Plantings & Bioengineering

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Darren Brice Cole
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1 Plantings & Bioengineering Cathy Rosenthal Watershed Coordinator Wyoming Association of Conservation Districts What is Bioengineering? A few definitions.. Bioengineering is also referred to as soil bioengineering, ecoengineering, biotechnical soil stabilization, and water bioengineering. They all basically refer to the use of live and dead herbaceous and woody plant materials in combination with natural and synthetic support materials for slope stabilization, erosion reduction, and vegetative establishment (Hoag, Fripp NRCS, 2002) Soil bioengineering is an applied science that combines structural, biological, and ecological concepts to construct living structures (plant communities) for erosion, sediment, and flood control. Although soil bioengineering implies that this type of work is an engineering feat, it is not. It is more horticultural. The goal is plant growth and bank stability. (USFS, 2002) 1

2 The most basic definition: streambank soil bioengineering uses plants, or plants and inert material to increase the strength and structure of the soil. Streambank soil bioengineering is dependent upon the establishment of plant species at the boundaries of a river or stream (Riparian Zone). Therefore, it is critical that practitioners understand the function and importance of this area. Riparian areas are where water saturates the soil more than adjacent areas and where waterloving vegetation is concentrated. 2

3 Riparian areas / zones are very important because they provide: Erosion control by regulating sediment transport and distribution Roots stabilize the streambank Enhance water quality (temp. & nutrients) Produce organic matter for aquatic habitats Provide food, Shelter for Animals Wild & Domestic Riparian Planting Zones Different zones require different plantings and different techniques. Flood Prone Elevation Transition Zone Upland Zone 3

4 Toe Zone Fascines Coir Log Engineered Log Jams (ELJs) Rootwads Brush/Tree Revetments Brush Box Hard Protection Lunkers Log Cribwall Brush Barbs Bank Zone Live Poles/cuttings/stakes Brush Layering Brush Mattress Wattle Fence Vertical Bundles Vegetated Reinforced Soil Slope MSE walls Joint Planting Overbank and Transition Brush Trench Live Clumps Containerized Erosion Control Fabric Lots of exceptions, combinations, modifications, and alternatives Transition Zone Upland Zone 7 The identification of the zone is not always an easy call The use of zones in planning and design should be used as a guide Bank Zone Toe Zone Overbank Overbank Connecticut Massachusetts Look for what is already growing in the banks. Bank Zone Toe Zone At this site, it appear P that the stream has eroded up to the alders. Alders 8 are more common in the bank zone in high precipitation areas. 4

5 TOE ZONE Elevation zone between the bed and the average water elevation. Zone of highest stress -Inundated the longest Toe Zone is very low in this small stream South Carolina If the toe isn t secure then nothing is secure! Maine Sedges along the Toe Zone P 9 Utah Coir Logs (FIBERSCHINE, FIBERROLL, BIOLOG) A manufactured product Generally made of natural materials (Photo courtesy of Hollis Allen) P 10 5

6 Often used with other techniques January 2003 Coir log toe with erosion control fabric placed on the overbank zone at construction disturbance November 2003 P 11 Little Colorado River November 2005 Fascines Long, cigar shaped bundles of live material anchored to bank Only placed at toe zone if used on a shallow stream Helps control Surface erosion Prevention of rill/gully formation Traps sediment Reduces slope steepness Protects against very shallow slides Fascines can also be used as drains to collected runoff Fascine toe and brush mattress P 12 Trout Creek,

7 Placing cuttings to get a uniform shape Tying bundle every 2 ft Building a Fascine Cuttings stacked so tops and bottoms are alternated Tie bundle tightly with string or twine every 2 ft Leave end untied so that they can be spliced together Finished bundle before splicing P 13 Baccharis Fascine Cherry Creek, AZ Finished Treatment Installation Note orientation of stake After one growing season P 14 7

8 A continuous line of dead, woody material placed along the toe of the bank P 15 Snake River, WY later Brush or Tree Revetments Provides physical protection Reduces the stream velocity Causes sediment to drop out and deposit around the branches. Builds up the streambank and develops substrate for planting 2006 P

