Riverbank Stabilization Guidelines

1
Riverbank Stabilization Guidelines

• Pend Oreille River in the Box Canyon Reservoir

Pend Oreille County Conservation District
Washington Department of Fish and Wildlife
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Background

• How Did We Get Here?
• History of the ISPG and the Pend Oreille River
  Guidelines
• Who Are We?
• Roles of the Washington Department of Fish
  Wildlife and the Pend Oreille Conservation
  District
• Instructor Background
• Your Interest in Bank Stabilization
• What Will We Do Today?
• Workshop Agenda
• Caveats and Excuses
• What Will We Get Out of This Workshop?
• Consider Opportunities, Constraints and New
  Approaches
• Appreciate Needs of Landowners, Contractors and
  Regulators

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Workshop Outline

• Reach Assessment
• Pend Oreille River in the Box Canyon
• Hydrology
• Soils
• Vegetation
• Site Assessment
• Mechanisms and Causes of Failure
• Undertaking an Assessment
• Solutions
• Considering a Solution
• Landowner Checklist
• Bank Stabilization Techniques and Materials
• Classroom Case Study
• Permit Requirements
• Field Assessment and Discussion

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Pend Oreille River in the Box Canyon

• Located Between Newport and Ione
• 54 Miles Long
• Different Conditions Along the River

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Pend Oreille River in the Box Canyon

• Common Dilemma We Encounter
• Desire to have my house near the river, to see
  the river, and to have access the river
• Desire to keep the river from eroding my bank (my
  house!)
• How We Think of Vegetation
• Prevents me from seeing the river
• It can be so messy!
• Provides important bank stabilization
• Well Just Change a Few Things Here
• Minor vegetation and slope modifications lead to
  need for major riverbank stabilization measures
• Natural Resources
• Protect the resource and the reason we live along
  the river

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Pend Oreille River in the Box Canyon

• What Values Are Often Lost With Bank
  Stabilization?

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Impacts of Bank Stabilization

• Visual Pollution and Loss of Natural Views
• Loss of Riparian Vegetation
• Degradation of Fish and Wildlife Habitat
• Create Additional Bank Instability
• We Can Do a Better Job of All This!

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Hydrology

• Regulated Flow
• Annual Hydrograph
• Flows of Various Recurrence Intervals
• Flow Duration
• Water Surface Level Variation

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Hydrology

• Flow Regulated by Dam
• Narrow Canyon Creates Backwater Effect

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Hydrology

• Annual Hydrograph

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Hydrology

• Flows of Various Recurrence Intervals

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Hydrology

• Flow Duration

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Hydrology

• Water Surface Elevation Within the Reservoir

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Hydrology

• Water Surface Level Variation

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Hydrology

• Water Surface Level Variation

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Soils

• Principle Soil Types
• Silt Loam
• Silty Clay Loam
• Sandy Loam
• Implications
• Bank Angle
• Vegetation Re-establishment
• Drainage

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Native Plants

• Vegetative Component Part I
• A Key Element

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Come High Water

• I was discussing music one day with an 89
  year-old fiddle player and he asked where I
  lived. I motioned to the north, "On the river
  near Ione. He smiled and replied,
  Ahhhupcountry and downriver. I like that!
• Unless one lives at the headwaters of our river
  systemwe are all downriver and that fact
  should give us pause for thought. Effects from
  land management practices along our shorelines,
  positive and negative, flowdownriver.

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Vegetation Bank Stability

• Vegetative Cover and Root System
• Intercepts precipitation slowing runoff,
  sediment soil compaction
• Stems vegetation buffer wave action
• Reduces soil moisture levels by transpiration
• Increases resistance to erosion by creating a
  mat-like buffer of dense, interlocking deep
  fibrous roots
• Provides cohesive structure, reinforcement to
  soil mass along slope
• Helps keep soil porous to reduce saturation load

20
Site Conditions

• Never Disturb Site Unnecessarily
• The less it is disturbed, the easier it will be
  to restore and stabilize

21
Site Vegetation Inventory

• Identification of Existing Vegetation
• Why is this important?
• Botanical Benchmark
• Used as a guideline for species type
  location on bank
• Retain native vegetation if possible
• Possible salvage for site replanting
• Landowner Resources
• Books and Websites
• Natural Resource Agencies
• Private Consultants

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Vegetative Function

• The Plant Communitys Role
• Wildlife Habitat Value Diversity
• Food, Cover, Nesting Brooding
• Stabilization/Erosion Control
• Floodwater Storage
• Filter Pollutants
• Aesthetic Value
• Privacy
• Ethnobotany
• Cultural Uses

