Soil bioengineering and ecological

Transcription

1 Soil bioengineering and ecological systems Techniques Click to proceed... Copyright 2001 Maccaferri Inc. All rights reserved. All reproduction, including photocopy, film and microfilm, is forbidden. Release

2 TABLE OF CONTENTS INTRODUCTION COIR MAT COIR NETTING TURF REINFORCEMENT MAT (TRM) PREVEGETATED BLANKET COIR ROLL ENVIROLOG GREEN GABION GREEN TERRAMESH VEGETATED REINFORCED SOIL SYSTEM VEGETATED GABION STRUCTURE VEGETATED GABION MATTRESS STRUCTURE PLANT SELECTION HARVESTING AND STORING LIVE CUT BRANCHES LIVE STAKING JOINT PLANTING LIVE FASCINE BRUSHLAYER BRUSHMATTRESS LIVE CRIBWALL REFERENCES CONTACT MACCAFERRI 2

3 INTRODUCTION This manual has been written for the benefit of engineers, landscape architects, biologists, and anyone who is concerned and interested in the protection and mitigation of ecosystems. It illustrates the compatibility of incorporating environmentally sound concepts into the design of engineering solutions. Guidance to solutions that combine engineering practices and ecological principles is provided. Definition of Soil Bioengineering This technology integrates sound engineering practices with ecological principles. It uses living plant material in combination with non-living, structural elements and manufactured products. The practice brings together biological, ecological, and engineering concepts to produce living, functioning systems for erosion and flood control, habitat, and aesthetic enhancement, and water quality improvement. Purpose of Soil Bioengineering Soil bioengineering integrates living plants, structural and manufactured materials together in mutually reinforcing complimentary roles. The structural components initially protect the site mechanically and develop a stable, healthy environment for the plants to establish. This technology is useful in the protection, stabilization, mitigation, and reclamation of slopes, streams, rivers, shorelines, wetlands, and buffers. 3

4 The Minimum Level of Energy The concept of the minimum level of energy takes in to consideration a wide variety of solutions. This concept considers the degree of intervention to solve an erosion or stability problem. The degree of intervention can go from level 0 meaning no intervention is required to a higher level requiring structural elements. The minimum level of energy requires the lowest level of intervention to achieve the optimum solution. Example, if the correct intervention is a revetment with a coir mat, the utilization of a solution with a higher level of energy like a retaining wall structure will be inappropriate. See Illustration 1. Illustration 1 Progression of Energy Levels COIR MAT BRUSHMATTRESS ENVIROLOGS GREEN TERRAMESH GABIONS LOW HIGH 4

5 Design Benefits: Soil bioengineering practices are appropriate for environmentally and aesthetically sensitive areas, such as parks, woodlands, rivers and transportation corridors, where recreation, wildlife habitat, water quality and similar values are critical. Soil bioengineering systems can be designed to withstand heavy events immediately after installation. Even if the vegetation dies, the system s structural elements continue to play an important protective role. Provides erosion control and creates hospitable conditions for native plant establishment. Helps to slow water velocities near the banks and down the faces of slopes. Offers an alternative to vertical retaining walls like gabions, concrete and blocks. Enhances conditions for the natural colonization and establishment of plants from the surrounding plant community. Dries excessively wet sites through transpiration as the vegetation grows. Provides for surface drainage and can positively affect the direction of seepage flow. Reinforces the soil as roots develop, adding significant resistance to shallow sliding and shear displacement for smaller slopes. The heavily vegetated banks filter and slow stormwater runoff and trap sediment, thereby improving water quality. 5

6 Design Considerations: Soil bioengineering is useful on sensitive or steep sites where the use of machinery is not feasible. Soil bioengineering practices are most successful where the medium has sufficient fines, nutrients, sunlight, and moisture to support plant growth. The combination of a mechanical structure and vegetation can be a good solution for even challenging environments. It is highly recommended to consult specific practitioners for specialized areas such as biological, geotechnical and hydraulic assessment. Also, consult a local plant specialist when selecting the appropriate vegetation for the project. Soil bioengineering systems are normally installed during the dormant season, usually late fall, winter or early spring. Constraints on planting times and/or availability of suitable plant materials may limit the usefulness of certain methods. Pre-planning typically avoids this problem. When using vegetation with a mechanical structure the vegetation is typically incorporated during the conventional installation, but in some cases may be added later. Select plant materials that are adapted to the site conditions. Local species are readily available and well suited to the climate, soil condition, and available moisture; therefore they make good candidates. Alternatively hybrids and ornamentals that are more tailored in appearance and produce showy flowers, fall color, and fruit may prove to be more appropriate for some solutions. 6

7 The most suitable location for plant growth should be considered. For example, emergent aquatic plants are best suited for the lower sections of a streambank or shoreline, whereas woody material generally performs better on the higher sections. Please see Illustration 2 showing suitable locations for specific plant types. Always consult with a local plant specialist. Illustration 2 Cross Section of a River Corridor (USDA Manual,1998) 7

8 Soil Bioengineering Methods Brushlayering: Live cut branches layered between successive lifts of soil to construct a reinforced slope surface. Brushmattress: Live cut branches layered on the ground and covered with soil to protect streambanks and wetland boundaries. Coir Mats and Netting: Coir mats and netting are dense, biodegradable fabrics made of coconut husk fiber (coir). They are used to trap sediment, protect streambanks and wetland shores from erosion, and to provide a stable substrate for plant establishment. Coir Roll: Coir rolls are made of coconut husk fiber bound together with twine in the shape of a cylinder. They are used to stabilize shorelines, streambanks, and wetland boundaries. Green Gabion: A structure built of double twist wire mesh baskets with the front face inclined 45 or 60 degrees, lined with coconut husk fiber mats and filled with a mixture of rock and soil. These structures are installed with plant material and used as revetments for erosion control. EnviroLog: A cylindrical double twist wire mesh unit, lined with coconut husk fiber and filled with a mixture of rock and soil. Vegetation establishes in the EnviroLog, and is used as a revetment for erosion control. Green Terramesh : A retaining structure made of double twist wire mesh and reinforced with a welded wire panel. The system can be inclined at 45, 60 or 70 degree angle from the horizontal. A coconut husk fiber or geosynthetic blanket on the front face helps the vegetation to become established and confines the soil. Joint Planting: Live stakes are placed between joints of riprap or in gabion mattresses. Live Cribwall: A rectangular frame of logs or timber, rock, soil, and live cut branches used to protect slopes and streambanks. 8

9 Live Fascine: A sausage-like bundle of live cut branches typically from a species that roots easily from cuttings. Live fascines are installed along slopes or streambanks to control the erosion by reducing the length of the slope and over time by providing a vegetative buffer zone. Live Stake: Live cut branches that root easily are tamped into the ground. They are most successful when combined with other methods and/or manufactured products. Prevegetated Blanket: A coconut husk fiber or geosynthetic blanket that has been vegetated with rooted emergent aquatic plants ready for installation. Turf Reinforcement Mat (TRM): A lightweight matting made with synthetic filaments that protects against surface erosion. It can be vegetated with seed prior or after installation. Vegetated Reinforced Soil System (VRSS): Is a retaining structure made of double twist wire mesh or high tensile strength polymeric material that is wrapped around lifts of soil. Live cut branches and/or rooted plants are placed between lifts at the front face. Conventional Structures that may be vegetated: Gabion Structure: Is a monolithic and flexible structure that is made from pre-assembled double twist wire mesh boxes filled with stone. They can be used for retaining walls, weirs and channel linings to control erosion. Gabion Mattress Structure: They are made from pre-assembled double twist wire mesh boxes filled with stone to form monolithic and flexible heavy revetment for erosion control. 9

10 COIR MAT Definition: Coir mats are manufactured from coconut husk fibers and frequently used as a temporary structural and rooting medium component for ecological engineering systems. The coir fiber material is natural and long lasting (3 to 5 years in most climatic conditions). Purpose: Coir mats are commonly used for erosion control revetments and sediment traps. The mats provide immediate erosion control and a stable medium to support healthy plant growth. The coir mats are installed with vegetation. Eventually the coir material biodegrades and the cohesive strength of the root systems and flexible nature of the plants become the primary stabilizing and protecting element. Photo 1 Coir Mat 10

