1/23/2017. Floodplain Update For Surveyors. Floodplain Updates For Surveyors. Sample FEMA Map with SFHA

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1 Floodplain Updates For Surveyors Ceil Strauss MN State Floodplain Manager February 9, 2017 Floodplain Update For Surveyors Finding FEMA Maps & Data Map / Data Updates & Status Other useful resources Letters of Map Change (review) - LOMAs - LOMR-Fs Sample FEMA Map with SFHA National Standard of 100-year flood chosen High Flood Risk Zone A & AE (old) Zone A & AE (new) Medium Flood Risk Zone B (old maps) Zone X (shaded) Low Flood Risk Zone C (old maps) Zone X (unshaded) 1

2 SYNONYMOUS TERMS One-Percent (1%) Chance Flood 100-Year Flood Base Flood Elevation, or BFE (FEMA) Regional Flood (MN DNR) Special Flood Hazard Area, or SFHA (FEMA) High Flood Risk Area 4 Status of FEMA Flood Insurance Rate Maps (FIRMs) in MN DFIRM Digital Flood Insurance Rate Map Preliminary DFIRMs Other paper FIRMs 5 County-Specific Status Updates ers/watermgmt_section/floodp lain/map_update_process_cou nty_timing.pdf Or go to mndnr.gov & search FEMA map update status 2

3 Preliminary & Effective DFIRMs DNR Eco/Waters posts electronic copies at: ftp://ftp.dnr.state.mn.us/pub/waters/floodplain/county_data/ Can view: FIRM panels as pdfs (FIRM) FIS as pdf (FIS) GIS files (DFIRM_DB) Documenting As Built Elevations FEMA Elevation Certificate (EC) DNR Sample As-Built form Link to both at MnDNR site Current FEMA EC has signature block on same page as elevations! Latest FEMA Elevation Certificate July 2015 Expires 11/30/ Types of Floodplain Delineation Zone AE or Zone A1-A30, AO, AH: Detailed engineering analysis supports BFEs shown on maps, profiles, floodway data tables Zone A: Approximate delineations without BFEs on the map and no profiles or data tables in the report 3

4 FEMA Mapped Floodplains Red=AE Blue=A APPROXIMATE DELINEATIONS Zone A Areas Little or no field work conducted Older FIRMs use existing data such as FHBM, USGS Flood Prone Quadrangle Maps Newer Digital FIRMs have supporting documentation for estimated Base Flood Elevations Where no existing data is available, appropriate methods for approximating floodplain boundaries must be selected and applied New FEMA Approximates In Map Modernization - zone A delineations will have an estimated BFE supporting the delineation Most have simple HEC-RAS models for support Data not on maps, but provided to zoning officials 4

5 MN GeoCommons Site Search FEMA floodplain or DFIRM MN Geo Commons - MnGEO Scroll halfway down and download the ESRI File Geodatabase MnGEO Import the layer files into your ArcMap document 5

6 MnGEO Database contains effective data: BFEs, DFIRM Cross- Sections, Flood Hazard Zones, DFIRM Panels Clay County DFIRM data available MnGEO Database also includes the pink lines, which are the elevations associated with Zone A areas or the best available data in areas that are not yet effective Polk County, No floodplain delineated (not effective yet) Mahnomen County Zone A delineated (effective) MnGEO Unmodernized floodplain information is also included for non-dfirm counties (if available) Aitkin County No pink lines or DFIRM data yet 6

7 FEMA Hydraulic Model Download Application DNR website where you can download models used for FEMA maps A work in progress, not all models have been uploaded model_download/index.html FEMA Hydraulic Model Download Application Model Availability FEMA Hydraulic Model Download Application 7

