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Regulations and Processes for Floodway/Non-Encroachment Area Encroachments. What to look for and what to require. Robert Billings, PE, PH, CFM Mecklenburg.

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Presentation on theme: "Regulations and Processes for Floodway/Non-Encroachment Area Encroachments. What to look for and what to require. Robert Billings, PE, PH, CFM Mecklenburg."— Presentation transcript:

1 Regulations and Processes for Floodway/Non-Encroachment Area Encroachments. What to look for and what to require. Robert Billings, PE, PH, CFM Mecklenburg County Storm Water Services November 15, 2008 NCAFPM Fall Floodplain Institute Asheville, NC

2 Overview of Presentation This presentation is based on the 44 CFR Sections These sections define the NFIP program. All participating NFIP communities in North Carolina are required to implement the minimum standards defined in the code. This presentation is based on the 44 CFR Sections These sections define the NFIP program. All participating NFIP communities in North Carolina are required to implement the minimum standards defined in the code. Local community standards may be more stringent than the minimum FEMA standards presented. Local community standards may be more stringent than the minimum FEMA standards presented.

3 “No-Impact” Studies Why do I need to worry about the “No-Impact” study – the engineer said the impact was essentially zero?

4 So, just what is a No- Impact Study? A No-Impact study or certificate is a summary of calculations, geographic information, and engineering judgments documenting impacts to water surface elevations from development in a defined floodway. (3) Prohibit encroachments, including fill, new construction, substantial improvements, and other development within the adopted regulatory floodway unless it has been demonstrated through hydrologic and hydraulic analyses performed in accordance with standard engineering practice that the proposed encroachment would not result in any increase in flood levels within the community during the occurrence of the base flood discharge; 44 CFR Section 60.3 (d)

5 Draft State Guidelines Characteristics of a No-Impact study… No increase in BFE as a result of the projectNo increase in BFE as a result of the project If there is a decrease of less than 0.1’, no additional action is required.If there is a decrease of less than 0.1’, no additional action is required. If there is a decrease of more than 0.1’, a LOMR will be necessary to correct the mapsIf there is a decrease of more than 0.1’, a LOMR will be necessary to correct the maps Of course, is there is an increase you must follow the CLOMR/LOMR pathOf course, is there is an increase you must follow the CLOMR/LOMR path

6 Your Role in “No-Impact” Studies Engineers Developers Property Owners Your Boss Commissioners, Council Members, Home owner associations FEMA North Carolina Certified Floodplain Manager

7 Your Role in “No-Impact” Studies Your Role as your communities Floodplain Administrator, in the “No-Impact” Study Process… Your Role as your communities Floodplain Administrator, in the “No-Impact” Study Process… Protection of your Community Communication with Stakeholders

8 Your Role in “No-Impact” Studies As your communities Floodplain Administrator, you should be prepared to answer general “No-Impact” questions. Community officials will look to you for logical and understandable answers to complex questions. What is a “No-Impact” study? What is a Manning’s “n” value? Do we need a CLOMR/LOMR from FEMA if we have a “No-Impact” study?

9 “No-Impact” Studies When is a “No- Impact” study required? (3) Prohibit encroachments, including fill, new construction, substantial improvements, and other development within the adopted regulatory floodway … Let’s look a little closer at 44 CFR section 60.3 (d):

10 Encroachments Is the Proposed Subdivision an encroachment? It is an encroachment into the flood fringe – a “No-Impact” study is not required.

11 Encroachments Is the Proposed Greenway an encroachment? It is an encroachment into the flood fringe and floodway. If the project will be constructed on grade (no fill), a “No-Impact” study may not be required.

12 Encroachments Is the Proposed Lot an encroachment? Is the New Home? The proposed lot is an encroachment into the floodway. If the project will be constructed on grade (no fill), a “No-Impact” study would not show any changes and may not be required.

13 Encroachments Is the Proposed Subdivision an encroachment? The proposed lots and structures in the floodway are encroachments. A “No-Impact” study showing a 0.00’ increase (or less) would be a minimum requirement for this situation.

14 “Your proposed building is encroaching in my non-encroachment area. To build this project, you must submit either a No-Impact Study or a CLOMR.” “Okay...???? I understand completely… what do I need to do?” Phase 1 – I have to do what?

15 “Our proposed building is encroaching in the encroaching area. We need a flood/LOMaR/encroaching study, and we need it yesterday.” “Okay...???? I understand completely… what do I need to do?” Phase 2 – Find a flood study person.

16 “Okay, I understand Completely…Now this is what I want to see in your study…” Water surface profiles are computed from one cross section to the next by solving the Energy equation with an iterative procedure called the standard step method. WS 2 + α 2 V 2 2 = WS 1 + α 1 V h e 2g 2g Phase 3 – Communicate with the flood study person.

17 “Include a detailed narrative.” State that you have followed our local ordinance, state statutes and guidelines and NFIP guidelines. State that your study was developed using standard engineering practices. State all assumptions and engineering judgments. If you are developing a No-Impact study…state the results in simple English: The proposed project will have a 0.00’ increase on the Base Flood Elevation. Phase 4 – The Study.

18 “Include supporting information.” Include a map showing the general vicinity of the project. Include a map showing your HEC-RAS Cross- Sections. Include photos or documentation supporting your Manning’s “n” values. Include a table showing Water Surface Elevations for your proposed conditions and existing conditions. Here are a few examples… Phase 4 – The Study.

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22 “My work here is Complete.” Thank you so much for your guidance. You are truly a great and wonderful Floodplain Administrator. Phase 4 – Close the deal.

23 Communication between the Floodplain Administrator and the food study person is essential to the success of your project and your program.

24 Questions & Answers


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