Proactive adaptive spill management - A case study from a pipeline trenching and backfilling project in Baltic Sea
Type:
Presented during:
CEDA Dredging Days 2026
Authors:
S. Saremi, S.E. Kristensen, B. Elsässer, C.F. Holm, U. Lumborg and I. Gudjonsson
Abstract
Marine pipeline trenching and backfilling operations can generate suspended sediment plumes that may pose environmental risks, particularly in sensitive and naturally low-turbidity environments such as the Baltic Sea. While adaptive management is commonly applied to mitigate such impacts, traditional approaches are often reactive, with mitigation measures triggered only after environmental thresholds are exceeded. This paper presents the application of a proactive adaptive sediment spill management system for a large-scale offshore pipeline trenching and backfilling project in the German Baltic Sea, executed between July 2023 and July 2024. The implemented Dredge Turbidity Management Plan (DTMP) integrated conservative numerical forecast modelling with real-time in-situ turbidity monitoring to predict, verify, and manage project-related suspended sediment concentrations ahead of potential non-compliance. A fully three-dimensional numerical modelling framework (MIKE 3 HD, SW and MT FM) was used to simulate hydrodynamics, waves, and sediment dispersion in forecast mode during construction and in hindcast mode following project completion. Forecast results were evaluated against clearly defined, tiered turbidity criteria at discrete compliance points along the pipeline route and around sediment disposal sites. Model forecasts and monitoring data were supported by an extensive measurement network comprising background monitoring stations, mobile and fixed turbidity buoys, wave buoys, and targeted autonomous underwater vehicle (AUV) surveys. Central to the implementation was the DHI PlumeCast online platform, which functioned as the project's decision-support system, integrating forecast simulation outputs, live monitoring data, dredging vessel tracks, and compliance status in near real time. This platform enabled timely communication between key stakeholders and facilitated proactive operational adjustments. The case study demonstrates that combining predictive modelling, adaptive monitoring, and a centralized digital decision-support platform enables effective management of sediment spill risks, supports regulatory compliance, and enhances operational efficiency in complex offshore construction projects.