Background/Objectives: The phased remedial investigation (RI) performed at the Berry"s Creek Study Area (BCSA) in Bergen County, NJ included multiple programs designed to assess natural recovery via chemical of potential concern (COPC) profile patterns and the assessment of sediment deposition by geochronology analysis.
As the RI progressed, the data quality objectives (DQOs) of these waterway sediment sampling tasks demanded expanding spatial coverage with increasing vertical depth and resolution.
Approach/Activities: Evolving DQOs for waterway sediment sampling, particularly toward high-resolution (2-centimeter) interval analyses, required the evaluation and incorporation of custom sampling equipment options beyond the standard Vibracore® equipment employed in the first study phase. The first version of customized sampling equipment used eight-inch diameter plastic tubes advanced using a modified Vibracore® head adapter. The method was effective and was utilized for high-resolution sampling in the second RI study phase.
For the third study phase, new DQOs governing high-resolution sediment sampling necessitated the collection of cores from subtidal locations in marsh tributaries and greater core integrity during processing. These requirements prompted modification to the high-resolution sampler design but also presented the opportunity for the identification of other areas for potential equipment and process improvements. Ultimately, the sampler was completely re-designed as an eight-inch square, two-meter long box core device.
Results/Lessons Learned: Based on this re-design, DQOs were more readily achieved in 2014, and later in 2015, with improved safety, efficiency, and data quality. The device"s capabilities include the following:
- Cores were collected both from exposed mudflats and intertidal and subtidal locations with a range of overlying water depths (up to twelve feet), fulfilling the primary objective of the design.
- Core recovery was no longer dependent on a vacuum for core retention, greatly reducing concerns related to vertical pore water and COPC migration in the core during collection.
- Sufficient sample mass was recovered from each interval using a single core, decreasing on-water sampling time and improving the confidence with which multiple parameters (COPCs, radioisotopes, and geotechnical parameters) could be correlated with depth.
- Sample processing required fewer repeated, precise measurements, and involved fewer safety hazards by eliminating the need for powered saws to separate sample intervals.
- Cores were collected with minimal compression or material loss, averaging 90% recovery, from various matrix compositions (including sands, silts, clays, and various mixtures).
- Device components were reusable following standard site decontamination requirements, minimizing investigative-derived wastes.