Photo on 22 October 2016 Post Matthew. Nags Head Shoreline Management Committee Public Meeting April 15, 2017

Transcription

1 Photo on 22 October 2016 Post Matthew Nags Head Shoreline Management Committee Public Meeting April 15, 2017

2 Presentation Outline Nags Head Beach Nourishment Planning History Review of the 2011 Beach Nourishment Project Project Overview Project Performance Beach Maintenance and Monitoring Plan Proposed 2018 Beach Nourishment Planning 2018 Beach Renourishment Goals and Objectives Committee Review Project Scale Renourishment Scenarios Project Schedule Post-Matthew Survey Results and FEMA Review Summary of Probable Construction Costs What to Expect in Moving Forward Discussion 2

3 Nags Head Beach Nourishment Planning History Year Main Funding Status Project Type Volume (cy) 2000 Federal Planned but not implemented Offshore dredging 8,040,000* 2005 FEMA Completed Truck 306, Local Completed Offshore dredging 4,600,000 * This volume is for the initial nourishment project. Average renourishment volume thereafter is ~1 mcy per year. 3

4 Dune Nags Head Beach Nourishment Planning History Town shoreline length: 11 miles Project Area spans from Bonnett St. (MP 11) to southern corporate limits (MP 21) High wave energy Erosion rates vary from north (2ft/yr) to south (8 ft/yr) and from year to year Average annual erosion rate is ~275,000 cy/yr (5.2 cy/ft/yr) from

5 Borrow Area 2: 320 acres and ~2.5 miles offshore Borrow Area 3: 306 acres and ~1.5 miles offshore Overview of 2011 Beach Nourishment Project length = 10 miles Max volume = 4.6 mcy (87 cy/ft) Fill density varies from north to south No sand placed on the dune Offshore borrow areas 2&3 Summer construction (May-Oct 2011) Hydraulic & Hopper dredges No environmental incidence 5

6 Overview of 2011 Beach Nourishment Total Project Cost: $36 Million $18 Million was funded through the Dare County Beach Nourishment Fund $10 Million from Revenue Bond from proceeds of a 1% occupancy tax increase $8 Million through an increase in ad valorem taxes Municipal Service District oceanside property tax increase Town wide property tax increase 6

7 R1 R2 R3 Overview of 2011 Beach Nourishment Project Reaches and Subreaches Reach 1 MP 11 to to (Bonnett St-Gov. St) Reach 2 MP 16.8 to to (Gov. St-James St) Reach 3 MP 19.2 to to o R3N MP 19.2 to to (James St-Lim. St) 0.6 o R3S MP 20.2 to to (Lim. St-Tern St) Reach 4 MP 20.8 to to (Tern St-Town Corporate Limits)

8 2011 Project Performance Methodology Beach Condition Analysis The Littoral Sand Box Lens 1 Foredune From the ~crest of dune to +6 ft NAVD* Lens 2 Beach Between +6 ft and -6 ft NAVD Lens 3 Underwater Between -6 ft and -19 ft NAVD *NAVD-North American Vertical Datum of 1988 = ~mean sea level 8

9 2011 Project Performance Total Volume by Reach

10 Beach Maintenance and Monitoring Program Established in accordance with FEMA Public Assistance Guidelines * for engineered beaches Developed a set of criteria for beach monitoring Annual beach condition surveys Utilize reference baseline and stationing Compute volume changes in the sand box Developed a set of criteria for maintenance Adopted an annual erosion rate of 275,000 cy/year Renourish every (6) years or when 50% of the volume of sand placed is lost, whichever comes LAST, (50%~2.3 MCY) Periodic nourishment funding * 44CFR j (Beaches) is further defined by FEMA Fact Sheet (Eligible Sand Replacement on Public Beaches). 10

11 Proposed 2018 Beach Nourishment Planning Selected a consulting coastal engineering firm in April 2016, Coastal Science and Engineering (CSE) Public meeting April 2016 Shoreline Management Committee formation Meeting monthly since June 2016 Short Term 2018 renourishment project Long Term 30-yr long-term strategy 11

12 Proposed 2018 Beach Nourishment Planning To Define a Target Beach Condition Provide higher level of storm protection Provide wider recreational beach Address south end of Nags Head erosion issue Integrate dune management plan into the renourishment design Replenish sand deficit in the sand box Maintain Nags Head s eligibility for future FEMA community assistance funds* Coordinated with long-term planning *FEMA Disaster Assistance Fact Sheet DAP Eligible Sand Replacement on Public Beaches: Renourishments must be to the project design; partial renourishments or hot-spot nourishments are not considered maintenance of the improved project. 12

13 Proposed 2018 Beach Nourishment Planning Committee Review Evaluated short-term and long-term strategies Established project schedule for implementation Aligned goals to specific action items Reviewed past project performance to develop project strategies Comparative volume analysis of varying beach fill scenarios Short-term project objectives which could be projected into a long-term outlook Reviewed project construction costs Maintain eligibility for future FEMA community assistance funds 13

14 Project Scale for the 2018 Re-Nourishment 10-mile from MP 11 to 21 Four reaches and two subreaches in Reach 3 Selected fill quantity = 2.5 MCY (~47 cy/ft) Fill density (# of cy per ft) varies from north to south Reaches 1 & 2 (8-mi) have economic fill density of 30 cy/ft Reaches 3 & 4 (2-mi) have restoration fill density of cy/ft North Boundary near Bonnett St. (MP 11) South Boundary near McCall Court (MP 21) 14

