Site assessment, compliance dredging, and monitoring activity associated with contaminated sediments at shoreside facilities represent a growing problem for the U.S. Department of Defense. This project evaluated an integrated field-screening for rapid sediment characterization (IFRSC) system that uses chemical and bioassay screening technologies to provide real-time data for field sampling activities.
The IFRSC uses x-ray fluorescence for screening metals, laser-induced fluorescence for screening polycyclic aromatic hydrocarbons (PAHs), and QwikSed as the bioassay. Integration of multiple techniques in parallel provides more effective characterization of the vertical and horizontal extent of site contamination.
The IFRSC was evaluated on sediments at the Naval Air Station Alameda and the Pearl Harbor Naval Center. IFRSC data was compared to standard laboratory analytical data obtained from split sediment samples. Correlation coefficients and relative standard deviations were used to classify the screening data into U.S. Environmental Protection Agency (EPA) Level 1, 2, and 3 criteria as defined for chemical screening techniques. X-ray fluorescence screening data for metals fell into Levels 1 and 2, depending on matrix effects. Accordingly, this method may only detect the presence or absence of the metal although it may be used to quantify concentration levels if consideration for matrix effects is incorporated into the procedure. Laser-induced fluorescence screening for PAHs fell into Level 2, indicating that this method may be used to obtain semi-quantitative screening data on PAHs that require a limited number of confirmatory laboratory sample analyses. The QwikSed data were compared to other laboratory bioassays through the construction of contingency tables, and the results fell into Level 1 (i.e., non-quantitative data used to determine presence or absence of biological sensitivity).
Field-screening techniques for onsite assessment and management of contaminated sediments can provide major cost reductions during site investigations, compliance actions, cleanup efforts, and dredging operations at both active and Base Realignment and Closure (BRAC) facilities. Field-screening methods will reduce the number of laboratory samples and improve the efficiency of sample collection. The cost of using the IFRSC is estimated to be as low as $200 per sample as compared to $2,000 per sample for combined laboratory costs. The use of IFRSC results in an estimated cost-savings of 50 percent over the use of laboratory analyses alone.
These results demonstrate that IFRSC can be used to conduct rapid and cost-effective screening of sediments at the U.S. EPA Level 2 criteria, which means that the IFRSC can be used to screen sediment contaminants in conjunction with laboratory confirmation samples. However, it should be noted that matrix effects are apparent, especially for analysis of metals. These effects will need to be determined prior to utilizing the technology at the U.S. EPA Level 2 criteria. (Project Completed - 2004)