Zuniga Jetty Shoals Marine Debris Removal

Zuniga Jetty Shoals Marine Debris Removal

The San Diego Unified Port District (District) proposes the removal of marine debris located east of Zuniga Jetty in the Zuniga Jetty Shoals. Zuniga Jetty Shoals (Shoals) is located in the Pacific Ocean, south of the entrance to San Diego Bay and east of Zuniga Jetty (32.6746, 117.2234). Zuniga Jetty is a rubble-mount structure, built by the Army Corps of Engineers in the 1890’s, which extends approximately 1 mile offshore of Zuniga Point at Naval Air Station North Island. The Shoals consist of a free anchorage area which stretches over 900 acres. In August 2023, a sonar survey was conducted in the Shoals to identify the location of eelgrass and to identify debris. This survey identified 90 items of debris, ranging in size from approximately 5 to 1,300 square feet. Among the 90 identified debris items, 5 were confirmed sunken vessels, 13 were potential sunken vessels, and the remainder were smaller items noted as debris or within debris fields. Attachment 1 is a map of the identified marine debris, the location and approximate object size, including the side scan sonar image of the larger items of debris. Due to the low resolution of the side scan sonar image, 63 of the 90 items of debris were listed as “unknown debris” and 20 items of debris were identified as non-vessel debris. Therefore, a diver survey was conducted to characterize the presence, nature, extent (i.e., quantity/size, position), and condition of the debris. The results of this survey will help the District prioritize debris removal based on factors such as navigational hazards, the presence of hazardous waste, the feasibility of complete removal, and potential impacts on critical habitat. The District intends to remove the marine debris, starting with the debris characterized as “high priority,” before the end of June 2026, however more time may be needed pending the discovery of new debris and the availability of funding and other resources. Caltrans is funding the initial debris removal through a “Funds Transfer Agreement” to address sunken marine debris at the Shoals, and the District is also continuing to pursue other funding opportunities. In addition to debris removal, the Caltrans funding is covering the enforcement of anchoring limits in the area to prevent future marine debris from abandoned vessels. The District is in the process of soliciting a contractor to remove the debris with an anticipated start in Winter 2025. The contractor may use three methods of debris removal for this project. The method used for each debris location would depend on the conditions of the debris, including but not limited to: debris embeddedness, pieces versus whole vessels, and if vessel structural integrity will hold while being removed. The following debris removal methods may be used: 1. Float Bags: The Float Bag method is a buoyancy-based technique used to remove heavy or sunken debris from the seafloor. Divers would attach inflatable lift bags to sunken objects. The bags are then filled with air, creating lift that raises the debris to the surface. Floated debris would then be towed to the demolition area. This removal method is ideal for intact sunken vessels or large, heavy pieces of debris. 2. Basket Pick: The Basket Pick method is a technique that consists of lowering a large basket to the sea floor to allow divers to place small debris pieces into the basket. The basket would then be raised back to the surface, and debris would be placed onto a vessel to be transported for disposal. This removal method is ideal for small and lightweight pieces of debris. 3. Light Crane: The Light Crane method involves using a vessel-mounted crane to lift large or fragmented sunken debris, such as parts of broken-up vessels, from the seafloor. Divers would first secure debris sections with lifting slings or rigging. The crane then hoists each piece individually to the surface and onto the vessel for transport to disposal. This method is ideal for removing large, heavy debris in manageable sections, especially when structural integrity of sunken vessels is poor. The contractor would use 2-3 vessels to support the dive team for sunken debris removal. The contractor personnel would include 1 supervisor, 2 divers, and a number of other top-side crew members to handle the surfaced debris. It is anticipated that once debris removal begins, the contractor team would be on site approximately 3-5 days per week. The frequency of work and number of individuals on-site may vary depending on weather and oceanographic conditions. A boat launch would be used to transport the removed debris to land, then it would be towed off Tidelands to the contractor’s boatyard for dismantling, if necessary, and final disposal. Debris would be disposed per federal and state laws and regulations. Any waste generated would be transferred to storage containers and appropriately disposed of according to the Best Management Practices listed in further detail below. The contractor would identify and photograph each piece of debris removed, then prepare a report on the debris removal operations. The contractor would prepare and abide by a Best Management Practices plan to mitigate any impacts during debris removal operations. Best Management Practices will include: • Having on site and ready to use, petroleum spill equipment, booms, spill containment bins should the contractor encounter any liquids, oils, or chemicals during debris removal. Provider to ensure that wastes are separated, contained, and disposed of properly at a permitted facility. • Contractor shall provide a copy of their "Dive Safety Plan" if they propose to use divers. The "Dive Safety Plan" is to include measures to ensure boats are aware that divers are in the water and otherwise conform with all requirements of OSHA. • Survey results indicate the area of known eelgrass habitat within the project site. The contractor will abide by California Eelgrass Mitigation Policy, Section II.C Avoiding and Minimizing Impacts to Eelgrass. The contractor will be required to avoid anchoring or spudding in the eelgrass beds. Large debris, located within eelgrass habitat and which requires the use of a crane, will be performed by idling vessel (not anchored or spudded) and lift lines will be attached by in-water divers, taking the utmost care to protect eelgrass and benthic habitat. Most locations with eelgrass are shallow and eelgrass can often be seen from the surface, which should aid in the avoidance of damage to existing eelgrass beds • Turbidity resulting from debris removal is anticipated to be minimal and temporary. If surface turbidity is seen during debris removal operations, the contractor shall slow, reduce, or stop work until the turbidity has ceased. • If a sea turtle or marine mammal is seen within 100 meters of the active daily operation or vessel movement, all appropriate precautions shall be implemented to ensure its protection. These precautions shall include cessation of operation of any moving equipment closer than 20 meters of a sea turtle or marine mammal. Operation of any mechanical construction equipment shall cease immediately if a sea turtle or marine mammal is seen within a 20-meter radius of the equipment. Activities may not resume until the protected species has departed the project area of its own volition or has not been re-sighted for 15 minutes. • The recovery of debris may involve the deployment of equipment that is tethered to the surface via lines or cables. To reduce the risk of entanglement in any lines, the crew will keep lines attached to sunken debris as taunt as possible and remove lines that are not in use. • The project will involve lifting submerged vessels and loose debris up the water column to be removed and disposed of at an appropriate upland location. At this time, the debris removal contractor has not been selected to confirm the methodology or tools involved. It is currently assumed that the debris removal will require the minimal use of underwater hand tools (e.g., drills) to attach crane lines or lift bags to the debris. Due to its nature and limited scope, the proposed project would generate a minor amount of vehicle trips and would require limited use of equipment. Therefore, impacts related to air quality, greenhouse gas emissions, and transportation and traffic are not anticipated to occur. Furthermore, the Applicant would be responsible for complying with all applicable federal, state, and local laws regarding demolition debris, hazards and hazardous materials, and stormwater.

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