Army Corps of Engineers Rockaway Reformulation study for Rockaway Beach and Jamaica Bay

1. US Army Corps of Engineers
BUILDING STRONG®
Atlantic Coast of New York
East Rockaway Inlet to Rockaway Inlet
and Jamaica Bay, NY
Draft Reformulation
Public Information
October 2016

2. BUILDING STRONG®
• Project Overview & History
• Problem Statement
• Plan Formulation Process
• Tentatively Selected Plan
• Shorefront features
• Inundation Features
• Tie-In features
• Residual Risk features
• Environmental Analysis
• Next steps
Presentation Outline
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3. BUILDING STRONG®
Meeting Purpose
 Public Information Session & NEPA Meeting
 Provide an update on the Reformulation Study and
Tentatively Selected Plan (TSP)
 Provide an opportunity for feedback on:
► Tentatively Selected Plan
► Alternatives considered in arriving at the TSP
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4. BUILDING STRONG®
Project Partners
►NY State Department of Environmental
Conservation (NYSDEC)
►New York City
• Mayor’s Office of Recovery and Resiliency
• Department of Parks and Recreation
• Department of Environmental Protection
►National Park Service, Gateway (Cooperating Agency)

5. BUILDING STRONG®
Study Area
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6. BUILDING STRONG®
Reformulation Goals
 Recommend long-term coastal storm risk reduction
for Rockaway and Jamaica Bay
 Address multiple risks in a comprehensive system
for Rockaway and Jamaica Bay that is
► Engineeringly Feasible
► Economically Justified
► Environmentally Acceptable
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7. BUILDING STRONG®
Risks
 Flooding (inundation) along Atlantic Ocean
Coast and Jamaica Bay
 Wave Damage
 Beach Erosion
 Effects of Sea Level Change

8. BUILDING STRONG®
Coastal Storm Risk Vulnerability
► Structures exposed to inundation, waves and erosion
► Naturally low-lying topography – inundation occurs
across broad areas
► Densely populated urban area
► Extensive low-lying infrastructure – Critical
infrastructure within inundation impact areas
► Degraded coastal ecosystems undermine natural
resiliency of the area
>41,000 structures at risk of inundation for 1%
event
Problem Statement
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9. BUILDING STRONG®
Scale of the Flooding Problem
Blue illustrates current 1% annual chance of flooding
Purple illustrates 1.3 feet of Relative Sea Level Change in 2070, (mid-range SLC) added to the 1% flooding
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10. BUILDING STRONG®
Sand Movement and Erosion
Simulation
+16 years

11. BUILDING STRONG®
Original Project (1970s)
Project Authorized in 1965 as a Beach Erosion Control and
Hurricane Protection Project
Beach Erosion Control Features:
 Beach Berm at +10 ft Mean Sea Level (MSL)
 5M Cubic Yards of sand place for initial construction
 Renourishment for a period of 10 years
Hurricane Protection Features:
Never Constructed and Subsequently De-authorized
 Hurricane Barrier w/ Navigation gate across Rockaway Inlet
 Floodwall at +18 ft MSL, for 7.7 miles along Rockaway
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12. BUILDING STRONG® 12
Original Authorized Project

13. BUILDING STRONG®
Original Project (1970s)
 1974 authorization – authorized separate construction of “beach erosion
control” portion plus 10 years of renourishment
 The “Hurricane Protection Features” were de-authorized by Congress
 Constructed in 1975-1977
 Terminal groin added at Beach 149th Street in 1979
 Project renourished regularly through 1987, and in 1996, 2000, and 2004
 Due to lack of renourishment, the beach was below design size when
Sandy hit
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14. BUILDING STRONG®
Original Authorized Project Cross-Section
As a beach erosion control project – no dune feature or
wall to offer protection against surge (flooding)
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15. BUILDING STRONG®
Planning Process Overview
Rockaway Project Area formulated as a system,
considering shorefront and bay
- First Planning step is to evaluate and screen measures
- Second Planning Step is to compare alternatives and
identify the Tentatively Selected Plan
- Following the Draft Report and EIS additional
feasibility-level design is conducted on TSP.

16. BUILDING STRONG®
Storm Risk Management Measures
 Coastal storm risk management can be achieved through a
variety of engineered features, designed as appropriate for each
project area.
 Features can include
► hurricane storm surge barriers
► hurricane dunes and levees
► seawalls
► revetments
► groins
► breakwaters
► beaches and dunes (beach nourishment)
► bypassing and backpassing of sand
► non-structural measures such as house-raising,
road raising, relocations and buyouts.