15 Review of 2018 Renourishment Scenarios Reach Length Low Fill Mid Fill High Fill Selected 1 29,300 ft 590,000 cy (20 cy/ft) 2 13,000 ft 390,00 cy (30 cy/ft) 3N 5,500 ft 300,000 cy (55 cy/ft) 3S 3,500 ft 420,000 cy (120 cy/ft) 4 1,500 ft 100,000 cy (67 cy/ft) 880,000 cy (30 cy/ft) 480,00 cy (35 cy/ft) 300,000 cy (55 cy/ft) 490,000 cy (140 cy/ft) 240,000 cy (160 cy/ft) 1,150,000 cy (40 cy/ft) 600,00 cy (45 cy/ft) 500,000 cy (90 cy/ft) 490,000 cy (140 cy/ft) 240,000 cy (160 cy/ft) 880,000 cy (30 cy/ft) 390,00 cy (30 cy/ft) 500,000 cy (90 cy/ft) 490,000 cy (140 cy/ft) 240,000 cy (160 cy/ft) Total 52,800 ft 1,800,000 cy (34 cy/ft) 2,400,000 cy (45 cy/ft) 3,000,000 cy (57 cy/ft) 2,500,000 cy (47 cy/ft) 15

16 Summary of Preliminary Design By Reach/Subreach More uniform dunes Reach Length (ft) Dune* Before (cy/ft) Dune** Added (cy/ft) Dune* After (cy/ft) Fill Density (cy/ft) 1 29, , N 5, S 3, , Total 52, *Dune volume includes frontal dune and back beach volume and is calculated from the crest of the dune to +6 ft NAVD. **Dune will be constructed during renourishment between +6ft and +10 ft NAVD. 16

17 Planning Goals of the 2018 Renourishment Provide higher level of storm protection Provide wider recreational beach Address south end of Nags Head erosion issue Integrate dune management plan in renourishment design Replenish sand deficit in the sand box Maintain Nags Head s FEMA eligibility Align w/long term plan 17

18 Project Schedule for the 2018 Re-Nourishment Month 1 May Initiate work Mon 2 5 Mon 6-8 Jun- Sept Oct- Dec 2016 (1) Define the ideal (target) beach condition (2) Conduct borrow area survey (3) Develop renourishment requirements, dune stabilization alternatives, and initiate engineering studies Design scenarios, cost estimates, initiate permit liaison 2017 (1) Select renourishment scenario Mon 9 13 (2) Obtain boring, and complete preliminary design Jan- (3) Pre-application meetings with regulatory & resource May agencies, and prepare supporting environmental documents Mon 14 Jun Submit permit applications with supporting documents Mon Jul-Dec Permit liaison to secure permits in time Mon Mon Jan-Apr May- Aug 2018 Receive permits / prepare plans and specifications, request bids, receive bids, select contractor, construction preparation Construction and construction administration

19 Hurricane Matthew - South Nags Head Near Seagull Dr. Before Matthew (June 2014) After Matthew (October 2016) 19

20 Post-Matthew Survey Results Summary 1,431,653 cy of sand was lost after Hurricane Matthew measured from the foredune to FEMA limit ( 19 ft NAVD) Overall lost ~30% of the nourishment sand R1 to R4 lost 22, 29, 37, and 46 cy/ft, respectively North Nags Head ~1 mile un-nourished beach lost 236,308 cy or 36 cy/ft out to 19 ft NAVD As of Jun 2016, ~90% of nourishment sand remaining Erosion rate was ~100,000 cy/yr (Nov 11 to Jun 2016) As of Oct 2016, ~60% of nourishment sand remaining Erosion rate was ~360,000 cy/yr (Nov 11 to Oct 2016) 20

21 Post-Matthew FEMA Review Summary Total uninsured losses in North Carolina resulting from Hurricane Matthew exceeded the federal financial assistance threshold for a declared disaster A pre-storm survey (June 2016) and post-storm survey (Oct 2016) was performed and analyzed to determine sand loss All pertinent nourishment design studies, plans, construction documents, as-builts submitted to FEMA for review An engineered beach maintenance and monitoring program involving periodic nourishment had been established and adhered to Town has worked with FEMA and NCEM since October to determine eligibility and public assistance grant amount 21

22 Summary of Probable Cost Estimates Project Length (ft) Volume (MCY) Unit Cost ($/cy) Total Const. (M$) Permitting/E ng* (M$) Total Cost (M$) 2018 Renourishment FEMA Restoration 52, MCY $9.50/cy^ $23.75 M $3.75 M* $27.50 M 52, MCY $12.29/cy^ $17.60 M $2.75 M** $20.35 M Includes the cost of permitting, engineering, legal, benthic studies, turtle monitoring, post-project monitoring, sand fencing, vegetation, contingency, etc. ** Assumes only FEMA qualifying expenses- cost of permitting, engineering, benthic studies, turtle monitoring, legal, etc. ^ Unit Price includes pumping cost and mobilization/demobilization costs 22

23 What to Expect in Moving Forward Continued coordination with FEMA to obligate public assistance grant funds for sand restoration Coordinate FEMA work with Town 2018 nourishment project Coordination with Dare County on funding for Town 2018 nourishment project Work with financial consultants to establish rates for MSD and Town-wide tax rates Board of Commissioners will establish MSD and Town-wide tax rates to begin FY 17/18 Permits acquired and project bid in Spring 2018 Projected construction to commence summer 2018, dependent on FEMA restoration project 23

24 Thanks to the Shoreline Management Committee Commissioner John Ratzenberger Chairman Engineering Consultants CSE Dr. Tim Kana and Dr. Haiqing Kaczkowski Cliff Ogburn, Andy Garman, Roberta Thuman, Michelle Gray, Carolyn Morris Keith Sawyer Lin Callis Ken Termini Bill Magann Bob Oakes Jim Morris Donny King Garry Oliver Randy Blanton Patrick McManus Michael Pfaff Perry White Presentation slides are provided courtesy of Coastal Science & Engineering 24

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