March 10, 2023
This month, MFD submitted its public comment on the Army Corps of Engineers Harbors and Tributary Study (HATS) "Tentatively Selected Plan" Alternative 3B (TSP 3B). Click the link to download a PDF, or read here:
Col. Matthew W. Luzzatto
Commander,
US Army Corps of Engineers, New York Division
26 Federal Plaza, Rm 17-302. New York, NY 10278.
Attention: NYNJHAT Study Team, Planning Division
U.S. Army Corps of Engineers 26 Federal Plaza, 17th Floor
New York, NY 10279-0090
Submitted via email to: NYNJHarbor.TribStudy@usace.army.mil
Dear Colonel Luzzatto, Mr. Wisemiller and Ms. Alkemeyer:
Metro Flood Defense (MFD) would like to thank the US Army Corps of Engineers New York
District for its efforts to study and design a system to mitigate the impacts of storm surges
and sea level rise on the New York-New Jersey Metropolitan region. The region is the
nation’s most densely populated with almost 20 million residents, the largest economic urban area with a current GDP of $2.5 trillion, and one of the busiest and most complex urban estuaries. As such, it is imperative that a bold and comprehensive plan is pursued in order to protect these various interests. We realize both the complexity and competing priorities you face in this process, and appreciate the difficulties of balancing the long-term protection of New York Harbor and tributaries. We additionally thank you and your colleagues for the opportunity to submit public comments on the Tentatively Selected Plan (TSP 3B) for the NY & NJ Harbor & Tributaries Focus Area Feasibility Study (HATS). Metro Flood Defense is a 501(c)3 non-profit organization with the mission to increase public understanding of the flooding challenges the NY-NJ Metropolitan Region faces in the era of climate change and steadily increasing sea level. MFD advocates for the advancement of science-based strategies designed to protect the entire region from these destructive threats. We translate and transform essential scientific, technological and urban planning issues in a coherent and readily accessible manner. This essential information is made available to elected officials at all levels of government, governmental agencies and workers, commercial, industrial, transportation and insurance sectors, public health and social justice workers, and the wider public of all ages and backgrounds.
The attached preliminary proposal, Regional Layered Flood Defense Strategy, is
co-authored by members of two affiliated organizations: the NY-NJ Storm Surge Working
Group and Metro Flood Defense, Inc. Our coalition consists of leading oceanographic,
weather, climate and ecology scientists, professional engineers (PE), urban planners,
architects, advocates, and social scientists with many years of experience in the estuarine
and urban regional area. This submission is informed by the members’ own areas of
professional expertise.
As representatives of the communities of New York City, New Jersey, and the metropolitan
regional area who will all be impacted by USACE’s proposed intervention, we hope that
the feedback in this letter and attached proposal will play a critical role in the reevaluation
and revision of the USACE’s Tentatively Selected Plan (TSP 3B). Additionally, we look
forward to working with and supporting the USACE during the process as it continues
forward. With our colleagues at the NY-NJ Storm Surge Working Group, we will go into
greater detail on concerns around the USACE’s TSP 3B, the process, and the lack of
adequate community education and engagement.
Our firm and clear position is that this TSP Alternative 3B is fatally flawed. This plan creates
an incomplete and piecemeal approach, leaving many of the region’s major infrastructure
systems exposed, such as subway entrances, LaGuardia Airport, the Hunts Point regional
food markets, Bayonne shipping terminals, as well as waterfront parks and national
landmarks, including the Statue of Liberty, Ellis Island, the Hudson River and Brooklyn
Bridge Parks. They all lie in serious danger of repeated inundations and destruction. TSP
3B additionally leaves dozens of communities and hundreds of thousands of residents -
many of them in low income and minority communities - unprotected from future flooding
from storm surges and sea level rise and intense rainfall events. This is a new form of
“climate redlining” - discriminating against these communities, and is a serious
environmental justice concern. Alternative 3B only protects 63% of the region, a
completely unacceptable level of protection. We stand with the social justice and environmental conservation advocates who demand comprehensive protection for ALL
communities in the region, not just some.
TSP Alternative 3B would also place multiple portions of the region behind seawalls up to
20 feet high, cutting off shoreline communities from their waterfronts. This will inevitably
lead to years or even decades of controversy and delay. Further, many of the Corps’
proposed onshore barriers consist of a multitude of movable walls and other devices that
would need to be activated or deployed hours to days before the arrival of a major storm.