9 before Initial Treatment Brush revetment at toe with vertical willow bundles 2 years later P 17 Engineered Log Jams (ELJs) Photo from Barry Southerland Based on stable, naturally Photo from Barry Southerland occurring log jams Large, woody material Stream stability enhancement Self healing Habitat restoration Slows velocity Promotes deposition Works best in wide, shallow streams with good floodplains P 18 9

10 Rootwads Large logs along bank with root mass projecting into the flow Often as a continuous line Been used in a variety of areas Stream bank stability enhancement Habitat restoration Shade and edge cover Terrestrial habitat P 19 Caution for use of tree revetments, ELJs, and rootwads: Loose trees in the stream can do bad things P 20 Think about what will happen if they break loose 10

11 Brush Box One year after installation. Note deposited sediment. Coeur d Alene River, ID P 21 Brush Box P 22 three years after installation. 11

12 BANK ZONE Often where we see the erosion Often see the erosion in the bank zone That portion of the bank from the average water elevation to the bankfull discharge elevation. Shrubby willows, baccharis and/or dogwoods are often successful woody species for this zone. Virginia Toe Overbank Bank Massachusetts Shrub; Redosier dogwood Upland Transition Bank Toe Maine P 23 Live Cuttings, Live Stakes, Live Poles Dormant Unrooted Cuttings Induces deposition Lowers velocities Mechanically pins the stream bank Often used with other techniques Gum Springs, MD P 24 Santa Maria, CA 12

13 Typical one year growth for a dormant unrooted cutting planted in the correct Riparian Planting Zone P 25 Willow Plantings P 26 13

14 Waterjet Stinger P 27 Brush Mattress Typically for stream banks Rapid immediate protection Traps sediment Labor intensive P 28 Photo from Hollis Allen 14

15 Vertical Bundles P 29 NOTE: Key to success is good soil to stem contact!! Vegetated Geogrid Also called brush layering with soil wrap and Vegetated Reinforced Soil Slope Similar to branch packing except that natural or synthetic geotextile materials are wrapped around each soil lift between the layers of live branch materials. (NRCS Chpt 16) Used above and below bankfull Constructed during low water Can be time consuming to construct Functions immediately Can be used on steep slopes. Not a retaining wall unless other work is done P 30 15

16 After 6 months and a high flow Note: consider project performance both long term and immediately after construction After 1.5+ year A Streambank soil bioengineering project is not as strong initially as it is once vegetation is firmly established. Massachusetts P 31 Overbank & Transition - Clump Planting Digging live willows including the above ground biomass and as much of the root system as will fit in the bucket. Pull sod over hole P 32 16

17 Excavate hole to water table Root collar below ground Backfill and water P 33 Oct 2005 Trim off ends June 2006 June 2006 P 34 Salmon River, ID 17

18 Geotextile Mat Turf Reinforcement Mat and Erosion Control Mat P 35 Sedge Sod Planting P 36 18

19 Streambank Soil Bioengineering - Problems The most commonly encountered problems are most often associated with planting in the wrong bank zone. Too low Too high Others: Inadequate soil to stem contact Improper harvesting and preparation of the live material Inadequate Installation Predation Unstable channel Excessive velocities P 37 Many things to consider! Observe the location and existing types of vegetation in and adjacent to the project Climate Is the stream bed and channel stable? Do you have adequate soil to stem contact? Will the veg. catch sediment, etc. Prepare for excessive velocities Need to select appropriate plant materials Specific for each zone Funding, can you spend more if you need more materials? 19

20 References & Useful Tools Lots of helpful information from NRCS to help you with a soil bioengineering project Questions?? 20

Various options are discussed below.these low cost, low impact interventions can also be applied as general erosion control methods.

Various options are discussed below.these low cost, low impact interventions can also be applied as general erosion control methods. Week 10 River Hydraulics Rehabilitating Urban Waterways (From http://hubpages.com/hub/river-bank-erosion-control-methods) See also the resources placed on Moodle. Water channels should be viewed as a resource