11 Applications: Streambank, shoreline and wetland boundary stabilization. Protection and mitigation of wetlands. Provides erosion control and creates hospitable conditions for plant colonization and establishment. Useful for temporary erosion control revetments on ditches, small slopes and embankments. Design Considerations: Coir mats have high moisture retention properties and generally last 3 to 5 years. The fiber strength, longevity and ability to retain moisture depend on the type, density and grade of the coir material chosen. Due to the degradation of the coir fibers over time, the slope should not be steeper than the natural friction angle. Live fascines can be used with coir mats as a securing device and to provide for a vegetated site. Live stakes can be used to install vegetation and to secure the mat. Vegetation such as pre-grown container plants can be installed in the coir mats. Coir mats can also be vegetated by seeding the slope. Seeding can be done before or after installation of the mat. For complete specifications and installation guidance, please contact your local Maccaferri office. 11

12 Slope Installation: Prepare the site for installation of coir mats by removing large rocks, obstructions or materials that may prevent the coir from making direct firm contact with the soil. Regrade slope per the design. If possible, save topsoil and replace once the subsoil has been removed or regraded. Store the topsoil away from the water's edge, move it to its final location and stabilize as quickly as possible. Photo 2 Installing Coir Mats 12

13 Anchor the mat at the top of the slope in a 150 mm (6 in.) deep trench. Backfill and compact the trench. Do not stretch the coir mats. Overlap parallel rolls mm (4-6 in.). Overlap from up to down stream on waterway banks and in ditches. Secure coir mats with wooden or steel stakes (typically mm (6-8 in.)long). Ensure there are sufficient stakes to maintain firm contact with the soil. Live stakes can be used instead of wooden stakes or in combination. Anchoring configuration depends upon the flow rates, soils and grading. Ensure that the coir mat is well secured and protected from overland flow, floodwaters and wind. Live fascines may be used to secure the mat, see live fascine specification for more details. Plant or seed per the design. Check all plants to ensure that they are the correct species and properly installed and maintained. 13

14 Channel Installation: Dig a trench 300 mm (12 in.) deep across the channel at the downstream end of the project. Secure the mat in the trench, backfill and compact the earth. Unroll the coir mat upstream. Secure the coir mat in intermittent trenches along the length of the channel. The mats also need to be secured in a trench along the water s edge to prevent undermining. Parallel rolls should be overlapped mm (4-6 in.) with the top overlapping the bottom in a downstream configuration. Secure the mats to the channel bed with live or wooden stakes to securely anchor the mats and maintain firm contact with the soil surface. Plant or seed per the design. Check plants periodically to ensure that they are the correct species and properly installed and maintained. 14

15 Photo 4 Established vegetation. 15 Photo 3 Coir Mats after installation.

16 COIR NETTING Definition: Coir netting is manufactured from coconut husk fiber (coir) and frequently used as the temporary structural and rooting medium component in ecological engineering systems. The netting is an open weave geotextile grid of coconut husk fibres. The coconut husk fibre material is natural, long lasting (3 to 5 years in most climates) and has high tensile strength. Purpose: Coir netting is commonly used for temporary soil reinforcement, slope and streambank stabilization, and shoreline and wetland boundary protection. The netting provides immediate erosion control and a stable medium to encourage natural invasion and support healthy plant growth. Eventually the coir material biodegrades and the cohesive strength of the root systems and flexible nature of the plants become the primary stabilizing element. Photo 5 Coir Netting 16

17 Applications: To provide temporary surface protection for slopes until vegetation is established. Provides immediate erosion control and creates hospitable conditions for plant establishment. Can be used for erosion control revetments, such as ditches, small slopes, and embankments. Protection and mitigation of wetlands. Design Considerations: Coir netting has high moisture retention properties and generally lasts for 3-5 years. However, the fiber strength, longevity and ability to retain moisture depend on the type, density and grade of the coir material chosen. Due to the degradation of the coir fiber over time, the slope should be at its natural friction angle. Live fascines can be used with coir netting to secure the netting and prevent formation of rills and gullies. Live cut branches can be placed between each layer of coir netting for shallow slope reinforcement. See the specification on brushlayering. Live stakes can be used to install vegetation and to secure the mat. 17

18 Vegetation, such as pre-grown container, tublings or bare root plants can be installed through the coir netting. The coir netting can also be vegetated by seeding. Seeding can be done before or after installation. For complete specifications and installation guidance, please contact your local Maccaferri office. Drawing 1 Cross Section of Coir Netting with Live Fascines on a cut slope. Live Fascines Coir Netting Existing Soil NOTE: Rooted/leafed condition of the plant material is not representative at the time of installation. 18

19 Slope Installation: Prepare the site for installation by removing large rocks, obstructions or materials that may prevent the coir netting from making direct firm contact with the soil surface. Regrade the slope per the design. If possible, save the topsoil and replace once the subsoil has been removed or regraded. Store the topsoil away from the water s edge, move the topsoil to its final location and stabilize as quickly as possible. Anchor the netting at the top of the slope in a 150 mm (6 in.) deep trench. Backfill the trench and tamp the soil. Unroll the netting down the slope. Overlap parallel rolls by mm (4-6 in.). Secure the netting to the slope using steel anchors, wooden or live stakes to securely anchor the netting to the slope and maintain firm contact with the soil surface. Anchoring configuration will depend upon flow rates, soils and slope gradient. Ensure that the coir netting is well secured and protected from overland flow, floodwater and wind. Live fascines may be used to secure the netting. Plant or seed per the design. Check the plants to ensure that they are the correct species and properly installed and maintained. 19

20 Channel Installation: Dig a trench 300 mm (12 in.) deep across the channel at the downstream end of the project. Secure the netting in the trench, backfill and tamp the trench. Unroll the coir netting upstream. Secure the netting in intermittent trenches along the length of the channel. Live fascines can be placed in the trench to act as a sediment trap. Specifically, the netting needs to be secured in a trench along the channel s edge to prevent undermining. Parallel rolls should be overlapped mm (4-6 in.). Secure the netting to the channel using steel anchors, wooden or live stakes to sufficiently anchor the netting and maintain firm contact with the soil surface Plant or seed per the design. Check the plants to ensure that they are the correct species and properly installed and maintained. 20

21 21 Photo 7 Coir netting with live fascine installation. Photo 6 Coir netting with live stake installation.

22 TURF REINFORCEMENT MAT (TRM) Definition: A permanent erosion control product composed of UV stabilized, non-degradable synthetic fibers. The mat is a reinforced matrix designed for permanent and critical hydraulic applications. Turf Reinforcement Mats (TRMs) provide sufficient strength and void space so that root systems can develop through the matrix. Purpose: TRMs provide permanent erosion protection on upland slopes, streambanks, wetland boundaries, and shorelines. The mats provide a stable medium to encourage natural colonization and support healthy plant growth. Photo 8 Turf Reinforcement Mat Plan View Side View Photo 10 TRM with wire mesh Photo 9 Flat Sided TRM Plan View Side View 22

23 Applications: Provides reinforcement and anchoring for vegetation. Provides erosion protection for steep slopes, channels, streambanks and shorelines. Creates a favorable environment for plant establishment. Can be used for erosion control revetments on transportation and transmission corridors. Design Considerations: Various vegetation techniques can be used with this system, including; live stakes, brushlayers, rooted woody plants, seeding, and herbaceous planting. Vegetation techniques can be incorporated before, during or after the installation of the TRM. Live stakes can be installed to secure the mat and for vegetation value. Live fascines can be used with TRM s to secure the mat and to prevent the formation of rills and gullies. The stability of the structure can be verified using the allowable shear stress of the TRM. Verify the allowable shear stress of the TRM with and without vegetation establishment. For complete specifications and installation guidance, please contact your local Maccaferri office. 23

24 Slope Installation: Prepare the site for installation of TRM by removing large rocks, obstructions or materials that may prevent the blanket from making direct and firm contact with the soil surface. Regrade the slope per the design. If possible, save topsoil and replace once the subsoil has been removed or regraded. Move the topsoil to its final location and stabilize as quickly as possible. Compact the topsoil after the installation of the mat to fill the voids. Begin at the top of the slope and secure the mat in a 150 mm (6 in.) deep trench. Backfill the trench and tamp soil. Roll the TRM down the slope. Secure the mat using steel, live and/or wooden stakes. Use sufficient stakes to secure the mat and maintain contact with the soil surface. Ensure that the TRM is well secured and protected from overland flow, floodwaters and wind. Place adjacent strips so that there is a mm ( 4-6 in.) overlap. Do not stretch the mat. Plant or seed per the design specifications. 24

