Download presentation
Presentation is loading. Please wait.
Published byGiles Walters Modified over 8 years ago
1
May 2013 Floodplain Management Training Course for the Ohio Department of Transportation Presented by Shawn Arden, PE, CFM ms consultants, inc.
2
May 2013 About the Instructor Shawn Arden, PE, CFM Water Resources Manager - ms consultants Professional Engineer Certified Floodplain Manager - Association of State Floodplain Managers Past-President - Ohio Floodplain Management Association
3
May 2013 Agenda Floodplain Management (FM) Background FM Considerations for Transportation Projects Floodplain Coordination Navigating a Project through FM Regulations Case Study Lessons Learned
4
May 2013 Goals Participants will learn: Floodplain management principles commonly associated with transportation projects How to identify floodplain management issues that will affect project programming
5
May 2013 Goals This course will not include: How to perform a hydraulic analysis
6
May 2013 Definitions 100-Year Flood – A flood that has a 1% annual chance of occurrence (i.e. in a single year) Floodplain – An area inundated by flood waters Floodway – A portion of the floodplain designated by FEMA as critical for flood flow conveyance. Fill in this area triggers no-rise performance standards
7
May 2013 Definitions
8
May 2013 Why is Floodplain Management Important? Reduce flood risk: Property damage Loss of life Economic damage
9
May 2013 Why is Floodplain Management Important? Maintain natural beneficial functions of the floodplain: Flood storage / attenuation Aquatic habitat Water quality
10
May 2013 Floodplain Management Background
11
May 2013 Floodplain Management Background Origination in United States Implementation of National Flood Insurance Program (NFIP) Floodplain Management Roles of Various Agencies Regulated vs. Unregulated Floodplains
12
May 2013 Origination in United States Gilbert White -1945 Published Human Adjustment to Floods “Floods are 'acts of God,' but flood losses are largely acts of man.”
13
May 2013 Implementation of NFIP Authorized by Congress under National Flood Insurance Act of 1968 NFIP is managed by the Federal Emergency Management Agency (FEMA)
14
May 2013 Implementation of NFIP Communities must enroll in NFIP for property owners to be eligible to purchase flood insurance from the government Communities must adopt floodplain development regulations as a condition of enrollment in the NFIP (created NFIP Development Permit)
15
May 2013 Implementation of NFIP Flood Disaster Protection Act of 1973 requires mandatory purchase of flood insurance for properties within the floodplain NFIP was intended to be self-sustaining
16
May 2013 Floodplain Management Roles of Agencies Local Communities
17
May 2013 Floodplain Management Roles of Agencies Administers NFIP Develops and issues flood insurance rate maps and flood insurance studies Audits community NFIP enrollment obligations
18
May 2013 Floodplain Management Roles of Agencies
19
May 2013 Floodplain Management Roles of Agencies
20
May 2013 Floodplain Management Roles of Agencies
21
May 2013 Floodplain Management Roles of Agencies Division of Soil & Water Resources Floodplain Management Program Serves as state NFIP coordinator Performs community audits on behalf of FEMA Acts as state resource for FM data and policy
22
May 2013 Floodplain Management Roles of Agencies Division of Soil & Water Resources Floodplain Management Program Does not issue permits
23
May 2013 Floodplain Management Roles of Agencies Enroll in NFIP Adopt and enforce floodplain (NFIP) development regulations Review NFIP permit applications and issue permits Maintain FIRM panels Local Communities
24
May 2013 Floodplain Management Roles of Agencies Designs flood protection works Require evidence of NFIP Permit as condition of 401/404 Permit Limits floodplain impacts under NPDES permits
25
May 2013 Floodplain Management Roles of Agencies NFIP Permit Applicant
26
May 2013 Regulated vs. Unregulated Floodplains FEMA has identified minimum floodplain development standards for community participation in the NFIP. Standards are tied to the 100-year (1% annual chance) flood event as identified by FEMA Regardless if FEMA has identified a 100-year inundation area, all drainage courses overtop their banks from time to time
27
May 2013 Regulated vs. Unregulated Floodplains Is the floodplain for this river regulated by FEMA? Will this river overtop its banks?