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Understanding the Problem and Undertaking an
Assessment

• Mechanisms of Failure
• Causes of Erosion
• Undertaking an Assessment
• Considering a Solution
• Landowner Checklist

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Mechanisms of Failure

• Seepage and Piping
• Toe Erosion

Original Bank
Eroded Bank
High Groundwater
High Water
Lowered Water Table
Subsurface Piping
Low Water
Clay Layer

• Mass Failure

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Causes of Erosion

• Vegetation Disturbance and Removal
• Wave Action
• Rapid Drawdown
• Increased Subsurface Seepage
• High Flow
• Freeze-Thaw Cycles
• Surface Ice

26
Undertaking an Assessment

• Location by River Mile
• Ground Elevation
• Soil Type and Internal Seepage
• Water Level Fluctuation
• Riverbed Configuration
• Wave Action
• Riverbank Configuration
• Cause of Erosion

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Undertaking an Assessment

• Location by River Mile From Appendix 2

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Undertaking an Assessment

• Ground Elevation
• Go to USGS Website
• Determine Flow For Date
• Determine Water Surface Elevation From Table 2

29
Undertaking an Assessment

• Soil Type and Internal Seepage

30
Undertaking an Assessment

• Water Level Fluctuation From Appendix 1

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Undertaking an Assessment

• Riverbed Configuration
• Abrupt Drop of Shallow Beach?

32
Undertaking an Assessment

• Wave Action
• Amount of Wave Action?

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Undertaking an Assessment

• Riverbank Configuration

34
Undertaking an Assessment

• Cause of Erosion

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Considering a Solution

• Risk and Cost
• Types of risk
• Levels of cost based on risk
• Design Criteria
• Bench dimensions, stone size and height, erosion
  control fabric, plants
• Habitat Impacts
• Construction activity impacts
• Direct loss of habitat
• Increased risk from perceived protection

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Landowner Checklist
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Native Plants

• Vegetative Component Part II
• A Key Element

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The Vegetation Plan

• Site-specific Project Design
• Planting techniques materials will vary with
  design
• Vegetation
• Budget
• Land Management Practices
• Will all or portions of existing vegetation be
  retained or salvaged for replanting?
• Materials Plant List
• Planting Diagram
• Schedule/Implementation
• Permits, Work Window, Flexibility

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Plant Selection Checklist

• Appropriate Plants for Site
• Botanical Benchmark
• Existing Native Plant Community
• Local Genetics
• Project Site Characteristics
• Slope Aspect, Elevation, Climate Topography
• Purpose of Planting
• Erosion Control, Bank Stability, Wildlife
  Habitat, View Corridor
• Soil Characteristics
• Drainage, Fertility, Water Capacity, etc.
• Hydrology
• Seasonal Inundation, Flow Velocity
• Supplemental Irrigation

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Plant Materials

• Hardwood Cuttings
• Dormant Leafless Stem Cuttings
• Willow Species
• Black Cottonwood
• Red-osier Dogwood
• Rooted Woody Vegetation
• i.e., Black Hawthorn, Common Snowberry,
  Kinnikinnick
• Plugs, Container Bare Root
• Herbaceous Vegetation
• i.e. Rushes, Sedges, Grasses Perennial
  Wildflowers
• Seed, Plugs Container

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Hardwood Cuttings

• Dormant
• Can be collected from fall leaf drop up until
  just before buds open in the spring
• Growing
• Can be gathered during growing season, with
  leaves removed before planting, but survival rate
  is reduced
• Cuttings
• Flexible cuttings are approximately 4 feet long
  and normally about ½ - ¾ inch in diameter at the
  basal end
• Cutting length diameter depends on application,
  but must be long enough in vertical placement to
  extend down into low water table

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Collection of Cuttings

• Choose Healthy, Local, Native Stands
• Collect straight cuttings that are at least 1 to
  2 years old
• Make clean, diagonal cuts on base end
• Cut terminal bud off with a clean, straight cut
• Remove cuttings from inside crown area
• Avoid cutting more than 2/3 of total individual
  plant
• Trim off all side branches
• Tie bundle for ease of handling
• Prior to planting
• If collected well in advance, cuttings must be
  stored in a cool
• (34-36 degree), dark, humid place
• Soak in water for 5 to 7 days (minimum 24 hours)

