Innovative Reuse of Dredged Materials

The Maryland Port Administration (MPA) is exploring ways to beneficially use 500,000 cubic yards per year of material dredged from Baltimore Harbor channels and stored at its Cox Creek facility to create “renewable” disposal capacity. MPA awarded its first contract under its new “Innovative Reuse of Dredged Material” program to Schnabel to conduct a beneficial use demonstration project.

The project involved the blending of dredged material (DM) and steel slag fines (SSF) to produce general, highway-embankment, and structural-grade fill materials for the Baltimore metropolitan market. The project included DM and slag characterizations, arsenic immobilization studies in dredged material, geotechnical laboratory studies, and field blending and construction DM, SSF, and DM-SSF blend embankments.

Phase 1 included DM, SSF, and blast furnace fines (BFF) characterizations, arsenic immobilization studies in DM, and the swell of DM-BFF and DM-SSF blends. In Phase 2, 100% DM, 100% SSF, and five DM-SSF blends were mixed and tested to determine their geotechnical design parameters and environmental quality/leaching as a function of blending ratios. Phase 3 included the construction of five single-lane embankments (100% DM, 100% SSF, and three DM-SSF blends). The DM-SSF blends were pugmilled, their ratios verified, and placed and compacted in 12-inch lifts to form each embankment, which was environmentally and geotechnically tested immediately after construction and again 12 months later to gauge aging effects. The results from this study provided a comprehensive set of geochemical and geotechnical data to evaluate the use of dredged material/steel slag fines mixtures as construction and general embankment fill material, and provided cost savings to the end user and MPA.