The proposed project is a pilot demonstration of a polychlorinated biphenyls (PCB) remediation technology at America’s Cup Harbor and Harbor Island East Basin in the City of San Diego. The project would use approximately 30 square feet of submerged area on existing tenant leaseholds in America’s Cup Harbor and approximately 30 square feet of submerged area on existing tenant leaseholds in Harbor Island East Basin. The purpose of the project is to demonstrate the effectiveness of the Sorbent Polymer Extraction and Remediation System (SPEARS) to extract PCBs from contaminated sediment through installation of the SPEARS. A “Blue Economy Agreement” by and between the District and ecoSPEARS, Inc. (ecoSPEARS) is currently in place, and other similar agreements may also be required. ecoSPEARS would be responsible for acquiring necessary right of entry permits from the existing tenants at the America’s Cup Harbor and Harbor Island East Basin locations where the SPEARS would be installed.
The proposed project would require the placement of ecoSPEARS’ in-situ soil remediation technology, SPEARS, at two locations in San Diego Bay: Harbor Island’s East Basin and America’s Cup Harbor. The SPEARS are plastic spikes filled with gravel and ethanol solution. The plastic SPEARS spikes absorb PCBs from the aquatic environment, from both porewater and sediment, like a sponge. When absorbed by the SPEARS, PCBs continue to migrate through the plastic and further dissolve into the ethanol solution. The SPEARS are placed throughout hexagonal mats, which are 31 inches across and are made of a conventional geosynthetic membrane. Each mat is approximately three (3) square feet in area and incorporates two-inch x two-inch square cutouts throughout to allow for proper exchange between the water column and sediment. A combination of 26 12-inch SPEARS would be placed in each mat.
Each location would consist of three mat clusters. The mat clusters at the Harbor Island East Basin would be placed at a water depth of approximately 15 feet. The mat clusters at America’s Cup Harbor would be placed at a water depth of approximately 20 feet. Each mat cluster is composed of three (3) mats and the three (3) mats within each cluster would be placed within a few feet of each other. In total, 18 mats would be deployed, nine (9) mats in Harbor Island’s East Basin and nine (9) mats in America’s Cup Harbor, and 468 SPEARS would be deployed (264 at each location).
The SPEARS deployment process would require the use of a boat equipped with a davit arm and an electric winch, which would allow a Vibecore Plate to be lowered in the water down to the sediment layer to deploy the mats into the sediment. An on-board GPS unit would be used to record the exact coordinates where each mat would be placed. Once the SPEARS are installed, the Vibecore Plate would automatically eject the mat and the Vibecore Plate would be raised back to the surface and into the boat. During deployment, an underwater camera would be used to inspect positioning and installation of the mat and anchor. Prior to installation, the camera would also be used to ensure that no eelgrass is present at the area of deployment. In addition, a third-party pre-construction eelgrass survey would be conducted prior to deployment to ensure that the SPEARS would not be placed on eelgrass.
Once in place, each mat would also be anchored via a secondary conventional marine anchor, to prevent the mats from being washed away with shifting currents. One (1) anchor would be positioned approximately six (6) feet away from each mat, totaling nine (9) anchors at each location. Each anchor would contain a small subsurface buoy that would float two (2) feet above the sediment and would serve as a locator for the mats as well as provide an access point for surface retrieval of the SPEARS.
The SPEARS retrieval process would require the use of a boat equipped with a davit arm and an electric winch. An underwater camera on an extending pole would be used with previously recorded GPS coordinates to locate the mats. The pole with a custom gaff and an underwater camera would be used to hook and capture the retrieval line to pull mats from the seafloor. After removal, the SPEARS would be processed at an offsite laboratory facility. It would take approximately six (6) days to install and remove the SPEARS and mats and up to four (4) people onsite for the installation and removal.
Post-treatment sediment sampling would be completed after the six-month deployment to establish concentrations within the sediment and porewater after the SPEARS deployment. Sediment sampling would involve collecting core samples through coring two (2) feet deep on a triangular grid at each of the sites where the SPEARS were deployed. Samples collected during sampling would be sent to a facility off-Tidelands for processing, sampling, and internal analysis by ecoSPEARS, as well as third-party analysis.
The pilot project requires a U.S. Army Corps of Engineers pre-certified Nationwide Permit #5 Scientific Measurement Devices, and a Regional Water Quality Control Board nationwide pre-certified permit notification #5 Notice of Intent as part of the entitlement process, which would be obtained prior to the proposed project start date. Furthermore, the applicant would be responsible for complying with all applicable federal, state, and local laws regulating construction demolition debris, noise, and stormwater.