New Jersey Wind Port – Future Proofing Design of Parcel B1 Marshalling Port

Abstract: The offshore wind (OSW) industry in the United States is a new industry that is poised for significant growth and development, with the New Jersey Wind Port (NJWP) currently being developed, designed, and constructed to support the OSW farm supply chain.
Compared to other material transiting throughout the U.S. ports, OSW components are large, heavy, and require significant laydown areas with high ground bearing capacities. The NJWP was designed and constructed to serve as a wind turbine generation (WTG) component marshalling facility to service the industry. As part of the marshaling process, WTG port facilities typically serve to import, stage, preassemble, and load-out large components for commercial-scale wind installation sites. These components consist of tower sections, nacelles, and blades.
The NJWP Parcel B1 OSW marshaling port comprises of an Installation berth, Delivery berth, and an upland storage yard for component laydown. The Port’s design was focused on a future-ready approach, with higher wharf and ground pressure capabilities than the industry currently provides, allowing flexibility to an ever evolving industry with many unknowns.
The operational design criteria of the NJWP Parcel B1 was a result of engaging industry leading developers with the intent of selecting design criteria for future-proofing the Port. The resultant yielded that the NJWP should be designed for OSW components corresponding to approximately 20 megawatt (MW) capabilities or more, given the current commercial scale projects in the US do not exceed 14 MW. For future- proofing, the weight and size of a 20 MW nacelle was extrapolated from available information for 12 MW nacelles and information provided by crawler crane manufacturers. The resultant max ground bearing pressure at the crawler tracks was limited by the operation limits of the crawler crane to 20,000 pounds per square foot (psf). By considering a crane mat and a layer of dense graded aggregate to distribute the load, the pressures at the wharf deck were reduced to under 6,200 psf, which is consistent with wharf design criteria established for the Port.
The solution for the structural design and the future-proofing of the marginal wharf was a pile supported ballasted deck with a steel sheet pile cut-off wall separating the wharf and relieving platform. The wharf section outshore of the bulkhead serves for vessel berthing, delivery, and loadout of OSW components. The bulkhead will be installed to retain the upland fill. The pile supported relieving platform will be inshore of the bulkhead and is designed to support loads from crane loading required to hoist the WTG components. After a cost-benefit evaluation, precast prestressed concrete piles were selected as the most suitable solution for the project.
The uplands yard design was controlled by the excessive settlements of the existing soft soils. Therefore, the upland yard was preloaded using soil surcharge embankments to reduce ground settlements to allowable limits and achieve the required soil ground bearing pressures. For 20 MW theoretical nacelles, the required ground bearing pressures are 3,000 psf, produced by a 60 metric tonne self-propelled modular transporter, and 4,800 psf by stored nacelles.

How does this project / topic contribute to the advancement of the industry and profession?: This project and paper provide insight into the development of design requirements for the anticipated loading of OSW components that are far more significant than what U.S. ports are typically designed to handle. The project has developed the design criterion and approach for OSW marshalling ports in the U.S., through research, stakeholder, and WTG manufacturer’s engagement to determine the required loading and future-proofing for the ever-evolving offshore wind industry. Furthermore, this project demonstrates how to design and construct these defined design criteria to achieve a cost-effective solution.

Does the project / topic implement new and innovative techniques, materials, technologies, and delivery methods?: To account for the much heavier component live loads, the project implemented a dense graded aggregate layer on top of the concrete marginal wharf deck, to reduce ground bearing pressures from crawler crane tracks onto the deck within allowable limits, whereas typical ports support cargo on a concrete deck topping. Through the use of precast prestressed concrete piles, the project is able to satisfy the design criteria of 6,200 psf at the marginal wharf, while most ports are designed for around 1,000 psf.

What was the most challenging aspect of your project / topic and how did you handle it to ensure success?: The primary challenge was the engagement of industry leading original equipment manufacturers (OEMs), developers, vendors, and contractors to obtain information on how to future-proof and design the port to support OSW components that have not been invented yet. These challenges are a result of OSW technical data being highly confidential and sensitive commercial information. The project resolved these challenges by adapting the design criteria to the existing equipment available to transport the components; therefore, the project was designed to account for the largest ground bearing pressures produced by the available equipment, and to the equipment limitations.

Who is the target audience for this paper?: The target audience for this paper comprises professionals in the offshore wind industry, which includes but is not limited to maritime engineers, environmental agencies, marine terminal operators, policy and decision makers, as well as OEMs who will benefit from this project and the recognition of the lessons learned.