floodplain zoning basics - macpza · 27-09-2017 · floodplain zoning basics ceil strauss, state...
TRANSCRIPT
Floodplain Zoning
• Roles
• Where do floodplain regulations apply?
• Main responsibilities
• Common oversights
• Resources (for reference; won’t be time to discuss)
Floodplain Roles & Responsibilities
• Zoning Authority (city, county or township)
• Most important!
• Adopts ordinance, enrolls in National Flood Insurance Program (NFIP),administers & enforces, KEEPS RECORDS
• State – Oversight; technical assistance & training; approve ordinances & somedata/mapping; coordinate between FEMA & community (& watersheds, HSEM,etc.)
• Watershed District – may have overlapping regulations &/or mitigation projects;often key data source
• FEMA – Oversees NFIP (enrolls; can suspend); produces / approves maps & data
Overall Process
1. In Floodplain? (If close, confirm & document)
2. In floodway, flood fringe or general floodplain?
3. Permitted Use or CUP?
4. Determine Regulatory Flood Protection Elevation (RFPE)
5. Meets Floodplain Standards?
6. Meets other Standards?
7. Issue Permit
8. Inspections
9. Record As-Built documentation
On DNR website
Main Responsibilities – Determine if in Floodplain (or Shoreland)
Look at your FEMA maps
• Paper copy
• Online at https://msc.fema.govor FEMA National Flood HazardLayer (NFHL) viewer or MnTOPO(see resources at end)
• Local GIS systems
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FEMA Map with Special Flood Hazard Area (SFHA)
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National Standard of “100-yr flood”aka Base Flood Elevation (BFE) or 1%
annual chance flood
High Flood Risk (must regulate)
Medium Flood Risk
Low Flood Risk
Zone A & AE (old)Zone A & AE (new)
Zone B (old maps)Zone X (shaded)
Zone C (old maps)Zone X (unshaded)
FEMA Map with Special Flood Hazard Area (SFHA)
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High Flood Risk (must regulate)
Medium Flood Risk
Low Flood Risk
In the Floodplain?
ProposedSite
We have LiDARstatewide now!
In Shoreland Districts remember MR 6120.3300, Subp. 3, B
• 1000 feet from OHWL for lakes
• 300 feet from OHWL for rivers/streams orfloodplain boundary, whichever is greater
Boundaries of Shoreland District
Minimum Low Floor Elevations inShoreland District
• If flood elevation determined – use RFPE = BFEplus 1 foot (plus stage increase on rivers)
• If no flood elevation determined - take highestof Ordinary High Water (OHW) or HighestKnown Water Level (HKWL), add 3 feet
DNR Sample Floodplain PermitApplication Form
Creates a record forelevations and a paper trailfor tracking substantialimprovements & lowestfloor, among other things.Communities must haverecords of lowest floor forall substantially damagedstructures.Available on DNR website
DNR Sample Floodplain Permit Application Form
Determine Base Flood Elevation (BFE) & if Floodway or Flood Fringe
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FLOOD FRINGE}
}} FLOOD FRINGE
FLOODWAY
100-year flood elevation/BFE
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MN REGULTORY FLOOD PROTECTIONELEVATION (RFPE) – Minimum lowest floor
+ Stage increase due to Flood Fringe
+ 1 Foot (minimum) of freeboard= Regulatory Flood Protection Elevation
(State of MN)
1% chance FEMA’slowest floorrequirement
* Mandatory after 1997 State law change
*
If DFIRMs, Can Use FEMA’s NFHL Viewer
9/27/2017 Optional Tagline Goes Here | mn.gov/websiteurl 13
• Floodplainlayers availablein counties withDigital FloodInsurance RateMaps (DFIRMs)that areeffective
• LOMAs shownstatewide
How To Find Base Flood Elevation (BFE)
• Current detailed study area: Use your Flood Insurance Rate Map (FIRM) & FloodInsurance Study (FIS) - DNR can help you learn to interpret
• Current A Zone, but have Detailed Preliminary: Can use the preliminary FIRM &FIS as best available data
• Current A Zone:
• Zone A modeling (i.e., “pink lines”) available?
• Previous estimate determination? Check with watershed district & DNR;Previous LOMA?
• Shoreland Method (on lakes/basins, use 2’ above highest of OHW/HKWL forBFE & 3’ above for RFPE)
• Have resident apply for LOMA & request BFE to be determined
Floodplain Map Updates (as of 3/2017)
2017-2018 CountyModernizations• A Zone models• 1% digitized• Will be able to use for
zoning & flood insuranceappeal (Letter of MapAmendment - LOMA)decisions
• Official updated mapswould be a future step
• Funded for next cycle“pink lines” availableat MnGeoCommons
A Zones & AE Zones with no Floodway Determined
• On lakes: Flood fringeabove the OHW, ifnot near tributary oroutlet
• On water courses:Must be treated asfloodway unless ananalysis is done todetermine it’s floodfringe
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Sample “pink lines” – estimated 1% WaterSurface Elevations used as best available data
BFEs. Add 1.5 feet to get RFPE
Shoreland Requirements (still minimum elevation if in SL!!)