8 South Dakota North Dakota NAVD88 - Conversion = NGVD Kittso n.80 Polk Clay.80 Marsh all No rm an W ilkin Trav erse Big S ton e Linco ln Ro ck 1.40 Gra nt Stev ens Lac Qui P arle Pipest on e Pen ning ton Re d L ake.70 Ro sea u Mah no me n Becke r Otter Tail Swif t Yellow Medicine Lyon Murray No bles Clea rwa ter Do ugla s Pop e Ch ip pe wa Re dw oo d Lake of the Woods.40 Beltram i Hu bba rd To dd Kan diyoh i Co tto nw ood Jackso n W ade na Re nville.30 Stea rns Brow n Mee ker W ato nw an Martin Ca ss Crow Wing Morrison McL eod Sibley Nico lle t.20 Ben ton Koo chichin g W righ t Blue Earth Fa rib au lt Itasc a.10 Aitkin Kan abe c Mille Lacs She rb urne Ca rve r Scot t Le Sueur Isan ti Ano ka Rice Free bo rn Version 5.11 or newer Da kota Ca rlto n Pine.20 He nne pin W ashin gto n Ra mse y W aseca Stee le Ch is ago Goo dhu e Do dge Mow e r St. Lou is.30 W aba sha Olmste d Fillmo re W in on a.00 Lake Ho usto n.40 Co ok.50 1/23/2017 Check the Datum! New Maps are in NAVD, 1988 Datum Old Data in: NGVD, Local Assumed There can be several feet of difference! NGVD, To convert vertical or horizontal 1929 datums you may versus NAVD 1988 obtain USACE's Corpscon Conversion Program conversion = Get this map by searching NAVD88 to NGVD29 at MnDNR site, or t_section/floodplain/datum_conversion.pdf 8

9 Who Determines BFE? Resident contacts community Community provides BFE to resident YES Community has BFE? NO Community checks online resources YES BFE available? BFE estimate made & given to community NO Community contacts DNR or watershed How To Find Base Flood Elevation (BFE) Current detailed study area: Use your Flood Insurance Rate Map (FIRM) & Flood Insurance 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: Limited detail available? Previous estimate determination? Check with watershed district & DNR; Previous LOMA? Have resident apply for LOMA & request BFE to be determined 9

10 County Modernizations A Zone models 1% digitized Will be able to use for zoning & flood insurance appeal (Letter of Map Amendment - LOMA) decisions Official updated maps would be a future step Sample of Effort Types in Each County 10

11 Find Current Effective Map New Look as of December 2015 Enter address or city or county here MSC After Address (or city) Entered To see panel Toggle to aerial Viewing Panels at FEMA s Map Service Center (MSC) 11

12 Make FIRMette Other Data at MSC To see all products, including when new maps are coming Get Effective, Preliminary, Pending and Historic files 12

13 Link to FEMA s National Flood Hazard Layer (NFHL) Viewer If DFIRM, will have this icon to link to FEMA s National Flood Hazard Data (NFHL) viewer FEMA s National Flood Hazard Layer (NFHL) Viewer If at city level, may need to zoom in to see other layers NFHL Viewer Background Options 13

14 FEMA NFHL Viewer Even in non- DFIRM Counties, LOMAs can be viewed! Click on purple dot to see LOMA document FEMA NFHL Viewer To print Useful Tool 14

15 Print from FEMA NFHL Viewer DFIRM FIRMette brand new! MnTOPO or search MNTOPO and proceed to viewer Use to view or download state LiDAR data Use to view FEMA floodplain data (not as up-to-date as MnGEO) Must be zoomed in or out to see certain layers 15

16 Search MNTOPO MnTOPO Site MNTOPO Options Help PDF document Zoom to your location Print a map Download LiDAR products Get a point elevation or elevation along a line Change Basemap: Road Imagery Color Terrain B&W Terrain Show map layers: 50-, 10-, 2-foot contours LiDAR flight lines FEMA Flood Data 16

17 MnTOPO Download LiDAR products Unmodernized Example Unmodernized NOT official; Q3 layer (quick digitization) Modernized Final Digital Flood Insurance Rate Map (DFIRM) layer Transparency slider bar Modernized Example 17

18 Lines and Point Elevations in MnTOPO MnTOPO Sample of Line Letters of Map Change (LOMCs) Letters of Map Amendment (LOMAs) Letters of Map Revisions based on Fill (LOMR-Fs) Letters of Map Revisions (LOMRs) 18

19 Floodplain Boundary Disputes Floodplain ordinance: community decides Lending/Flood Insurance: FEMA decides (LOMC): Letter Of Map Amendment (LOMA) Letter of Map Revision based on fill (LOMR-F) Letter of Map Revision (LOMR) What s the Option if House is Really High? Zone AE Location on FIRM for existing house Lender must require flood insurance if they are in the Special Flood Hazard Area (Zone A) on the map, no matter how high they really are. Can only be changed by FEMA with Letter of Map Amendment (LOMA) LOMA - Letter of Map Amendment A letter from FEMA stating that an existing structure or parcel of land that has not been elevated by fill would not be inundated by the 100-year flood The FEMA map is wrong better topographic contour lines or a field survey shows site is above BFE 19

