APPENDIX C. PROJECT EXAMPLES1

ERDC TN-DOER-C27

July 2002

APPENDIX C

PROJECT EXAMPLES1

Example 1

The first example compares costs for the following six dredging and disposal alternatives for a

one-time project, such as a remediation action, with a 2-year period of analysis:

1. Hydraulic dredging, CDF disposal

2. Hydraulic dredging, sand separation, CDF disposal of fines

3. Hydraulic dredging, sand separation, CDF placement of dewatered fines

4. Hydraulic dredging, sand separation, dewatering and offsite disposal of fines

5. Mechanical dredging, CDF disposal

6. Mechanical dredging, offsite disposal

Dredging costs are applied to in situ project volume. Separation, dewatering, and transportation

costs are applied to processed volumes or weights. Unit CDF construction costs are based on

sediment storage requirements, and are adjusted upward for alternatives requiring higher dikes to

provide freeboard and ponding volume. For each alternative, a total project cost is calculated,

including dredging, processing, transport, and disposal costs. These costs are then converted to a

project cost/year, based on the duration of the dredging (Tables C1, C3, C5,...C11). Costs for CDF

construction and closure capping are also calculated. Interest during construction is then calculated

for each alternative and applied to the annual project costs, plus CDF construction and capping

costs, which are added to the annual project costs in the respective years in which they occur

(Tables C2, C4,...C12). This gives a Total Financial Investment cost for each alternative, which is

the basis for the economic comparison of each alternative. The least-cost CDF disposal alternative

without separation (mechanical dredging, CDF disposal) is the base condition. The results of this

analysis indicate that, for the assumptions made, a negative benefit is derived from the use of

separation, where mechanical dredging and CDF disposal is an alternative (Table C13). A positive

benefit is seen where offsite disposal is required. For separation alternatives, beneficial use of sand

with no associated transport or disposal costs is assumed. No real estate acquisition is included in

CDF construction costs, as the site is normally provided by the sponsor and is not a government

expense.

To convert measurements given in tons in these examples to kilograms, multiply by 907. To convert

measurements given in cubic yards to cubic meters, multiply by 0.7645.