17. BUILDING STRONG®
Final Array of Alternatives
A - No Action Alternative
B - Non-Structural Alternative
C - Rockaway Storm Surge Barrier (2 Possible
Alignments)
• Beachfill with reinforced dune
• Groins & Groin extensions
• Barrier with navigation and sector gates
• Tie In Features
D - Jamaica Bay Perimeter Plan
• Beachfill with reinforced dune
• Groins & groin extensions
• Living Shoreline and/or T-Wall where appropriate
• Smaller inlet closure gates to reduce wall length

18. BUILDING STRONG®

19. BUILDING STRONG®
Tentatively Selected Plan

20. BUILDING STRONG®
Elements Common to All Alternatives
 Atlantic Shorefront Features (Composite Seawall,
Beachfill, Groins)
 Atlantic Shorefront East and West Tie-ins*
 Rockaway Bayside Tie-in*
 Coney Island Tie-in*
* Alternative tie-ins will be developed further during detailed design
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21. BUILDING STRONG®
Tentatively Selected Plan
(Shorefront Component)
• Composite Seawall, beach berm
• Construction of 12 new groins between Beach 90th to Beach 122nd
• Enhancement of existing groin field from Beach 36th to Beach 49th
(extending groins) and new groin at Beach 34th
Groin Construction
34th St new groin - 526 ft
37th St extend groin - 175 ft
40th St extend groin - 200 ft
43rd St extend groin - 75 ft
46th St extend groin - 150 ft
49th St extend groin - 200 ft
92nd St new groin - 326 ft
95th St new groin - 326 ft
98th St new groin - 326 ft
101st St new groin - 326 ft
104th St new groin - 326 ft
106th St new groin - 326 ft
108th St new groin - 326 ft
110th St new groin - 351 ft
113th St new groin - 376 ft
115th St new groin - 376 ft
118th St new groin - 376 ft
121st St new groin - 326 ft
Typical groin section Typical groin layout

22. BUILDING STRONG®
Shorefront Component includes Initial sand placement and
renourishment 50 years
Red line indicates previous
Authorized project elevation

23. BUILDING STRONG® 23
Composite Seawall Cross-Section

24. BUILDING STRONG®
Barrier Alignment Alternatives
Three alignments of the storm surge barrier originally considered
- Hydrodynamic modeling undertaken for design of openings
- Effects of scour on Gil Hodges Bridge eliminated C-1W
- Impacts to existing utilities considered
C-1E is the preferred alignment, C-2 is close in comparison
Preliminary Water Quality modeling undertaken to evaluate plans
Additional modeling to be undertaken for the final design

25. BUILDING STRONG®
Surge Barrier Details
Hurricane Barrier Alternative Alignment Gate Opening Aggregate Length
Alignment Total Opening (ft)
Number of 100-foot
Vertical Lift Gates
Number of 200-foot
Sector Gates
C-1E 1,100 7 2
C-2 1,700 11 3
Both Alignments
• Maximum tidal amplitude change of 0.2 feet, Minimal change to flow speeds and direction
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Oosterscheldekering Storm Surge Barrier
with lift gates
Source: (https://beeldbank.rws.nl Rijkswaterstaat / Harry van Reeken)
Spijkenisse - Hartelkering Storm Surge Barrier
with sector gates (credit: Quistnix!)

26. BUILDING STRONG® 26
Lake Borgne, New Orleans Surge Barrier
built by the USACE in 2011 (1.8 miles long)

27. BUILDING STRONG®
Residual Risk Features
 Areas vulnerable to SLC or high frequency
events will be protected in the short term prior to
construction of the barrier
 NNBFs and some structures identified
 Small scale Non-Structural solutions will be
explored in final design
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28. BUILDING STRONG®
Typical Residual Risk Measures
FLOOD SIDE LAND SIDE
FLOOD SIDE LAND SIDE
Generic measures are assigned
considering:
► Shoreline Type and Condition
► Alignment
► Land Use
Generic measure is either:
► Retrofit Existing Structure
► New Construction
Cost developed for each project
based on measure and length
Retrofit L-Wall
Retrofit Crown Wall

29. BUILDING STRONG®
Generic Residual Risk Measures (cont’d)
FLOOD SIDE LAND SIDE FLOOD SIDE LAND SIDE
New I-WallBulkhead
FLOOD SIDE LAND SIDE
Revetment
FLOOD SIDE LAND SIDE
Berm

30. BUILDING STRONG®
Edgemere Residual Risk Concept

31. BUILDING STRONG®
Mott Basin Residual Risk Concept
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32. BUILDING STRONG®
Cost Breakdown
Construction, Mitigation, and Real Estate Costs
Alternative C-1E Alternative C-2 Alternative D
Construction $3,328,135,000 $3,361,337,000 $4,467,352,000
Mitigation $90,833,000 $75,783,000 $123,383,000
Real Estate $29,436,000 $17,386,000 $179,955,000
First Cost Total $3,448,404,000 $3,454,506,000 $4,770,690,000
IDC $333,029,000 $336,274,000 $424,262,000
Total Construction
Cost
$3,781,433,000 $3,790,780,000 $5,194,952,000
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FY 2016, 50 year study period, 3.125 discount rate

33. BUILDING STRONG®
Annual Costs
Annual Costs
Alternative C-1E Alternative C-2 Alternative D
Construction $150,474,000 $150,846,000 $206,722,000
Renourishment $5,740,000 $5,740,000 $5,740,000
OMRR&R $7,424,000 $7,124,000 $14,954,000
Total AAEQ $163,638,000 $163,710,000 $227,416,000
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FY 2016, 50 year study period, 3.125 discount rate

