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A wellpoint dewatering system was required to temporarily lower groundwater at the downstream toe of Weston Lake Dam, Fort Jackson, South Carolina. The groundwater lowering was required to facilitate construction of a permanent piped subsurface drainage system and improvements to the plunge pool for the principal spillway conduit. These improvements were required to mitigate dam safety risks arising from uncontrolled seepage at the toe of the existing embankment dam. This paper describes the wellpoint system design, associated subsurface exploration and seepage analyses, installation, and operational performance. The subsurface exploration included a desk study, field reconnaissance, monitoring of observation wells, cone penetration test (CPT) soundings with dissipation tests, and particle size by sieve analyses. The subsurface profile comprised an interbedded sequence of granular and clayey soils of the Upper Cretaceous Coastal Plain physiographic province. Hydraulic conductivity values were estimated in the sands from an empirical relation to gradation, and results of prior falling and rising head tests at the site performed in piezometers. Dissipation tests performed in CPT soundings were used to estimate hydraulic conductivity in the clayey layers. Values of hydraulic conductivity used in the seepage analyses for the sandy soils that dominated the ground profile were in the range 1×10−4 m/s to 5×10−6 m/s. The proposed open cut excavation required side slopes of 3H:1V to a maximum depth of approximately 4.6 m below grade. The proposed excavations for improvements to the plunge pool required 2H:1V side slopes to a depth of approximately 6.7 m below grade. To achieve the excavations and construct the drainage improvements, groundwater drawdowns of approximately 6 m and 7 m were required for the trench drain and plunge pool, respectively. Seepage analyses were performed to evaluate the layout, depth, and spacing of wellpoints on both sides of the proposed excavations. Observations made during the initial drawdown are discussed as well as measures taken to improve system performance as lessons learned for future practice, including lowering the pumps in excavations and sealing leaks.