base condition, reflecting the added cost of processing

incoming material.

Evaluating and Comparing Alternatives

Step 1: Evaluate the alternatives. Calculate the average annual cost of each alternative and

compare to the base condition. The net benefits of the alternative are equal to the average annual

cost of the base condition less the average annual cost of the alternative. The benefit-to-cost ratio

is equal to the average annual cost of the base condition divided by the average annual cost of the