25 Channel Installation: Dig a trench 300 mm (12 in.) deep across the channel at the downstream end of the project. Secure the mat in the trench, backfill and compact the soil. Unroll the mat up the stream or drainage channel. Secure the TRM in intermittent trenches along the length of the channel. Overlap parallel rolls mm (4-6 in.). Secure the mat using steel, live and/or wooden stakes to sufficiently anchor the mat and maintain firm contact with the soil surface. The voids of the mat can be filled with topsoil. Plant or seed per the design specifications. Drawing 2 Channel Lined with Turf Reinforcement Mat NOTE: Rooted/leafed condition of the plant material is not representative at the time of installation. 25

26 26 Photo 12 Established Vegetation Photo 11 TRM Slope Installation

27 PREVEGETATED BLANKET Definition: Prevegetated blankets are turf reinforcement mats or coir mats that have been established with rooted vegetation prior to installation, see Photo 13. Purpose: Prevegetated blankets provide immediate and long-term erosion protection on shorelines, wetland boundaries and streambanks. The blankets provide a stable medium to support the healthy growth and development of plants. Photo 13 Prevegetated Blanket 27

28 Applications: Aids in the establishment of rapid vegetative cover. Protects streambanks, wetland boundaries and shorelines from erosion. Can be used on existing structural elements, such as gabion revetments, when the gabions are filled with stone and soil. Useful when an instant vegetative cover is needed. Photo 14 Prevegetated Blanket ready to install. 28

29 Design Considerations: When using native plants, allow a few months for the vegetation to become established in the blanket at the nursery before installing the blanket on the site. Various plant species can be used. However, in selecting the plant species, be sure to consider the surrounding environment including the flood and drought periods and elevations. Because the plants are established before installation on site, the plants are not stressed when the blankets are installed. Therefore the plants develop quickly on site and success rates are typically high. Filling the voids in the gabion mattress with topsoil allows prevegetated blankets to be used overtop of an existing gabion mattress structure. This type of structure works best on a silt or silty clay soil. On riverbanks, ensure that the prevegetated blanket is anchored securely so that floodwaters will not carry the blanket and vegetation away. For complete specifications and installation guidance, please contact your local Maccaferri office. 29

30 Installation: Prepare the site for installation of prevegetated blankets by removing any large rocks, obstructions or materials that may prevent the blanket from making direct and firm contact with the soil surface. Cut the blanket to the desired size and secure with steel rods, wooden stakes or live stakes. Ensure that the entire blanket including the corners and edges of the blanket are securely anchored. Ensure that the prevegetated blanket is along the water s edge so that there is adequate moisture for the herbaceous emergent aquatic plants to grow. Inspection of the site should be done a few weeks after the installation to ensure that the blanket is securely anchored and is developing in a healthy manner. Always inspect a new installation after a flood event. 30

31 31 Photo 16 Healthy Established Vegetation Photo 15 Immediately after Installation

32 COIR ROLL Definition: Coir rolls are manufactured from a high-density coconut husk fiber with an exterior netting of 100% coir mesh. The coir material is natural, long lasting and has high tensile strength. Purpose: Coir rolls are commonly used for streambank stabilization and shoreline protection on low energy flows. These components provide immediate erosion control and a stable medium to support healthy herbaceous plant growth. Eventually the coir material biodegrades and the cohesive strength of the root systems and flexible nature of the plants become the primary stabilizing element. Photo 17 Coir Roll with Live Branch Cuttings 32

33 Applications: To provide stabilization along low energy stream, wetland boundary and shoreline systems. Provides immediate erosion control and creates favorable conditions for healthy plant establishment. Protection and mitigation of wetlands. Design Considerations: Coir rolls have high moisture retention properties and generally last 4 to 8 years. The fiber strength, longevity and ability to retain moisture depend on the type, density and grade of the coir material chosen. The diameter of a coir roll is typically 300 mm (12 in.). Light density coir, 8.0 kg/m (5.4 lbs/ft), is suitable for wetland mitigation, if plant establishment is the primary goal. Coir rolls work better on a streambank when the native soil is cohesive clay-like material. For complete specifications and installation guidance, please contact your local Maccaferri office. 33

34 Drawing 3 Cross Section of Coir Roll Existing Soil Lacing Twine Coir Roll Stakes Streambed NOTE: Rooted/leafed condition of the plant material is not representative at the time of installation. 34

35 Installation: Determine mean water elevation. Mark the mean water level on a stake driven into the substrate, m (1-2 ft) offshore. Installing the materials and plants on the edge of the stream at the correct elevation is the most important aspect to ensure success of the project. Determine where the installation will begin and end. Begin installation at the downstream end. Ensure that each end is well keyed into the bank 1 to 2 m (3-6 ft). Prepare the site for installation of coir rolls by removing any large rocks, obstructions or materials that may prevent the coir from making direct and firm contact with the soil. Regrade bank as per the design. Gradual slopes of 2:1 or less are preferred. If possible, save topsoil and replace once the subsoil has been removed or regraded. Store topsoil away from the water's edge and move it to its final location and stabilize as quickly as possible. Place coir rolls parallel to the streambank or shoreline. Install the coir roll so that approximately 50 mm (2 in.) of the roll extends above the mean water elevation. Lace adjacent rolls together, end to end, securely using coir bristle twine. Use untreated wooden stakes made from strong, durable wood species that does not have knots or flaws to secure the coir rolls. The stakes should be pointed at one end, not wedge shaped. Stakes for coir rolls are approximately 40 mm (1.5 in.) in diameter unless otherwise specified. For typical applications at the water edge, coir rolls are held in place with a single row of stakes, each side of the unit 300 mm (12 in.) on center. Stakes are driven through the netting on the outer edge of the roll to ensure a secure anchor system. 35 Place coir rolls along the stream banks at a height sufficient to protect the shore from flows or waves. Additional coir rolls may be required above the lower rolls, to protect the upper shore or stream bank. It is often possible to incorporate woody vegetation in the existing bank soil between the coir rolls.

36 Using bristle coir twine, lace across the stakes to hold the coir rolls in place. Weave twine back and forth across the roll and securely attach the twine to each stake by circling the stake with the twine. When planting the coir rolls, install small plants as specified in the design. When putting the plants into the coir roll, use a planting iron or pilot bar, wedging it back and forth to create a hole for the plant. It is extremely important that the root system of the plant be placed below the water level. The plants can be placed off to the side of the coir roll center line to assure the plant is low enough to be in contact with the water. 36

37 Photo 19 Installation of Coir Rolls along a shoreline combined with other living methods. Photo 18 Installation of Coir Rolls along a streambank. 37

38 ENVIROLOG Definition: The EnviroLog is an elliptical type of wire basket made of PVC coated double twist hexagonal wire mesh. It is available in 2 meters (6 ft) long, 0.5 (1.5 ft) meter high and 1 meter (3 ft) and lined with a coconut fiber blanket, as shown in Drawing 4. The coconut fiber blanket is used to contain soil and act as a substrate for insertion of woody cuttings, bare root plants or for planting herbaceous plants. The unit is filled with a combination of stone and soil. Purpose: The EnviroLogs are used as a revetment for erosion control. They form a structure when all the units are connected together. Drawing 4 EnviroLog Unit PVC coated wire 38

39 Applications: Provides immediate and long-term erosion control protection for rivers, shorelines and stream banks. Aids the establishment of a vegetative cover by creating hospitable conditions. Provides aquatic riparian cover and wildlife habitat value. EnviroLogs help to slow water velocities near the banks and trap sediment when vegetated. Design Considerations: The toe of the slope and structure will be protected from undermining by installing the units into the bed below the scour depth. These units are typically filled with stone. Various vegetation techniques can be used with this system, including live stakes, brushlayers, rooted plants and herbaceous emergent aquatic plants. Some vegetative techniques are incorporated during and others after the installation of the structure. Use site reconnaissance to identify plant species, growth form, soil and site conditions on adjacent sites and compare their conditions to the construction site. Planting will be more successful as soil, site and species selected match stable, vegetated nearby sites. The EnviroLog is not a retaining wall system and is not designed to withstand large lateral earth stresses. The design of the structure is verified by comparing the tractive force and the allowable shear stress of the envirolog. 39 The structure can be constructed during the dry low water season and the planting can be done at a more suitable time because the fill and coconut fiber blanket protect the slope from erosion until vegetation is established.

