Complex Geotechnical Engineering for a Levee Project-Paper

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The Paddy’s Run Flood Pump Station in Louisville, Kentucky, is being replaced to increase capacity from 875 to 1,900 million gallons per day and reduce interior flood risk. The new station will be constructed within an existing levee, where excavation through roughly 60 feet of groundwater-bearing sands and gravels creates significant construction and levee-safety challenges.<br /><br />The design uses a diaphragm-wall system extending into bedrock. The walls serve as temporary excavation support, permanent foundations and structural walls, and a long-term seepage cutoff. They must also maintain levee stability under unbalanced soil loads, flood conditions, and seismic events. Internal concrete and temporary steel bracing support the walls during staged, top-down construction.<br /><br />The design team used PLAXIS 2D finite-element models to assess soil–structure interaction across representative sections. The models incorporated site-specific soil properties, groundwater conditions, excavation and bracing sequences, and permanent and temporary load cases. The Hardening Soil model was selected to represent nonlinear soil behavior and the differing stress paths around the excavation. Undrained conditions were used for temporary excavation stages in cohesive soils, while both drained and undrained conditions were considered for the completed structure.<br /><br />Analyses showed that wall deflections, moments, and shears vary substantially with construction sequence, soil conditions, loading, and structural layout. Consequently, accurately representing construction stages and short-term loading is essential: these factors can govern the reinforcement required for the permanent walls. The project demonstrates how detailed geotechnical modeling can guide the design of a diaphragm-wall system that functions as both excavation support and a critical permanent component of a levee.

Keywords

Paddy's Run Flood Pump Station

Louisville Kentucky

diaphragm wall

flood control

levee stability

groundwater excavation

PLAXIS 2D

soil-structure interaction

Hardening Soil model

geotechnical modeling