Flexible Under-Pier Sediment Assessment NESDI Project Number 572

This project was conducted in response to NESDI need N-1196-18 submitted by Len Sinfield of the Naval Facilities Engineering Systems Command (NAVFAC) Southwest. Remediating contaminated sediments in Navy harbors is estimated to be a $2 billion problem. Recontamination of previously remediated sites can compound these costs, requiring further cleanup and monitoring efforts than originally planned. One potential source of recontamination is sediment built up underneath Navy piers, where sediment assessment and dredging typically do not occur. These sediments may contain legacy contaminants such as heavy metals, polychlorinated biphenyls (PCBs), and pesticides; the specific types and quantities of potential contaminants of concern vary by site. This report details our results of our testing validating and assessing the volume and contaminant levels of sediments underneath Navy piers. The goal of the testing was to determine whether sediments under the piers should be considered a significant potential source of adjacent re-contamination. The project has demonstrated and validated the use of three (3) main technologies to quantify the volume and potential contaminant loads of under-pier sediments:1. Under-pier bathymetry using a small unmanned platform.2. Sediment volume and erosion assessment.3. Quantifying contaminant concentrations.The goal of this report was to create a simple and cost-effective solution to quantify the volume and contaminant loads of under-pier sediments. This challenging environment is constrained by tides, ship movements, varying pier architectures, and sporadic or non-existent GPS signals.