Under this plan, a network of local agencies would be responsible for maintaining and
activating these components. This is highly problematic from not only a practical and
economic standpoint, but also because if only a handful of these devices failed to be
deployed due to suffering from poor maintenance, agency activation delays or
disagreement, or absent employees at critical times, large areas of the City and region
would experience catastrophic flooding. In addition, during extreme rainfall events, similar
to 2021’s Hurricane Ida’s rainfall, the Corps’ tall onshore barriers would impound vast
volumes of storm water as well as backed-up untreated sewage in the communities they
are meant to protect.
Metro Flood Defense supports the ambitious alternative solution which has been proposed
by the NY - NJ Storm Surge Working Group, which would create a system of “layered
defense” to protect the region for the next century and beyond from extreme storm surges,
rainfall events, and sea level rise. This proposal is based in part on the experience of
dozens of flood barrier systems currently installed and successfully operating in both US
and overseas cities.
This proposal has been prepared with input from leading Dutch coastal engineers who
hold the world’s longest uninterrupted track record of protecting major population centers
from both storm surges and sea level rise. This layered defense proposal is described in
the attached report.
This proposed Regional Layered Flood Defense System has four components:
First line of defense: A network of detention basins, swales, green roofs, rain gardens
and other stormwater best management practices.
These will provide additional interior drainage management during coastal surge events
and reduce urban street and basement flooding. Detention basins, green roofs, swales
and other measures will help to reduce interior flooding during intense precipitation events,
such as was experienced during 2021’s Hurricane Ida.
Second line of defense: Nature based systems
Nature-based defenses, including restored or created wetlands, enhanced oyster beds,
and other natural ecosystems can help dissipate wave scouring and beach erosion while
also improving water quality and maintaining a healthy marine ecosystem. Several environmental groups have suggested that nature-based ecosystem services alone will protect the region from flooding. The reality is that such restored wetlands and other so-called natural systems will not reduce storm surges by more than a few inches at best. Deriving benefits from ecological services is desirable, however, they will never protect the region or its citizens from major storm tides of many feet.
Third line of defense: A network of low (3-6 feet high) onshore levees or fortified dunes
These will be constructed in sections of waterfront at low elevation to protect against king
tides flooding experienced along with gradually rising sea levels. These low barriers should
obviate the need for frequent closure of offshore sea gates even as sea level rises decade
by decade throughout the working life of the major sea gate systems. Importantly, from a
community perspective, the low perimeter levees will not obstruct visual access to
waterfronts from coastal communities, in contrast with the high onshore barriers proposed
in Alternative 3B.
Fourth line of defense: Offshore movable sea gates
The fundamental lesson from planners of similar systems in The Netherlands, London UK,
St Petersburg Russia and the US eastern seaboard communities of Stamford CT,
Providence RI and New Bedford MA is that it is necessary to “shorten the coastline” to
make protecting the almost 1,000 mile perimeter of New York Harbor and the lower
Hudson River possible. This is essential to its effectiveness in keeping surges from entering
the Harbor at all. The unique topography and shape of the metropolitan area creates the opportunity to protect many hundreds of miles of shoreline with two sets of movable sea gates (each a combination of navigational sector gates plus a suitable number of adjacent low form-drag horizontal-axis sluice gates to allow healthy tidal flows and river discharges in settled weather) built at the Harbor’s two choke points:
i) The Atlantic Ocean primary line of defense will hold back storm surges originating
in the New York Bight and flowing into the harbor beneath the Verrazano Bridge. It
would be located in the Lower Bay as far away as possible from regions of dense
development (Corps’ Alternative 2), stretching from Breezy Point (on the Rockaway
Peninsula) NY to Sandy Hook NJ (or possibly a shorter barrier, built from Coney
Island to Swinburne and Staten Islands - but with lesser effectiveness).
ii) The Long Island Sound primary line of defense would be located near Throgs Neck
(Corps’ Alternative 2). This one-mile wide sea gate system would protect the region
against devastating storm surges propagating through the Sound and traveling
through the upper East River into the Harbor, to meet the ocean surge in the lower
East River (where the highest Sandy surges were experienced).