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Shoreland District*HKWL – HighestKnown Water Level
** For lakes. Addstage increase onwatercourses
Lowest floor 1 ft** above calculated 100-yr, if known. Otherwise, 3 ft above OHWor HKWL (whichever higher)
3’
Highest of OHWor *HKWL
100-yr (aka BFE)
**100-yr + 1’
Floodway Developments
• Is it an allowable Use? (No structures)
• Is it allowed as CUP? (Structures only if accessory toopen space, i.e., park shelter)
• ANY filling/grading or obstruction needs todemonstrate it does not cause ANY rise (0.00 feet) inthe flood stage.
- Obtain “no rise certificate” or- Conditional Letter of Map Revision (if allowed)
• “No Rise” required• Community determines
if adequate supportingdata and keeps on file
• DNR can assist withreview, but does not“approve”
Floodway Development
Flood Fringe Development
• ALL development requires permit
• Grading, filling, excavation – review erosion/sedimentation;impacts on others
• Accessories, tanks, any manmade objects (unless travelready RV or temporary, i.e., tents)
• Buildings – lowest floor meets Regulatory Flood ProtectionElevation (or equivalent shoreland lowest floorrequirements)
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All Structures Need Permits*
ALL Includes:
• Insurable buildings (2 rigid walls and roof, not over water)
• All other buildings, including agricultural buildings
• Accessory structures – sheds, “boat storage structures,” pavilions
• Decks (no matter how high), gazebos, pergolas
• Tanks
*(1) Call Zoning Permit or Land Alteration Permit or similar if not “Building Permit”
(2) Permit can be no fee, or general permit that lays out standards for smallerstructures
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ALL Structures Elevated or Floodproofed, Including Utilities
22Source: MnDNR (Lehman) Source: MnDNR (Youngsma)
Wet Floodproofing Option
RFPE
Flood resistantmaterial up to
RFPE
In floodplain, allowed if:• only used for parking
and storage of non-hazardous materials
• If < 576 sq ft
Must be anchored
State Minimums for Structures in Flood Fringe Areas
*RFPE = 100-year flood (BFE) + stage increase + 1' freeboard (minimum)
Common Permitting Oversights
• Not keeping elevation documentation (required by federalregulations & your ordinance)
• Not processing as CUP when required
• Not enforcing floodplain regulations when available data showsbelow BFE (but beyond zone A or AE). Maps will eventually getcorrected!
• Regulating floodplain when no DNR permit required (A or AEZone, but not public watercourse, or activity is de-regulated)
Don’t Forget About Culverts!
26Source: MnDNR (Christman)
Replacement of Culverts
• In local city/county floodplain regulations, permit requirement waived(in current state model floodplain ordinance) if that project appliesfor DNR PW permit.
• If no DNR permit, community MUST require permit and hydraulic data- If shown on FEMA map, but not public water
- If deregulated since < 5 square miles
- Where 2015 state law says no DNR permit for replacement of culvert that’ssame size/elevation
1092.3
1092.3
1091.31092.31091.31090.3
• If proposed meets required,issue permit.
• Note inspections required• Require as-builts
Verify Project Meets Standards & Issue Permit
DOCUMENTATION
• Explicitly detailed in 44 CFR 60.3(c)(5)
• Typically done through use and recording of our Sample PermitApplication, Elevation Certificate, and As-Built Forms
• Or, use of FEMA Elevation Certificate
• Helps resident in long run
Community MUST have “as built” documentation (including Recordof Low Floor) for ALL Development
Get Documentation of As-Built Elevations
DNR SampleAs-Built Form
FEMAElevation
Certificate
Resources
• DNR website – search MN Floodplain Management
• Water Talk newsletter – sign up at
Map & Data Resources – (links & info sheets):
• FEMA’s Map Service Center - https://msc.fema.gov
• FEMA’s National Flood Hazard Layer (NFHL) viewer
• MNTOPO - http://arcgis.dnr.state.mn.us/maps/mntopo/
• *MN GeoCommons (get GIS data)- https://gisdata.mn.gov/
• *FEMA Hydraulic Model Download application
31* More technical – for GIS and/or engineers
FEMA’s Map Service Center
• Use to view or download effective or historical maps
• Only place to find historical maps
• https://msc.fema.gov/portal
Search bylocation
Link to FEMA’s National Flood Hazard Layer (NFHL) Viewer
If DFIRM county, will have this icon to link to FEMA’sNational Flood Hazard Data (NFHL) viewer
Zooms to that address at National Flood Hazard Layer (NFHL) viewer
To print
FEMA NFHL Viewer
Useful Tool
Print as: “Map” or “Map with Legend”
Click on purple dot to seeLOMA document (available innon-DFIRM counties)
Print from FEMA NFHL Viewer – “Map”
Print from FEMA NFHL Viewer – “Map with Legend”
DFIRM FIRMettehttp://tinyurl.com/j4xwp5e
MnTOPO Sitehttp://arcgis.dnr.state.mn.us/gis/mntopo/ or search for “MNTOPO”
MnTOPO Site
Zoom to your location
Download LiDAR products
Print a map
Get a point elevationor elevation along a line
Show map layers:• 50-, 10-, 2-foot contours• LiDAR flight lines• FEMA Flood Data
Change Basemap:• Road• Imagery• Color Terrain• B&W Terrain
Help PDF document
“Unmodernized”NOT official; Q3layer (quickdigitization) “Modernized”
Final Digital FloodInsurance RateMap (DFIRM)layerTransparency
slider bar
MnTOPO Site
MN Geo Commons - https://gisdata.mn.gov/
Search “FEMA floodplain” or“DFIRM”
MN GeoCommons Site
FEMA Hydraulic Model Download Application
Model Availability
