Expert-Opinion Elicitation for the Risk Analysis of Design-Improvement Alternatives to the Lindy Claiborne Boggs Lock and Dam
ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS INFORMATION TECHNOLOGY LAB
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This report documents the expert-opinion elicitation performed to meet risk analysis needs of the lower lock approach sediment management improvement alternatives to the Lindy Claiborne Boggs Lock and Dam. A companion report ERDCITL TR-02-1 describes the review and assessment of the Preliminaty Hazard Analysis conducted for the alternatives. The Lindy C. Boggs Lock and Dam experiences large water-level fluctuations. To accommodate the large fluctuation of water levels, floating guide walls upstream and downstream of the lock were incorporated into the plans. To retain the riverside lock wall backfill, a concrete T-wall was constructed for a distance of 130 ft approximately 40 m perpendicular from the lock on the downstream end. Anticipating that sediment would deposit in the navigation channel underneath the downstream floating guide wall, provisions were included in the original plans in the form of an earthen dike and a composite I-wall steel sheetpiling and concrete wall on top of the dike. The I-wall was connected to the T-wall and continued 130 ft offset from and parallel to the floating guide wall for 1,100 ft 335 m. The purpose of the dike and I-wall was to divert the flow and sediment from the floating guide wall and the navigation channel, thus providing a slack-water lock approach channel. Nonetheless, an average of approximately 310,000 cu yd of silt has been removed annually from the lower lock approach channel at Lindy C. Boggs Lock and Dam. Three alternative improvements are proposed to control this sedimentation a new fixed guide wall with dike removal, a new fixed guide wall with retention of the dike, and barrier extension and use of concrete panels.
- Civil Engineering