Robert Billings, PE, PH, CFM Mecklenburg County Storm Water Services November 15, 2008

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 50-79. 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.

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

4. “No-rise” Studies You need to worry about “No-rise Studies” to avoid explaining the meaning of “essentially zero impact” to adjacent property owners, elected board members, county commissioners, attorneys, and juries.

5. “No-rise” Studies • Okay, I’m not overly fond of explaining floodplain management topics to attorneys, what do I need to do? • What exactly is a “No-rise Study”? • What kind of records should I keep? • Do I need to become a HEC-RAS expert?

6. So, just what is a No-Rise Study? A No-Rise 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. 44 CFR Section 60.3 (d) (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;

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

8. Your Role in “No-rise” Studies • Your Role as your communities Floodplain Administrator, in the “No-Rise” study chain, will generally involve: • Communications with the engineer and developer • This will usually involve expectations of your community, rules and regulations, nuts and bolts issues • Communications with community officials • This will usually involve explaining “No-Rise” terms, what is involved with a “No-Rise”, and liability issues

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

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

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

12. 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-rise” study may not be required.

13. 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-rise” study would not show any changes and may not be required.

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

15. What information will you need when reviewing a No-Rise Study? • Effective FIRM and Flood Insurance Study • Topographic Maps • Construction Drawings • Hydrologic Models • Regression Equation Information • Hydraulic Models • Annotated FIRM from Engineer • Narrative from the Engineer With References

16. Effective FIRM and FIS • Flood Data Table • Floodway Lines • Floodplain Lines

17. Topographic Maps • Pre-construction Conditions • Post-construction Conditions

18. Construction Drawings • Engineering drawings showing the existing conditions and proposed improvements. • Usually the existing topography, proposed topography and proposed improvements are shown on the same drawing.

19. Hydrologic Models • Computer models used to determine the channel flow for the 100-year storm event. • USGS developed regression equations • HEC-1 developed by the U.S. Army Corps of Engineers • Typically the engineer uses the results of the hydrologic model that is the basis for the FIS. • Results are shown on the Flood Data Table.

20. Hydraulic Models • Computer models that reflect the channel geometry, roughness and flows to produce water surface elevations. • Hydraulic models are the bulk of the No-Rise Submittal. • HEC-RAS is the preferred hydraulic model for flood studies.

21. Annotated FIRM

22. Narrative Explaining Purpose of Proposed Improvements and Impacts • The engineer should include a narrative that ties the various pieces of information together for the reviewer. • This is one of the most important aspects of a flood study submittal and engineers typically neglect the narrative.

23. Reviewing the No-Rise Study • Begin with the Engineers Narrative • Review FIRM and FIS • Certified Topographic Maps • Construction Drawings • Annotated FIRM • Field Visit to Verify Information • Verifying Floodplain and Floodway Information provided by Engineer

24. Engineers Narrative Why types of development happen in floodways? • Road Crossings or Culverts • Residential Subdivisions • Waste Water Treatment Facilities • Stream Restoration Projects • Greenways • Commercial Development

25. Engineers Narrative What is this $#%&! engineer trying to say? • Sometimes it’s necessary to have a conversation with the engineer to gain a better understanding of the project.

26. A Good Narrative A good narrative should include at least the following information: • Statement of the purpose of the project. • Description of the type and extent of the encroachment into the floodway. • Description of the project boundaries and geographic references such as streets or buildings.

27. A Good Narrative A good narrative should include at least the following information: • Description of the basis for the roughness coefficients contained in the HEC-RAS model including photographs of existing conditions in the project area. • A clear statement of the engineering assumptions and references. • Common reference is “Open-Channel Hydraulics” by V.T. Chow.

28. A Good Narrative A good narrative may also include the following information: • Aerial photographs of the project area. • Photographs of the project area with a location map.

29. Review FIRM and FIS Information • The engineer should provide a copy of the effective FIRM annotated to show the project limits. • If the engineer doesn’t provide the annotated FIRM • Locate the project area on your copy of the FIRM. • Determine the cross sections affected by the proposed project.

30. Effective Firm

31. Review FIRM and FIS Information Once you have narrowed your focus by locating the project boundaries, extract the important information from the Flood Hazard Data Table. • Water Surface Elevations • Flood Discharge • Floodway Widths

32. Floodplain and Floodway Information

33. Certified Topographic Maps The maps should contain the following information: • Existing and Proposed Contours • Existing and Proposed Floodplain and Floodway Delineations • Planimetric information such as streets and buildings

34. Certified Topographic Maps Important Information Continued… • Suitable Scale • Street Addresses or parcel identification numbers. • Reference to the appropriate vertical datum such as North American Vertical Datum 88 (NAVD 88). • Certified by a Registered Land Surveyor.

35. Construction Drawings Construction drawings should contain the following information: • A clear picture of the proposed improvements. • Existing structures, fences etc. • Existing utilities. • Existing right-of-way information.

36. Construction Drawings Construction drawing items continued… • Street addresses or parcel identification numbers. • Floodway and Floodplain boundaries. • Certification by a North Carolina Professional Engineer.

37. Construction Drawings Channel Revisions: • Plan view of channel revisions. • Pre-construction contours. • Grading plan and/or post construction contours. • Channel cross-sections. • Channel lining and accessory structures.

38. Construction Drawings Bridges and Culverts: • Dimensions – length, width, number of barrels, span. • Shape of culvert and material. • Type of inlet conditions – endwalls, projecting from fill, beveled, skew • Stream and structure invert information. • Location of cross-sections from the HEC-RAS model.

39. Summary Tables

40. Annotated FIRM Annotated FIRM should show: • Effective floodplain and floodway boundaries. • Proposed floodplain and floodway boundaries.

41. Field Visit to Verify Information Get some perspective on this project. Drawings and maps are great, but visiting the site is very important. Is the existing terrain similar to the depiction in the maps and drawings? Is the ground cover like the description in the narrative?

42. Field Visit to Verify Information • Take photographs of the area. • Note the locations of structures – houses, sheds, fences, existing storm water structures. • What is located directly upstream and downstream? • What is the condition of the existing channel?

44. Future Conditions Flood Fringe Area FEMA Flood Fringe Area FEMA Floodway (0.5’Floodway) Community Encroachment Area (0.1’ Floodway)

45. Floodplain Regulations and the FIRM • Layers v. specific areas Also apply in these areas. Two floodways and two floodplains Rules and Regulations in this area…

46. Two Types of Floodplain Development Review • Projects Only in Flood Fringe • Projects Within Floodway

47. Flood Fringe Development Floodway Flood Fringe Flood Fringe This is an encroachment into the flood fringe – a “No-Impact” study is not required.

48. Flood Fringe Check Sheets

50. Floodway Encroachments NFIP 44 CFR Section 60.3 (d) (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; (4) Notwithstanding any other provisions of §60.3, a community may permit encroachments within the adopted regulatory floodway that would result in an increase in base flood elevations, provided that the community first applies for a conditional FIRM and floodway revision, fulfills the requirements for such revisions as established under the provisions of §65.12, and receives the approval of the Administrator.