Public Meeting Impact of Hurricane Irma on Central Beach

Transcription

1 Public Meeting Impact of Hurricane Irma on Central Beach CITY OF NEW SMYRNA BEACH October 11, 2017 at 6:00 pm

2 Presentation Outline Hurricane Irma Impacts Flooding Caused by Hurricane Irma Original Goals of the Central Beach Flood Mitigation Project Storm Surge Protection Measures Frequently Asked Questions Alternatives to Mitigate Structural Flooding associated with Storm Surge FEMA Grant Opportunities What to Expect Contact Information Question and Answers Page 2

3 Hurricane Irma Impacts September 10, September 11, 2017 Additional home flooding occurrences not reported to the City, if any, are not depicted in this figure. Page 3

4 Hurricane Irma Impacts September 10, September 11, 2017 Floodplain Datum: NGVD29 (consistent with surveyed Finish Floor Elevations) Page 4

5 LiDAR Datum: NAVD88 Page 5

6 Flooding Caused by Hurricane Irma Total Recorded Rainfall Amounts 5.64 inches Hurricane Matthew 6.57 inches Hurricane Irma Sources of Rainfall Data: Hurricane Matthew: National Oceanic an Atmospheric Administration (NOAA) (at Daytona International Speedway) Hurricane Irma: Weather Underground (at Daytona Beach International Airport) 10/06/16: 1.36 in 10/07/16: 4.28 in 09/09/17: 1.70 in 09/10/17: 4.10 in 09/11/17: 0.77 in Page 6

7 Flooding Caused by Hurricane Irma Combination of Tide and Storm Surge Date Day Time Pred High/ Low 9/10/2017 Sun 5:05 AM 0.12 L 9/10/2017 Sun 11:27 AM 4.46 H 9/10/2017 Sun 5:44 PM 0.43 L 9/10/2017 Sun 11:45 PM 3.95 H 9/11/2017 Mon 5:56 AM 0.15 L 9/11/2017 Mon 12:19 PM 4.47 H 9/11/2017 Mon 6:42 PM 0.55 L Peak Stage at Trident Pier, Port Canaveral: 6.5 ft, NGVD Page 7

8 Central Beach Flood Mitigation Project Original Goals To construct stormwater conveyance systems (drainage inlets, pipes and pump stations) within existing roadway rights-of-way to alleviate structural and roadway flooding within the Central Beach area. Construct underground exfiltration systems designed to provide water quality treatment, where feasible. The project improvements encompassed: Columbus Avenue, Cedar Avenue, Oakwood Avenue, Carol Avenue, Ocean Avenue, Hope Avenue, Maralyn Avenue, Canova Drive, Goodwin Avenue, South Pine Street, Cooper Street, and 2nd Avenue. Page 8

9 Central Beach area prior to the Flood Mitigation Project Page 9

10 Central Beach area prior to the Flood Mitigation Project Page 10

11 Central Beach Implemented Improvements (Phases 1, 2, & 3) Page 11

12 Storm Surge Protection Measures Top Duckbill Tidal Automatic Hinged Style Floodgate Tidal Flapgate Check With Manual Floodgate Valve Mechanism Page 12

13 Storm Surge Protection Measures Flap Gates were considered during the design of the Phase III improvements to protect against storm surge. 2 nd Avenue Outfall at Callalisa Creek Page 13

14 Storm Surge Protection Measures PROS CONS Prevents storm surge from backing-up into the upstream drainage system Can be blocked by sedimentation or debris and stop functioning Introduces additional head losses into the upstream drainage system Sediment and debris preventing flapgate from performing properly Page 14

15 Frequently Asked Questions The storm drains are full of water even if it is not raining. Callalisa Creek is tidally influenced due to its proximity to the Atlantic Ocean. The amount of water present in the pipes and drainage inlets will vary based on the tide. 08/03/2011 9:35 AM 08/03/ :17 AM Observed tidal effect at the intersection of 2 nd Avenue and Yupon Avenue prior to construction of the Central Beach Phase III improvements. Page 15

16 Frequently Asked Questions The storm drains are full of water even if it is not raining (continuation) The design of the Phase III improvements was limited by: the flat topography and the elevation of the Callalisa Creek These factors prevent the pipes from remaining dry. The design of the storm sewer system accounted for the normal high tide conditions. The mean high water elevation is estimated at 1.9 ft, NGVD. The design condition conservatively assumed 2.5 ft, NGVD. Page 16

