Studies

Southern Manhattan Coastal Protection Study

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Background

New York City, like many global port cities, is highly vulnerable to the effects of climate change, including sea level rise and the associated threat of extreme storm events. The city's tremendous population and valuable assets compound that risk significantly.

As seen during Hurricane Sandy, Southern Manhattan is particularly vulnerable to the potential impacts of climate change, including costly damage, due to its high population density, its concentration of global businesses, and the significant amount of infrastructure located inside the 100-year floodplain. Approximately 1,600 residential and commercial buildings, including historic landmarks, are located within the 100-year floodplain for Southern Manhattan. This includes approximately 61,000 residents, more than half of whom live in Chinatown and the Lower East Side in low- to moderate-income housing. Hospitals, telecommunication facilities, subway stations and lines, power substations, and vehicular tunnels, among other critical infrastructure, are located within the floodplain.

As described in "A Stronger, More Resilient New York," the City's 2013 resiliency plan, storm surge from Sandy overtopped bulkheads in Southern Manhattan, causing water from the East River to flood the South Street Seaport area and buildings along South Street, up to eight feet in depth for some areas. Throughout Southern Manhattan, over 950 residential buildings (containing more than 40,000 units) and over 700 commercial and non-residential buildings were affected by floodwaters; the building damage was clustered on the eastern edge of Southern Manhattan, impacting residences, offices, and retail. Critical infrastructure was also damaged: local hospitals were evacuated, power infrastructure was impacted, local telecommunications infrastructure was disrupted for several months, and area subway stations flooded, affecting transportation citywide.

One of the 257 initiatives recommended in the City's 2013 resiliency plan was to further study a multi-purpose levee concept on the East River to protect the eastern edge of Southern Manhattan against the risks of sea level rise and storm surge while also providing opportunities for economic and community development. Multi-purpose levees generally combine functions such as buildings, transit, parking, highways, and parks either on top of and/or within a large levee structure. Globally, multi-purpose levees have demonstrated the ability to optimize coastal resiliency, visual quality, and sustainability of metropolitan waterfronts around the world, and they are consistently selected as the flood protection method of choice for the following reasons:

  • More seamlessly integrated into existing urban fabric
  • Allow for interaction with the waterfront instead of being divided from the waterfront
  • Create areas for new public space and a mix of other land uses
  • Provide opportunity for infrastructure improvements
  • Less likely than conventional levees to experience structural failure

The multi-purpose levee concept for Southern Manhattan is grounded in these global best practices.

Feasibility Study Overview

A collaboration among NYCEDC and the Mayor's Office of Recovery and Resiliency, the "Southern Manhattan Coastal Protection Study: Evaluating the Feasibility of a Multi-Purpose Levee" study looked at the technical, legal, and financial feasibility of a multi-purpose levee concept that would protect a 1.3 mile area along the eastern edge of Southern Manhattan against the risks of climate change while also providing opportunities for economic and community development. The study area stretches from the Battery Maritime Building (Broad Street) at its southern bound to Pier 35 (Rutgers Street) at its northern extent; the western boundary of the study area is South Street and the eastern boundary is the U.S. Pierhead Line.

Through a public RFP released in July 2013, NYCEDC selected engineering firm ARCADIS to lead the feasibility study. The ARCADIS team also included firms specializing in marine engineering, environmental planning and law, real estate and economic development, architecture, urban planning and urban design. Throughout the course of the study, the team engaged with stakeholders to ensure the analysis was responsive to the needs of the community.

The study team first explored and documented the study area's existing conditions, including its in-water and upland physical conditions. The team also studied relevant local and global precedent projects and applicable local, state and federal regulations. The team then identified multi-purpose levee options, including, among others, an integrated flood protection system option, a land reclamation option, a platform option, and a no-build option. The team evaluated these options based on technical (engineering and environmental), legal (regulatory and permitting), and financial feasibility criteria. The feasibility study concluded that a multi-purpose levee is a technically, legally, and financially feasible flood protection solution for the study area. The multi-purpose levee option that best meets the project goals outlined in the study would be contextual with adjacent neighborhoods, concentrate density near existing transit hubs, and create a large park between the Brooklyn and Manhattan Bridges.

The feasibility study was completed in Spring 2014 and can be downloaded from the Updates section below. The options and conceptual development programs evaluated as part of the study were defined for feasibility analysis purposes only and do not constitute a development proposal. The feasibility study marks only the beginning of a long and complex process to refine and assess a project concept.

In the coming months, the City will engage with stakeholders and community residents to discuss the improved understanding of the challenges and risks facing the area yielded by the study, as well as gain feedback about pursuing feedback future technical studies.

Updates

Report

Southern Manhattan Coastal Protection Study: Evaluating the Feasibility of a Multi-Purpose Levee - May 2014 Report

Presentations

June/July 2014 Community Boards 1 & 3 Presentation - Presentation on the findings of the feasibility study

November 2013 Community Boards 1 & 3 Presentation - Presentation on the scope of work for the feasibility study and introduction to the selected consultant team

September 2013 Community Boards 1 & 3 Presentation - Presentation on the purpose of the feasibility study and the details of the RFP that had been released

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