Design and Implementation of

Large Wood Structures at

Twelvemile Creek

Prince of Wales Island

Tongass National ForestThe Nature ConservancyTEAMS Enterprise Unit

Prepared By:Sean ClaffeyNovember 2013

recap…

Habitat Attribute Percentile FP3 FP4 FP5*

Process Group

FP CCAFP5

LowerFP5

Upper FP4 Rating

WD

25 10.9 18.5 23.1 16.5 23 Fair _low

25-50 Good 50 14.9 20.2 27.2 19.3

50-75 33 Fair_high 75 19 32.8 43.6 26.7 35 Poor

TKWD/m

25 0.10 0.06 0.02 0.04 0.02 0.02 0.02 Poor 25-50 Fair

50 0.17 0.11 0.03 0.10 50-75 Good

75 0.25 0.15 0.08 0.15 Excellent

Pools/km

25 30 30 10 30 Poor 25-50 11 11 Fair 50 40 40 20 45 50-75 43 Good

75 70 60 25 70 Excellent * low sample size (n<10)

Pool Size (rpd/avbfd)

25 0.67 0.68 0.58 0.65 Poor 25-50 Fair

50 1.14 0.84 0.65 0.84 50-75 0.93 0.91 Good

75 1.58 0.94 0.95 0.95 2.06 Excellent

RPD/CBW

25 0.06 0.04 0.03 0.04 0.04 Poor 25-50 Fair

50 0.07 0.04 0.03 0.05 50-75 Good

75 0.09 0.05 0.03 0.06 0.06 0.08 Excellent

Priority Watershed

Habitat Surveys and Data collection

Data guided our efforts

to evaluate condition of watershed

Treatment Reach

Twelvemile vs. Unmanaged Reference StreamsData comparison defined our restoration objectives.

Objectives• Objectives based on reference unmanaged floodplain channels.

Design Concepts• Concepts based on the parameters provided by the Twelvemile

references.

For Example: Reference pools were formed by LWD creating a constriction at the pool head. Either spanning or on one or both sides of the channel.Pool head width (31’-38’) and bankfull width (70’-80’).

Using LWD structures to restore Hydrological Function.

Used Data to define our objectives

Objective Design Concept (How can we use wood)

A) Increase large wood & key wood Add wood. Use to meet other objectives

B) Maintain or increase pool frequency

• Use wood to constrict pool head, • stabilize outside bank of an accelerated meander, • supplement existing pool forming woody debris.

C) Decrease width/depth ratio • Reduce rapid bank erosion by adding structure to

unstable banks,• Encourage or increase lateral/point bar development

D) Improve pool quality • Add complexity and cover to pools, • Increase scour potential.

E) Improve side water habitat connections and/or quality.

• Use wood to maintain or improve inflow,• Use wood to backwater outflow.

Energy!

Rapidly eroding bankExisting pool

Design Concept Site Selection

Shallow, clean pool

Objective

Flow

Flow

Energy!Outside Meander Bend

Low bar, wide cross section with uniform shallow depth

Intense Focus of Energy dissipation caused by the wood.

riffle

Site selection

• Site selection was determined by the channel.o Was not new channel construction or realignment

o Multiple objectives could be met at each site and each structure has multiple objectives.

o This was by design. Each LWD structure was strategically placed according to the existing scour and deposition features, intervals and cross sectional area.

Didn’t force anything.

Diversity, mobile debris source

Enhance scourOverall channel stability, riparian health

Enhance depositional feature to constrict local channel widths

Bank Stabilization, Habitat

• Sites Selected

Design for Site Specific Objectives• What type of structure will accomplish objective/s– Formidable Multi-Faceted (FMF)– Bar buddy– Spanning member – Floodplain– Single piece or small cluster

Often a combination of the above. One structure may be in response to another.

Design Concept Site Selection

Site Design

Objective Design Concept Site Design (Structure type)

A) Increase large wood & key wood

Add wood. Use to meet other objectives ALL

B) Maintain or increase pool frequency

• Use wood to constrict pool head, • stabilize outside bank of an

accelerated meander, • supplement existing pool forming

woody debris.

FMF, Bar buddy, Spanning

C) Decrease width/depth ratio

• Reduce rapid bank erosion by adding structure to unstable banks,

• Encourage or increase lateral/point bar development

FMF, Bar Buddy

D) Improve pool quality

• Add complexity and cover to pools, • Increase scour potential.

Convenient by product of all structures. Spanning

E) Improve side water habitat connections and/or quality.

• Use wood to maintain or improve inflow,

• Use wood to backwater outflow.Can be incorporated into all of the

above.

Site Selection

Site Design

Permitting

Contracting

Implementation

Title 16

404

Wood Collection About 85% of project used ~50 yr old young

growth. Spread collection out in “gaps”.

Rootwad harvest against existing roads.

Getting the wood to the creek...

Flying Trees

Helicopter decked trees on bars and adjacent floodplain in creek.

Equipment to the creek• Six points of access. • All off of old roads adjacent to creek. Some required

a short trail from the road surface to the creek.From Phase 1

• Equipment was power washed before entering the stream• Vegetable based hydraulic fluid replaced petroleum products.• Oil absorbent booms were deployed downstream of worksite in event of a spill.

• Work Completed at low flow• Travel concentrated to riffles and bars • Fish and game provided the timing window of July 5th - August 5th

• Duration in channel- For example Phase II - there were ~300 trees placed with two excavators in about a mile reach. Only 4 days in the channel.

•

Objective Design Concept

A) Increase large wood & key wood

Add wood. Use to meet other objectives

B) Maintain or increase pool frequency

• Use wood to constrict pool head, • stabilize outside bank of meander, • supplement existing pool forming

woody debris.

C) Decrease width/depth ratio

• Reduce rapid bank erosion by adding structure to unstable banks,

• Encourage or increase lateral/point bar development

D) Improve pool quality

• Add complexity and cover to pools, • Increase scour potential.

E) Improve side water habitat connections and/or quality.

• Use wood to maintain or improve inflow,

• Use wood to backwater outflow.

Instream Placement

HOW

Example Site #XX

Low bar. Wide uniform shallow cross section

Poorly developed shallow pool

Pool head 50+ feet

Site Design (Structure type)

ALL

FMF, Bar buddy, Spanning

FMF, Bar Buddy

Convenient by product of all structures. Spanning

Can be incorporated into all of the above.

We are going to build• FMF, • Bar Buddy, • and Spanning member.

WITH

Placement

• FMF first• Set the base

Rootwad

Spanning member

Bar Buddy

Formidable Multi-Faceted Structure

Spanner

Flow

Flow

Before, June 1013

After, July 2013

Example Site #XX

Site #XX after its first good flow event…

FMF

Improved Scour

Flow

September 2013

Notes on implementation…

• Notice there was no cable or large rock used. • Structures are meant to stay dynamic.

• They will shift and individual pieces may move between structures.

• Design also had to be dynamic• Built to field conditions at each site

• 100% on-site supervision• Great operators

Site Design

PermittingContracting

Implementation

Design Concept Site SelectionObjectives(Parameters)(DATA)

Monitor

Notes on implementation…

Thank you to: Southeast Roadbuilders,S&S General Contractors,

Columbia Helicopters

&

The Nature ConservancyAlaska Sustainable Salmon Fund

National Forest FoundationNational Fish & Wildlife Foundation

END