NJ Transit – Longslip Bulkhead Restoration | Hoboken, NJ Engineering
The subject site is occupied by New Jersey Transit for their Hoboken Terminal Facility. The long slip is bordered by a bulkhead along the western, northern, and southern borders, with the Hudson-Bergen Light Rail Bridge along its eastern border. The bulkhead is in poor condition and had collapsed along a portion of the northern section. Historic Fill maps from the NJDEP database indicate that the majority of the site area is located within a region that has been raised by historic fill material. The fill is characterized by borings as a combination of miscellaneous soil mixed with significant quantities of wood, concrete, and rock fragments.
NJ Transit proposed the restoration of the existing bulkhead. The bulkhead consists of a concrete gravity wall bearing on timber cribbing. The gravity wall is approximately 8 ft tall and is 3 ft wide at the top and approximately 6.5 ft wide at the base. The timber cribbing extends to a depth of approximately 40 feet below grade. On the west side the bulkhead wall consists of timber sheeting and soldier piles with a fender system. The channel length is approximately 1650 ft along the north wall and approximately 1440 ft along the south wall. The channel width is approximately 100 ft throughout its length.
The existing bulkhead has the following issues: The concrete portion of the gravity wall on the south bulkhead has deteriorated significantly in several areas exposing rebar that has also deteriorated. For the north bulkhead, it has collapsed along an approximate 360 foot length. That section has subsequently been repaired with cantilever steel sheetpile as an emergency repair. Along the westerly portion of the north bulkhead, the bulkhead wall is leaning towards the water. The western wall’s timber sheeting and cribbing is in a deteriorated condition overall.
E2PM performed the following tasks:
- Bulkhead Monitoring – E2PM implemented a bulkhead monitoring plan for the north bulkhead wall. That wall was monitored for horizontal and vertical movement.
- Underwater Inspection – E2PM partnered with MG McLaren to perform an underwater dive inspection of the condition of the existing bulkhead.
- Design of Bulkhead Repair – E2PM in conjunction with it’s subconsultant McLaren Engineering prepared four alternative repair/replacemet schemes for the existing bulkhead. Design challenges included spanning existing PATH tunnels running beneath the site.
- Environmental Investigation – E2PM performed an environmental investigation consisting of six soil borings and four test wells. The boring investigation was coordinated with the geotechnical investigation to save costs.
- Geotechnical Investigation – E2PM contracted with SOR Consulting Engineers to perform a geotechnical investigation for the site. The investigation consisted of six soil borings advanced to bedrock.
- Screen Site for Wetlands – E2PM evaluated the perimeter of the site for the presence of wetlands.