Soil mixing and dewatering with artificial recharge for the construction of a mutifunctional complex-Paper

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The 2022 Hof van Saeys multifunctional complex in Dendermonde, Belgium, included a large excavation for a two-level underground car park and nine elevator shafts. Because nearby buildings and an abbey garden were sensitive to settlement, groundwater lowering had to be carefully controlled. The site lacked an economically accessible impermeable layer beneath the excavation, so the retaining soil-mix walls could not fully isolate it from surrounding groundwater.<br /><br />The dewatering system used 22 deep wells inside the excavation to pump groundwater out and 22 recharge wells immediately behind the walls to return it to the aquifer. This closed-loop approach reduced discharge to the city sewer and limited groundwater drawdown outside the site. Around 80% of the extracted water was reinjected—about 80 units for every 100 pumped—and the project aimed to preserve more than 720,000 m³ of water. Groundwater lowering beyond the excavation was limited to approximately 0.55–0.75 m.<br /><br />Recharge wells are vulnerable to clogging from suspended particles, gas bubbles, mineral deposits, and biological growth. The paper therefore emphasizes water-quality control, minimizing aeration, careful well development, continuous monitoring of flow and pressure, and periodic well regeneration. Numerical groundwater modelling, preferably calibrated with pumping and recharge tests, is also important for system design. The retaining-wall depth must prevent a hydraulic short circuit between extraction and recharge wells, and groundwater-level limits should be set to protect nearby structures.<br /><br />The project demonstrates that artificial recharge combined with retaining walls can support construction dewatering in sensitive urban areas while conserving water and reducing settlement risks.

Keywords

Hof van Saeys

Dendermonde

Belgium

construction dewatering

groundwater recharge

deep wells

recharge wells

retaining walls

groundwater modelling

settlement control