18 October 2012

WATERSHED Science & EngineeringWEST Consultants

Chehalis River Basin Chehalis River Basin Hydraulic Modeling and Hydraulic Modeling and Flood Relief Alternatives Flood Relief Alternatives

EvaluationEvaluation

OverviewAccomplishments under WSE Flood Authority

contract    model development    evaluation of flood relief projects coordination and communication

Summary of model development efforts    for Flood Authority (WSE and WEST)    for USACE (WEST)

Evaluation of potential flood relief projects    15 separate projects modeled    10 alternatives (combinations of projects)

Reporting (WSE report and OFM report) & Meetings

Questions

Project Milestones WSE-WEST Team Selected – September 2011

Work Plan Finalized – October 2011

Initial Data Collection and Basin Reconnaissance – October 2011

New Channel Surveys – November /December 2011

Preliminary Hydraulic Model Distributed – March 2012

Review by State Tech Team and USACE – March and April 2012

Final Existing Conditions Model Distributed - May 3, 2012

Preliminary With-Project Runs – May 9, 2012

Modeling of Alternatives–May 31, 2012

Draft Reporting and Presentation of Results – June 2012

Refined Alternatives and Analysis – June/July 2012

Final Analysis and Reporting – July 2012

Model Development

Evaluation of Flood Relief Projects    Upstream retention on mainstem Chehalis    USACE Twin Cities Project Skookumchuck Levees Airport Levee    WSDOT I-5 flood protection project    Mellen Street Bypass Scheuber Road Bypass    Channel Dredging (Mellen Street to Lincoln Creek Confluence)    Complete Bridge Replacement Option    Specific Bridge Replacements

Highway 6 Mellen Street Galvin Road

Sickman Ford S. Elma (Wakefield) Road Porter Creek Road

Results Reported for All Projects for Four Flood Events

Results Reported for All Projects for Four Flood Events

Preliminary Alternatives1. Mainstem dam and airport levee improvements

2. WSDOT floodwalls/berms and airport levee improvements

3. Scheuber bypass, Mellen Street bypass, and airport levee improvements

4. Dam, airport levee improvements, WSDOT floodwalls/berms

5. Dam, airport levee improvements, WSDOT floodwalls/berms, downstream bridge removals

6. Scheuber bypass, Mellen Street bypass, airport levee improvements, WSDOT floodwalls/berms, downstream bridge removals

7. Scheuber bypass, Mellen Street bypass, airport levee improvements, small floodwall along I-5 near Dillenbaugh Creek

OFM AlternativesA. Mainstem Dam on the Chehalis River, Airport

levee improvements, small floodwall along I-5 near Dillenbaugh Creek, Skookumchuck Levees, Sickman Ford Bridge modification, and Wakefield Road (South Elma) Bridge Modification.

B. Same as Alternative “A” with the addition of WSDOT’s proposed I-5 berms and floodwall protection project.

C. WSDOT’s I-5 berms and floodwalls, Airport levee improvements, Mellen Street and Scheuber Road Bypasses, Skookumchuck Levees, Sickman Ford Bridge modification, and Wakefield Road (South Elma) Bridge Modification.

