Bioengineering Demonstration and Education Project: Technical Project Details

The Bioengineering Demonstration and Education Project is located between Pearce Estate Park and the Inglewood Bird Sanctuary on the Bow River in the community of Inglewood.

The site was initially identified by The Government of Alberta (GOA) as a candidate site for a bioengineering demonstration and education project under the department’s Fisheries Habitat Enhancement and Sustainability (FISHES) program.

The area was unique in southern Alberta as it was heavily eroded during the 2013 flood, had extremely unstable slopes, and prior classical “hard” engineering treatments installed immediately following the flood (rock groynes and rip rap bank protection) and could be used for comparison to the proposed bioengineering treatments.  

These physical elements provided an excellent opportunity to apply a variety of bioengineering treatments to address riparian health, slope stability, bank erosion, and fisheries habitat issues which varied significantly from site to site across the project area.

Early in the planning stages, it was recognized that the project aligned with and complemented a wide variety of The City of Calgary and Government of Alberta policies and programs. The project achieves key outcomes and speicifc actions under the City’s Riparian Strategy and Riparian Action Program and the Government of Alberta’s FISHES Program and the Watershed Resiliency and Restoration Program’s Strategic Plan. 

Project design

Design consultants, Kerr Wood Leidal Associates Ltd. and Hemmera Envirochem Inc., were engaged by GOA prepare bioengineering designs for each of the separate sites within the project area, with an aim to demonstrate a diverse and broad variety of bioengineering treatments in different environmental (i.e. moisture, soil and slope conditions). The scope of work also included preparation of an education plan and a long-term. 10 year monitoring plan for the project.

The designers worked closely with a number of geophysical, bioengineering, landscape and environmental education sub-consultants and local groups including, Thurber Engineering Ltd., Terra Erosion Control Ltd., Polster Environmental Services Ltd., O2 Planning and Design Inc., River Watch and Bow Habitat Station to create a final plan for the project.

"The designs are based on providing rock armor extending to the vegetation trim line to protect against scour, bank erosion and ice abrasion, and various bioengineering treatments to the top of bank to provide bank protection and improve riparian, aquatic and terrestrial habitats while also improving aesthetics. Several bioengineering treatments have been included in the design to showcase a diversity of techniques applicable to each site. Human and wildlife passage are factored into the design and have highly influenced the final layout“

HEMMERA DESIGN REPORT (4. Proposed Design, Page 4-1 – 31/142)

The Bioengineering Demonstration and Education Project ​uses a variety of bioengineering techniques (such as brush mattress and fascines) along with other fish habitat enhancements (such as boulder clusters) to stabilize steep slopes along the west bank, create habitat and enhance visual aesthetics.

​​The existing topography, river hydraulics, geomorphology, habitats and erosion protection influenced the design of each sub-site, where different bioengineering techniques were selected to address these conditions and to showcase a range of treatments.

About the project

This project offers a unique opportunity to urban planners, environmental consultants and engineers to scientifically evaluate soil bioengineering techniques and their use in riparian restoration projects.

Questions?

Do you have questions about the project, monitoring results or bioengineering?

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Key design features of each site

Site One

Approximately 370m in length, located along the west bank of the Bow River extending approximately 280m upstream of the Cushing Bridge on 17th Ave. to the first rock groyne (upstream groyne).

Pre-Construction Conditions: While the bank did not retreat during the 2013 flood, larger trees were uprooted exposing the existing concrete rubble riprap beneath.

Design features:

  • Vegetated wildlife corridor and regional pathway
  • Vegetated riprap with rooted live cuttings
  • Vegetated timber crib wall
  • Fish habitat rock spurs
  • Fish habitat boulder clusters
  • Vegetated soil wrap
  • Brush Mattress with rock toe
  • Brush layer with contour fascline

Site Two

Approximately 120m in length, located on the river-right bank of the Bow River. The site abuts and starts immediately downstream of Site 1 and is bounded by the two existing rock groyne structures installed prior to the Bioengineering Demonstration and Education Project.

Pre-Construction Conditions: Bank receded 17m during the 2013 flood (KWL, 2016)

Design features:

  • Box Fascine
  • Slope treatment A: Brush Mattress with Contour Fascine
  • Slope treatment B: Hedge Brush Layers
  • Slope treatment C: Live Staking

Site Four

Extends from the downstream groyne of Site 2, a distance of approximately 360m on the river-right bank of the Bow River. The site includes the pre-existing rip rap bank protection, installed immediately following the 2013 flood, which ends near the Inglewood Bird Sanctuary. Site 4 is immediately adjacent to 8 Avenue S.E.

Pre-Construction Conditions: Consisted of existing riprap bank protection with vegetated upper bank slope, above the 5-year flood level.

