This project was designed to demonstrate, commercialize, and promote regulatory awareness and acceptance of the Sediment Ecosystem Assessment Protocol (SEAP), an integrated assessment ecological risk assessment approach developed under Strategic Environmental Research and Development Program (SERDP) Project ER-1550 (Burton et al. 2012; Rosen et al. 2012), that focuses largely on the performance of a field deployed device referred to as the Sediment Ecotoxicity Assessment Ring (SEA Ring).

The specific technical objectives of the technology demonstration were to:

  1. Refine the prototype SEA Ring to be more robust, user friendly and cost-effective for commercial application, and standardize test and quality control procedures;
  2. Generate sufficient pertinent and high-quality data to scientifically validate the SEAP technology, introduce the Department of Defense (DoD) user community to the technology, and promote regulatory acceptance through rigorous demonstrations at select DoD sites located in geographically diverse settings; and,
  3. Develop cost and performance data to support the commercialization of the technology and establish a pathway for full-scale DoD implementation.

These technical objectives were carried out at three DoD field demonstration sites and performance was assessed using previously developed performance objectives.

Technology Description

SEAP technology integrates in situ biological uptake and effects measures with passive sampling devices (PSDs) and physicochemical tools to assess the sediment-water interface, surficial sediment, overlying water, and advective exposure pathways at contaminated sediment sites. Minor modifications also allow for direct application to surface water exposure pathway assessment. The commercially available SEA Ring, developed and refined under this project, consists of a circular carousel capable of housing an array of in situ bioassay chambers and PSDs. The SEA Ring represents a valuable alternative over traditional laboratory-based approaches to toxicity and bioaccumulation testing, particularly for scenarios where laboratory testing cannot sufficiently characterize exposure or effects. 

Demonstration Results

Results from a total of eight SEA Ring deployments at three demonstration sites, in addition to third party technology verification under the United States Environmental Protection Agency’s (USEPA) Environmental Technology Verification (ETV) program, were used to assess performance. The incorporation of the technology into monitoring at the demonstration sites provided useful data in all cases. The performance objectives of the SEA Ring largely focused on functional aspects of the commercial prototype to assess practicality for deriving high quality data with which to make site management decisions, including those at for gauging sediment remedy effectiveness and assessment of receiving water impacts from stormwater runoff.

Puget Sound Naval Shipyard (Pier 7). At Puget Sound Naval Shipyard (PSNS), SEA Rings were used at 10 stations to monitor bioaccumulation of polychlorinated biphenyls (PCBs) during a baseline event and for three years following application of powdered activated carbon (PAC), using the AquaGate+PAC™ composite aggregate system (leveraged with Environmental Security Technology Certification Program [ESTCP] Project ER-201131). The goal of the PAC was to decrease the bioavailability of PCBs, which was assessed by conducting in situ exposures using SEA Rings loaded with the bent-nosed clams (Macoma nasuta) and polychaetes (Nephtys caecoides) transplanted from clean sites. Pre-and post-remediation bioaccumulation results have shown that the amendment is achieving the desired performance criteria for Project ER-201131 by substantially reducing bioavailability of PCBs at the site, with post amendment site average sum PCB congener concentrations up to 90 percent (%) lower in clams and worms deployed in SEA Rings. Synoptic placement of passive samplers revealed similar reductions in porewater PCB concentrations. Performance objectives for this project were largely achieved, with a few notable challenges, including difficulty with installation and recovery at stations with cobble and/or high degrees of shell hash, and loss of some polychaetes. Contributors to worm loss included factors such as escape and predation, but also challenges with capping chambers during recovery operations. Demonstration of Version 3 SEA Rings with improved pump performance and battery longevity virtually eliminated any water quality concerns.