28
May 2013 Floodplain Management Background
29
May 2013 Floodplain Management Considerations for Transportation Projects
30
May 2013 FM Considerations for Transportation Projects NFIP Minimum Design Standards ODOT L&D Manual, Volume 2 Additional Local Design Standards Engineering Best Practices
31
May 2013 NFIP Minimum Design Standards Title 44 CFR 60.3 – See Appendix No Rise Definition: 0.00 ft
32
May 2013 ODOT L&D Manual Section 1005 discusses highway encroach- ments on floodplains (see appendix) Designs shall permit conveyance of 100-year discharge without causing significant damage to the highway, the watercourse, or other property
33
May 2013 Additional Local Design Standards Be aware that communities can adopt more stringent floodplain development standards Freeboard No rise in all areas No fill Etc.
34
May 2013 Engineering Best Practices No adverse impact Minimize fill placement within the river channel
35
May 2013 FM Considerations for Transportation Projects
36
May 2013 Floodplain Coordination
37
May 2013 Floodplain Coordination Pre-Application Meeting Permit Submittal Post-Permit Issuance Requirements
38
May 2013 Pre-Application Meeting Per L&D Manual Section 1006.4, confirm allowable headwater and permitting requirements with local community early in the design process (Floodplain Coordination) For complex projects, request key decision makers from the local community attend the pre-application meeting
39
May 2013 Permit Submittal Submittal will consist of: Community specific permit application Design plans* Hydraulic analysis (if required)* CLOMR application (if required)* No rise certification (if required; see appendix)* *Requires Professional Engineer Seal
40
May 2013 Permit Submittal Important Note: If a CLOMR is required, the community cannot issue the NFIP permit until FEMA reviews and approves the CLOMR application. Depending on project complexity, obtaining FEMA approval of a CLOMR can take up to 12 months!
41
May 2013 Permit Submittal Community may also require: Permit and hydraulic analysis review fees Storm Water Pollution Prevention Plan (SWP3) Conservation easements Review can require 1-4 weeks depending on the community and project scope
42
May 2013 Post-Permit Issuance Requirements NFIP Development Permits may be issued with conditions that must be followed upon issuance: Expiration date (typically 6 or 12 months) Letter of Map Revision As-built survey documentation
43
May 2013 Floodplain Coordination
44
May 2013 Navigating a Project through Floodplain Management Regulations
45
May 2013 Navigating a Project through Floodplain Management Regulations Identifying Existing Conditions Hydrologic and Hydraulic Analyses Interpreting Post-Project Results Advanced Topics
46
May 2013 Identifying Existing Conditions Interpreting a FEMA Flood Insurance Rate Map Interpreting a FEMA Flood Insurance Study Using FEMA Digital FIRM (D-FIRM) Information Local Community Engagement
47
May 2013 Identifying Existing Conditions Interpreting a FEMA Flood Insurance Rate Map Appendix 4
48
May 2013 Identifying Existing Conditions Interpreting a FEMA Flood Insurance Study Appendix 5
49
May 2013 Identifying Existing Conditions Using FEMA Digital FIRM (D-FIRM) Information
50
May 2013 Identifying Existing Conditions Local Community Engagement County Engineer and Local Floodplain Administrator can assist in identifying unmapped flood-prone areas
51
May 2013 Hydrologic and Hydraulic Analyses When are they required? Who can prepare? Who reviews? What software / methods are acceptable? Notes on requesting data from FEMA
52
May 2013 Hydrologic and Hydraulic Analyses When are H&H analyses required for floodplain permitting? When placing fill within a floodway When requested by the local community
53
May 2013 Hydrologic and Hydraulic Analyses Who can prepare? The hydraulic analysis must be sealed by a Professional Engineer
54
May 2013 Hydrologic and Hydraulic Analyses Who reviews? Local community (or their consultant)
55
May 2013 Hydrologic and Hydraulic Analyses What software / methods are acceptable? Hydrology: Rational Method, Unit Hydrograph Method, Regression Equations, Stream Gage Analysis Hydraulics: Standard step backwater analysis
56
May 2013 Hydrologic and Hydraulic Analyses What software / methods are acceptable? FEMA Approved Software “Numerical Models Meeting the Minimum Requirement of the NFIP”
57
May 2013 Hydrologic and Hydraulic Analyses Notes on requesting data from FEMA Budget 6 weeks and $500 for data request Many older models have been archived on microfiche FEMA will typically provide a paper print of the microfiche for the WSP-2 or HEC-2 hydraulic model input file