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Installation of Cuttings

• Joint Planting in Existing Riprap
• Pre-punch hole with a planting bar, slightly
  larger diameter than cutting diameter, between
  rocks
• Plant 2/3 of presoaked cutting length, with
  minimum of two buds above ground buds pointing
  up
• Plant at least two offset rows on approximate 2
  ft. centers/1 ft. between rows spacing varies
  with gaps in riprap
• Backfill with a mud slurry
• Vertical Willow Fascine Beneath Riprap
• Maximum 2-inch diameter presoaked cuttings of at
  least 5 ft. in length (or longer) a portion of
  top must extend approximately 1 ft. above riprap
• Tie individual cuttings securely with twine, but
  allowing enough space for soil to filter in
  finished bundle should be approximately 8 10
  inch diameter
• Excavate vertical trench on approximate 3 ft.
  centers bottom of trench must be under water
  during low flow. Trench soil should be moist at
  installation
• Place bundles, buds up, with base ends in water
  secure with stakes
• Partially backfill around the bundles with soil
  cover with filler gravel or staked coir fabric
  before riprap is placed

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Installation Continued

• Horizontal Willow Fascine with Coir Fabric
• Alternate direction of buds on presoaked cuttings
  when preparing bundles
• Trench depth should be approximately 1/2 - 2/3 of
  bundle diameter. Soil should be moist at
  installation
• Overlap the tapered ends of bundles as they are
  placed
• After fascines have been placed in trench, drive
  stakes through them, with extra stakes added
  where they overlap
• Soil should be added around sides and into
  bundles working it into them and compacting to
  help soil contact for rooting and prevent water
  pooling
• Vegetated Geogrid with Live Branches
• Each layer with branches should have min. 6
  inches of soil for branches to rest on
• Live branches should be varying species, age and
  thickness to promote diversity in rooting and
  canopy. Place crosswise to each other (i.e. not
  parallel) with a 10 15 degree backslope for
  each layer
• Branches should be at least 20 to 25 longer
  (minimum 3 ft.) than depth of bench and tips of
  branches must protrude
• Cover with a layer of soil, lightly compact and
  work soil into branches. Thoroughly wet each
  layer if installed during dry part of the year

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Vegetation Care

• Handling, Delivery and Storage
• Protect all plant material from drying
• Roots exposed to sun and wind will not survive
• Store in cool, humid conditions or heel plants in
• Container plants must be kept shaded
• General Planting
• Avoid planting during especially hot, cold or
  windy days
• Plant one at a time
• Backfill using native soil and do not fertilize
• Water plants in thoroughly
• Water again in one week Water accordingly for
  seasonal establishment
• Seed Drill or Broadcast Rake in Moisten
  Mulch

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Vegetation Summary

• Do Not Disturb Site Unnecessarily
• Take a Vegetation Inventory
• Prepare Project Plan/Schedule
• Select Appropriate Species/Planting Location
• Provide Root Species Diversity
• Plant a Multi-layered Vegetative Canopy
• Properly Install and Care for Plants
• Monitor

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Bank Stabilization Measures

• Technique 1 No stabilization action with
  monitoring
• Technique 2 Vegetation establishment
• Technique 3 Toe armoring without bank slope
  reduction
• Technique 4 Low Bench (with and without bank
  slope reduction
• Technique 5 Bioengineered upper bank
  stabilization
• Discuss Materials As First Encountered

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Bank Stabilization Measures

• Technique 1 No stabilization action with
  monitoring

Do Nothing, But Monitor For Changes
49
Bank Stabilization Measures

• Technique 2 Cross-section of toe protection
  using vegetation plantings and coir fabric (Fig
  16)

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Bank Stabilization Measures

• Willow Cuttings, Brush Bundles, Fascines and
  Wattles

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Bank Stabilization Measures

• Willow Cuttings, Brush Bundles, Fascines and
  Wattles

52
Bank Stabilization Measures

• Technique 3 Cross-section of toe armoring
  without bank slope reduction (Fig 17)

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Bank Stabilization Measures

• Technique 4 Cross-section of low bench without
  bank slope reduction (Fig 18)

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Bank Stabilization Measures

• Technique 4 Cross-section of low bench with
  bank slope reduction (Fig 18)

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Bank Stabilization Measures

• Examples of Low Bench

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Bank Stabilization Measures

• Examples of Low Bench

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Bank Stabilization Measures

• Examples of Low Bench

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Bank Stabilization Measures

• Examples of Low Bench

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Bank Stabilization Measures

• Examples of Low Bench

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Bank Stabilization Measures

• Technique 4 Details of low bench with
  variations in surface treatment (Fig 19)

