T
his section contains preliminary findings
related to flooding, flood insurance availability,
and sea level rise. It also contains recommended flood control measures to be implemented
on the Fort.
This section was prepared by
Kimley-Horn and Associates, Inc.
It was completed October 2008.
7C
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flood control strategy
THE TECHNICAL SUPPORT MANUAL FOR THE REUSE OF FORT MONROE
FLOODPLAIN ASSESSMENT
Located on the southernmost point of the
Hampton Roads Peninsula, Fort Monroe lies
almost entirely in a designated floodplain. As
designated by the Federal Emergency Management Agency (FEMA) Flood Insurance Rate
Map, almost all of the land area of the Fort lies
in flood zone A7 with a 100-year base flood elevation (BFE) of nine feet (NGVD 29 datum).
The only part of the base not in a floodplain
zone is a strip of land running north-south
along the northeastern edge of the Fort, which
lies in flood zone C, outside the 100-year
floodplain.
EXISTING GENERAL CONDITIONS
Surrounded almost entirely by water, Fort
Monroe resides at the southern tip of a low-lying peninsula which protrudes into the Chesapeake Bay. Significant portions of the Fort
have been created by filling adjacent wetlands
and bottomlands. Because of historical flooding and erosion, a number of flood protection
improvements have been made throughout
the Fort. An area of beach (called Dog Beach)
makes up the eastern edge of the peninsula,
extending approximately two miles from
Buckroe Beach to the southern tip of the base.
The beach surface is protected from erosion
by an approximately seven-foot tall man-made
dune comprised of mainly rubble covered with
sand, as well as a series of groins extending
eastward into the Chesapeake Bay. Despite
these erosion control measures, the beach
still faces major erosion hazards, especially as
significant floods wash sand outward into the
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bay and blow over the dune, which occurred
during Hurricane Isabel. The other shorelines
around the Fort are protected by concrete
sea walls which range from six to eight feet
in elevation, as well as an extensive area of
rip-rap and a berm along the shoreline facing
Mill Creek and along the shoreline adjacent to
McNair Drive.
As Fort Monroe is the third oldest military institution in the United States, historical structures make up a significant percentage of the
buildings on the Fort. The Fort is a National
Historic Landmark and many of the buildings
have not been elevated or altered since their
initial construction, making them especially
prone to flood damage. First floor elevations
of these structures, as determined by the U.S.
Army Corps of Engineers’ (ACOE) 2004 structure inventory of Fort Monroe, range from approximately four to nine feet, with ground elevations ranging from three to five feet, which
is well below the flood elevations reached
during Hurricane Isabel. Preservation for
historic purposes limits modifications which
can be made to the structures to flood-proof
them or raise first floor elevations to conform
to current floodplain requirements, especially
structures along Ingalls Road, Bernard Road,
Matthews Lane, and Fenwick Road.
Figures 7C-1 - 7C-2: Hurricane Isabel caused severe flooding
along Ingalls Road.
Figure 7C-2
Flooding History
Hurricane Isabel flooded Fort Monroe in
September of 2003 with peak flood elevations
of 6.26 feet on the North American Vertical
Transportation, Infrastructure, and Flood Control Details: Flood Control Strategy
THE TECHNICAL SUPPORT MANUAL FOR THE REUSE OF FORT MONROE
Datum (NAVD 88). This flooding was comparable to the 1933 hurricane, which brought
peak storm surges of approximately 7.41
feet (NAVD 88, See Figures 7C-1 and 7C-2).
Initially making landfall near Drum Inlet, NC
as a Category II hurricane, Isabel’s westerly
track caused severe storm surges to move into
the lower Chesapeake Bay. This caused severe
flooding at Fort Monroe from flooding up
through storm drains, beach over washes, sea
wall topping, and berm failure and blowouts.
The storm also caused the collapse of several
piers and extensive tree loss from high winds.
Flooding occurred from both the Chesapeake
Bay side and from the Mill Creek side. A
major source of flooding was water forced up
through the storm drain pipes which normally
discharges into Mill Creek and the Chesapeake
Bay. As storm waters reached their peak elevation, sea walls on the southern tip of the Fort
Monroe peninsula; the southwestern portion
along Mill Creek; and the northeastern portion
near Dog Beach incurred significant damage
during overtopping, allowing water to completely submerge the southern portion of the
Fort, filing the moat and flooding most of the
land area within the fortress walls. Many historical buildings that reside in this section of
the Fort were flooded with substantial damage
to basements and lower level floors of some
of the buildings. Washouts on sections of Dog
Beach contributed to even greater beach erosion, dune degradation, and damage to roads
and buildings.
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RECOMMENDED FLOOD CONTROL
MEASURES
In response to the substantial damage sustained on Fort Monroe during Hurricane
Isabel, in May 2005 the Norfolk District, U.S.
