Bulkhead Pile Jacketing & Sheet Pile Repair
March , 2021
Massachusetts Clean Energy Center’s New Bedford Marine Commerce Terminal is a multi-purpose marine cargo facility, constructed with a high capacity bulkhead to allow for the load-out of the heavy components used in offshore wind farm construction. The bulkhead is comprised of a system of sheet-pile cellular walls and steel pipe piles, which provide the required reinforcement and support. The Terminal is key to a variety of industries, in addition to serving as an important materials transportation hub for the rapidly expanding U.S. offshore wind industry. Global was contracted to perform bulkhead repairs and protect the sheet piles and steel pipe piles with Denso SeaShield series 500 and 2000HD systems.
Upon award of the contact, Global performed a full scale mock-up test of the proposed repair. This was accomplished by engineering and constructing a section of sheet pile wall at Global’s facility in Seattle to the replicate the existing structure at the Terminal. The mock-up allowed the crew to try different construction and forming methodologies, as well as conduct trials of proposed coating repair products under the supervision of Foth Engineering. Upon completion of the mock-up, destructive testing was performed to ensure integrity and conformance of the selected coating repair product, Denso SeaShield 550 Epoxy Grout. After successful testing of all components, the repairs on the terminal began.
Most of the work was performed from work floats positioned under the terminal overhang, with diver support often required in 2 places at once. At the lowest tides, topside crews were limited in headroom when working under the overhang. As the tide rose, headroom rapidly decreased to a height of a few inches or less. This required Global’s Project Manager, supervisors, and foreman to plan the upcoming work based on the predicted tides and weather forecasts. As a result, scheduled day-to-day tasks varied constantly with crews often working ahead to ensure production would not be impacted by tides or inclement weather. The Terminal also remained active with vessel traffic throughout the project, requiring coordination between the Global crew, the Owner, and vessel operators.
Working methodically in sections along the bulkhead, the project required divers and topside crews to perform abrasive blasting of all existing exposed steel of the cellular sheet piles and pipe piles before repairing. Once a section of sheet pile wall was cleaned, the FRP (Fiber Reinforced Polymer) fiberglass panels and jackets were fastened above and below the waterline to the existing steel cellular bulkhead on the outward facing side. The void between the fiberglass panels and existing steel cellular bulkhead was filled with the specified epoxy grout. Along with the sheet wall repairs, Denso SeaShield 2000HD jackets were installed on the steel piles of the bulkhead. Any anodes removed during the repairs were reinstalled after the jacketing was completed.
The curved, irregular faces of the sheet pile cells required custom forming and sealing at every location along the wall; the forming system was designed and engineered by Global in-house. Major structural components of the forming system were designed in a modular configuration, allowing the components to be completely reusable, minimizing costs by saving material and reducing waste. This also allowed the panel installation process to be expedited; once the grout was cured on one section, the crews could begin removing the framework and shifting it piece by piece to the adjacent panel to begin the next section. Minor components of the forming system were fabricated onsite to allow for a custom fit at each repair location.
Global’s project management and diving teams were supplemented by local union hires for additional diver/tenders and pile bucks. Crews from Moran Environmental Recovery (MER), Global’s parent company, performed the above-water abrasive blasting and assisted with other topside tasks. The majority of the panel and jacket installation work was performed with 5-person dive teams working in two shifts, supported by additional members of the surface crew. All staff on site followed Global’s directive on preventive measures to mitigate the risk of COVID throughout the course of the project.