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Bank Stabilization Measures

• Technique 4 Details of low bench with
  variations in surface treatment (Fig 19)

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Bank Stabilization Measures

• Technique 4 Details of low bench with
  variations in surface treatment (Fig 19)

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Bank Stabilization Measures

• Coir Fabric (Woven and Non-Woven)

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Bank Stabilization Measures

• Coir Fabric (Woven and Non-Woven)

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Bank Stabilization Measures

• Technique 5 Generalized cross-section of
  bioengineered bank stabilization (Fig 20)

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Bank Stabilization Measures

• Technique 5 Bioengineered bank with variations
  of toe stabilization (Fig 21)

Upper Slope Treated With One or a Combination of
Bioengineered Stabilization Measures (See Figures
22 to 27)
Existing Ground
Existing Bank Configuration and Height Varies
Stone Surface
Stone Height B (See Table 4)
Compacted Fill Material to Provide a Foundation
for Upper Slope
Note Low Bench Can Be Used At Bank Toe (See
Figure 18)
21 HV Slope
Bioengineered Bank With Toe of Stone Surface
67
Bank Stabilization Measures

• Technique 5 Bioengineered bank with variations
  of toe stabilization (Fig 21)

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Bank Stabilization Measures

• Technique 5 Bioengineered bank slope with
  willow fascines and coir fabric (Fig 22)

Woven Coir Fabric
Wooden Stake with Tie Down
Willow Fascine
Wooden Stake
Existing Ground
Flat Slope Break
1 Ft
5 Ft
Modified Slope at 21 HV or Flatter
Undisturbed Native Material
Stone Surface
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Bank Stabilization Measures

• Technique 5 Bioengineered bank slope with
  willow brush bundles and coir fabric (Fig 23)

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Bank Stabilization Measures

• Technique 5 Bioengineered bank slope with
  willow brush bundles and coir fabric (with
  optional geogrid and gravel filter) (Fig 23)

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Bank Stabilization Measures

• Geogrid

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Bank Stabilization Measures

• Technique 5 Bioengineered bank slope with
  vegetated geogrid (Fig 24)

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Bank Stabilization Measures

• Technique 5 Bioengineered bank slope with
  vegetated geogrid (with optional gravel filter)
  (Fig 24)

74
Bank Stabilization Measures

• Vegetated Geogrid, Fabric-Encapsulated Soil and
  Soil Wrap

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Bank Stabilization Measures

• Vegetated Geogrid, Fabric-Encapsulated Soil and
  Soil Wrap

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Bank Stabilization Measures

• Technique 5 Bioengineered bank slope with
  geocell surface (Fig 25)

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Bank Stabilization Measures

• Technique 5 Bioengineered bank slope with
  stacked geocell (Fig 26)

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Bank Stabilization Measures

• Stacked Geocell

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Additional Considerations

• Shoreline Access Docks

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Additional Considerations

• Shoreline Access Stairs

Why is wood more environmentally appropriate?
Dont reshape bank for stairs!
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Case Study Team Exercise

• Break Into Groups of 5 or 6
• Complete Landowner Checklist
• Discuss Existing Site Conditions
• Discuss Problems and Causes
• Consider Solutions
• Present Preferred Solution

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Case Study Overview
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Case Study Details
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Case Study Details
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Case Study Details
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Case Study Site Description

• Land Use
• Soils
• Vegetation
• Hydrology
• Bank Configuration
• Mechanism of Failure
• Cause of Erosion

87
Case Study

• Hydrology

Use Table 2 to Determine Ground Elevation From
Discharge
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Case Study Site Description

• Bank Configuration

89
Landowner Checklist
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Select Stabilization Technique

• What are Ground Elevations? What is Typical
  Annual Water Level Fluctuation?
• What Stabilization Approach Seems Appropriate?
• Consider
• Degree of water fluctuation and erosion problem
• Construction access limitations
• Opportunities for benefits associated with bank
  stabilization
• Identify a Spokesperson to Present Solution

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Possible Solution Low Bench
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Permit Requirements

• Joint Aquatic Resources Permit Application
  (JARPA)
• Hydraulic Permit Approval (HPA)
• Washington Department of Fish Wildlife
• Addition to JARPA Fish Habitat Enhancement
  Projects
• Shoreline Master Plan
• Pend Oreille County
• Section 404 of Clean Water Act
• US Army Corps of Engineers