By Ron Hine | FBW | July 28, 2016
The Hudson River Rebuild by Design program, initially designed to be comprehensive, is currently focused on the “Resist” strategy, comprised of a series of floodwalls, revetments and deployable barriers to protect against future surges. The cost of building these structures is estimated to exceed the $230 million HUD grant awarded for this program now being administered by the New Jersey Department of Environmental Protection (NJDEP). The surges that the “Resist” structures are designed to prevent, however, are uncommon events. At a July 12, 2016 presentation, Dr. Alan Blumberg of Stevens Institute of Technology stated that a Sandy-type surge has a likelihood of occurring once every 260 years. The “resist” structures are designed to have a life of perhaps 100 years assuming the local government can provide for annual maintenance cost estimated to be $1.4 to $2.4 million. Perhaps more important, the flooding that regularly occurs in Hoboken is the result of a major rainfall events, not surges. The floodwalls and other barriers will do nothing to protect Hoboken area residents from this type of flooding.
Fortunately, the City of Hoboken has been addressing other flood prevention strategies apart from the Rebuild by Design project. These programs may actually provide the key to making Hoboken and other urban communities more flood-resilient and also could serve as a more cost-effective model. In December 2013, the City of Hoboken amended its flood ordinance and zoning code to ensure that new construction is built to a standard to withstand future flooding. These codes require a combination of wet and dry floodproofing below what is called the Design Flood Elevation so that the new buildings will be resistant to flood damage. The wet floodproofing would actually allow the water to come into a building and then leave when waters recede without causing significant damage. This conforms to the Dutch concept of “learning to live with water.” The use of concrete, ceramic tile, brick and other materials resistant to water damage meet wet floodproofing requirements.
Design Flood Elevation (DFE) is the base flood elevation associated with a flood that has a 1% probability of being equaled or exceeded in a given year plus the freeboard which is a margin of safety added to account for waves, miscalculations or environmental changes. In the Hoboken ordinance, the freeboard for residential structures is 1 foot in the A flood zone and 2 feet in the V coastal high hazard zone.
Floodproofing buildings provides protection against future flooding events — both major rainfalls as well as a Sandy-type surge. Dry floodproofing, which is by far the more costly alternative, would involve designing the building below DFE to keep floodwaters out and must be constructed to resist the hydrostatic pressure that would be exerted outside the structure by rising waters.
Both types of floodproofing involve raising heating, electrical and other mechanical systems above the DFE. Where this is not possible, such as an elevator on the ground floor, there could be a protective barrier that would be deployed if a flooding event is anticipated.
After securing a grant from the New Jersey Department of Community Affairs, the City hired the firm of Princeton Hydro to work with City of Hoboken staff to develop Resilient Buildings Design Guidelines which was published in October 2015. This report details how residential and commercial buildings can be floodproofed in accordance with FEMA standards. Case studies are provided on existing buildings that were retrofitted with floodproofing measures appropriate for that site. By undertaking these measures, the building residents were able to realize substantial reductions in flood insurance payments.
The report includes recommendations to preserve much of the ground floor features that help to maintain a lively streetscape that exists throughout much of Hoboken. Non-residential uses such as commercial offices and retail spaces are permitted below DFE and can be dry floodproofed. Parking and storage are also permitted below the DFE which poses the risk of blank walls at street level.
The financial burden for the other proposals in the original Rebuild by Design program are falling on City of Hoboken or state programs that aid in municipalities’ infrastructure improvements. The City of Hoboken is paying for a new flood pump on 11th and Hudson Streets that will have a capacity for pumping 50 million gallons a day to relieve flooding on the low-lying western portions of Hoboken. This pump is currently in its final phase of construction and falls under the RBD “discharge” strategy.
The City of Hoboken has also initiated acquisition and creation of public park space at three locations to also serve as underground water retention basins, thus providing for part of the RBD “store” strategy. Construction of an acre at SW Parks will begin soon paid for by a low-interest loan from New Jersey Environmental Infrastructure Trust Fund. The acquisition of the park was paid mostly from the Hudson County Open Space Trust Fund. The recently approved redevelopment plan for 7th Street and Jackson Street will add another two acres provided by the developer. The City has been in negotiations to acquire the BASF site in northwest Hoboken that would provide over 5 acres of parkland with a 250,000 gallon underground stormwater storage system. It now appears that the $230 million Rebuild by Design grant will not cover any of these costs which could total $100 million dollars.
It also remains to be seen if any major infrastructure projects will be initiated to begin separating stormwater from sewerage systems. These combined systems are major problem in municipalities throughout the region and contribute to much of the flooding problem. They are also a major source of pollution for the Hudson River and other bodies of water when rainstorms overwhelm sewage treatment plants and sewage ends up being dumped into waterways. Thus, the warning: don’t going swimming after a major rainstorm.
FBW Comments to NJDEP 8-17-2016
Flood Hazard Assessment for New York Harbor
City of Hoboken’s Resilient Buildings Design Guidelines
Walling off Hoboken’s waterfront meets fierce resistance
Scoping out Hudson River Rebuild by Design project
Questions about Hoboken’s flood strategy
Dutch-led team: Resist, Delay, Store & Discharge – A Comprehensive Strategy for Hoboken
Comprehensive flood plan for Hoboken in high-stakes competition for federal funding
Are we devising flood remedies based on a 1,000 year storm?
Dutch Dialogues: A model for Hoboken
Flood insurance rates will skyrocket
79% of Hoboken falls into FEMA’s flood zone
Post Sandy: After repairing the damage, then what?
12-Point Plan in preparation for the next Sandy