17 Frequently Asked Questions The drainage pipes made the surge come faster to the homes. 1. The water elevation during Hurricane Irma in Callalisa Creek exceeded the surrounding grade (low lying areas). 2. Prior to the construction of the Phase III improvements, hydraulic connections existed between Callalisa Creek and Peninsula Avenue, Goodwin Avenue, Ocean Avenue, and Canova Avenue. Page 17

18 Frequently Asked Questions Figure dated May 2013 Page 18

19 Frequently Asked Questions The drainage pipes made the surge come faster to the homes (continuation) 3. The Phase III improvements did not increase flooding within the low lying areas. All the observed / reported structural flooding occurred within FEMA s mapped floodplain. 4. The Phase III improvements did not increase the flood risk of the existing properties located within the FEMA floodplain. Page 19

20 Frequently Asked Questions The City purchased lots on the beach side to make them retention areas, but were not used as retention areas, why not? The use of the purchased lots as retention areas was not conducive to the stormwater design due to their location and the existing topography as they did not provide sufficient retention volume. To fulfill the retention requirements, we opted for implementing underground exfiltration systems. Page 20

21 Alternatives to Mitigate Structural Flooding associated with Storm Surge Elevate Existing Homes Page 21

22 Alternatives to Mitigate Structural Flooding associated with Storm Surge Acquisition and Demolition of Existing Homes Page 22

23 Alternatives to Mitigate Structural Flooding associated with Storm Surge Acquisition and Relocation of Existing Homes Before relocation After relocation Original site after home relocation Page 23

24 FEMA Grant Opportunities HAZARD MITIGATION GRANT PROGRAM (HMGP) FLOOD MITIGATION ASSISTANCE PROGRAM (FMA) PRE-DISASTER MITIGATION ASSISTANCE PROGRAM (PDM) MITIGATION PROJECTS: Home Elevation Acquisition/Demolition Acquisition/Relocation x x x x x x x x x Application Period Following a Major Disaster Declaration Annually Annually Funding Source Federal assistance provided for Disaster Recovery Appropriation Funding Appropriation Funding Page 24

25 FEMA Grant Opportunities HAZARD MITIGATION GRANT PROGRAM (HMGP) FLOOD MITIGATION ASSISTANCE PROGRAM (FMA) PRE-DISASTER MITIGATION ASSISTANCE PROGRAM (PDM) Competitive Nationwide? No Yes Yes Flood Insurance Requirement No Yes No Cost-Share Requirements 75% Federal Match 75% Federal Match (generally) or up to 90% Federal Match (for RL properties) or up to 100% Federal Match (for SRL properties) 75% Federal Match * Project must be cost effective (benefits > costs) Page 25

26 FEMA Grant Opportunities Repetitive Loss (RL) property Has incurred flood-related damage on 2 occasions, with repair costs equaled to or above 25% of the structure market value at the time of each flood event At the time of the second incidence of flood-related damage, the contract for flood insurance contains increased cost of compliance coverage (ICC). and Increased Cost of Compliance (ICC) is flood insurance coverage that provides up to $30,000 to help pay the costs to elevate, demolish, or relocate a flood-damaged structure to meet local floodplain requirements in Special Flood Hazard Areas. ICC coverage is in addition to the coverage for the repair of the structure s actual physical damage caused by flooding. Page 26

27 FEMA Grant Opportunities Severe Repetitive Loss (SRL) properties (a) Is covered under a contract for flood insurance made available under the NFIP (b) Has incurred flood related damage 4 or more separate claim payments of more than $5,000 each (including building and contents payments) and with the cumulative amount of such claims payments exceeding $20,000; or 2 or more separate claim payments (building payments only) where the total of the payments exceeds the current market value of the structure. Page 27

28 What to Expect Be able to provide: Flooding History (questionnaires, photographs, flood insurance claims) FEMA-required forms that demonstrate: Voluntary Participation Legal status Privacy Release Coordination with Elevation or Demolition Contractor Coordination with City of New Smyrna staff Public Meeting Public Notice on local newspaper Three years to project completion Page 28

29 Contact Information City of New Smyrna Beach o Kyle Fegley, P.E. City Engineer kfegley@cityofnsb.com o David Hamstra, P.E., CFM Project Manager , ext. 309 david@pegasusengineering.net Page 29

30 Questions and Answers Page 30