Evaluation of

Alternatives

Baseline Alt A Change Alt B Change Alt C Change Baseline Alt A Change Alt B Change Alt C ChangeDescription X-section (ft NAVD) (ft NAVD) (ft) (ft NAVD) (ft) (ft NAVD) (ft) (ft NAVD) (ft NAVD) (ft) (ft NAVD) (ft) (ft NAVD) (ft)Near Doty 100.95 318.1 307.2 -10.9 307.2 -10.9 318.1 0.0 328.1 315.8 -12.3 315.8 -12.3 328.1 0.0Curtis Store (on S Fork Chehalis) 1.81 233.1 231.1 -2.1 231.1 -2.1 233.2 0.0 238.9 232.8 -6.1 232.8 -6.1 238.9 0.0Downstream of South Fork 86.42 222.4 219.0 -3.5 219.0 -3.5 222.4 0.0 227.7 222.1 -5.6 222.1 -5.6 227.7 0.0Near Adna 80.23 196.6 195.0 -1.6 195.0 -1.6 196.4 -0.2 197.9 196.3 -1.6 196.3 -1.6 197.9 0.0Labree Road (on Newaukum R) 4.11 204.6 204.6 0.0 204.6 0.0 204.6 0.0 204.7 204.7 0.0 204.7 0.0 204.7 0.0Newaukum Confluence 75.2 185.1 183.9 -1.3 183.9 -1.2 183.4 -1.8 186.6 184.5 -2.2 184.5 -2.1 185.6 -1.0Along Airport Levee 71.49 180.3 179.3 -1.1 179.3 -1.0 179.5 -0.8 182.1 179.7 -2.4 179.7 -2.4 181.3 -0.8Dillenbaugh Storage Area SA #301 185.1 183.8 -1.3 183.8 -1.3 183.5 -1.7 186.6 184.4 -2.2 184.4 -2.2 185.8 -0.8Airport Storage Area SA #2 180.3 159.4 -20.9 159.4 -20.9 159.4 -20.9 182.2 159.4 -22.8 159.4 -22.8 159.4 -22.8Long Road Storage Area SA #5 177.5 169.4 -8.1 169.4 -8.1 169.4 -8.1 179.1 169.4 -9.7 169.4 -9.7 169.4 -9.7Centralia Storage Area SA #610 176.1 175.9 -0.2 176.1 -0.1 174.7 -1.5 178.5 175.8 -2.7 175.9 -2.6 175.8 -2.7Mellen St 67.43 177.3 176.2 -1.1 176.2 -1.1 174.7 -2.6 178.6 176.1 -2.5 176.1 -2.5 175.8 -2.8Bucoda (Skookumchuck R) 11.1 251.4 251.4 0.0 251.4 0.0 251.4 0.0 244.3 244.3 0.0 244.3 0.0 244.3 0.0Pearl Street (Skookumchuck R) 2.43 191.3 191.4 0.2 191.4 0.2 191.4 0.2 186.6 186.6 0.0 186.6 0.0 186.6 0.0Skookumchuck Confluence 66.88 175.5 174.5 -1.0 174.5 -1.0 174.3 -1.2 176.4 173.8 -2.7 173.8 -2.6 175.0 -1.4Upstream of Galvin Road 64.9 167.1 165.5 -1.6 165.5 -1.6 167.5 0.4 168.2 164.8 -3.4 164.9 -3.4 168.4 0.2Grand Mound (Prather Road) 59.909 146.9 146.3 -0.6 146.3 -0.6 147.2 0.3 147.4 145.8 -1.6 145.8 -1.5 147.5 0.1Near Rochester 54.476 123.7 122.9 -0.8 122.9 -0.8 124.0 0.4 124.2 122.1 -2.1 122.2 -2.1 124.4 0.2Anderson Road 51.499 105.9 105.7 -0.2 105.7 -0.2 106.0 0.1 106.0 105.4 -0.7 105.4 -0.6 106.1 0.1Black River Confluence 46.937 92.6 91.7 -0.9 91.7 -0.9 92.6 0.1 92.9 90.9 -2.0 90.9 -2.0 92.8 -0.1Sickman Ford Bridge 44.175 85.0 83.0 -2.1 83.0 -2.0 84.1 -0.9 85.5 82.1 -3.4 82.1 -3.4 84.4 -1.1Porter Creek Road 34.497 56.7 55.9 -0.8 55.9 -0.8 57.1 0.4 57.0 54.8 -2.1 54.9 -2.1 57.2 0.3Wakefield Road 24.52 40.1 38.4 -1.7 38.5 -1.6 39.6 -0.5 40.2 37.2 -3.0 37.2 -3.0 39.6 -0.6Satsop Confluence 19.89 34.7 34.5 -0.2 34.5 -0.2 35.0 0.3 34.5 33.2 -1.3 33.2 -1.3 34.7 0.3Montesano 12.5 17.6 17.4 -0.2 17.4 -0.2 18.0 0.4 17.3 15.7 -1.6 15.7 -1.6 17.7 0.4Cosmopolis 1.99 9.3 9.2 -0.1 9.2 -0.1 9.5 0.2 10.9 10.9 0.0 10.9 0.0 10.9 0.0Note: Negative change means that the alternative has lower simulated water levels, positive change indicates the alternative raises water levels.