Army Corps of Engineers conducted a flood
evaluation and protection study to evaluate
the flooding and develop measures to reduce future flooding from storms of similar
strength. The study evaluated the physical
features, weather patterns, and general flooding hazards on the Fort peninsula, as well as a
flooding history of the peninsula dating back
to the hurricane of 1933 but focused on damages sustained during Hurricane Isabel. The
report assessed these damages combined with
natural physiology of the peninsula to draft a
plan to protect the Fort in the future, including installing backflow prevention valves on
storm drains, raising sea walls, constructing
berms in particularly risk-prone areas, and
installing pump stations throughout the base.
In 2004, the ACOE conducted a field inventory
of all structures on Fort Monroe, including
the structures’ first floor elevations, elevations
at which water would enter building basements, and high water marks reached during
Hurricane Isabel. The goal was to evaluate
the susceptibility to flooding of the on-base
structures and develop recommended actions
to reduce future flooding. An evaluation of a
number of potential flood protection measures
was undertaken by the study. From these
measures a recommended flood protection
plan was developed consisting of the following
elements:
• Installation of backflow prevention
valves on the outlets from the Fort Monroe moat to prevent back flooding during
large storm events
• Construction of a new seawall in the
southern Fenwick Road region with a
higher elevation of 9.5 feet NAVD, extending from the Navy Pier to the Battery Parrott to include a “toe” of armor
stone to prevent scouring of the base of
the wall
• Construction of an interior berm southward across the northern end of the
moat and into the southern portion of
the base to prevent flooding from Mill
Creek. The interior berm would be installed in the moat with an elevation of
eight feet (NAVD 88)
• Construction of a series of beach berms
and breakwaters from the southern end
of the northern seawall at Battery Parrott
to the intersection of the proposed berm
and the existing seawall
• Lowering of the berm existing north of
Bowling Alley in Mill Creek to reduce
the ponding of water trapped behind the
berm during heavy rainfalls and flooding
from other locations on the Fort
Figure 7C-3 shows the proposed flood protection measures recommended in the report. In
2005, the anticipated cost for flood protection
measures proposed under this protection plan
had been estimated at $26.4 million.
Transportation, Infrastructure, and Flood Control Details: Flood Control Strategy
THE TECHNICAL SUPPORT MANUAL FOR THE REUSE OF FORT MONROE
Figure 7C-3: Fort Monroe Seawall Repairs Plan Sheet 1
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THE TECHNICAL SUPPORT MANUAL FOR THE REUSE OF FORT MONROE
Figure 7C-3: Fort Monroe Seawall Repairs Plan Sheet 2
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WORKING DRAFT Date Completed: October 2008
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THE TECHNICAL SUPPORT MANUAL FOR THE REUSE OF FORT MONROE
In 2007, the Department of Defense approved
approximately $22 million in funding to construct some of the improvements proposed in
the ACOE study. These improvements are currently under construction and mainly include
the following elements of the original recommendations:
• Reconstruction of the flood wall along
the southern end of the Fort at an elevation approximately 2.5 feet higher than
the existing flood wall elevation
• Construction of the three southernmost
breakwaters
• Construction of a terminal groin at the
southern tip of the Fort
In addition to these improvements, the Army
secured some additional funding and has
recently installed backflow prevention valves
on approximately 14 of 38 of the storm sewers
that discharge into the Chesapeake Bay and
Mill Creek as well as inflow and outfall pipes
located in the moat. This represents a critical
element of the original COE recommendations
since much of the flooding that occurred during Hurricane Isabel was due to storm surge
through these drainage systems. Two additional valves have recently been funded and
are to be installed prior to base closure.
The Army indicated that there also may be
additional funds available based on the favorable bid that was received for the funded
flood protection project. It is possible that
these funds would be used to fund more of the
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WORKING DRAFT Date Completed: October 2008
improvements in the original ACOE study and
could include the construction of one or two
additional breakwaters northward of the three
that are currently under construction.
As redevelopment planning and implementation for reuse of the Fort continues, it is recommended that a funding source be identified
to provide the additional funding required to
complete the ACOE recommendations.
The City of Hampton is also undertaking a
shoreline protection study of the City's entire
shoreline along the Chesapeake Bay including
Fort Monroe. They expect the study to conclude that breakwaters will be required along
the entire 4 - 5 mile distance inclusive of Fort
Monroe. This study will require review upon
its completion.
