The reuse potential and sustainability of locally borrowed sand in levees-Paper

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The Waalbanddijk levee in Neder-Betuwe, Netherlands, requires reinforcement because wave overtopping can saturate its sandy inner slope, build excess pore pressure, and reduce slope stability. The preliminary design used imported, high-quality drainage sand, which was costly, environmentally burdensome, and difficult to work with.<br /><br />Researchers assessed whether locally excavated sand could serve as an effective drain. They used Plaxis 2D numerical modelling to examine drainage performance under a 48-hour overtopping event and optimize drain dimensions. Modelling identified a suitable drain height and opening of 1.2 m, and showed that the required drain permeability depends on the permeability of the surrounding sand.<br /><br />Site and laboratory investigations—including 104 sieve tests, additional soil characterization, and cone penetration tests—measured sand properties and their spatial variation. For the densely packed sand at the site, Beyer’s formula provided permeability estimates consistent with the more detailed Kozeny–Carman method. Locally available sand met the required permeability criteria across all nine assessed sections, enabling the drain to be built without importing new drainage sand.<br /><br />A life-cycle assessment compared three design alternatives. Reusing local sand reduced environmental impacts by about 96.8–96.9%; combining reuse with optimized drain geometry raised the reduction to approximately 97.5–97.6% compared with the original design. The study demonstrates that targeted investigation and modelling can support safer, more economical, and more sustainable levee reinforcement through local material reuse.

Keywords

Waalbanddijk levee

levee reinforcement

wave overtopping

slope stability

drainage sand

local sand reuse

Plaxis 2D modelling

permeability assessment

life-cycle assessment

sustainable engineering