Tillamook County, OR Tillamook County, OR Flood Study Flood Study

Board of Commissioners’ Board of Commissioners’ meetingmeeting

Tillamook County, OR Tillamook County, OR Flood Study Flood Study

Board of Commissioners’ Board of Commissioners’ meetingmeeting

June 23, 2010

AgendaAgendaAgendaAgenda

•National Flood Insurance Program (NFIP)

•Map Modernization Program•Tillamook County Flood Insurance Study (FIS) Review

•Map Adoption Process

Purpose of the NFIPPurpose of the NFIPPurpose of the NFIPPurpose of the NFIP

•Maps the flood risk and assign insurance rates (FIRMs)

•Makes flood insurance available•Sets minimum floodplain construction standards

•Reduces dependency on structural flood control

•Promotes floodplain management practices

Reduce economic loss caused by flood events

NFIP FactsNFIP FactsNFIP FactsNFIP Facts

•5.6 million flood insurance policies

•20,532 participating communities

•$1.2 trillion in flood coverage

Nationally...

How the NFIP WorksHow the NFIP WorksHow the NFIP WorksHow the NFIP Works

Three disciplines of the NFIP:

•Mapping – Flood Studies

•Regulations•Insurance

Flood StudiesFlood StudiesFlood StudiesFlood Studies

• FIS creates maps that show Special Flood Hazard Areas (SFHA); base (100-yr) floodplain

• FIS sets flood insurance rates per the maps• Lenders must require flood insurance in the 100-year

floodplain for Federal-related loans• FIS provides communities with data to enforce their

ordinances• Study Report: Describes flood history, principal flood

problems, flood protection measures, hydrology and hydraulic methods, floodway data tables, water surface profiles

• Flood Insurance Rate Map (FIRM): Shows floodplain limits, base flood elevations (BFEs), floodways, surveyed cross sections, corporate limits, roads, insurance zones

Flood Insurance Rate Maps (FIRM)Flood Insurance Rate Maps (FIRM)Flood Insurance Rate Maps (FIRM)Flood Insurance Rate Maps (FIRM)

Who uses the FIRM?

• Local Jurisdictions- Community Officials- Building and Zoning Departments

- Economic Development- Planners- Emergency Managers

• Lending Institutions• Surveyors & Engineers• Builders/Developers• Insurance Agents• Property Owners• State and Federal Agencies

When Will it Flood?When Will it Flood?When Will it Flood?When Will it Flood?

Flood Frequency % chance over

Years Chance in any Year 30 yr mortgage

10 10 out of 100 96%

50 2 out of 100 46%

100 1 out of 100 26%

500 .2 out of 100 6%

Base FloodBase FloodBase FloodBase Flood

•A flood that has a 1% chance of being equaled or exceeded in any given year.

•Base Flood Elevation (BFE) - the elevation that the base flood is expected to reach.Base Flood = 100-year flood

What is Map Modernization?What is Map Modernization?What is Map Modernization?What is Map Modernization?

Through Map Modernization……FEMA will provide digital flood insurance rate maps and studies… …for communities nationwide……that are more accurate, easier to use, and more readily available.

Why Modernize?Why Modernize?Why Modernize?Why Modernize?

• Outdated maps (10+ years old)• Physical changes in floodplains – man-made

and natural• Digital format enables overlays/analysis• Easier to update maps• Maps are foundation for flood risk reduction

and insurance (5.6 million policies, 1.2 trillion coverage)

2005 2007 2009

Tillamook County Flood Study Details

Contractors: WEST Consultants, Inc., & Michael Baker Jr., Inc.

FEMA Funds: $520,000

Tillamook County Preliminary FIS: Tillamook County Preliminary FIS: December 31, 2009December 31, 2009

Tillamook County Preliminary FIS: Tillamook County Preliminary FIS: December 31, 2009December 31, 2009

Pre-Scoping Report – January 2006Establish Community Contacts, Retrieve Data (models, LOMRs, needs), Level of Study, Available Base Map Data

Scoping Meeting – March 11, 2006Discuss proposed scope of work, identify available data and update needs, 14 Attendees (FEMA, County, Cities of Tillamook and Garibaldi, State, USACE, WEST)

Large Flood Event – November 6, 2006 – Wilson River near Tillamook - 38,600 cfs vs FIS 100-year – 36,300 cfs

Large Flood Event – December 3, 2007– Wilson River near Tillamook – 33,100 cfs

History

Scope of WorkScope of WorkScope of WorkScope of Work

•Re-assess hydrology•If not within tolerance, evaluate effects on the BFE

•Re-delineate floodplain extents along reaches where we obtained newer topography and aerial photos

•Refine floodplain boundaries•Digitally convert effective FIRMS

– All effective panels, except for detailed re-study of Miami, Kilchis, Wilson, Trask and Tillamook Rivers

Hydrologic AssessmentHydrologic AssessmentHydrologic AssessmentHydrologic Assessment

