Mouth of the Columbia River JettiesMajor Rehabilitation

Pacific

Ocean

Baker Bay

North Jett

y

South Jetty

Clatsop Spit

Peacock Spit

Washington

Oregon

Sand Island

Ilwaco

AstoriaHammond

Chinook

Jetty “A” Sand Island Pile Dikes

Long Beach

North Head

Columbia River Estuary

MCR

Nav

igatio

n

Lower Columbia River Nav Channel

N

Channel

Pacific

Ocean

Baker Bay

North Jett

y

South Jetty

Clatsop Spit

Peacock Spit

Washington

Oregon

Sand Island

Ilwaco

AstoriaHammond

Chinook

Jetty “A” Sand Island Pile Dikes

Long Beach

North Head

Columbia River Estuary

MCR

Nav

igatio

n

Lower Columbia River Nav Channel

NN

Channel

MCR North Jetty - Construction and Repair History

1917

1939

1965 2005

(Receded approximately 1800’ in length since 1916)

MCR South Jetty - Construction and Repair History

1913 1886

1931-1934

1961- 1962

1982

2006

2007

(Receded approximately 5000’ in length since 1885 - 1913)

Design Development

• Least cost, most reliable repair, environmentally acceptable.

• Jetty cross section options:

– Dimensions: crest elevation, crestwidth, sideslope

– Material types: stone, concrete, combination

• Due to the variability in design climate and repair history, design applications will vary:

– Between the three structures

– Along the length of each structure.

• Both physical and two numerical modeling are used to assess and fine tune the designs.

Physical Modeling of Cross Design Options – Optimize Reliability

Jetty Resilience Compromised by Wave Action

= reliability-based decision point

Reach of North Jetty NOT Repaired Since

1917 Original Construction

Severe Deterioration of Jetty Heads MCR Jetty Breach Feb 2006

Threatened Jetty Section

Progr

essiv

e Dam

age

2005 North Jetty = 58,000 tons Armor Stone (5-12 tons)

2006 – 2007 South Jetty = 160,000 tons Armor Stone (5-30 tons)

Sand infill from north side throughdamaged structure.

Submerged head of north jetty helping to hold Peacock Spit and Benson Beach.

Major Rehab Considerations

• Engineering Features– Lagoon Fill– Spur Groins– Capping

Repaired in 2005

Sep 2002

MCR North Jetty

12 m

10 m8 m

14 m

SOUTH JETTY

6 m

MCR Navigation channel

Existing spur groins on south jetty.

North Jetty

South Jetty

Clatsop Spit

MCR Channel

Peacock Spit

NJS

Use the NJS to reduce the scour rate along the southern toe of the north jetty (place 0.2 - 0.5 Mcy/yr)

Use the SWS to feed material onto Peacock Spit and Sustain the sediment budget north of MCR (place 1.5-2.5 Mcy/yr):

SWS

1939

Benson Beach

Shoreline 1913North Head

*

*head of jetty in 2002

2002

North Head

Shoreline receded 2,000 ft since 1939

North

Jetty

Shoreline 1913

*

As shoals recede, jetties become vulnerable to foundation scour and

wave attack

South Jetty Head – 4000 ft loss in length

Major Rehab Alternatives

• Scheduled Repair

• Immediate Rehab– Minimum Template– Large Template– Composite Template

• Scheduled Rehab

N

2030405060708090100

110

120

= spur groin

-40

-30

-20

-10

0

10

20

30

40

50

-260 -240 -220 -200 -180 -160 -140 -120 -100 -80 -60 -40 -20 0 20 40 60 80 100 120

Ocean/Beach Side

Channel Side

Existing Core Stone

Present Seabed

Original Seabed

NB1 stone: 25 to 5 ft MLLW = 10-30 ton (mean = 22 ton)NB2 Relic Stone: -10 to -20 ft MLLW = 6-26 ton (mean = 16 ton)

NB3 Surplus Relic Stone and New Filler: below -20 ft MLLW = 1-15 ton (mean = 8 ton)Reworked Relic Armor Stone = 5-15 ton (mean = 10 ton)

Reworked Core Stone = 0.25 - 3 ton (mean = 1.5 ton)all stone has gamma=167 lb/ft3

1v:2h

South North

1v:1.5h

= NB1 select armor units: 5 to -10 ft MLLW: for stone = 20 - 40 ton (mean =28 ton)

Scoured seabed armored with relic stone

Relic Stone

Gravel

Sand

Existing Ground

-40

-30

-20

-10

0

10

20

30

40

50

-260 -240 -220 -200 -180 -160 -140 -120 -100 -80 -60 -40 -20 0 20 40 60 80 100 120

Ocean/Beach Side

Channel Side

Existing Core Stone

Benson Beach

Original Seabed

NC1 stone: 25 to 5 ft MLLW = 10-30 ton (mean = 22 ton) NC2 Relic Stone: -10 to -20 ft MLLW = 6-26 ton (mean = 16 ton)