40 Geogrids can be used in combination with the EnviroLog as a reinforced soil system. The system can be inclined up to a maximum of 60 degrees from the horizontal. If the inclination exceeds 60 degrees it becomes difficult for the vegetation to become established. The coconut fiber blanket typically has a life span of 3 to 5 years, allowing sufficient time for vegetation to become established. The system provides increased strength and function once vegetation is established. For complete specifications and installation guide, please contact your local Maccaferri office. Drawing 5 Cross Section of EnviroLogs EnviroLog Live Branch Cuttings Backfill Existing Soil NOTE: Rooted/leafed condition of the plant material is not representative at the time of installation. 40

41 Installation: EnviroLogs are supplied pre-assembled in bundles. Unfold and attach end panels to the base to create an open cylinder. Place the EnviroLog in its final position. Connect the unit to the lower row and adjacent units together using lacing wire or stainless steel rings. Line inside the unit with coconut fiber blanket as specified in the design. Fill units above the water level with stone (50-70 % per volume) and topsoil. Ensure that all corners are filled. Totally submerged units should be filled with stone only. Use more stone in the lower elevations (70%) and less above (50%). Fasten the lid down and ensure that the coconut fiber blanket covers the entire surface of the EnviroLog. When live cut branches or rooted plants are being used to establish vegetation, place the branches between each layer of envirologs, above or at the low water level. See the brushlayering specification for more details. Place the next unit on top, stepping it back from the front of the unit below by mm (6 20 in.) and continue with the preceding steps. When a wider low riparian zone is desired, for example, to establish a herbaceous vegetation zone at the base the units should be stepped back 500mm (20 in.). This may be important for specific wildlife such as raccoon or mink. 41

42 Drawing 6 Installation of EnviroLogs 1. Unfold the unit. 3. Line the unit with coir mat. Connect adjacent units together using lacing wire or clips. NOTE: Rooted/leafed condition of the plant material is not representative at the time of installation. 2. Connect corners together using lacing wire or clips. 4. Place vegetation on the top of the installed unit and place next unit above. 42

43 Photos 20 and 21 Installation of EnviroLogs

44 GREEN GABION Definition: The Green Gabion is a PVC coated, trapezoidal wire basket made with an inclined front face of 45 or 60 degrees and lined with a coconut fiber blanket. The coconut fiber blanket is used to contain soil and act as a substrate for insertion of cuttings and rooted woody plant stock or for planting herbaceous plants. The unit is filled with a combination of stone and soil. Purpose: Green Gabions are used as revetments for erosion control or for streambank and shoreline protection. They provide immediate erosion protection and create hospitable conditions for healthy plant growth on a steepened embankment. Drawing 7 Green Gabion Unit PVC coated wire Coconut fiber blanket 44

45 Applications: Provides immediate and long term erosion protection for rivers, streambanks and shorelines. Provides aquatic and riparian cover and wildlife habitat value. Provides a wide variety of aesthetic looks ranging from very natural using native plants to tailored using ornamentals. Helps to slow water velocities near banks and traps sediment. Can be used as a deflector in a stream. Aids in the establishment of a vegetative covering by creating hospitable conditions for plant establishment. 45

46 Design Considerations: The units have a 45 or 60 degree inclining face. Various vegetation techniques can be used with this system, including; live stakes, brushlayers, rooted woody plants, herbaceous emergent aquatics and grasses. Vegetation techniques can be incorporated during or after installation. Use site reconnaissance to identify plant species, growth form, soil and site conditions on adjacent sites and compare their conditions to the construction site. Planting will be more successful as soil, site and species selected match stable, vegetated nearby sites. Green Gabions are not a retaining wall system. They are not intended to withstand large lateral earth stresses. The stability of the Green Gabion is verified by comparing the tractive force and the allowable shear stresses. The system provides increased strength and function once the vegetation is established. The coconut fiber blanket has a typical life span of 3-5 years, allowing the vegetation to become established. The structure can be constructed during the dry season and the planting can be done at a more suitable time. The coconut husk fiber blanket protects the slope from surface erosion until vegetation is established. For complete specifications and installation guidance, please contact your local Maccaferri office. 46

47 Drawing 8 Cross Section of Green Gabions Emergent Aquatic Plants Coir Roll and Soil Green Gabions Live Cut Branches Existing Soil NOTE: Rooted/leafed condition of the plant material is not representative at the time of installation. 47

48 Installation: Installation begins at the base of the slope and possibly below the channel bed. Unfold the units and place the coconut fiber blanket on the inside of the front face. Be sure to overlap the coconut blanket 300 mm (12 in.) on the top and bottom of the face unit. Secure the coconut fiber blanket to the woven wire mesh with lacing wire. Erect the corners of the Green Gabions and connect them to the side panels with lacing wire. The front panel of the Green Gabion should only be connected to half its height. Finish connecting the front face after the Green Gabion has been filled half way. Connect the Green Gabions together by lacing the edges of the adjacent units together using the proper technique. Fill the Green Gabion with stone (50-70% by volume) and vegetative soil. Fill all corners. Connect the lid. Place the next unit on top and continue with the preceding steps. If the vegetation to be used is live cut branches or rooted woody plants, place the branches or plants between each layer of Green Gabion, above the low water level. Plant per the design specifications. For proper installation of the brushlayering, rooted plants and live staking, see those specifications in this document. 48

49 Drawing 9 Green Gabion Installation 1. Unfold the units. 2. Line the front face with coconut fiber blanket. 3. Erect and connect corners to side panels. 4. Fill with mix of stone and soil. 5. Plant vegetation. NOTE: Rooted/leafed condition of the plant material may not representative at the time of installation. 49

50 22 23 Photos 22, 23 and 24 Green Gabion installation and initial vegetation growth

51 GREEN TERRAMESH Definition: Green Terramesh is a structure of PVC coated double twist hexagonal wire mesh used for soil reinforcement applications. The front element is reinforced with a welded wire panel and is lined with a biodegradable or synthetic blanket. Steel brackets are used to give the inclination of the front face. A continuous wire mesh panel forms the facing element and anchor sections. Green Terramesh units are supplied cut to the specified measurements therefore no cutting is required on site. Purpose: Green Terramesh systems are used for erosion control, soil reinforcement and slope stability applications. This system integrates well into natural surrounding environments. Top Tail Coconut Fiber Blanket Steel Bracket Welded Wire Panel Photo 25 Green Terramesh Unit Anchor 51

52 Applications: Green Terramesh is an alternative to near vertical retaining structures. Provides protection for rivers, streambanks and shorelines. Green Terramesh is ideal for land development projects on steepened landscape sites. Provides aquatic and riparian cover and wildlife habitat benefits. Provides a wide variety of aesthetic looks ranging from very natural using native plants to tailored using ornamentals. Provides immediate and long term protection from surface erosion and geotechnical failures. Design Considerations: The units have a 45, 60 or 70 degree inclining face, to enhance vegetative growth. Using a continuous mesh panel for the facing element and anchor offers the advantage of reducing connection failure. Various vegetation techniques can be used with this system, including; live stakes, rooted woody plants, herbaceous emergent aquatics, and grasses. Vegetation techniques are incorporated after the installation of the structure. Use site reconnaissance to identify plant species and soil conditions on adjacent sites and compare their conditions to the construction site. Planting will be more successful if the species selected is similar to plants found on nearby sites. Install drainage at the back of the reinforcement if seepage is a factor. 52

53 The system is a mechanically stabilized earth structure. It is important to verify the stability of the slope prior to construction. Slope stability analysis programs are available and should be used. For complete specifications and installation guidance, please contact your local Maccaferri office. Drawing 10 Cross Section of Green Terramesh Live Cut Branches Gabionmat or Reno Mattress Backfill Existing Soil Green Terramesh NOTE: Rooted/leafed condition of the plant material is not representative at the time of installation. 53

54 Installation: Unfold the Green Terramesh units and place at the bottom of the slope or streambank. In a channel situation, the structure needs to start below the scour depth. The units are pre-cut to the length specified in the design; therefore no cutting needs to be done on the site. Raise the front face of the units, attach the steel bracket to the top of the welded wire panel, then connect the steel bracket to the reinforced bar in the anchor panel. Place the units side by side and secure them together using lacing wire or stainless steel rings. Topsoil should be placed on the back of the facing element (minimum of 300 mm (12 in.)). Compact using a small machine such as a skid compactor. Place granular backfill on the anchor panel in 250 mm (10 in.) lifts and compact. Compaction of the backfill should be done as specified in the design. Place the next unit on top and connect the units together. Continue with the preceding steps until desired height is reached. When live stakes or rooted woody plants are used to establish vegetation, install them in the face. See the live stake specification for more details. Vegetate per the design specifications. 54

