floodplain zoning basics - macpza · 27-09-2017  · floodplain zoning basics ceil strauss, state...

Floodplain Zoning Basics

Ceil Strauss, State Floodplain Manager

ceil.strauss@state.mn.us – 651-259-5713

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

5

FEMA Map with Special Flood Hazard Area (SFHA)

6

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)

7

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

11

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