Jan 09 Alt A Change Alt B Change Alt C Change 100-year Alt A Change Alt B Change Alt C ChangeDescription X-section (ft NAVD) (ft NAVD) (ft) (ft NAVD) (ft) (ft NAVD) (ft) (ft NAVD) (ft NAVD) (ft) (ft NAVD) (ft) (ft NAVD) (ft)Near Doty 100.95 314.4 306.7 -7.7 306.7 -7.7 314.4 0.0 323.2 313.0 -10.3 313.0 -10.3 323.2 0.0Curtis Store (on S Fork Chehalis) 1.81 228.1 227.7 -0.5 227.7 -0.5 228.1 0.0 233.6 230.2 -3.3 230.2 -3.3 233.6 0.0Downstream of South Fork 86.42 216.9 213.3 -3.7 213.3 -3.7 216.9 0.0 223.2 219.1 -4.1 219.1 -4.1 223.2 0.0Near Adna 80.23 193.9 191.7 -2.2 191.7 -2.2 193.6 -0.3 197.1 195.5 -1.6 195.5 -1.6 197.1 -0.1Labree Road (on Newaukum R) 4.11 204.7 204.7 0.0 204.7 0.0 204.7 0.0 204.9 204.9 0.0 204.9 0.0 204.9 0.0Newaukum Confluence 75.2 183.5 182.1 -1.4 182.1 -1.4 181.6 -1.9 185.7 184.1 -1.6 184.1 -1.6 184.0 -1.7Along Airport Levee 71.49 178.8 177.4 -1.3 177.4 -1.3 178.0 -0.8 180.8 179.4 -1.4 179.4 -1.4 179.9 -0.8Dillenbaugh Storage Area SA #301 184.1 183.7 -0.4 183.7 -0.3 183.7 -0.3 185.8 184.3 -1.5 184.3 -1.5 184.4 -1.4Airport Storage Area SA #2 172.0 159.4 -12.6 159.4 -12.6 159.4 -12.6 180.8 159.4 -21.4 159.4 -21.4 159.4 -21.4Long Road Storage Area SA #5 169.4 169.4 0.0 169.4 0.0 169.4 0.0 177.9 169.4 -8.5 169.4 -8.5 169.4 -8.5Centralia Storage Area SA #610 174.5 174.3 -0.2 174.3 -0.2 172.8 -1.7 176.7 175.9 -0.8 176.1 -0.6 175.0 -1.7Mellen St 67.43 175.6 174.5 -1.1 174.5 -1.1 172.8 -2.8 177.6 176.1 -1.5 176.1 -1.5 174.9 -2.7Bucoda (Skookumchuck R) 11.1 250.9 250.9 0.0 250.9 0.0 250.9 0.0 252.0 251.9 0.0 251.9 -0.1 251.9 0.0Pearl Street (Skookumchuck R) 2.43 190.5 190.6 0.1 190.6 0.1 190.6 0.1 191.7 192.4 0.7 192.4 0.7 192.4 0.7Skookumchuck Confluence 66.88 173.9 173.0 -0.9 173.0 -0.9 172.5 -1.5 175.7 174.3 -1.4 174.3 -1.4 174.4 -1.3Upstream of Galvin Road 64.9 165.1 164.1 -1.0 164.1 -1.0 165.5 0.4 167.3 165.3 -2.0 165.3 -2.0 167.6 0.3Grand Mound (Prather Road) 59.909 146.0 145.5 -0.5 145.5 -0.5 146.2 0.2 147.1 146.2 -0.8 146.2 -0.8 147.3 0.2Near Rochester 54.476 122.5 121.8 -0.7 121.8 -0.7 122.8 0.3 124.0 122.9 -1.1 122.9 -1.1 124.3 0.3Anderson Road 51.499 105.5 105.3 -0.3 105.3 -0.3 105.6 0.1 106.1 105.8 -0.3 105.8 -0.3 106.2 0.1Black River Confluence 46.937 91.6 90.8 -0.8 90.8 -0.8 91.8 0.1 93.0 91.9 -1.2 91.9 -1.2 93.1 0.0Sickman Ford Bridge 44.175 83.8 81.9 -1.9 81.9 -1.9 83.1 -0.8 85.6 83.2 -2.4 83.2 -2.4 84.7 -1.0Porter Creek Road 34.497 55.6 54.8 -0.8 54.8 -0.8 56.0 0.4 57.4 56.3 -1.1 56.3 -1.1 57.8 0.5Wakefield Road 24.52 38.8 37.2 -1.5 37.2 -1.5 38.5 -0.3 41.6 39.3 -2.3 39.3 -2.3 40.8 -0.7Satsop Confluence 19.89 33.7 33.4 -0.2 33.4 -0.2 34.1 0.4 35.4 34.9 -0.5 34.9 -0.5 35.7 0.2Montesano 12.5 17.7 17.7 -0.1 17.7 -0.1 17.8 0.1 18.8 18.2 -0.7 18.2 -0.7 19.2 0.3Cosmopolis 1.99 11.7 11.7 0.0 10.6 -0.4 11.7 0.0 11.0 10.6 -0.4 10.6 -0.4 11.2 0.2Note: Negative change means that the alternative has lower simulated water levels, positive change indicates the alternative raises water levels.

