Background:
Contaminants enter shallow coastal waters from many sources, including ships, shoreside facilities, municipal outfalls, spills, and non-point source runoff. Sediments are typically considered a primary sink for these contaminants. Sediments in many bays, harbors, and coastal waters used by the Department of Defense (DoD) are contaminated with potentially harmful metal and organic compounds. DoD is required by the Comprehensive Environmental Resource Conservation and Liability Act, as amended by the Superfund Amendment and Reauthorization Act of 1986, to assess and if necessary remove and remediate these sites and discharges in order to protect the public health or welfare of the environment. To determine whether contaminants are moving into, out of, or remaining immobilized within the sediments, a determination of contaminant flux must be made.
Objectives of the Demonstration:
The primary objective of the demonstrations of the Benthic Flux Sampling Device 2 (BFSD2) was to perform deployments at contaminated sites in San Diego Bay and Pearl Harbor under the observation of California Environmental Protection Agency (EPA) certification evaluators and other observers, including local, state, and federal regulators; remediation program managers; academics; industry; and other DoD representatives. Each site offered different validation opportunities. San Diego Bay was used to show instrument repeatability and comparison with historical trends, and Pearl Harbor was used to show site differences and geochemical trend analysis. The specific planned objectives of the demonstrations were to:
1. Evaluate the quality of water samples collected using the BFSD2, specifically for use in determining if a statistically
significant flux was occurring at the test locations in comparison to the blank flux results for the BFSD2.
2. Evaluate the BFSD2 for repeatability.
3. Evaluate the logistical and economic resources necessary to operate the BFSD2.
4. Evaluate the range of conditions in which the BFSD2 can be operated.
Another objective was to expose various user communities to the technology to encourage continued interest and applications.
Demonstration Results:
This project included demonstrations of the commercialized BFSD2 at sites in San Diego Bay (Paleta Creek) and Pearl Harbor (Middle Loch and Bishop Point). BFSD2 performance assurance indicators showed that (1) a proper seal was achieved during both sets of demonstration deployments and chamber isolation of test water was maintained; (2) oxygen levels were maintained close to ambient levels except for the Bishop Point organics test; and (3) silica, oxygen, and pH trends varied as expected. The samples collected were thus considered valid for laboratory analysis. The resulting flux calculations demonstrated statistically significant contamination mobility.
Earlier sets of deployments of BFSD2 at Paleta Creek and at Pearl Harbor demonstrated consistent performance and the ability to measure trace metal mobility at distinctly different sites. The subsequent single deployments at Paleta Creek and Pearl Harbor demonstrated continued consistent performance and the extended ability to measure trace levels of organic contaminants. The applicable performance capabilities and demonstration objectives were met. Ease of operation and reliability were also demonstrated. It was further concluded that BFSD2 provides accurate and repeatable measurements of the mobility of metal and organic contaminants to and from shallow water marine sediments when the prerequisite performance assurance indicators are met. These sediment flux rates can be established with high confidence when the routine procedures, standard methods, and protocols are followed. Comparison of measured sediment fluxes with blank-chamber fluxes provides a statistical benchmark for the significance of the measured flux rates. Where statistically significant fluxes are observed, evaluation of impacts on water quality can be carried out, or comparisons can be made to bioaccumulation measurements to help identify exposure pathways. The resulting analysis will provide a significant new tool in evaluating potential cleanup options at contaminated sediment sites.
Implementation Issues:
These demonstrations were used by evaluators from California EPA as part of their Technology Certification Program process. Accurate, precise, and repeatable results were obtained at both locations. The San Diego sites were used to emphasize repeatable performance, and the Pearl Harbor sites were used to emphasize the range of conditions for operation. Routine and standardized methods and procedures were used throughout the operations.
The BFSD2 and its support equipment are mobile by air transport, field portable, and can be operated with a minimum of resources. One technician experienced with standard BFSD operational procedures and the part-time assistance of a deck hand plus a skilled small boat operator are required.
Technical performance, schedule, and cost data were collected during the demonstrations, and they document the utility of the BFSD2 technology to measure, in situ, the mobility of contaminants in marine sediments effectively, efficiently, and in a timely manner. This new approach has no directly comparable technology in current use and thus represents an innovative and new resource to the environmental community.
Related Documents:
1. ESTCP Cost and Performance Report - Organics (January 2009)
2. ESTCP Cost and Performance Report - Metals (November 2000) 3. 3. Davidson, B., Hampton, T.W. & Chadwick, D.B. (2008). Final Report: Quantifying In Situ Contaminant Mobility in Marine Sediments.
Prepared for the Environmental Security Technology Certification Program by SPAWAR Systems Center, San Diego, California.
4. Hampton, T.W. & Chadwick, D.B. (2000). Final Report: Quantifying In Situ Metal Contaminant Mobility in Marine Sediments (TR 1826).
Prepared for the Environmental Security Technology Certification Program by SPAWAR Systems Center, San Diego, California.
Principal Investigator:
Mr. Bradley Davidson
SPAWAR Systems Center, Pacific
Code 71750
53560 Hull Street
San Diego, California 92152
Telephone: (619) 553-2804
Fax: (619) 553-6305
E-mail: bradley.davidson@navy.mil
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