For the past 5 years, CSA has supported The Ocean Cleanup, a non-profit foundation, with environmental consulting services in support of their mission to develop advanced technologies to rid the oceans of plastic. To achieve this objective, engineers, operations, and environmental staff at The Ocean Cleanup and their partners have developed and tested several different cleanup system designs and operational parameters to gather and remove floating plastics caught in the Great Pacific Garbage Patch (GPGP), at each stage implementing lessons learned from previous system testing to inform an ever more robust and effective system design. The floating systems are designed to capture plastics ranging from small pieces up to large debris, including discarded fishing nets (ghost nets). The Ocean Cleanup’s early solution, System 001 (S001), was a passive floating U-shaped barrier with an attached screen for collecting the plastic, which was subsequently removed by a crewed vessel.
CSA prepared an Environmental Impact Assessment (EIA) of the S001 in 2018, to help evaluate the potential environmental impacts of deploying the system in the GPGP. CSA also prepared an Environmental Management Plan (EMP) to assist The Ocean Cleanup with the impact monitoring requirements of the project, which included the supply of Protected Species Observers (PSOs) by CSA’s strategic partner Marine Ventures International, to watch for marine mammals and sea turtles and an operations manager to assist with oceanographic data collection during the test.
While S001 confirmed the concept’s ability to concentrate and collect plastic debris, S002 was developed to enhance the scalability of the existing design. This adaptive management approach included changing from a passive system to a towed system.
Image 1. The Ocean Cleanup retention system (S002).
The S002 Retention System (Image 1) is comprised of two 391-m wings made of a float line, ballast line, and 10-mm × 10-mm Dyneema netting that is 3 m deep. The wings are towed by two vessels and the plastic is collected and guided towards a removable retention zone (RZ), also made of netting, where the debris accumulates (Image 2) before being retrieved by one of the vessels and sorted onboard.
Image 2. S002 removable retention zone where plastics accumulate.
In 2021, CSA updated the EIA to assess the potential impacts of S002 deployment. The EIA includes a number of designed mitigation measures to minimize impacts to the environment, with a particular focus on marine mammals and sea turtles. CSA assisted The Ocean Cleanup with the evaluation of potential mitigation measures to include in the design and operation of the S002, which included measures such as colored netting, fyke openings, lights, pingers for deterrents, an underwater camera system monitored by PSOs, use of different size netting, pre-warning line, remotely operated emergency release, breathing hatches, different towing speeds, and resting of RZ prior to extraction.
During EIA preparation for both systems, it was determined that there were some data gaps in knowledge, particularly for plankton and neuston communities, in the GPGP project area. Therefore, a sampling program was designed to collect data focusing on these two components of the pelagic environment during the 6-week test cruises with the S002, which is now on Cruise 9. This sampling program consists of performing net sampling with bongo nets and manta nets, both in front of and behind the S002 to characterize the baseline environment and determine whether there is a difference in the species and numbers of organisms collected in front of the system and behind the system after it has passed.
CSA is providing Environmental Coordinators (ECs) on each cruise to perform this sampling and then analyze the samples taken. These ECs also assist with the sorting of the biological material/organisms from the plastics after the RZ has been retrieved. This biological component is identified, measured, weighed, and photographed. The data collected during the S002 ongoing cruises have been processed, analyzed, and the 2021 EIA for S002 has recently been updated by CSA to include these new plankton and neuston community baseline data, as well as identifying the effectiveness of the implemented mitigation measures.
CSA also updated the EMP for use on the S002 cruises providing not only the requirements for performance monitoring reporting for the project, but also providing guidance for adaptive management while in the field, roles and responsibilities for all offshore and onshore staff, and providing procedures for all data collection activities.
The Ocean Cleanup is currently working on their next system design, a full-scale S003, applying adaptive management from the data and information collected during the ongoing cruises with S002. The S002 updated EIA will again be conducted by CSA and will include the new field collected data and new S003 design. In addition, the EMP will be updated by CSA for use when the S003 is deployed later this year, again incorporating adaptive management for the updates.
CSA looks forward to continuing its working relationship with The Ocean Cleanup and assisting them with environmental consulting services as they work to realize their goal of cleaning up the garbage patches around the globe.
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