Atlantic Coast of New York East Rockaway Inlet to Rockaway Inlet and Jamaica Bay, NY

Transcription

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

2 Presentation Outline 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 2

3 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 3

4 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 Study Area 5

6 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 6

7 Risks Flooding (inundation) along Atlantic Ocean Coast and Jamaica Bay Wave Damage Beach Erosion Effects of Sea Level Change

8 Problem Statement 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 8

9 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 9

10 Sand Movement and Erosion Simulation +16 years

11 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 11

12 Original Authorized Project 12

13 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 Terminal groin added at Beach 149 th 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 13

14 Original Authorized Project Cross-Section As a beach erosion control project no dune feature or wall to offer protection against surge (flooding) 14

15 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 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 A - No Action Alternative Final Array of Alternatives 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 Tentatively Selected Plan

20 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 20

21 Tentatively Selected Plan (Shorefront Component) Composite Seawall, beach berm Construction of 12 new groins between Beach 90th to Beach 122 nd Enhancement of existing groin field from Beach 36th to Beach 49th (extending groins) and new groin at Beach 34 th Typical groin section Typical groin layout Groin Construction 34th St new groin ft 37th St extend groin ft 40th St extend groin ft 43rd St extend groin - 75 ft 46th St extend groin ft 49th St extend groin ft 92nd St new groin ft 95th St new groin ft 98th St new groin ft 101st St new groin ft 104th St new groin ft 106th St new groin ft 108th St new groin ft 110th St new groin ft 113th St new groin ft 115th St new groin ft 118th St new groin ft 121st St new groin ft

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

23 Composite Seawall Cross-Section 23

24 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 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, C-2 1, Both Alignments Maximum tidal amplitude change of 0.2 feet, Minimal change to flow speeds and direction Oosterscheldekering Storm Surge Barrier with lift gates Source: ( Rijkswaterstaat / Harry van Reeken) Spijkenisse - Hartelkering Storm Surge Barrier with sector gates (credit: Quistnix!) 25

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

27 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 27

28 Typical Residual Risk Measures Generic measures are assigned considering: Shoreline Type and Condition Alignment FLOOD SIDE Retrofit L-Wall LAND SIDE Land Use Generic measure is either: Retrofit Existing Structure New Construction Cost developed for each project based on measure and length FLOOD SIDE Retrofit Crown Wall LAND SIDE

29 Bulkhead Generic Residual Risk Measures (cont d) New I-Wall FLOOD SIDE LAND SIDE FLOOD SIDE LAND SIDE Revetment Berm FLOOD SIDE LAND SIDE FLOOD SIDE LAND SIDE

30 Edgemere Residual Risk Concept BUILDING STRONG

31 Mott Basin Residual Risk Concept 31 BUILDING STRONG

32 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 FY 2016, 50 year study period, discount rate 32

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

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

35 Consideration of Environmental Impacts Impacts Considered: Benthic Communities, Fisheries, Shorebirds, Water Quality, Air Quality and Noise, Cultural Resources, Aesthetics, Surfing, Fishing, Beach Usage. Impacts Avoided or Minimized Benthic: Short term, recovery expected within 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 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 Air Quality and Noise: Temporary impacts, during 24-7 construction only Aesthetics: New sand similar to the existing beach. 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

36 Hydrodynamic modeling to date: 1) Tidal Amplitude impacts Barrier Analysis 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. 36

37 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 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) 38

39 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 39

40 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 40

41 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 41

42 Real Estate Required Perpetual beach easements for all parcels where sand is placed Fee acquisition required for structural components 42

43 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 Questions