58
May 2013 Hydrologic and Hydraulic Analyses Notes on requesting data from FEMA Data request form is on FEMA’s website
59
May 2013 Interpreting Post-Project Results Compare Pre-Project and Post-Project peak water surface elevations at common points along the watercourse (river stations) Identify peak water surface elevation increase Compare peak increase to maximum allowable increase from local community development regulations
60
May 2013 Interpreting Post-Project Results
61
May 2013 Advanced Topics Conditional Letters of Map Revision (CLOMR) and Letters of Map Revision (LOMR) Parallel Bridges (Divided Highway Scenario) Temporary Fill (Causeways) Common Additional Local Standards
62
May 2013 CLOMR’s and LOMR’s CLOMR – Conditional Letter of Map Revision LOMR – Letter of Map Revision
63
May 2013 CLOMR’s and LOMR’s CLOMR – Conditional Letter of Map Revision Letter from FEMA stating proposed project, if built per plan, is in compliance with NFIP requirements Does not revise flood maps
64
May 2013 CLOMR’s and LOMR’s LOMR – Letter of Map Revision Revises flood maps and effective flood elevations Based on as-built information
65
May 2013 CLOMR’s and LOMR’s Submittal Requirements: Application forms Application fee (currently up to $5,300) Hydraulic analysis Proof of public notice Proof of no impacts to insurable structures* *No impact = 0.0 ft, or mitigate impact
66
May 2013 CLOMR’s and LOMR’s Submittal Requirements: Proof of compliance with threatened and endangered species requirements Community signature Construction plans
67
May 2013 CLOMR’s and LOMR’s Tips and Tricks: Processing can require 9 - 12 months CLOMR application can be based on “conceptual data” at applicant’s risk Have FEMA approve hydraulic analysis prior to performing public notice activities
68
May 2013 Parallel Bridges
69
May 2013 Parallel Bridges Parallel bridges can typically be analyzed as a single hydraulic structure Widening to the inside of the bridges will typically not affect the hydraulic performance (i.e. no rise condition) Refer to HDS-1 for more information
70
May 2013 Temporary Fill Temporary fill is often required to construct causeways for bridge projects Temporary fill is not specifically addressed in the NFIP… …and is typically not required to be a part of the NFIP permit
71
May 2013 Common Additional Local Standards Freeboard Compensatory Storage Future Conditions Analysis Mandatory LOMR
72
May 2013 Freeboard Freeboard is a minimum amount of clearance between the high water elevation and bridge low chord
73
May 2013 Compensatory Storage Compensatory storage requires the volume of fill placed in the floodplain to be offset by an equal or greater volume of excavation Goal is to maintain available flood plain storage volume available to attenuate streamflow Franklin County, Medina County, Columbus
74
May 2013 Compensatory Storage Compensatory storage requirements can be difficult to satisfy on linear transportation projects due to limited right-of-way. Linear transportation projects are sometimes exempt from this requirement; verify with each local community
75
May 2013 Future Conditions Analysis Future conditions analysis requires a project to be analyzed against existing and future flood discharge rates Currently used in Licking County
76
May 2013 Mandatory LOMR Some communities require a LOMR for all development in the floodplain as a means to keep their flood maps up to date Requirement should be discovered during Floodplain Coordination effort Be aware of any budget or schedule implications this may have on your project
77
May 2013 Navigating a Project Through Floodplain Management Regulations
78
May 2013 Case Study
79
May 2013 Lessons Learned
80
May 2013 Lessons Learned Pre-application meetings are invaluable Make sure local community’s decision makers are present for complex projects
81
May 2013 Lessons Learned Avoid the CLOMR/LOMR process if possible Adds to the project cost Adds to the project schedule Strict notification process
82
May 2013 Lessons Learned Make sure the proposed plan makes sense May appear to be obvious Hydraulic analyses are not an exact science Sometimes a minimal flood profile rise can be justified…
83
May 2013 Upcoming Conferences 2013 Ohio Floodplain Management Conference August 28-29, 2013 – Columbus www.ofma.org for more information www.ofma.org
84
May 2013 QUESTIONS Shawn Arden, PE, CFM ms consultants, inc. 2221 Schrock Road Columbus, Ohio, 43229 614-898-7100 sarden@msconsultants.com
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.