NC3 Surplus Relic Stone and New Filler: below -20 ft MLLW = 1-15 ton (mean = 8 ton)Reworked Relic Armor Stone = 5-15 ton (mean = 10 ton)

Reworked Core Stone = 0.25 - 3 ton (mean = 1.5 ton)all stone has gamma=167 lb/ft3

1v:3h

South North

1v:1.5h

1v:2h1v:2h

=optional area to use concrete armor units

= NC1 select armor units: 5 to -10 ft MLLW; for stone = 20 - 40 ton (mean =28 ton)

Scoured seabed armored with relic stone

=area to use concrete armor units - would preclude land access along crest for futre repair unless cap is placed

Relic Stone

NORTH JETTY MAJOR REHABILATION-80-70-60-50-40-30-20-10

01020304050

-260 -240 -220 -200 -180 -160 -140 -120 -100 -80 -60 -40 -20 0 20 40 60 80 100 120 140 160 180 200

Ocean/Beach SideChannel Side

Present Seabed

Relic Armor Stone Original Seabed

1v:3h

1v:2.5h

South North

Scoured seabed armored with relic stone

1v:2.5h

1v:3h

= NH1 concrete armor units: 10 to -10 ft MLLW = 15-25 ton (mean = 20 ton), or sized as needed to resist wave actionNH2 Relic Stone: -10 to -20 ft MLLW = 25-45 ton (mean = 34 ton)

all stone has gamma=167 lb/ft3

-40

-30

-20

-10

0

10

20

30

40

50

-260 -240 -220 -200 -180 -160 -140 -120 -100 -80 -60 -40 -20 0 20 40 60 80 100 120

Ocean/Beach Side

Channel Side

Existing Core Stone

Relic Armor Stone Benson Beach

Original Seabed

Interim Repair = 6-15 ton (mean = 10 ton)Relic Armor Stone = 5-15 ton (mean = 10 ton)

Core Stone = 0.25 - 3 ton (mean = 1.5 ton)all stone has gamma=167 lb/ft3

1v:1.5h

South North

Scoured seabed armored with relic stone

10 T

New Rock

Sand Foundation

Existing Rock

-40

-30

-20

-10

0

10

20

30

40

50

-260 -240 -220 -200 -180 -160 -140 -120 -100 -80 -60 -40 -20 0 20 40 60 80 100 120

Ocean/Beach Side

Channel Side

Existing Core Stone

Relic Armor Stone

Original Seabed

Interim Repair = 6-15 ton (mean = 10 ton)Relic Armor Stone = 5-15 ton (mean = 10 ton)

Core Stone = 0.25 - 3 ton (mean = 1.5 ton)all stone has gamma=167 lb/ft3

1v:1.5h

South North

Scoured seabed armored with relic stone

New Rock

Sand Foundation

Existing Rock

Gravel

Sand

Existing Ground

Selected Plan

0 10 20 30 40 50 60 70 800

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Year, after 1917

Pro

ba

bilit

y o

f S

ati

sfa

cto

ry P

erf

orm

an

ce

, P

(S)

MONTE CARLO: Variation in North Jetty "Structure Reliability" during :1917-2006

Historical Condition - Dynamic Reliability, P(s)

0 10 20 30 40 50 600

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Year, after 2006

Pro

bab

ility

of

Sa

tisf

act

ory

Per

form

ance

, P(S

)

MONTE CARLO: Variation in North Jetty "Structure Reliability" during :2006-2070

REHAB Option B - Dynamic Reliability, P(s)

Reliability: Major feature restoration consisting of structural work on Corps operated and maintained facility

• Goal: Develop the most cost-effective reliable structure that serves the purpose for the navigation channel

Applicable Environmental Laws

• NEPA (National Environmental Policy Act)– Mitigated FONSI Environmental Assessment

• CWA (Clean Water Act)• CZMA (Coastal Zone Management Act)• ESA (Endangered Species Act)

– Biological Assessment– Biological Opinion

• Marine Mammal Protection Act• Magnuson-Stevens Act

Potential Impacts

• Listed Species and Critical Habitat• Impacts to Aquatic Organisms• Impacts to Commercial and Recreational

Fisheries• Essential Fish Habitat• Cultural Resources• Socio-Economic• Section 404 Waters and Wetlands

ESA Species in Project Vicinity 13 Runs of Salmonids

Chinook Salmon

Juvenile Fish Studies

North Jetty Disposal Site

Jetty A

ESA Species in Project Vicinity Pelagic Mammals and Turtles

Right Whale

Green Sea Turtle

ESA Species in Project Vicinity Birds (Pelican, Eagle, Murrelet, Plover)

Pelican

Plover

Eagle

Murrelet

ESA Species in Project Vicinity

Steller Sea Lions

Other Species of Concern

Dungeness CrabCalifornia Sea Lion