55 Drawing 11 Installation Steps for Green Terramesh 1. Single, factory made unit, folded ready to place in position. 3. Backfill. 2. Open the Green Terramesh unit along the lower reinforcing wire. 4. Fold the top tail down and place the next unit on top. 55

56 Photo 26 Green Terramesh immediately after installation. 56 Photo 27 Green Terramesh in the first growing season.

57 VEGETATED REINFORCED SOIL SYSTEM (VRSS) Definition: Vegetated reinforced soil systems can be constructed using geogrids. Geogrids are high tensile strength polymeric panels formed by intersecting ribs joined at the junctions. The reinforcing panels are wrapped around layers of soil with live cut branches, rooted or herbaceous plants installed in between the layers. The front face of the vegetated reinforced soil system is lined with a coconut fiber or geosynthetic blanket. Purpose: Vegetated reinforced soil systems are used to stabilize slopes, particularly fill slopes. The reinforcing anchors interact by friction and interlocking with the soil to achieve the desired stability. This system integrates well into natural surrounding environments. Drawing 12 Vegetated Reinforced Soil System Coconut Blanket Geogrid 57

58 Applications: Can be used for upland slopes, streambanks and shoreline areas. The VRSS is an alternative to near vertical retaining walls. Provides immediate and long-term protection from surface erosion and geotechnical failures. Provides a wide range of aquatic and riparian cover and wildlife habitat benefits. Provides a wide variety of aesthetic looks ranging from very natural using native plants to tailored using ornamentals. Helps to slow near bank water velocities and trap sediment. Design Considerations: The system can be inclined up to 60 degrees from the horizontal. The maximum of 60 degrees enables the vegetation to establish on steeper slope angles. If seepage is a concern incorporate a drain into the back of the reinforcement, or use a product that has a drain incorporated into the grid. For example, Terram Paradrain. The system is a mechanically stabilized earth system. The stability of the slope should be verified using a slope stability analysis program. Use site reconnaissance to identify plant species, growth form, soil and site conditions on adjacent sites and compare their conditions to the construction site. Planting will be more successful as soil, site and species selected match stable, vegetated nearby sites. Grass is not recommended as a vegetation treatment on the VRSS. 58

59 Various vegetation techniques can be used with this system, including brushlayering, live stakes and rooted woody plants. Vegetation techniques are incorporated during installation of the structure. For complete specifications and installation guidance, please contact your local Maccaferri office. Drawing 13 Cross Section of Vegetated Reinforced Soil System Live Branch Cuttings Backfill Geogrid Existing Soil Gabionmat or Reno Mattress NOTE: Leafed condition of the plant material is not representative at the time of installation. 59

60 Installation: Installation begins at the base of the slope and below the scour limit. Install batter boards at the front, the height of the wrapped lift. Cut the reinforced panel to the exact length as specified in the design Lay the panel flat at the required level and position with the wrap-over portion extending beyond the front profile line of the slope, up and over the batter boards. Approved backfill should be placed on the reinforced panel in layers as specified in the design, typically mm (4-6 in.) lifts. Compact using a small machine as specified in the design. The bottom wrap that will be submerged in water should be filled with a 50/50 mix by volume of rock and approved backfill. For all other wraps above the water use backfill only. Approved backfill should be placed on the back of the facing element (minimum of 300 mm (12 in.)). Wrap the extended portion of the panel back over the top and secure by staking it down. Repeat the preceding steps until the desired height is reached. If live cut branches or rooted plants are being used to establish vegetation, place these materials between each layer of reinforcing panels. See the brushlayering specification for more details. Plant per the design. Do not overseed these systems with grasses. 60

61 Drawing 14 Vegetated Reinforced Soil System Installation 1. Place the reinforcing panel and coconut fiber blanket in position. Place a temporary batter board on the front face. 3. Wrap front face and top tail around backfill and remove the batter board. 2. Place the backfill in layers onto the reinforcing panel. 4. Install vegetation and place next piece of reinforcing panel on top of the previous, repeating the process until design height is reached. NOTE: Leafed condition of the plant material is not representative at the time of installation. 61

62 Photo 28 Installation of the Vegetated Reinforced Soil System (VRSS) using EnviroLog and geogrid as the reinforcement. 28 Photo 29 Development within the first growing season

63 VEGETATED GABION STRUCTURE Definition: Gabion structures are made from pre-assembled double twist wire mesh boxes filled with stones to form monolithic, flexible structures. Gabions are free draining elements. Live cut branches or rooted plants can be installed between the rows of gabion baskets. Purpose: Gabion retaining structures are used to stabilize slopes and for erosion control. Gabion structures can integrate with the surrounding environment, permitting the preservation or mitigation of a natural environment. Drawing 15 Gabion Element PVC coated Wire Mesh Lid Diaphragm 63

64 Applications: Can be used for upland slopes, streambanks and shoreline areas. Provides immediate and long-term protection from surface erosion and geotechnical failure. Provides a wide variety of aesthetic looks ranging from very natural using native plants to tailored using ornamentals. Helps to slow near bank water velocities and trap sediment. Design Considerations: The system can be near vertical or the facing can be inclined for a more suitable environment for plants. When gabions are used on streams, shorelines, and wetlands, the wire should be PVC coated. The system is a retaining wall. The stability of the slope should be verified using a slope stability analysis program. Use site reconnaissance to identify plant species, growth form, soil and site conditions on adjacent sites and compare their conditions to the construction site. Planting will be more successful as soil, site and species selected match stable, vegetated nearby sites. Various vegetation techniques can be used with this system such as live stakes and rooted woody plants. Vegetation techniques are incorporated during installation of the structure. When live stakes or live cut branches are used with a structural element like gabions, plantings should be done with caution because the structure is free draining. Drought tolerant vegetation will work best. It is preferable to use this technique on structures that are less than three meters (9 ft)in height. 64

65 It is recommended that vegetation be long and installed more densely due to the survival rate. For complete specifications and installation guidance, please contact your local Maccaferri office. Drawing 16 Cross Section of Vegetated Gabion structure Live Branch Cuttings Gabion Backfill Existing Soil NOTE: Leafed condition of the plant material is not representative at the time of installation. 65

66 Installation: Installation begins at the base of the slope and below the scour limit. Open and unfold the gabion baskets. Eliminate all folds due to packaging. Pull up the sides and the diaphragms to form an open box. Join the edges together, using appropriate lacing techniques. Install a few empty gabion baskets in their final location, placing them side-by-side and back-toback. Lace them together tightly at the contact edges. The rows above and below should be laced together at the edges. Fill the gabions with stone ranging from 100 to 200 mm (4-8 in.) in diameter. The connecting wires are placed at the 1/3 and 2/3 levels for gabion baskets of one metre height and at half-height for gabion baskets of 0.5 meter (1.5 ft) height. Lace the lids to the edges of the basket s selvedge wire. A crow bar or steel bar can be used to facilitate lid closure. Repeat the preceding steps until the desired height is reached. If live cut branches or rooted plants are being used to establish vegetation, place these materials between each row of gabions, ensuring that the vegetation is well into the backfill behind. Typically one meter (3 ft) in length beyond the back of the gabion structure is recommended. The root systems should reach the groundwater table during the summer. 66

67 Drawing 17 Vegetated Gabion Structure Installation 1. Gabions are supplied in bundles. 3. Lace sides and diaphragms to form open box. 2. Unfold the gabions 4. Fill the gabions with stone and lace lid closed. NOTE: Rooted/leafed condition of the plant material is not representative at the time of installation. 67

68 Photo 30 Installation of the Vegetated Gabion Structure immediately after construction. 30 Photo 31 Vegetated Gabions in the first growing season

69 VEGETATED GABION MATTRESS STRUCTURE Definition: Gabion mattress structures are made from double twist wire mesh boxes. They are filled with stones to form monolithic flexible structures. Gabion mattresses are free draining structures. Live cut branches or rooted plants can be inserted in between the stones in the unit. Cells can be completely or partially filled with soil. Purpose: Gabion mattresses are used for erosion control. They can develop and integrate with the surrounding environment, permitting the preservation or mitigation of a natural environment. Drawing 18 Gabion Mattress Element Filled with Top Soil Gabionmat or Reno Mattress Stone Topsoil Erosion Control Blanket Vegetation NOTE: Rooted/leafed condition of the plant material is not representative at the time of installation. 69