Design features:

  • Vegetated rip rap method A: Soil covered riprap with container shrub plantings
  • Vegetated rip rap method B: Void filled riprap using top soil and plug plantings
  • Vegetated rip rap method C: Void filled riprap using pitrun and live cutting plantings
Pearce Estate Park

Putting down roots

Riparian restoration designs should incorporate the use of native species that are adapted to the environmental characteristics of the restoration site and to the desired end land use.

Specific plant species were chosen based upon “Classification and Management of Riparian and Wetland Sites of Alberta’s Prairie Biome” (Thompson and Hansen, 2002) and an approved planting list provided by The City of Calgary.

Native woody vegetation with adventitious roots, like willows and poplar, are best suited for bioengineering projects. Examples of live cuttings used in the Bioengineering Demonstration, and Education Project include:

  • Yellow Willow (Salix lutea)
  • Sandbar Willow (Salix exlgua)
  • Balsam Poplar (Populus balsamifera)
  • Red Osier Dogwood (Cornus stolonifera)

What is a cutting?

A cutting is a portion of a branch or stem harvested from a parent plant for the production of a new independent plant that will form shoots and roots under the right environmental conditions.

Cuttings are the main live vegetation material used in bioengineering construction. When plant roots and branches grow along the river’s edge they weave together forming a sturdy network that helps hold soil in place and provides natural habitat for fish and wildlife.

Willow stakes

Photo of willow stakes used on site.

The table below describes the bioengineering techniques used on-site.

Technique Use Example
Vegetated Riprap with Rooted Live Cuttings:
Rooted live cuttings are carefully planted into joints or open spaces between existing or placed riprap. Special backfilling and soil amendments are needed to protect and support the delicate root mass.
  • Provides instant leaf cover
  • Provides a jump start to normal willow stake pocket plantings growth where dense cover is desired quickly
  • Improves riparian habitat
  • The willow stakes further strengthen the riprap’s erosion resistance
  • Allows construction of bioengineering projects outside of the recommended window for live cutting dormancy
Vegetated Riprap with Rooted live cuttings
Timber Crib Wall:
A structure made of interlocking logs with live vegetation placed between the seams of each layer.
  • The timber structure acts as a retaining wall.
  • Effective means of stabilizing steep slopes
  • Timber provides immediate protection and stability.
  • Vegetation provides overhanging cover for fish
  • Live cuttings grow and the resulting root mass binds together the internal fill and the adjacent undisturbed soil further strengthening the structure
Timber crib wall
Timber Crib Wall with Fish Shelters:
Submerged fish habitat niches are created by placing the crib wall on concrete blocks and large rocks.
  • Provides instant bank cover while the vegetation cover grows in
  • Can provide rest area in fast moving water for fish and waterfowl
  • Targeted to fish species e.g. brown trout that prefer complex bank cover
Timber crib wall with Fish Shelters
Vegetated Soil Wrap:
Multiple layers of planting material wrapped in a biodegradable geotextile separated by rows of live cuttings.
  • Allows earthen slopes to be constructed at steeper angles then would be possible with rock materials
  • Protects against surface erosion while vegetation is still maturing
  • Useful on slopes that are difficult to vegetate because the wraps can be filled with enriched soils without washing away
  • Live stakes will root and grow, stabilizing the soil by reinforcing and binding soil particles together.
Ss
Brush Mattress:
A layer of interlaced live cuttings placed like a flat mattress on the riverbank.
  • Can replace rock rip rap armoring
  • Rapidly achieves dense vegetative cover and intensive rooting in stream bank
  • Provides immediate soil reinforcement
  • Traps overbank sediment and holds soil moisture
  • Produces a filter barrier reducing erosion and sedimentation
Brush mattress
Box Fascines:
Horizontal bundles of live plant material placed at the bottom of an eroding bank often secured in place withwooden poles and wire.
  • Typically used at the toe of slopes to provide a physical barrier to trap sediment coming off the slope from entering the river
  • Roots and shoots which develop from the cuttings in the bundle help bind the toe of the slope and prevent toe erosion which is the primary mechanism for bank failures
  • Provides habitat for fish and wildlife by creating shade and, cover
Box fascines
Brush Mattress with Contour Fascine:
A layer of interlaced live cuttings placed like a flat mattress at the toe of the riverbank followed by rows of cylindrical bundles on contour and equally spaced up to the top of the slope.
  • Used primarily for bank erosion protection.
  • Can replace rock riprap armoring.
  • Forms an immediate vegetative cover on the bank
  • Contour Fascines act as a sediment barrier
Brush mattress with Contour fascine
Hedge Brush Layers:
Several horizontal rows of live cuttings interspersed with native shrubs. Plants are driven in perpendicular to the slope or placed horizontally into a trench and backfilled.
  • Plants produce deep roots in the soil and provide greater support and slope stability
  • Provides protection against surface erosion.
  • Rooted plants can be added to the brush layer for additional benefits such as nitrogen fixing, food sources for wildlife, plant species diversity, etc.
Hedge brush layers
Live Staking:
Single live cuttings inserted into the ground like stakes and spaced between 20cm to 1m apart
  • A common bioenginnering technique to establish vegetation on disturbed slopes. Installation can be simple when soil conditions are favorable.
  • Live stakes will root and grow, stabilizing the soil by reinforcing and binding soil particles together.
  • Technique takes time for vegetation to mature but will eventually provide the same riparian density and cover as other methods
Live staking

