Characterization at Confined Disposal Facilities Promotes Innovative Beneficial Use of Dredged Materials

Fort Mifflin, PA, and Pedricktown, NJ

To facilitate beneficial use programs on the Delaware River, Weston Solutions, Inc. (WESTON^®) designed and executed a large-scale dredged material charac-terization program for two mid-Atlantic confined disposal facilities (CDFs). WESTON negotiated sampling plans that met the characterization requirements of regulators and potential users, and then collected and analyzed chemical and geotechnical properties data for 1.7 million cubic yards of dredged material. In addition to meeting project requirements, the approach WESTON developed has direct application to the Delaware River deepening project and the mandated beneficial use of dredged material.

As the first large-scale interim private use of U.S. Army Corps of Engineers (USACE) CDFs, WESTON facilitated real estate agreements between two Philadelphia-area refineries and the USACE to temporarily store dredged material in two USACE CDFs at Pedricktown (Salem County, NJ) and Fort Mifflin (Philadelphia County, PA). To beneficially use the dredged material stored in the CDFs, environmental characterization and permitting requirements in both Pennsylvania and New Jersey had to be met prior to removal and use of the dredged material. However, a sampling and analysis plan to characterize dredged material stored in a federal facility for beneficial use had never been submitted to either the New Jersey Department of Environmental Protection (NJDEP) or the Pennsylvania Department of Environmental Protection (PADEP). 

Regulatory Experience Streamlines Process

For each CDF, WESTON incorporated sampling plan requirements from all stakeholders for chemical and geotechnical analysis of dredged material. WESTON successfully obtained Sampling and Analysis Plan (SAP) approvals from both state regulatory agencies (NJDEP and PADEP), USACE, the Delaware River Port Authority, and the refineries. Negotiation of the SAP requirements was challenging due to the varied state requirements, large volume of material to be characterized, large number of reviewers, and high potential project costs. Drawing on our close working relationships with stakeholders, WESTON streamlined this process and ensured regulatory compliance in the SAPs while minimizing client costs where possible. Additionally, WESTON was cognizant during the negotiations that the SAPs would set precedents for future beneficial use programs in the region.

After conducting extensive sampling, WESTON characterized large quantities of hydraulically placed dredged material within the CDFs. Approximately 900,000 cubic yards of material from the Pedricktown CDF and 800,000 cubic yards of material from the Fort Mifflin CDF were analyzed for a suite of geotechnical and chemical characteristics. Overall, the analysis focused on assessing material properties most essential to beneficial use.

• Chemical parameters included volatile organic compounds (VOCs), semivolatile organic compounds (SVOCs), polychlorinated biphenyls (PCBs) (Aroclors), pesticides, metals, cyanide, and diesel range organics.
• Geotechnical parameters included particle size analysis, moisture content, Atterberg limits, organic content, and soil classification.
• Additional engineering properties were also conducted on dredged material at a lower frequency, including compaction (Modified Proctor), permeability (flexible wall), sheer strength (UU triaxial and CIU triaxial tests), and consolidation.

Using the results of the chemical and physical characterization, WESTON assessed which potential beneficial uses would be feasible given the type of material present in the CDFs. WESTON also evaluated the homogeneity in the sediments, and determined, with the exception of the areas immediately surrounding pipe outfalls, that the material within the CDFs is largely physically and chemically homogenous.

WESTON is Regional Proponent of Beneficial Use

Since completing the characterization project, WESTON has distributed the results of the testing to the most likely beneficial users including land developers, landfill operators, soil manufacturers, and transportation project managers in the region. WESTON has educated many potential users on the qualities of the available material, and has overcome the negative perception of dredged material as a waste stream. Several pilot-scale projects involving blending have since been initiated using dredged material.

Furthermore, WESTON has presented the characterization results to generators of dredged material, specifically maritime clients with berthing areas on the Delaware and Schuylkill Rivers. Through these presentations, the maritime clients have begun to evaluate the potential of the most common on-site uses of dredged material, such as parking lots and containment dikes. Several of these small-scale beneficial use projects are expected to begin construction shortly.