70 Applications: Can be used for streambanks and shoreline areas. Provides immediate and long-term protection from surface erosion. Provides a wide variety of aesthetic looks ranging from very natural using native plants to tailored using ornamentals. Helps to slow near bank water velocities and trap sediment. Design Considerations: Use site reconnaissance to identify plant species, growth form, soil and site conditions on adjacent sites and compare their conditions to the construction site. Planting will be more successful as soil, site, and species selected match stable, vegetated nearby sites. The toe of the slope and structure will be protected from undermining by installing the units into the bed below the scour depth. Various vegetation techniques can be used with this system, including live stakes, brushlayers, rooted plants, and herbaceous emergent aquatic plants. Vegetative techniques are incorporated during or after the installation of the structure. During the right season prevegetated blankets may be installed and held in place with the wire mesh lid. The gabion mattress structure is not a retaining wall system and is not designed to withstand large lateral earth stresses. 70

71 The design of the structure is verified by comparing the tractive force and the allowable shear stress of the gabion mattress. The structure can be constructed during the dry low water season and the vegetation, such as joint planting, can be done at a more suitable time. For complete specifications and installation guidance, please contact your local Maccaferri office. Drawing 19 Cross Section of Vegetated Gabion mattress structure Emergent Aquatic Plants Gabionmat or Reno Mattress Topsoil confined with an erosion control blanket in a cell Existing Soil NOTE: Rooted/leafed condition of the plant material is not representative at the time of installation. 71

72 Installation: Unroll the gabion mattress on a flat, hard surface. Pull up the sides, diaphragms and ends to form open cells. Be sure the top of the ends and the sides are at the same level. Attached the diaphragms to the sides and ends using the appropriate connecting procedures. Edges are joined together, using appropriate lacing techniques. Fill the gabion mattresses with stones. The diameter of the stones should be between 85 to 140 mm (3-6 in.). Lace the lids to the edges of the gabion mattress s selvedge wire. A crow bar or steel bar can be used to facilitate lid closure. If live cut branches or rooted plants are being used to establish vegetation, place these materials between the stones. See the joint planting specification for more details. Topsoil can be place between the stones to fill the voids in the gabion mattress to create a better environment for the development of vegetation. Plant per the design. 72

73 Drawing 20 Gabionmat Installation 1. Open the gabionmat. 3. Cover stone with topsoil. Place erosion control blanket on top of stone and attach lid. 2. Connect the sides, ends and diaphragms. Fill with stone. 4. Plant with live stakes. NOTE: Rooted/leafed condition of the plant material is not representative at the time of installation. 73

74 Photos 32 and 33 Installation of the Vegetated Gabionmat and Reno Mattress Structures.

75 PLANT SELECTION The selection of a plant species must consider its potential for successful establishment, long term maintenance, and project enhancement such as aesthetics, habitat value, or water quality improvement. In addition, the selection should consider salt inundation, shade, sun, and drought tolerances. A wide range of species may be selected for different purposes from native pioneer plants to ornamentals and woody plants to herbaceous aquatics. Identify plant species, growth form, and soil and site conditions on adjacent sites and compare their conditions to the construction site during the site reconnaissance. Planting will be more successful as soil, site, and species selected match stable, vegetated nearby sites. When selecting plant species, it is best to use several varieties that meet the required criteria. In doing so consider the growth rate and competitiveness of each species. Some plants are considered very invasive and should be used cautiously. Others may be too sensitive for establishment. It is best to choose hardy, broad spectrum species. Availability of the desired species and the construction time frame needs to be carefully planned. Determine whether live cut branches, container, bare root stock, and/or prevegetated mats are appropriate for the project. When specific nesting or feeding habitat values are required it may be necessary to choose container plants. Plants have several different growth forms, from shrubs to large trees. Small to medium sized shrubs are useful for planting channel banks. Upland species are found in relatively dry areas and should be used on similar sites. Trees maybe selected for over the bank and flood plain areas. 75

76 Consider what the end function of the plant will be in the initial construction and in the developed system when it is mature, for example; Woody vegetation has stronger and deeper root systems than herbaceous plants; therefore they are better suited for shallow mass stability applications. Herbaceous plants, such as grasses, legumes, and forbes, and emergent aquatics provide a dense ground cover that are well suited for preventing surface erosion and intercepting rainfall. However, emergent aquatic plants may be tolerant to submerged conditions. Construction personnel should handle the live plant material with care. In urban settings, such as commercial landscapes, ornamentals that produce showy flowers, berries, and/or fall colours may be the best choice. It is recommended to consult a local plant specialist when determining which vegetation to use for a project. Be sure to take natural succession into account. In specific soil bioengineering applications, species selection may be as follows: The ideal plant material for live fascines: roots easily from cuttings; is long, straight and flexible. Willow (Salix spp.) and shrub dogwood (cornus spp.) make ideal live fascine material. Use a mixture of young and older wood (1 to 4 years). The best plant materials for brushlayering are bushy branches. Plant material such as willow (Salix spp.), dogwood (Cornus spp.) and viburnum make ideal brushlayering material. When choosing live plant material for brushmattresses, use young flexible willow or cornus species for the mattress material. They are easy to install and sprout and root easily. Older wood (2 to 4 years old) that has greater vegetative energy reserves will work well for the additional live stakes. Mix young and old wood in the installation. 76

77 HARVESTING AND STORING LIVE CUT BRANCHES Harvest and install cuttings while the plants are dormant. This period is generally from late fall when the plants are entering dormancy to early spring, before the buds break. When harvesting live cut branches, select healthy, living wood from two or more locations. Use live wood that is 1to 4 years old, reasonably straight and flexible. Make clean cuts using a chain saw or similar tool. During the dormant season, when the live cut branches can not be installed immediately after harvesting store in the following manner for two to four days: In a shaded pond, lake or stream; Under a tarp in a cool moist area; or Healed in moist earth in a cool shady area. Never store on asphalt roadsides or in the sun. During the growing season, live cut branches may be under refrigeration up to two months. However, they must be harvested in the dormant season. The fresher the material the lower the stress and the better the success. 77

78 LIVE STAKING Definition: Live stake planting involves the insertion and tamping of live, vegetative, woody cuttings into the ground in a manner that allows the live stake to take root and grow. Purpose: Using a system of live stakes creates a root mat that stabilizes the soil by reinforcing and binding soil particles together and by extracting excess soil moisture. Over time top growth forms to protect the soil surface and further enhance the system. This method is commonly used in conjunction with other practices to provide for additional stability and environmentally sound site conditions (i.e., used to anchor turf reinforcement mats (TRM), coir mats, Green Terramesh, etc.). Photo 34 Live Stakes starting to sprout 78

79 Applications: Repair of small, simple, shallow, local earth slips and slumps. Areas best suited for live staking are the bottoms and banks of small incipient gullies; sediment fills behind check dams and bare gully banks. Live stakes can be tamped through interstices or openings in green gabions, Green Terramesh, EnviroLogs, riprap, or cellular confinement systems, over time offering additional environmental, mechanical and aesthetic benefits. Live stakes can be used to anchor and enhance the effectiveness of live fascines, coir rolls, geosynthetic blankets, coir mats and other erosion control materials. Live staking improves conditions for the natural colonization of the surrounding plant community. As a temporary measure, live staking performs an important function in stabilizing and modifying the soil, serving as a pioneer species until other plants become established. It is useful when a quick, simple and inexpensive repair is needed and is appropriate. 79

80 Design Considerations: On small systems, plantings can adversely affect water hydraulics and cause blocking or current deflection. Live cut stakes should be 0.75 meter (30 in.) to 1.0 meter (39 in.) long and mm ( in.) in diameter. They should be straight for easy insertion into the ground, and be long enough to reach the midsummer watertable. Live cut branches should have one or two terminal buds exposed above the ground level. Drawing 21 Cross Section of Live Stakes Live Stakes) NOTE: Rooted/leafed condition of the plant material is not representative at the time of installation. 80