Vegetated RipRap Techniques:
On site we used three techniques on existing rock armored slopes to recover shoreline vegetation and its benefits. These techniques are:

  • Soil Covered RipRap with Container Shrub Plantings: A granular filter and a layer of topsoil is placed on top of existing rip rap and planted with shrubs.
  • Void Filled RipRap with plug Plantings: Planting material inserted into the opening between and over riprap and planted with plugs.
  • Void Filled RipRap with Live Staking: Planting material inserted into the opening between and over riprap and planted with live stakes.
  • Live staking of existing riprap improves riparian, aquatic, and terrestrial habitat while softening rock appearance.
  • Suitable for enhancement or retrofit of existing riprap of shallow to moderate thickness.
  • Provides bank stability and prevents erosion of stream bank by combining both rock and live root systems protection.
  • Provides habitat for fish and wildlife by creating shade, cover and small organic debris input to the watercourse
Vegetated Soil wrap
Void-filled Riprap with Plug Plantings
Void-filled Riprap with Joint Plantings

Please note: A soil amendment was placed on all soils used in the project - particularily the soils in immediate contact with live cuttings. The application of soil amendments within bioengineering techniques will address deficiencies in soil chemistry (e.g. soil salinity, available nitrogen, phosphorous, potassium, pH, soil toxins) and will enhance soil moisture retaining capacity.

The table below describes the fish and wildlife habitat strategies used on site:

Technique Use
Fish Habitat Structures:
  • Fish Habitat Rock Spurs: Located in front of rock boulders that support the timber crib wall. Structure extends out from the bank into the stream to deflect flowing water away from the bank
  • Fish Habitat Boulder Clusters: Consists of three boulders placed in a triangular pattern in the stream
  • Overhanging Vegetation: The live cuttings installed as part of the bioengineering treatments will grow into overhanging vegetation, and will provide cover along the bank
  • Provide fish with areas of refuge from predators, competitors and periods of high flow
  • Overhanging vegetation provides cover, shade and a food source by providing habitat for insects. Young or small fish are especially dependent on areas with cover to feed
  • Rock spurs provide in stream cover by creating small scour holes and providing velocity shelter below the boulders
Wildlife Corridor:
  • Wildlife need to move between habitats for many reasons including breeding, hunting and finding new food sources
  • A wildlife-friendly corridor was created to allow wildlife to safely move through this area
  • Mature plant height was considered in the design of the wildlife corridor in order to maintain clear passage and sightlines for wildlife and humans
  • Shrubs adjacent to the bridge underpass will allow cover for animals approaching the structure and no large vegetation was planted directly under or adjacent to the structure so that wildlife can see thru the structure to suitable habitat on the other side
  • Microhabitat complexity was maximized using materials salvaged from site clearing to encourage use by smaller wildlife
  • Using native species enhances the riparian zone as nesting habitat for birds, cover for small mammals and habitat for various insects
Bank Swallow Nests:
  • Bank swallows are protected under the Federal Migratory Birds Act. An area of nesting habitat at site 2 was left untouched
 

The table below describes the “hard” engineering techniques existing on site.

Technique Use
Riprap:
  • The placement of rock along a shoreline to armor the bank
  • Well proven method of mitigating erosion
  • Relatively permanent in nature with minimal maintenance needed when properly designed
  • Can be used where water velocity is too high to allow for bioengineering alone
  • Should be combined with bioengineering techniques on big rivers to prevent erosion below the water line at the toe of the bank
  • Considered ecologically harmful due to lack of overhead cover and impacts to wildlife migration
Riprap Groyne:
  • A rock structure that interrupts water velocity and redirects flow away from the bank
  • Protects banks from erosion

Project resources

  • Site Assessment Report: Summarizes background knowledge and initial site assessments made by Hemmera’s Integrated Project Team
  • Final Design Report: Provides a summary of the analysis and final design of the works associated with bank protection, fish habitat enhancement and riparian restoration of the Bow River.
  • Construction Drawings

Planning Resources

For more information on planning Riparian Restoration projects in Alberta, or determining priorities for fish habitat restoration projects, the following may be useful:

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