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NYCT South Ferry Station
Scope – Curtain grouting of station box, mezzanine, concourse, entrance and running tunnels.
The original South Ferry Loop Station was constructed in 1905 as part of the original IRT subway line in New York City. This station was decommissioned in 2009, when a new South Ferry platform was constructed beneath the original loop. In October 2012, the new South Ferry station was severely impacted when Lower Manhattan suffered extensive flooding due to Hurricane Sandy. Service was suspended, and the old loop was reopened in 2013 until such time that the new South Ferry could be rehabilitated. Initial demolition of flood damaged finishes and transit systems was finished in 2014, at which time rehabilitation and flood resiliency became the Transit Authority’s top priority.

Preliminary investigations were conducted by the owner’s engineer to assess the extent of leakage in the station and 700-ft of tunnel running north of South Ferry in late 2014. After all available options were considered, they concluded that polymer-based emulsion was the best option for ensuring a dry station without risk of delay to project schedule.

At the beginning of treatment, the water infiltration at South Ferry was mostly observed as damp surfaces throughout the tunnel and station. There were many areas where previous attempts at grouting with resins had been unsuccessful, and those resins were being forced out of station wall and roof cracks. The first areas treated were the exterior tunnel walls immediately north of the station portal, so as to form a gasket preventing water from traveling between the tunnel and station. The goal was to push the water south and out of the system. The main station cavern is a cut-and-cover reinforced concrete box roughly 40-ft tall, 55-ft wide and 600-ft long. The east and west walls were treated sequentially, working south in 200’ x 40’ treatment areas at a time. Altogether 470 holes were drilled through a 2’-9” reinforced concrete liner and 36,370 liters of NOH2O® were injected over a two month period, treating 41,378 square feet.

Following the successful sealing of the station box, the remaining mezzanine and concourse levels were grouted, as well as all entrances and rail tunnels running north of the station to the project limits. In total, 1,231 holes were drilled throughout the course of production grouting and 60,372 liters (15,948 gallons) of NOH2O® were pumped in five months from February to June 2015, treating 91,753 square feet. Additional response work covered by warranty has been performed in ancillary locations throughout the facility since completion of primary treatment. In the months that followed, monitoring of treated areas for leak recurrence was carried out on a periodic basis. Treatment has successfully mitigated groundwater inflow, allowing the general contractor to advance installation of finishes and station systems.
Incline Station Wall Before – 02/07/2015
Incline Station Wall After – 06/01/2015
Tunnel Wall Before – 02/13/2015
Tunnel Wall After – 05/06/2015