81 Design Considerations: When live stakes or live cut branches are used with a structural element like gabions or the Terramesh system, plantings should be selected with caution because the structure is free draining. Live cut stakes or branches should be 1.5 to 3 meters (4.5-9 ft) long and mm (2-3 in.) in diameter. They should be straight for easy insertion into the ground, and be long enough to reach the midsummer watertable. Live cut branches should have one or two terminal buds exposed outside of the unit. Live cut branches should be protected with coir mat or geotextile from rock impact damages. Drawing 22 Cross Section of Live Cut Branches with Terramesh System Terramesh System Live Cut Branches Groundwater NOTE: Rooted/leafed condition of the plant material is not representative at the time of installation. 81

82 Installation: Install live stakes with basal ends in the ground. Leaf bud scars or emerging buds are oriented up. Live stakes must not be allowed to dry out. Live cuttings may be stored in water before installation. Cuttings installed the same day are typically highly successful. Install live stakes meters ( ft) apart in moist areas and 0.15 to 0.25 meters (6-10 in.) apart on dry sites. Set the live stake as deep as possible into the soil, preferably with 75 percent of its length in the soil and if possible, in contact with mid-summer water table. Live cut stakes should have one to two terminal buds exposed above the ground after installation is complete. Use an iron stake or bar to make a pilot hole in firm soil by driving it into the ground and carefully extracting it. Do not rotate the bar to enlarge the hole. It is essential to have good soil contact along the length of the stake for roots to develop. Tamp the soil around the cutting after it has been installed. Do not damage the buds, strip the bark or split the live stake during installation. Cut, remove and replace split or damaged stakes. 82

83 35 Photos 35 and 36 Green Terramesh installed with live stakes, illustrating live stakes establishing in the first growing season

84 JOINT PLANTING Definition: Joint planting is a system that installs live stakes in between the joints of previously placed riprap rock or gabion mattresses. Purpose: Joint planting increases the effectiveness of riprap rock or gabion mattresses by forming a living root mat and water filtering system in the base upon which the riprap or gabion mattress have been placed. Joint plantings also increase sediment deposition, improves water quality, habitat value, and aesthetics. Applications: Can be used on upland slopes, streambanks, riparian zones and wetland areas. Vegetation establishment improves aesthetics and provides cover by developing wildlife corridors for movement, nesting, rearing, feeding, and resting areas. Joint planting enhances conditions for natural invasion and the establishment of other plants from the surrounding plant community. Joint planting assists in protecting steep gradient streambanks from high flows. Acts as an energy dissipater on the streambank. Through consolidation of the soil particles it helps to prevent washout of fines. 84

85 Design Consideration: The riprap rock or gabion mattresses can have a maximum thickness of 0.50 meters (20 in.). The percentage of survival is somewhat lower than live staking, considering the damage during installation and drying out due to depth requirements. This may be compensated by increasing the density. On small systems, plantings can adversely affect water hydraulics and cause blocking or current deflection. Live stakes for joint planting are mm ( in.) in diameter and meters (3-4 ft) long. Drawing 23 Cross Section of Joint Planting through a gabion mattress Live Stake Gabion Mattress Existing Soil NOTE: Rooted/leafed condition of the plant material is not representative at the time of installation. 85

86 Installation: Install the joint plantings with basal ends in the ground, leaf bud scars or emerging buds oriented up. Live stakes must not be allowed to dry out. Live cuttings may be stored in water before installation. Cuttings installed the same day they are harvested are typically highly successful. Install the joint plantings meter (12-39 in.) apart. Set the live stake as deep as possible into the soil, preferably with 50 to 75 percent of its length into the soil below the rock or mattress, and if possible, in contact with mid-summer watertable. It is essential to have good soil contact along the length of the live stake for roots to develop fully along its length. Use an iron stake or bar with a smaller diameter than the live stake, to make a pilot hole in firm soil. Carefully extract the iron stake or bar. Do not rotate it to enlarge the hole. Do not damage the buds, strip the bark, or split the live stake during installation. Remove and replace split or damaged live stakes. This system typically has a lower survival rate than live staking. 86

87 Photo 37 Joint Planting in the first season (Schiechtl, 1994) Photo 38 Joint Planting after three seasons (Schiechtl, 1994) 87

88 LIVE FASCINES Definition: Live fascines are live branch cuttings, usually willows or cornus species, bound together into long, sausage-like shaped bundles used to stabilize cut slopes, streambanks and shorelines. Purpose: The live fascine bundle is a component that offers immediate stabilization to the surface layers on a slope and resists hydraulic forces along streambanks and shorelines. Live fascines are useful in the repair and prevention of rills and gullies by reducing the effective slope length and thereby dissipating the energy of water moving down slope. Live fascines control surface erosion from occurring immediately after installation. The terraces formed by a series of live fascines trap sediment and debris. Infiltration is increased as runoff is somewhat slowed. On dry sites this increases the available water for the initial establishment of vegetation. On moist slopes the live fascines may be installed on angle to collect and direct water across and down the slope. Vegetation establishment is enhanced because live fascines provide a suitable environment for plants to establish on the terraces. Drawing 24 Live Fascine Illustration Live branches Twine or strapping 88

89 Applications: Live fascines may be used for road cuts, gullies or slumped areas, surface erosion sites on upland slopes, shorelines, streambanks and along riparian and wetland buffers. Useful for the repair of small earth slips or to protect slopes from shallow slides that are meter (8-12 in.) deep. Live fascines are useful on slopes requiring other planting materials such as container plants, live stakes, grasses, legumes and fords. Live fascines enhance conditions for natural colonization and improve the establishment of plants from the surrounding plant community. Assists in drying wet sites through angular placement and augmented by transpiration as they root and produce top growth. Design Considerations: For best results, harvest and install plant material during its dormant season. Plantings on small stream systems can adversely affect water hydraulics by partially blocking or deflecting currents. Take stream size and elevation of the installation into account. Coir mats or netting can be used under and between each row of live fascines to enhance surface protection. For spacing of live fascines see Table 1. 89

90 Table 1 Recommended Spacing for Live Fascines on Slopes (Gray, Sotir 1994) Slope Steepness (H:V) Slope Distance Between Trenches m (ft) On Contour On Angle 1:1 to 1.5: (3-4) (2-3) 1.5:1 to 2: (4-5) (3-5) 2:1 to 2.5: (5-6) (3-5) 2.5:1 to 3: (6-8) (4-5) 3.5:1 to 4: (8-9) (5-7) 4.5:1 to 5: (9-10) (6-8) Live Fascine Preparation: Choose plant materials that are adapted to the site conditions from species that root easily from cuttings. Use long, straight and flexible branches that are 1.25 to 3.0 meters (4-6 ft) long and 25 mm (1 in.) in diameter. The number of stems varies with the size and kind of plant material. Tie cuttings together to form bundles, 3-10 meters (10-30 ft) in length, depending on site conditions and handling capabilities. The completed bundles are typically mm (6-8 in.) in diameter, but may be as large as 300 mm (12 in.), when used for specific drainage purposes. Stagger the cuttings in the bundles so that the tips and basal ends are evenly distributed throughout the length of the bundle. Compress the live fascine bundles and tie tightly with twine of sufficient strength and durability. Tie the live fascine bundles 0.3 meter (12 in.) apart. 90 For optimum success, install the units on the same day they are harvested and prepared. Live fascines must be stored in the shade in water. Live fascine bundles may be soaked overnight to improve success.