20 LOMA Lowest Adjacent Grade (LAG) Natural Grade BFE LOMA Lowest Adjacent Grade (LAG) BFE Natural Grade LOMA - Cross Sectional View BFE Lowest Adjacent Grade (LAG) Lowest Floor LAG below BFE NOT REMOVED 20

21 Why Attached Decks Matter to FEMA Lower Garvin Brook at Minnesota City BFE ~1128 Letter of Map Amendment (LOMA) Owner contends FEMA map in error Need: (1) Lowest adjacent grade (LAG) (2) Base Flood Elevation (BFE), aka 100-year Survey of LAG required (exceptions noted later) No fee for FEMA s review (will be cost for survey and maybe for preparing submittal) FEMA responds within 60 days Forms: FEMA form MT-1 (multi-lot or single lot) FEMA form MT-EZ (single lot only) 21

22 Letter of Map Change (LOMC) Application Options Paper Application - with MT-EZ (for single lot LOMA) or MT-1 (for LOMR-Fs and multi-lot LOMAs or LOMR-Fs) Online Application Submit same items as in paper, but in digital format. Search FEMA online LOMC eloma Only available to licensed surveyors and PEs. Search FEMA eloma application. First one is audited, and then randomly. elomas are processed in less than a day! Only for LOMAs & where there are detailed studies or certain A zone BFEs (based on the pink lines basic engineering, or have determination memo/letter from DNR, Corps, Watershed, or community). 64 Letter of Map Amendment Out as Shown (LOMA-OAS) Provide better information on where STRUCTURE IS on the lot Don t need survey data Need community logo / name ~ 15% of LOMA requests LOMA & LOMA-OAS Guidelines At MN DNR site, search for LOMA or LOMA-OAS 22

23 Use of LiDAR for LOMAs This abbreviated LOMA application process is intended for locations where it is clear that the entire building (or the entire lot) is above the base flood elevation (BFE) based on review of the LiDAR derived contour elevations compared to the base flood elevation. Only in Minnesota (and a few communities nationally) Search LOMA with LiDAR at MnDNR Site Include everything on checklist Map prepared by city, county, surveyor or PE Include LiDAR certification letter (available on DNR site) for that county 68 When Can LOMA LiDAR Be Done? Calculating the Lowest Adjacent Grade (LAG): 1. Determine the closest contour lower than the building footprint. NOTE: You must choose a contour that does NOT go through the building. Use the contour that is just below or just barely touching the structure (but not going through). 2. Subtract either ½ the contour interval or 1 foot (whichever is greater). NOTE: Minnesota certified LiDAR contours 69 are 2 foot intervals, so subtract 1 foot. 23

24 LiDAR Data Collected by Blocks SE Minnesota SW Minnesota Arrowhead Region Metro Area Individual Counties North Central MN Red River Valley Can be done by city, county, surveyor or PE In Anoka County Anoka County GIS staff prepared map app that can be used by local officials and other professionals (surveyors, engineers) Nice features that others may want to use in their templates (i.e., disclaimer notes FEMA BFE and local regulation elevations different, still floods above BFE, etc.) 24

25 Hennepin Co Natural Resources us/naturalresources/ map/ Hennepin Co Natural Resources Hennepin Co Natural Resources 25

26 LOMR-F Letter of Map Revision (Based on Fill) A letter from FEMA stating that an existing structure or parcel of land that has been elevated by fill would not be inundated by the 100-year flood LOMR-F Fill BFE LOMR-F Diagram Part 65 of the NFIP Regulations requires that the following be equal to or higher than the BFE: the lowest ground touching the structure; and For existing structures, the lowest floor (including basement or crawl space) (this also means that the community certifies the structure is complaint with Section 60.3 of the NFIP regulations) 26

27 Community Acknowledgement Form (CAF) Community signature you are saying: - Not in floodway - Complies with Endangered Species Act - Have all necessary Federal, State & Local permits (if CLOMR, will obtain) - Existing and proposed structures will be reasonably safe from flooding (NOTE: The supporting documentation must be available to submit to FEMA upon request!) In MN, LOMR-F Does Not Remove from Regulated Floodplain Additional requirements to get removed: Meets MN Rules , subp. 2: - filled above the Regulatory Flood Protection Elevation (RFPE), and - contiguous to other lands lying outside the floodplain OR flood control measures meeting are constructed and operating Community amends ordinance and adopts the LOMR-F or LOMR LOMA? LOMR-F? BFE 27

28 Ceil Strauss