Marine Corps Base Quantico. At Marine Corps Base (MCB) Quantico, SEA Rings were used for assessing changes in Dichlorodiphenyltrichloroethane (DDT; and DDT breakdown products) bioavailability before and after the placement of a thin layer sediment cap. This demonstration, leveraged with ESTCP Project ER-201368, involved 14-d in situ bioaccumulation exposures using the freshwater Blackworm (Lumbriculus variegatus) and the Asian clam (Corbicula fluminea). Assessment of bioaccumulation potential occurred pre- and post-remediation at 5 locations where the thin layer cap was placed, and at two nearby reference locations. Overall, performance objectives were achieved with good success deploying and retrieving SEA Rings and test organisms. Clam and worm tissue for analysis of DDX, consisting of DDT and its degradation products dichlorodiphenyldichloroethane (DDD) and dichlorodiphenyldichloroethylene (DDE), was successfully recovered from 100% and 90% of SEA Rings deployed, respectively. As with PSNS, a substantial reduction in tissue concentrations was observed following cap installation. Within SEA Ring replicates, variability was low and similar to that of laboratory exposures, but not unexpectedly, significant differences were observed when comparing in situ bioaccumulation from laboratory exposures conducted on intact cores collected during the SEA Ring deployment.

Naval Base San Diego. A storm water impact assessment in the receiving waters of San Diego Bay was conducted during a series of large storm events occurring between February 28 and March 1, 2014 at Naval Base San Diego (NBSD). At several locations, SEA Rings were placed at two depths, 1- and 3-meters (m) below the surface to assess potential impacts related to vertical stratification of freshwater entering a marine environment. Four marine species were tested: 1) embryo development of the Mediterranean mussel Mytilus galloprovincialis; 2) spore germination and growth of giant kelp Macrocystis pyrifera; 3) survival of the mysid shrimp Americamysis bahia; and 4) survival of the polychaete worm Neanthes arenaceodentata. Results of the study found physical conditions in the receiving water to vary dramatically both temporally and spatially among a few of locations due to the dynamics between rainfall periods, salinity stratification, and tides/currents. When compared to the far-field reference site at NBSD, limited toxic effects to bivalve embryos and mysid shrimp were apparent in situ at a few locations where salinity was not identified as a confounding factor. With the exception of bivalve embryo development, significant effects were observed for all species exposed near the surface (top 1 m) in the Chollas Creek channel, most likely due to extended periods of low salinity. Performance objectives were achieved with good success deploying and retrieving SEA Rings and test organisms at all targeted sites. Incorporation of passive samplers (diffusive gradients in thin films [DGTs]) into the sampling program showed statistically significant relationships between labile metal concentrations and dissolved metal concentrations in composite samples collected from 8 grabs over a 24-hour period, and provided added benefit for toxicity test data interpretation. Stormwater monitoring is inherently challenging, particularly in active industrialized locations such as NBSD. The successful accomplishment of this ambitious demonstration provided confidence in using the SEAP technology for similar future efforts, with lessons learned providing a solid foundation for future use at such sites.

Implementation Issues

The ability for a third party to verify the technology with multiple species and sediment and water types under the USEPA’s ETV program should instill confidence from regulators and DoD end users to consider this technology in relevant monitoring and regulatory programs. The SEA Ring technology also performed well at all three demonstration sites, providing useful data for assessing the performance of two different sediment remedies and the receiving water impacts associated with stormwater runoff. Regulatory interest was high at all three sites. Implementation is underway in numerous ways, including continued incorporation of the SEA Ring in upcoming monitoring efforts MCB Quantico, incorporation into the assessment of receiving water impacts from stormwater particles under SERDP ER-2428, ongoing use for Area of Biological Significance monitoring requirements at Scripps Institution of Oceanography (SIO), potential inclusion in future southern California Bight monitoring efforts, integration into a recently approved Navy Environmental Sustainability Development to Integration (NESDI) FY17 new start project, and potential incorporation into sediment quality monitoring at PSNS and Intermediate Maintenance Facility (IMF) under direction of Dr. Bob Johnston ( Space and Naval Warfare Systems Center [SPAWAR] Pacific/PSNS). Corrective actions for all issues were identified and addressed throughout the project, which led to the development, procurement and demonstration of the commercially available Version 3 SEA Ring (Zebra-Tech, Ltd), which we recommended for end-user consideration.