Analytical Testing Support for Dredging Operations
The U.S. is a maritime nation with 95% of our international trade moving through our ports. Seeking more efficiency and lower costs, cargo carriers are building ever larger ships and waterways must modernize to accommodate the deep draft ships. Port construction and maintenance activities have an impact on the marine environment and invoke testing and monitoring programs. Eurofins Calscience supports an array of sediment programs including dredged material projects, contaminated sediment remediation projects, sediment capping and water quality assessment, total maximum daily load (TMDL) studies and compliance initiatives.
Dredging activities may require the following testing protocol:
- Bulk sediment physical/chemical analysis
- Elutriate Testing
- Water column toxicity
- Benthic Toxicity
Eurofins Calscience supports testing of sediments, surface waters, tissues, pore water, groundwater and soils. Common chemicals of potential concern (COPCs) performed for marine sediments and tissues include trace metals, TOC, petroleum hydrocarbons, sulfides, pesticides and PCBs, PCB congeners, PAHs, pyrethroids, dioxins & furans, grain size, and other semi-volatile compounds. Achieving the low reporting limits required for these parameters requires special sample cleanup/preparation procedures developed by Eurofins Calscience and incorporated into its SOPs. The low-level analysis of sediment, tissues, pore water and elutriates also requires specialized instrumentation.
Testing of sediments is necessary as:
- Sediments are the source and sink for persistent aquatic contaminants
- Contaminants in sediment can harm aquatic organisms and/or accumulate in their tissues
- Species can be threatened
- Bioaccumulation may occur in marine organisms
- Organisms may be consumed by humans
Bioaccumulation is synonymous with “tissue testing” and is generally performed only if sediment bioaccumulation triggers are exceeded. Testing of marine tissue is the most direct method of determining if COPCs are available to organisms.
Elutriate testing is a bench-scale test designed to simulate and predict the water quality impacts from dredging or dredged material disposal. Dredging operations are routinely conducted in local ports and coastal areas and in inland waterways. Elutriate testing involves mixing site sediment and overlying water, followed by testing of the supernatant. This testing has been routinely applied for decades to support navigational dredging and disposal.
Eurofins Calscience has supported dredging and dredged material disposal projects over the years, and has developed procedures for the following elutriate tests:
- SET - Standard Elutriate Test (Open Water Disposal) - Often referred to as the “Open Water” Elutriate Test, simulates the release of the dissolved constituents into the receiving water during open water disposal.
- MET/EET - Modified Elutriate Test/Effluent Elutriate Test (Confined or Diked Disposal) - Simulates the quality of water discharged as effluent from a confined disposal facility (CDF).
- DRET - Dredging Elutriate Test (Point of Dredging) - Accounts for geochemical charges occurring in the CDF during active disposal operations. Predicts both dissolved contaminant concentrations and fraction of contaminants in the suspended solids.
Each of these procedures can be tailored to meet the specific objectives of a project. For any elutriate testing project, chemical analysis of the following sample sources is provided: site sediment, site water, and the elutriate, including the filtered supernatant and unfiltered supernatant.