Complex Geotechnical Engineering for a Levee Project-Presentation Video

Presentation Video

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The document describes the complex geotechnical design of a new Paddy’s Run Flood Pump Station in Louisville, Kentucky, built within an existing levee system. The Louisville and Jefferson County Metropolitan Sewer District needed to nearly double pumping capacity to reduce interior flooding risk, but the age and location of the existing station made upgrading it difficult. The solution was to construct a new station inside the levee prism using diaphragm walls (D-walls) that would serve multiple purposes: temporary excavation support, permanent foundation walls, seepage cutoff, and levee stability protection during floods.<br /><br />Because the project sits over thick glacial outwash soils and near groundwater, the design had to avoid active dewatering and control under-seepage to bedrock. The site includes levee fill, a clay blanket, and alluvial sands and gravels over shale bedrock. Detailed soil characterization from sampling, lab testing, CPT, seismic testing, and shear wave velocity informed the soil parameters used in design.<br /><br />The structure consists of an influent channel, pump station, and access ramp, each with different excavation depths and wall geometries. The D-wall system includes concrete struts, temporary steel struts, and a permanent base slab, all installed in a top-down construction sequence. This staging was critical because excavation, bracing installation, groundwater conditions, existing levee loads, flood conditions, and seismic effects all influence wall behavior.<br /><br />Finite element modeling in PLAXIS 2D was used to simulate staged construction and soil-structure interaction. The Hardening Soil model was selected to better capture nonlinear soil behavior under unloading and reloading, which is important in excavation problems. The analysis showed that wall deflection, shear, and moment demand depend heavily on construction sequence, loading condition, soil behavior, and wall location.<br /><br />Overall, the paper emphasizes that designing a permanent, flood-critical D-wall inside a levee is highly unusual and requires careful geotechnical modeling to ensure safe construction and long-term performance.

Keywords

geotechnical design

flood pump station

diaphragm walls

levee system

under-seepage control

groundwater

PLAXIS 2D

Hardening Soil model

top-down construction

Louisville Kentucky