Location

Max Water Surface Elevation (feet NAVD) or Change in Flood Water Surface (feet)

Max Water Surface Elevation (feet NAVD) or Change in Flood Water Surface (feet)

LocationFebruary 1996 Flood Event December 2007 Flood Event

January 2009 Flood Event 100-Year Design Flood Event

Evaluation of

Alternatives

-6.0

-5.0

-4.0

-3.0

-2.0

-1.0

0.0

1.0

Near

Dot

y

Curti

s Sto

re (o

n S

Fork

Che

halis

)

Dow

nstr

eam

of S

outh

For

k

Near

Adn

a

Labr

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oad

(on

New

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)

New

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Alon

g Ai

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t Lev

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Dille

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gh S

tora

ge A

rea

Airp

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tora

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rea

Long

Roa

d St

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ea

Cent

ralia

Sto

rage

Are

a

Mel

len

St

Buco

da (S

kook

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R)

Pear

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Skoo

kum

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Skoo

kum

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Upst

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of G

alvi

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ound

(Pra

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Near

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Ande

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Sick

man

For

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idge

Port

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reek

Roa

d

Wak

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Mon

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Cosm

opol

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Chan

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Wat

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urfa

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leva

tion

(fe

et)

Change in Water Surface Elevations under Alternative A

February 1996 Flood

December 2007 Flood

January 2009 Flood

100-Year Flood

-6.0

-5.0

-4.0

-3.0

-2.0

-1.0

0.0

1.0

Near

Dot

y

Curti

s Sto

re (o

n S

Fork

Che

halis

)

Dow

nstr

eam

of S

outh

For

k

Near

Adn

a

Labr

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oad

(on

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auku

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)

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ence

Alon

g Airp

ort L

evee

Dille

nbau

gh S

tora

ge A

rea

Airp

ort S

tora

ge A

rea

Long

Roa

d St

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e Ar

ea

Cent

ralia

Sto

rage

Are

a

Mel

len

St

Buco

da (S

kook

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uck

R)

Pear

l Str

eet (

Skoo

kum

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Skoo

kum

chuc

k Con

fluen

ce

Upst

ream

of G

alvi

n Ro

ad

Gran

d M

ound

(Pra

ther

Roa

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Near

Roc

hest

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Ande

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Roa

d

Blac

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Sick

man

For

d Br

idge

Port

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reek

Roa

d

Wak

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Mon

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Cosm

opol

is

Chan

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Wat

er S

urfa

ce E

leva

tion

(feet

)

Change in Water Surface Elevations under Alternative B

February 1996 Flood

December 2007 Flood

January 2009 Flood

100-Year Flood

-6.0

-5.0

-4.0

-3.0

-2.0

-1.0

0.0

1.0

Near

Dot

y

Curti

s Sto

re (o

n S

Fork

Che

halis

)

Dow

nstr

eam

of S

outh

For

k

Near

Adn

a

Labr

ee R

oad

(on

New

auku

m R

)