•Wilson/Trask/Tillamook hydrology modified because of large floods in 2007 and 2008

•Kilchis hydrology unchanged (within 2% of effective)

•Miami 100-year hydrology increased from 6,600 cfs to 9,550 cfs based on flood frequency analysis

Hydrologic AssessmentHydrologic AssessmentHydrologic AssessmentHydrologic Assessment

Location

Drainage Area

(square miles)

Frequency

2008 FFA Computed Discharge (cfs)

2002 FIS Discharge

(cfs)Discharge

Confidence Limits

25-percent

75-percent

Gage 14301500

Wilson River near Tillamook,

OR through

2008

161.0

10-Year 28,500 29,700 27,400 25,000

50-Year 37,600 39,700 35,800 33,000

100-Year 41,400 43,900 39,300 36,300

500-Year 50,200 53,800 47,200 43,500

Trask River 100-year Flow went from 27,400 to 33,500 CFS

FloodwayFloodwayFloodwayFloodway

•Area where water velocities and depths are the most destructive

•Defined as the channel of a river or other watercourse and the adjacent land areas that must be reserved in order to discharge the base flood without cumulatively increasing the water surface elevation more than a designated height (1 foot).

FLOODWAY SCHEMATIC

100 YEAR FLOODPLAIN

SURCHARGE

FLOODWAY

FLOODWAY + FLOODWAY FRINGE = 100 YEAR FLOODPLAIN

SURCHARGE NOT TO EXCEED 1.0 FEET

Hydraulic ModelHydraulic ModelHydraulic ModelHydraulic Model

•Based on Corps flood reduction model (2004)

– Cross sections from a variety of sources (County, previous FEMA, and Corps surveys)

– Sections extended the overbanks using 2-ft topo from late 1999

– Calibrated to events in Nov. 1999, May 2001 and Nov. 2001

•Some modifications to:– Expand the sections to contain the 0.2%

flood– Fix split flow in SW part of model

Floodway DevelopmentFloodway DevelopmentFloodway DevelopmentFloodway Development

•Lower Trask River and Tillamook River did not have defined floodways

•Wilson River floodway needed updating to new hydrology and hydraulics

•Initially “adopted” effective floodways

– Worked for upper Wilson and Trask, but not downstream

•Floodplain and floodway mapped to 2-ft contours

DFIRM Conversion Reaches DFIRM Conversion Reaches Detailed Study – Approximately 80 milesDetailed Study – Approximately 80 miles

DFIRM Conversion Reaches DFIRM Conversion Reaches Detailed Study – Approximately 80 milesDetailed Study – Approximately 80 miles

Distance (mi)

Nehalem Bay 4.0

Nestucca Bay 3.7

Nehalem River 15.1

NF Nehalem River 5.2

Nestucca River 16.0

Three Rivers 4.9

Wilson River 4.3

Pacific Ocean 28.4

DFIRM Conversion of 28 FIRM and 7 FBFM Panels

•New maps are county-wide•Follows a USGS Quad layout – countywide coverage with no city “cut-outs”

•Contains 100- & 500-year floodplains (AE/X zones)

•10, 50, 100, 500 year flood elevations published

•Re-delineation of flooding sources where better topography was available

•Vertical Datum change (NGVD 1929 to NAVD 1988)

What’s newWhat’s newWhat’s newWhat’s newFlood Insurance Study

What’s newWhat’s newWhat’s newWhat’s newVertical Datum Change

•NGVD 29 – Based on a mean sea level from 21 tidal

stations in the US & 5 stations in Canada

•NAVD 88– Based on the density of the Earth instead of

varying values of sea heights – More accurate

•Conversion for Tillamook County Varies– NGVD + (vertical adjustment’) = NAVD– Conversion factor for County for FIS is 3.54

feet

Digital Flood Insurance Rate MapsDigital Flood Insurance Rate MapsDigital Flood Insurance Rate MapsDigital Flood Insurance Rate MapsVertical Datum and FIRMs (e.g. uses 3.54’ conversion)

NGVD 29

NAVD 88

BFE = 5.54 ft

BFE = 2 ft

15

0

5

10

0

15

10

5

Digital Flood Insurance Rate MapsDigital Flood Insurance Rate MapsDigital Flood Insurance Rate MapsDigital Flood Insurance Rate MapsDigital Format

Aerial Imagery

Elevation

Geodetic Control

Boundaries

Surface Waters

Transportation

Land Ownership

Special Flood Hazard Areas

Apply local parcel and topo layers…Digital Flood Insurance Rate MapsDigital Flood Insurance Rate MapsDigital Flood Insurance Rate MapsDigital Flood Insurance Rate Maps

Digital Flood Insurance Rate MapsDigital Flood Insurance Rate MapsDigital Flood Insurance Rate MapsDigital Flood Insurance Rate MapsZone Designation Changes

Old FIRMs New FIRMs Definition

A A Approximate Floodplain (SFHA)

A1- A30 AE Detail River Floodplain (SFHA)