34. Alternative Plan – Benefit Cost Ratio
Plan Total Cost Benefits Net Benefits BCR
C-1E $163,638,000 $509,233,000 $345,595,000 3.1
C-2 $163,710,000 $509,233,000 $345,523,000 3.1
D $227,416,000 $497,582,000 $270,166,000 2.2
FY 2016, 50 year study period, 3.125 discount rate
Project Costs and Economics
The TSP is the NED Plan, identified as the plan that has highest net benefits

35. Consideration of Environmental Impacts
Unavoidable, Minimal &Temporary
Recreational and Environmental Impacts
Beach Access:
Temporary disruption to beach access via walkovers over the
Aesthetics:
Potential impacts to view of beach from north side of the dune
Surfing and Fishing:
Will be temporary and will dissipate as the beach returns to equilibrium
Beach Usage:
Impacts end as construction moves along Beach
Groins/Jetties:
Impact local shoreline sand supply, disrupt benthic habitat,
provide vertical and structural habitat for many marine organisms; Potential
adverse effect to buried cultural resources
Seawalls:
Reduce aquatic-terrestrial connectivity. Reduce spawning habitat for forage
fish. Potential loss of upper beach and backshore altered sediment
transport (loss of beach shoreward of the structure); Potential adverse
effects to buried cultural resources
Storm Surge Barrier Impacts:
Potential to affect tidal hydraulics and water quality parameters such as
temperature, dissolved oxygen, nutrient concentrations, etc. Impacts to bay
bottom, potentially limiting wetland areas along the shoreline area
Adverse effects to Gateway National Recreation Area historic districts
Impacts Avoided or Minimized
Benthic:
Short term, recovery expected within 2 - 6.5 months
nearshore and 1.5 to 2.5 years offshore following
construction
Fisheries:
No long-term impacts expected, will generally avoid
construction area
Shorebirds/Endangered Species:
No construction during breeding season
Avoidance and enhancement of existing
foraging/nesting habitats
Water Quality:
Short term turbidity (including impacts to dissolved
oxygen), ends as soon as each element is
constructed
Air Quality and Noise:
Temporary impacts, during 24-7 construction only
Aesthetics:
New sand similar to the existing beach.
Impacts Considered: Benthic Communities, Fisheries, Shorebirds, Water Quality, Air Quality
and Noise, Cultural Resources, Aesthetics, Surfing, Fishing, Beach Usage.

36. BUILDING STRONG®
Hydrodynamic modeling to date:
1) Tidal Amplitude impacts
► Identified reductions in tidal amplitude of less than 0.2 feet
► Results consistent
• over full 35-day simulation period, and
• for all hurricane barrier alignments and configurations
evaluated for the TSP
2) Jamaica Bay Eutrophication Model
Bay specific model to assess impacts in greater detail.
Barrier Analysis
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37. BUILDING STRONG®
Next Steps
 Public and agency input on features, locations and
scales
 Refine design and evaluation of specific plans
► Detailed, coordinated Water Quality Modeling
► Refine design
► Identify scale of barrier and tie ins
 Department of Interior (Gateway) agreement with plan
 Final Report and Environmental Impact Statement

38. BUILDING STRONG®
Implementation
 The Selected Plan will be built incrementally,
Atlantic Shoreline will be in the first phase
 Significant Federal funding is available for
construction (Sandy Funding to USACE for
projects like this totals $3.5B)
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39. BUILDING STRONG®
Schedule
 Draft General Reevaluation Report available for public
and agency review: November 17, 2016
 Final Report (June 2017) must be reviewed and
approved both internally within the USACE and
externally, including local, state, and other Federal
oversight
 Construction start of first phase (Targeted for 2019) will
depend on length of reviews and approvals, and relative
complexity of design
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40. BUILDING STRONG®
Local Sponsor
Responsibilities
Local Sponsor
►Must cost-share construction and renourishment
►Must commit to doing O&M
►Must indemnify State and Federal Governments
►Must obtain all necessary real estate
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41. BUILDING STRONG®
Operation and Maintenance
Local Sponsor must maintain project once built
► Maintain public access
► Prohibit excavation and alterations
► Grade and reshape beach to original elevations to repair erosion
► Operate and Maintain the Storm Surge Barriers
► Conduct quarterly inspections and take beach width
measurements
► Send quarterly inspection reports to State and Corps
► Conduct pre-storm & post-storm inspections
► Participate in yearly inspection with State and Corps
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42. BUILDING STRONG®
Real Estate Required
 Perpetual beach easements for all parcels
where sand is placed
 Fee acquisition required for structural
components
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43. BUILDING STRONG®
Public Access Overview
 Federal funding requires public access open to all
 Public accessways to beaches must be within ¼ of a mile in each direction
 Local Sponsor responsible for developing a Public Access Plan

44. BUILDING STRONG®
Questions