Additional benefits of offshore sea gates when built as part of this layered defense system:
First, in settled weather, offshore sea gates would slightly reduce the speed of tidal
streams flowing throughout the Hudson River Estuary. Some environmental groups have
argued that offshore sea gates would seriously restrict tidal and sediment flows, harm
fisheries and hinder the natural flushing of the Hudson River estuary. The reality is that
carefully designed gate piers with low form-drag and skillfully-operated offshore sea gates
would reduce flows by only 10-15% from current levels. Ironically this is approximately the
same as the increase in tidal flows resulting from historic dredging of the deep Ambrose
shipping channel and other channel-dredging projects since the late 19th century.
During extreme weather events, the Lower Bay sea gates will prevent dangerous storm
surges from propagating up the length of the Hudson River, temporarily driving salty water
well into the river’s central reaches, potentially compromising extraction of potable water
and disrupting fin and shellfish fisheries.
Rather than damaging the estuary’s ecological health, the proposed layered defense
system could actually help to restore and protect these systems. In London UK, the
Thames River has seen improved water quality and signs of improving marine life upstream
of its highly effective storm surge barrier in recent years.
Critics of offshore sea gates have also argued that they would retain and lead to backups
in the city’s sewers during major storms. The reality is just the opposite: the two regional
sea gates systems would be open the vast majority of the time during settled weather and
would only be closed at dead low tide a few hours before the arrival of approaching storm
surges. The gates would be reopened a few hours after the winds and surges had
dissipated, releasing the temporarily accumulated waters into the New York Bight as soon
as possible.
When closed, the Outer Harbor and Throggs Neck sea gates would provide what might be
called a huge internal storage basin, holding upstate precipitation discharge flowing down
the Hudson River into the Harbor, while still maintaining impounded waters at near low tide
levels. Treated sewage would be discharged continuously from all discharge points (including combined sewer discharges in held-low receiving waters, avoiding the horrors of
sewer backups).
By comparison, the Army Corps’ Alternative 3B which proposes to build many smaller
barriers across Jamaica Bay, the Arthur Kill, Kill Van Kull, Newtown Creek, Gowanus Canal
and other smaller inlets would inevitably back up treated sewage and storm water in large
areas of the City, coastal New Jersey and many suburbs up the Hudson River.
Flaws in the Corps’ Benefits versus Costs Analyses
The Corps was constrained by restrictive federal regulations that we and the NY-NJ Storm
Surge Working Group allege resulted in a poorly-conceived economic cost/benefit model
that might be appropriate for say a low-density beach community, but totally inadequate
for the nation’s largest metropolitan region.
We believe that the Corps also i) unnecessarily doubled the cost of regional offshore sea
gate systems by adding unjustified induced flooding and residual risk features; and ii) the
projected 25–32 year construction period for regional offshore systems (Alternatives 2 and
3A) severely cut the benefits of these alternatives.
An accelerated construction plan, such as was authorized for the protection of
post-Katrina New Orleans, would reflect more accurately true costs and benefits of a
regional barrier system.
The Corps’ designed and built New Orleans’ $14 billion flood prevention system in less
than five years, when Congress mandated that they did so! An independent analysis by
consulting engineers for the Port Authority estimated that the outer harbor seagate could
be constructed in eight years for a fraction of the USACE’s cost estimate. We believe with
strong Congressional support, a layered - defense regional protection system as we
described above could be constructed in a fraction of the time assumed in the current plan
we allege is flawed.
Houston’s recent flooding experiences, proves that the Corps is capable of meeting the
challenge: Congress has just authorized Houston’s $34 billion “Ike Dike” - the most
expensive project ever recommended by the USACE in its history. Plans for this project
emerged only after the Corps’ initial flood prevention plan died, principally due to extensive
community opposition. However, the Corps’ Gulf Coast colleagues of the NY Division did
get it right on their second try.
Similarly we can save the Metro region with a robust regional plan that, while expensive,
complicated and controversial, will provide by far the maximum protection for generations
to come.
We respectfully request that the USACE reevaluate and redevelop an improved
comprehensive plan to protect the entire Metropolitan Regional New York - New Jersey
area from the extreme flooding the area will inevitably face, for at least the next 100 years.
We believe that the attached proposal outlines such a plan, and we encourage the USACE
New York District to work with us to develop it further and to communicate it to the public.
We look forward to working with you on this next phase of planning for flood defenses.
Sincerely,
Sam Jackson
Co-President, Metro Flood Defense
508.330.2445
sam@metroflooddefense.org
and
Sally Bowman
Co-President, Metro Flood Defense
516.768.8059
sally@metroflooddefense.org
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