New

auku

m C

onflu

ence

Alon

g Ai

rpor

t Lev

ee

Dille

nbau

gh S

tora

ge A

rea

Airp

ort S

tora

ge A

rea

Long

Roa

d St

orag

e Ar

ea

Cent

ralia

Sto

rage

Are

a

Mel

len

St

Buco

da (S

kook

umch

uck

R)

Pear

l Str

eet (

Skoo

kum

chuc

k R)

Skoo

kum

chuc

k Co

nflue

nce

Upst

ream

of G

alvi

n Ro

ad

Gran

d M

ound

(Pra

ther

Roa

d)

Near

Roc

hest

er

Ande

rson

Roa

d

Blac

k Riv

er C

onflu

ence

Sick

man

For

d Br

idge

Port

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reek

Roa

d

Wak

efiel

d Ro

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ence

Mon

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no

Cosm

opol

is

Chan

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Wat

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urfa

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leva

tion

(fe

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Change in Water Surface Elevations under Alternative C

February 1996 Flood

December 2007 Flood

January 2009 Flood

100-Year Flood

Evaluation of

AlternativesTwin Cities Area

– Change in Water Surface

Elevation

Evaluation of

AlternativesTwin Cities Area

– Change in Water Surface

Elevation

Evaluation of

AlternativesTwin Cities Area

– Change in Water Surface

Elevation

ReportingStand Alone

Report – included as Appendix in Ruckelshaus

Center Report

Model also documented in USACE Report

by WEST

Presentation of Results• Flood Authority Meetings (April and May

2012)

• Meeting with WSDOT (May 2012)

• Chehalis Basin Technical Workshop (May 2012)

• Chehalis Basin Policy Workshop (June 2012)

• Lower Chehalis Basin Meeting (June 2012)

• Various Discussions (July – September 2012)

Questions• What can we do to get back to pre-1990 flood conditions in the lower basin?

• Which projects reduce flooding throughout the basin?

• Why doesn’t the WSDOT I-5 Project show downstream water level increases (like the USACE project)?

• What about other projects (e.g. levee setbacks, floodplain storage easements, etc.)?

• Other questions?

What can we do to get back to pre-1990 flood conditions?

Date Flow (cfs) Rank 1 Date Flow (cfs) Rank 1 % 2 Date Flow (cfs) Rank 1 % 2 Date Flow (cfs) Rank 1 % 2 Date Flow (cfs) Rank 1 % 2

12/04/2007 79100 1 12/03/2007 3600 55 5% 12/03/2007 12900 3 16% 12/03/2007 20710 1 26% 12/03/2007 63100 1 80%02/09/1996 74800 2 02/08/1996 11300 1 15% 02/08/1996 13300 1 18% 02/08/1996 9540 4 13% 02/08/1996 28900 2 39%01/10/1990 68700 3 01/10/1990 8540 8 12% 01/09/1990 10400 6 15% 01/09/1990 9880 3 14% 01/09/1990 27500 3 40%11/25/1986 51600 4 02/01/1987 6470 22 13% 11/24/1986 10700 5 21% 11/24/1986 6430 12 12% 11/24/1986 17900 9 35%01/08/2009 50700 5 01/08/2009 10500 3 21% 01/07/2009 13000 2 26% 01/08/2009 11660 2 23% 01/08/2009 20100 7 40%01/21/1972 49200 6 01/21/1972 8190 11 17% 01/21/1972 9770 10 20% 01/20/1972 6540 10 13% 01/20/1972 22800 4 46%12/29/1937 48400 711/25/1990 48000 8 11/25/1990 8400 9 18% 11/24/1990 10300 7 21% 11/24/1990 7400 7 15% 11/24/1990 20600 6 43%12/21/1933 45700 912/05/1975 44800 10 12/04/1975 6110 27 14% 12/04/1975 8020 17 18% 12/04/1975 6590 9 15% 12/04/1975 17400 10 39%

