and subsequent adjustments to those mitigation activities, described as an “adaptive mitigation” strategy. The steps in this approach are reasonable. But on a broader scale, this adaptive mitigation strategy is insufficient. The environmental effects of additional barge traffic and construction are not known with a reasonable degree of precision. Consequently, the extent to which these effects might be mitigated, and the associated costs, are also not known. The Corps ' approach to considering environmental resources only after locks have been extended is inadequate. In this approach, the environment is treated as a planning constraint rather than as a resource on par with waterway infrastructure investments. Moreover, the process by which adaptive mitigation measures would be identified, implemented, evaluated, and consequently adjusted, is not described. This process should include relevant federal and state agencies, as well as representation of the public. The Corps' adaptive mitigation strategy is inconsistent with the principles of adaptive management articulated in the natural resources management literature.

ENGINEERING

If the UMR–IWW locks are extended, the costs of rehabilitating the existing, aging locks, would be greatly reduced. The Corps estimates that the savings through these reduced rehabilitation costs would be considerable. The committee reviewed the basis for these savings and their magnitude. The committee finds the Corps' modeling approach to be sensible, however, benefits should be recalculated based upon new waterway traffic demand forecasts.

During the feasibility study, the Corps revised the contingency estimates for the costs of extending the locks. The committee recognizes the Corps' expertise in designing and building structures such as locks and dams. The Corps proposes a novel method for lock extension. Although the Corps has not used the method, it has been used extensively. As the Corps gains experience, with this method in modifying the first few locks, they should be able to estimate future costs more accurately and to find means to lower costs. However, many factors have escalated lock and dam costs in the past and it seems prudent to expect that construction costs might increase significantly due to a variety of factors. A 25 percent cost contingency is likely to be too low, particularly since recent experience with Lock 26 suggests that major escalation of costs can occur.



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