in2Dredging Successfully Delivers Soil Improvement Project

In April 2019, Buss Terminal Eemshaven (BTE) reached out to in2Dredging (i2D) to find out how to evaluate spudcan stability of jackup vessels jacking in front of their quay walls, at the Eemshaven Seaport in The Netherlands. These vessels are used to install offshore wind farms. Due to frequent jacking, local elevation differences occurred in the seabed, causing jack-up vessels to increasingly require longer jacking times.

Large wind farm vessels are a growing market for BTE and the Eemshaven. BTE are already successfully serving this market with their strategic port facilities.

Results of Spudcan Punch-Through Analysis

i2D performed a spudcan punch-through analysis and found that the clay’s shear strength more or less matched the spudcans’ bearing pressure. Consequently, over time, some vessels’ spudcans punched through the clay and some not. This explains the differences in the seabed and the instability. To alleviate the problem with jacking, i2D proposed conducting a soil improvement project. This involved removing the clay and replacing it with coarse sand to properly anchor the spudcans. Horizontal interpolation of the cone penetration testing data showed the bottom surface of the clay.

In February 2020, BTE concluded a new service contract for a large windfarm installation vessel. Consequently, the soil improvement project became a necessity. As a result, i2D was tasked with providing an experienced project manager to define and deliver the project before 1st October 2020.

Soil Improvement Project Delivered on Time and on Budget

In a short timeframe, i2D had to develop the scope of the work together with all relevant stakeholders. i2D also had to develop and deliver contractual documents that would provide sufficient definition and be easy for dredging contractors to understand. A FIDIC contract became the basis for the contract drawn up for the selected contractor. FIDIC contracts are straightforward, cover all aspects, and consider both the contractor and the owner. As a result, minimal time was spent on contract negotiations and no contractual issues were encountered during the dredging works.

i2D’s estimates provided the necessary insight into the execution of the dredging works and its budget and schedule. Several contractors provided bids at competitive prices. However, the selected contractor, Van den Herik, had the most suitable equipment and the best turnaround times.

The Contractor provided survey and equipment performance data throughout the project. This data helped the project team easily zoom in on any anomalies or possible concerns. Furthermore, equipment performance data analyses provided evidence of the dredging and backfilling campaigns’ quality. This absolute evidence also helped reduce concerns.

Open and transparent communication with all stakeholders was key to the soil improvement project’s success. As was i2D project manager Marcel de Ruiter’s involvement. He has the knowledge and experience to explain the works to stakeholders, alleviate concerns or take appropriate action. He delivers added value solutions.

Reindert-Jan Visser, Managing Director of Buss Netherlands, stated: “i2D did an excellent job on all the various phases of the project. Their in-depth technical knowhow combined with their ability to prepare and execute complex projects makes them an excellent partner to oversee dredging projects from A to Z.”