Restoring the Ecosystem

Leveraging Innovative Design for Sediment Remediation and Landfill Closure

As remediation specialists clean up industrial manufacturing properties, the legacy contamination that makes its way into adjacent rivers and wetlands represents a significant liability and challenge. The science of sediment cleanup is difficult due to a long history of industrial discharges, the complex chemistry of comingled contaminants, and the impacts on ecosystems. Additionally, the scale of the problem, located beneath the water’s surface and spread by the tides and currents, often results in expensive remediation due to the volumes of sediment requiring potential removal and disposal. Responsible parties are challenged with efficiently navigating the complex sediment investigation and risk assessment process, including the ability to work with agencies to successfully identify satisfactory cleanup levels and select a protective remedial approach.

Solving Sediment Remediation Challenges

Langan effectively addresses these challenges with a team of experts who navigate the limited-but-critical world of sensitive underwater environments, helping clients balance costly sediment removals driven by risk assessment with protective, long-term management through sediment capping.

Langan’s team recently provided full-time oversight and construction management for sediment remediation activities within a 40-acre shallow tidal estuary in New Jersey. The remedial action included GPS-controlled hydraulic and mechanical dredging, and subsequent sediment capping of select portions of the estuary where impacted sediment remained. The team worked through these complex issues by providing innovative 3D sediment modeling to illustrate existing site conditions, predicting post-remedial conditions, and conducting a cost-benefit analysis that supported agency approval of the proposed remedy. In addition, the 3D sediment model demonstrated the successful completion of the remedy and verified that remedial action objectives were satisfied during remedial construction.

Implementing Innovative—and Sustainable—Solutions

The project also involved dredging approximately 70,000 cubic yards of impacted sediment and constructing a six-acre subaqueous cap over select areas along the shorelines and near sensitive structures. Post-dredge sediment results were then compared to the 3D model to evaluate the effectiveness of the sediment removal and modification of the dredging approach, which limited unnecessary over-dredge volume and associated costs. By constructing the subaqueous sediment cap, the project team successfully reestablished the ecosystem and habitat within the creek.

The remediation also introduced green and sustainable solutions at the site, including the placement of all impacted dredged material at the inactive on-site landfill for dewatering prior to landfill closure. This collaborative and risk-based approach reduced costs by removing the need for off-site transport and disposal, which would have required over 4,500 trucks, and significantly minimized the project’s carbon footprint.

Timothy Sattler, PE has over 10 years of environmental engineering experience. His experience includes environmental due diligence, investigation, design, and remediation management on award-winning projects.