A Robust System of Steel Wave Attenuators Makes for Smooth Waters in New York Harbor.
By Editorial Staff
New York City’s first new marina in over 50 years had its soft opening in May, with the design team working out the final touches over the following weeks. With over 100 berths for vessels up to 200 feet, a Sailing Club and School, and community programs, the facility offers the calmest waters in New York Harbor thanks to advanced technology and design.
Located just south of the Brooklyn Bridge, across the East River from Wall Street and South Street Seaport, the marina offers incredible views and easy access to Manhattan. Part of the vibrant Brooklyn Bridge Park, ONE°15 Brooklyn is home to the city’s largest community dock.
Civil + Structural Engineer asked Estelle Lau, ONE°15 Brooklyn Marina’s deputy CEO, about a few of the challenges of building on such a busy waterway.
C+S: Looking at the press surrounding the opening of the marina, it seems that this was the second time around for this project. The fact that any shortcomings with the original facility were rectified speaks to the resiliency among the project’s planners. Tell us about the process of “going back to the drawing board” on such a high-profile project.
EL: The decision to redesign the marina was a thoughtful process that took into account the desired wave climate and amenities that our ownership group envisioned for the project. Changes in the use of the waterways in front of the marina have seen an increase in traffic at high speeds which impacted the original design and would continue to worsen. Obviously budget and time to accomplish the redesign were factors but we moved quickly to commission new studies to find a solution. This led us to build a team with long histories of waterway expertise in the NYC area to work on the project with strong input from the operational team, so that we could achieve the desired results. We worked closely with permitting agencies to find the most effective solution. One that would have the least environmental impact and meet our goals and be able to reuse the original design elements to contain costs and limit waste and time. This whole process was complicated by the fact that we continued to be operational during the boating season and had to work to maintain the original infrastructure and minimize disruption to the boating community using the marina. While work along the waterfront in NYC is a complicated endeavor, we feel that we’ve managed the process well and are pleased with the results we are seeing.
C+S: The sub-grade R train tunnels had to be taken into consideration for this project. Talk about the regulatory and design challenges associated with a commuter tunnel running beneath the project.
EL: Our original design used a newer system of elastic moorings which did not impact the sub-grade train tunnels, but proved to be insufficient to provide the wave protection needed for the marina. A number of options were considered, but ultimately a more robust series of steel wave attenuators set on steel pilings was the most effective and least environmentally impactful. Internal to the marina we continued to use the elastic mooring system wherever possible so as to minimize impacts over the tunnels. The placement of the piles along the attenuators (and the design of the attenuation system) was carefully laid out to avoid the impact area of the tunnels – requiring a longer attenuator which spans the actual tunnels. The permitting process with the SBS, Army Corp, Environmental Agency and finally MTA was lengthy, requiring us to set up a sophisticated monitoring system when the piles would be driven, but overall the professionalism and knowledge of the agencies’ staff helped the process move as quickly as possible.
C+S: The wave attenuators were critical to the success of this project. Tell us about the design, manufacture, and installation of the attenuators.
EL: No doubt the biggest challenge was the design, build, and installation of the attenuation system to defend against the increased waterway traffic wave climate. We looked at off-the-shelf, third party attenuators and found few companies that have a record of building them for recreational boating locations in these conditions. Ultimately we found that designing and building our own system made the most sense and brought the process in-house. For such a large production, we chose to have the attenuators built in Texas and towed up from there. Unfortunately, the manufacture of the system was met head-on with a couple of issues: First, the larger political environment caused delays during the sourcing process for the steel needed for the attenuators; and then manpower issues due to temporary labor shortages. We were fortunate to have found a shipyard that we trusted and worked closely with during the build. Our engineers, project managers and operational team visited during the process. Secondly, extreme inclement weather impacted the build as materials were waylaid in various locations due to weather and the transport of the attenuators was elongated. Ultimately, once the attenuators arrived, the installation went smoothly and we have seen the performance enhancement that we had hoped to achieve.
Sustainable, Environmentally Friendly and ADA Compliant:
- The team used a variety of materials to build the marina which considered environmental, maintenance and durability concerns – as ONE°15 Brooklyn Marina is subject to challenging New York City weather and harbor conditions.
- The marina’s internal docks for small- to medium-sized vessels were made from light-weight frame aluminum docks with a lattice decking to permit light to transmit to the water below. While larger concrete docks were used elsewhere in the marina, where possible, these environmentally sustainable docks and decking were deployed.
- Additionally, a majority of the marina was moored using an elastic mooring system instead of the traditional metal chain system. By doing so, the team was able to deploy concrete blocks to anchor the docks that have a lower footprint on the seabed.
- Due to the natural conditions in the harbor, as well as increased traffic from ferries and high-speed boats, the team determined that to create the calmest marina in the New York Harbor and protect and provide its customers with the best water experience, the use of piles in certain locations – most notably for its wave attenuator and large craft berthing areas – would be advantageous.
- The team worked with city officials and the Brooklyn Bridge Park on a set of large steel wave attenuators which were ballasted down on piles to protect the marina. A smaller set of concrete attenuators, anchored on the elastic mooring system, was deployed along Pier 5 to protect the marina from waves beneath the open pier.
- Integration (and protection) of anchoring and dock materials remained a priority for ONE15. While larger boats and areas needing more protection had concrete docks and piling deployed, smaller boats and less exposed areas utilize lighter weight materials. Finally, the community dock has sturdier concrete docks for stability and ease of access for larger groups.
- The team also installed a solar-powered lighting system within its docks to provide additional safety and considered ADA needs to create the only handicap-accessible marina on the New York Harbor.
*This article was originally published in Civil + Structural Engineer in July 2019