A99 A99 Protected by Levee

AH AH Shallow Floodplain with BFE

AO AO Shallow FP without BFE

B X (shaded) 500 Year Floodplain

C X (un-shaded) Outside 500 Year Floodplain

D D Undetermined Floodplain

V V Approx Coastal Floodplain

V1-30 VE Detailed Coastal Floodplain

•AE Zone

•X Zone (shaded)

•Floodway

Digital Flood Insurance Rate MapsDigital Flood Insurance Rate MapsDigital Flood Insurance Rate MapsDigital Flood Insurance Rate MapsFIRM Labels

Digital Flood Insurance Rate MapsDigital Flood Insurance Rate MapsDigital Flood Insurance Rate MapsDigital Flood Insurance Rate MapsSome new labels on dFIRMs look like this…

X (Un-shaded )

X (Shaded) (500-year)

Floodway

A & AE ZonesSFHA (100-year)

Tillamook County Adoption Process

Post PreLiminary ProcessingPost PreLiminary ProcessingTimeline of eventsPost PreLiminary ProcessingPost PreLiminary ProcessingTimeline of events

• Preliminary maps issued ……….........

• Hold Coordination Meeting ……........

• Public Meeting…………………….................................

• 90 day appeal period begins ……...

after 2nd public notice in local newspaper

• 90-day appeal period ends…….........

FEMA reviews submitted technical appeals and modifies or maintains maps as appropriate

• FEMA issues “Letter of Final Determination (LFD)” ………………………...

to communities and publishes the BFEs in the Federal Register

Communities have 6 months to adopt the study before the data becomes “effective”. Failure to adopt results in suspension from NFIP

• Effective date ……………………………............

December 31, 2009

March 31, 2010

May 12, 2010e.g. June 15, 2010

e.g. September 15, 2010

Est. December, 2010

Est. June, 2011

AppealsAppealsAppealsAppeals

44 CFR 67.6A –

The sole basis of appeal under this part shall be the possession of knowledge or information indicating that the elevations proposed by

FEMA are scientifically or technically incorrect. Because scientific and technical correctness is often a matter of degree rather than absolute (except where mathematical or measurement error or changed physical conditions can be demonstrated), appellants are required to demonstrate that

alternative methods or applications result in more correct estimates of base flood elevations, thus demonstrating that FEMA's estimates are incorrect.

AppealsAppealsAppealsAppeals

Signed Letter with Backup Technical InformationMail to:

STARR - Region X Support Center901 Fifth Avenue, Suite 3100

Seattle, WA 98164

Informal Comments not needing a response:Email: RSC10@STARR-team.com

Questions:Phone: 206-682-1159 ext. 2225

CommentsCommentsCommentsComments

•#1– Floodway crosses across school despite the entire area uniformly being raised 10 feet above river bank. Can the floodway be adjusted to not include school since it looks like it would either convey over the entire area or not at all?

Backup Documentation – Zoomed in map of area, address topography

•#2 – Area has flooded numerous times in the past. Why is it mapped as dry?

Backup Documentation – Zoomed in map of area, address, photos, topography

Comments Not Able to AddressComments Not Able to AddressComments Not Able to AddressComments Not Able to Address

#1 - My house has never flooded in xx number of years, why am I being shown wet?

Problem – The 100-year flood is generally larger than recent floods. We need technical information that shows the calculations are incorrect (flow, stage, topography)

#2 - There is newer topography since you started the study. Please redo study to newer topography.

Problem – Too expensive and time-consuming and would never be able to complete a study. Not a valid appeal by definition.

Letters of Map Change (LOMC)Letters of Map Change (LOMC)(ways to appeal at any time)(ways to appeal at any time)Letters of Map Change (LOMC)Letters of Map Change (LOMC)(ways to appeal at any time)(ways to appeal at any time)

•LOMA - for property owners who believe a property was incorrectly included in a SFHA. An elevation certificate supports a LOMA, but by itself, does not remove the insurance requirement.

•LOMR – removes land that has been graded or filled (physical changes) since the date of the map. A LOMR can waive flood insurance requirements.

•(LOMA) Hotline - 1-877-FEMA-MAP

Future Steps afterFuture Steps afterAppeal period endsAppeal period endsFuture Steps afterFuture Steps afterAppeal period endsAppeal period ends

• FEMA addresses submitted comments

• Local jurisdictions adopt an ordinance that is compliant with your map and FEMA standards

• Local jurisdictions develop and implement outreach strategies, if desired.

• Upon receipt of LFD, local jurisdictions begin enforcing the maps

Letter of Final Determination (LFD)Letter of Final Determination (LFD) Letter of Final Determination (LFD)Letter of Final Determination (LFD)

•Starts with the Letter of Final Determination (LFD) stating that the Appeals have been resolved, if applicable

•Officially notifies community of final base flood elevations

•Indicates effective date of FIRMs as 6 months from the date of the letter

•Ordinance meeting FEMA regulations MUST become effective by end of 6 months or community will be suspended