Figures 7C-4: Newly constructed breakwaters and beach nourishment
CITY OF HAMPTON FLOODPLAIN STUDY
The City of Hampton is currently undertaking a watershed and floodplain study of 19
defined sub-watersheds throughout the city
of which one sub-watershed Fort Monroe is
included. The city is currently undertaking the
first of these studies and the Fort Monroe subwatershed area is number two on the City's
schedule. However, there is no funding in
place yet for the next study. It is strongly recommended that the city be urged to fund the
Fort Monroe study given the flooding history
of the Fort and the continued risk of flooding
until the entire ACOE flood protection improvements are completed.
Figures 7C-5: Newly constructed seawall and armor stone
Transportation, Infrastructure, and Flood Control Details: Flood Control Strategy
THE TECHNICAL SUPPORT MANUAL FOR THE REUSE OF FORT MONROE
FLOOD INSURANCE REQUIREMENTS
AND POTENTIAL AVAILABILITY
In order for any future private leaseholds or
other private investment in Fort Monroe to
take place, it will be important to secure federally subsidized flood insurance and comply
with the City of Hampton’s floodplain ordinance. The buildings at the Fort will need to
qualify for flood insurance under a National
Flood Insurance Program (NFIP) and, in
order to do so, must meet Federal Emergency
Management Agency (FEMA) regulations.
Additionally, it must be clear what buildings
and types of building additions are required to
meet the building requirements of the NFIP if
covered by a federally subsidized policy.
An examination of the existing buildings on
the base indicates they fall into three general categories. The first category consists
of historic buildings. The second category
includes buildings that are not historic but
which were built prior to the time of the City
of Hampton’s July, 1987 Flood Insurance Rating Map (FIRM) study. These buildings will
be classified as pre-FIRM. The third category
is buildings constructed since the flood insurance study was completed (post-FIRM
buildings). Buildings constructed after July
of 1987 are considered post-FIRM buildings
and, therefore, must adhere to elevation and
flood-proofing regulations to qualify for flood
insurance.
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Figures 7C-7: View across the Moat at Fort Monroe
FEMA’s regulations indicate that localities can
exempt historic structures from the requirements of the NFIP by either exempting them
through the definition of substantial improvement or issuing variances to the structures
(44 CFR 60.6). However, the improvements
exempted must not preclude the continued
designation as a historic structure. Thus all
historic buildings on the base will qualify for
pre-FIRM exemption as long as they meet the
FEMA definition of a historic building. Refer to
the National Flood Insurance Program Flood
Insurance Manual. “Definitions: Historic Building.” Section XXI: Definitions. Def 15. Accord-
ingly, such structures may be exempt from the
building requirements of the NFIP but may
still be eligible for flood insurance coverage.
Pre-FIRM buildings will be exempt from FEMA
regulations and the Hampton City Flood Ordinance. However, if there are any additions,
extensions, or major improvements amounting
to more than 50 percent of the market value
of the structure, the entire structure will have
to meet FIRM regulations. Refer to the National Flood Insurance Program Flood Insurance
Manual, “Rating Steps: Pre-Firm Construction.” Section V: Rating. Rate 15.
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THE TECHNICAL SUPPORT MANUAL FOR THE REUSE OF FORT MONROE
SEA LEVEL RISE
All new construction (post-FIRM) must conform to the current flood zone construction
requirements. The base engineering office
indicates that since 1987, all new buildings
have been constructed in accordance with the
building requirements of the NFIP. The ACOE
has inventoried all structures on the Fort and
determined the ground elevation around the
structures and the elevation of the first finished floor. This information may be used in
the future to assess what, if any, modifications
may need to be made to existing buildings for
them to be eligible for federal flood insurance
if adaptively reused by private residents or
businesses. Additional consultation with FEMA
and the City of Hampton will be required to
determine the specific procedure for complying with flood insurance program requirements.
The effects of sea level rise need to be considered in any long-term infrastructure planning
and costs for Fort Monroe. Nearly the entire
Fort is in the 100-year floodplain with a base
flood elevation of nine feet (NGVD). Sea level
has been estimated to rise approximately two
feet in the next century. Climate changes are
anticipated to increase the frequency, as well
as the intensity of tropical storms and hurricanes. Although flood protection measures
have been, or will be undertaken, these measures may not be sufficient to deal with the
increased flooding potential created by longterm sea level rise.
Planning for Fort Monroe reuse should include
a site specific evaluation of the impact of sea
level rise (under various height predictions
based on different models) on additional flood
protection measures at the Fort. The specific
focus should be on the capability of existing
systems to withstand storm surges and anticipated additional flooding pathways during
storm events as sea level rises. This information should be used to identify the nature
and cost of additional short- and long-term
additional flood protection measures at the
Fort. This study is currently ongoing and will
provide a basis for providing additional flood
protection recommendations.
Sea level rise predicted by Wetlands Watch in draft paper
being developed in consultation with the Virginia Institute of
Marine Science.
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THE TECHNICAL SUPPORT MANUAL FOR THE REUSE OF FORT MONROE