39 136 14% 51 19% 48 17% 42 45%

01/26/1971 40800 11 12/09/1953 10930 2 24 11/07/2006 11200 4 26 11/06/2006 8130 5 26 02/07/1945 21400 5 3212/30/1996 38700 12 12/11/1955 10150 4 23 12/02/1977 10300 7 17 11/25/1998 7420 6 17 01/18/1986 18100 8 2701/23/1935 38000 13 01/25/1964 9760 5 22 11/26/1998 10000 9 17 01/30/2006 7080 8 15 12/16/2001 16600 1102/10/1951 38000 13 02/17/1949 9400 6 17 12/29/1996 9700 11 01/18/1986 6500 11 02/24/1999 16300 1201/31/2006 37900 15 12/28/1949 8710 7 36 01/31/2003 8940 12 12/15/1999 6350 13 01/30/2006 16000 1301/17/1974 37400 16 12/30/1996 8380 10 12 01/30/2006 8720 13 02/07/1945 5700 14 02/09/1951 15700 14

Chehalis near Doty

Data not available

Data not available

Chehalis near Grand Mound Skookumchuck at Bucoda Newaukum SF Combined (extended w Doty)

Date Flow (cfs) Rank 1 Date Flow (cfs) Rank 1 Date Flow (cfs) Rank 1 % 2 Date Flow (cfs) Rank 1

12/04/2007 139000 12/03/2007 12000 29 12/03/2007 36400 13 12/05/2007 102000 1 129% 12/04/2007 79100 102/09/1996 126300 11/29/1995 17700 10 11/29/1995 30800 28 02/09/1996 80700 2 108% 02/09/1996 74800 201/10/1990 105700 02/10/1990 13800 23 02/10/1990 27300 43 01/11/1990 60400 4 88% 01/10/1990 68700 311/25/1986 107000 11/23/1986 18900 7 11/23/1986 39300 9 11/25/1986 45900 9 89% 11/25/1986 51600 401/08/2009 127600 01/07/2009 22700 3 01/07/2009 45500 5 01/09/2009 68100 3 134% 01/08/2009 50700 5

01/20/1972 31000 25 01/22/1972 55600 5 113% 01/21/1972 49200 612/28/1937 30100 32 12/29/1937 48400 7

11/25/1990 105200 11/24/1990 21500 4 11/24/1990 38200 10 11/26/1990 43000 11 90% 11/25/1990 48000 812/21/1933 24500 51 12/21/1933 45700 9

12/05/1975 97100 12/03/1975 16400 14 12/26/1975 34200 18 12/05/1975 48100 7 107% 12/05/1975 44800 1090 151 42 107% 39

03/19/1997 25600 1 12 03/19/1997 63600 1 12 01/27/1971 49600 6 11 01/26/1971 40800 1112/15/1999 25100 2 29 12/15/1999 54500 2 29 01/02/1997 46000 8 12 12/30/1996 38700 1212/10/1993 20700 5 79 12/20/1994 50600 3 21 01/13/2006 43200 10 15 01/23/1935 38000 1311/06/2006 20100 6 26 01/22/1935 46600 4 13 02/26/1999 42000 12 02/10/1951 38000 1312/19/1994 18300 8 21 01/19/1968 43100 6 40 12/19/2001 41200 13 01/31/2006 37900 1512/26/1972 18100 9 52 11/07/2006 40100 7 26 01/07/1954 40800 14 01/17/1974 37400 16

Data not available

Data not available

Chehalis at Porter Chehalis near Grand MoundSatsopWynoochee

Data not available

Data not available

Flow at Mouth (est)

Sum Wyn-Sat-Port (cfs)

Which projects reduce flooding throughout the basin?

Why doesn’t the WSDOT I-5 Project show downstream water level increases (like the USACE project)?• It does, but the

increases are not as large

• WSDOT project does not include all of the levees that were in the USACE Project

• In particular, WSDOT Project does not include Galvin Road Levee

• Modeling approach for complex hydraulics in Twin Cities may affect results at very fine resolutions

What about other projects (e.g. levee setbacks, additional floodplain storage, etc.)?For 100-year event:

Peak Storage in HEC-RAS Model = 584,000 Acre-ft

Storage along main stem Chehalis = 458,000 Acre-ft

For comparison:

Flood storage in proposed retention facility = 80,000 Acre-ft

Flood storage in Twin Cities reach = 60,000 Acre-ft

Other Questions