Taking a closer look at the impacts of the Corps of Engineers mandate to remove trees from the Rosenberry Drive dike, a local engineering firm was engaged by North Idaho College to review options for the City of Coeur d’Alene. In the review, the firm estimated that the costs of removing trees and roots, and then reconstructing the dike, would cost upwards of $1.6 million. The cost estimate was presented at a recent meeting of the ad hoc committee formed by the City of Coeur d’Alene regarding the dike road trees issue.
The engineering firm also provided a feasibility study for a modification to the dike system that could preserve the trees. By installing “sheet pilings” – essentially a metal floodwall driven through the center of the dike system – the vast majority of the vegetation on the dike could be preserved. The project appeared to be entirely feasible, but could cost up to $3 million and would require permit approvals that could take some time to assemble.
Neither option is particularly attractive, however, given the enormous costs and construction hassles that would be involved. The options are especially unattractive since there is no demonstrated historic, scientific or technical need to remove trees to keep floodwaters at bay.
For the immediate future, the Committee agreed to continue to explore other options to removing the trees. Working directly with FEMA regarding floodplain mapping, for example, rather than the Corps of Engineers regarding dike certification, could be an important key to solving the problem.
Meanwhile, slowly shifting regulatory frameworks and different approaches by federal agencies could result in new options. FEMA is currently working to provide better flexibility in its flood-mapping procedures, and new flexibility for FEMA could give new flexibility to local jurisdictions on how to approach levee vegetation problems. And, for what it’s worth, the Corps of Engineers is also reviewing national policies on levee vegetation.
So far, there is no obvious path forward for the city to preserve both the trees and the officially sanctioned floodplain protection at a reasonable cost. But the City and the ad hoc committee are committed to finding just such a solution. Stay tuned.