Evaluating the Efficacy of Instrumented Settlement Plates (ISP) in Monitoring Geotechnical Properties of Dredged Sediments in Marsh Creation Projects

Rapid wetland loss in coastal Louisiana necessitates effective marsh restoration through dredged sediment placement. However, current sediment management practices depend largely on laboratory-based predictions, which often lack field validation, resulting in uncertainties and conservative designs. This study evaluates in situ sediment behavior using Instrumented Settlement Plates (ISPs) deployed in two marsh creation projects (Bayou Bonfouca and Lost Lake), which provided continuous measurements of settlement and pore-water response. Results show that consolidation and zone settling behavior are strongly linked to sediment plasticity, with highly plastic, organic-rich clays consolidating more slowly than sandy, low-plasticity sediments. In addition, dredging and dewatering rates influenced settlement progression and dredge volume management. While ISPs proved valuable for tracking consolidation trends, they were not sufficient alone to fully characterize sediment behavior, underscoring the need to integrate complementary monitoring tools.