91 Installation: Work progresses from the bottom to the top of the slope. Perform any slope repairs, such as gully repair, slope scaling, diversion dike, or toe wall construction, prior to live fascine installation. Starting at the base of a dry slope, dig a trench on contour. Starting at one end of a moist slope dig a trench which angles from the base up the face of the slope at an angle. The trench depth is about 7/8ths of the diameter of the live fascine and the same width or a little wider, when used alone. Dig it deeper when fabrics are embedded in the trench. Place the live fascines into the trench immediately after digging to reduce desiccation of the soil, and the loss of micro-organisms. Firmly install the live fascines with one row of dead stout stakes driven directly through the bundle and flush on the top exposed side of the live fascine bundle every meter. Install a live stake 0.75 meter (2.5 ft) long 1.0 meter (3 ft) apart in between the previously installed dead stout stakes along the downslope side of the bundle, leaving mm (2-3 in.) exposed above the ground elevation. Overlap the tapered growing tips of adjacent live fascines on top of the basal ends and stake down. Use two stakes at each bundle overlap. Live stakes are typically 0.75 meter (2.5 ft) long in most soils. Dead stout stakes are typically 1 meter (3 ft) long in unconsolidated soils and 0.75 meter (2.5 ft) long in cohesive soils. Proper backfilling is essential to the successful mechanical function and growth of the live fascines. Backfill live fascines with soil from the trench. Work the moist backfill into the live fascine bundle between the branches and at each dead stout stake. A practical method to compact behind and below the bundle is by walking on it. 91

92 Ameliorate the excavated/backfill soil as necessary to promote plant growth. Repeat the proceeding steps to the top of the slope in the slope face. The top of the bundle should be slightly visible when the installation is completed. Seed and mulch slope as specified by hand in between the live fascine bundles. Erosion control blankets are typically used to protect the slope in between the live fascine bundles from erosion until the vegetation is established. Do not seed on top of the live fascine bundles as the competition with the grass may cause the live fascines to perform poorly from the living aspects. 92

93 Photo 39 Fabricating a Live Fascine (Schiechtl, 1994) Photo 40 Installing Live Fascines on a slope with Coir Netting (Sotir, 1992) 93

94 BRUSHLAYER Definition: Cuttings or branches of easily rooted shrub and tree species that are layered between successive lifts of soil fill to reconstruct a slope or embankment to its natural angle of repose. Brushlayering is also used with vegetated reinforced soil systems, when constructing steepened slopes or embankments. Purpose: This technique is used to stabilize cut and fill slopes, particularly road slopes where construction disturbance has or will result in unstable soil conditions. Brushlayering places live branches approximately horizontal in successive layers up the face of the slope at its natural angle of repose. The brushlayer live cut branches, especially after rooting, add reinforcement to slopes by serving as tensile inclusions, which provide a measure of frictional resistance to shallow sliding or other types of surficial displacement. The protruding brush retards runoff and reduces surface erosion, by offering direct overhanging surface protection. Brushlayering is best used concurrently with the construction of cut or fill slopes or embankments. Cuttings are placed by hand while heavy equipment is used to fill and compact each successive lift of soil backfill. This practice is also a good remedial action to repair gullies on existing slopes. Brushlayers may be used in the following applications: On cut slopes the live cut branches are placed on formed terraces that are dug into the slope face. They are useful when deeper reinforcement is needed, beyond that which can be provided by the live fascine method. The cut brushlayer method is often combined with live fascines on slopes composed of low cohesive soils. On fill slopes, the live cut branches are placed on formed terraces that are constructed during the conventional backfill operations that form the new slope. These are useful when much deeper reinforcement in needed. 94

95 Applications: Breaks up a long slope into a series of shorter slopes separated by rows of protruding branches. May be used on a slope with a steeper angle than the natural soil friction angle, with reinforcing materials for additional strength. Reinforces the soil surface initially with the branches and over time the roots develop, adding resistance to shallow sliding and shear displacement for smaller slopes. Reinforce or protect the facing element using brushlayering in combination with geogrids, wire mesh reinforcement or coir netting. Useful for trapping debris on the slope and aids infiltration on cut sites. They are more useful on dry cut slopes because of their deeper installation. Dries excessively wet sites through transpiration as the vegetation grows. Adjusts the site's microclimate, thus aiding seed germination and natural regeneration. Promotes natural invasion of plants from the surrounding plant community. Enhances the development of wildlife corridors, food sources, nesting and cover protection for wildlife. 95

96 Design Consideration: When using brushlayering techniques without a reinforced soil system, such as geogrids or woven wire mesh, the slope angle should be at the natural angle of repose or less. Spacing between the brushlayers is determined by the erosion potential of the slope (i.e., soil type, rainfall, and length and steepness of the slope). For recommended spacing see Table 2. On long slopes, brushlayer spacing should be closer at the bottom and may increase near the top of the slope. On cut slopes the dug terraces are typically 0.75 to 1 meter (2.5-3) deep. On fill slopes the formed terraces may be 2 to 3 meters (6-10 ft) or wider. When used in combination with woven wire mesh or geogrids, the layers need to be installed between each layer of the reinforced soil system layers. Table 2 Recommended Brushlayer Spacing on Slopes (Gray, Sotir 1994) Approximate Slope Distance Between Brushlayer Rows Slope Steepness On Angle On Contour (H:V) Wet Slopes m (ft) Dry Slopes m (ft) 1.5:1 to 2: (3-4) (4-5) 2:1 to 2.5: (3-4) (5-6) 2.5:1 to 3: (4-5) (6-8) 3:1 to 4: (5-6) (6-10) 96

97 Drawing 25 Cross Section of a Fill Brushlayering Compacted Backfill Live cut branches protrude from backfill Layer of live cut branches laid in crisscross pattern with basal ends lower than growing tips. NOTE: Rooted/leafed condition of the plant material is not representative at the time of installation. 97

98 Installation: Slope the surface of the excavated or constructed bench so the outside front edge is higher than the inside or back. The basal ends of the live cut branches angle down into the slope at 10 to 20 degrees when placed on the bench. Live cut branches must be kept moist and cool at all times between harvesting and installation. Live cut branches need to be covered with tarps before being transported. Llive cut branches should be harvested within 48 hours of installation. Place the live cut branches, mm (3-6 in.) thick, in a crisscross or overlapping configuration. The growing tips should protrude mm (6-12 in.) from the slope face. Immediately cover the brushlayer branches with 150 mm (6 in.) of fill soil and compact. Compact according to the construction specification. Earth moving equipment should not travel directly over the cuttings. There must be at least 150 mm (6 in.) or more soil between the brushlayer branches and equipment at all times. Fill and compact the soil placed above the brushlayer in successive lifts, maximum mm (6-8 in) in depth. Install the next brushlayer meters (2.5-8 ft) (face measurement) above the previously installed row. Seed and mulch slope using one half the normal seed weight. Slopes are generally seeded and mulched by hand. Do not seed over the brushlayer installation. Steeper slopes are seeded by hand with coir netting installed between and beneath the layers of live cut branches. 98

99 Photo 41 Brushlayering installed on a fill slope (Sotir, 1989) Photo 42 After vegetation has become established (Sotir, 1990) 99

100 BRUSHMATTRESS Definition: Brushmattress forms an immediate protective surface cover using a combination of living units. The living units that are used include live stakes and a layer of live cut branches placed directly against a graded slope. Purpose: A brushmattress system is used to stabilize the soil on a cut streambank slope face, and is useful as a buffer around wetlands. Applications: Provides immediate surface protection. Brushmattresses capture sediment during flooding, which assists in rebuilding the bank and the establishment of both the installed vegetation and the capturing of new seeds for germination. Provides surface stability for the natural colonization of plants from the surrounding plant community. Enhances opportunities to restore wildlife corridors, food sources, nesting and protection. The heavily vegetated banks filter and slow stormwater runoff, thereby improving water quality. 100

101 Design Considerations: Typically the toe of the slope will need to be protected. This can be done using eco-logs, ecogabions, rock, live fascine etc. A careful site assessment will be required to determine the best toe protection solution. Drains are required if there is significant subsurface seepage. The slope should be graded to the friction angle of the native soil or natural angle of repose or less, especially on outside meander bends of stream systems. A single brushmattress is typically 3 meters (10 ft) in face measurement. They may be doubled on the slope face, but if the slope is wet or excessively dry, it is not advisable to go higher than 3 meters (10 ft) on the slope face. 101

102 Drawing 26 Cross Section of Brushmattress Green gabion to anchor live cut brushmattress Twine Dead Stout Stakes Live cut branches Existing Soil NOTE: Rooted/leafed condition of the plant material is not representative at the time of installation. 102

103 Installation: Prepare the slope surface by grading to a uniform, smooth surface. Install the dead stout stakes in a square pattern mm (12-16 in.) apart on the prepared slope face. The live cut branches are 2 to 3 meters (6-10 ft) long, and should be young and flexible. Place the live cut branches, mm (2-3 in.) thick, up against the cut slope face. The basal ends are inserted into a trench at the toe of the slope. Green gabions may be used at the toe to help secure the live cut branches placed against the slope. To hold the brushmattress in place, secure the live cut branches against the slope using strong twine, weaving back and forth between the dead stout stakes over the live cut branches. Earth moving equipment must not travel over the cuttings. Lightly cover the area with soil immediately and ensure good contact between the branches and the soil. About 75 percent of the brushmattress should be covered with soil. The exposed areas will allow for sprouting of stems and leaves. 103

104 104 Photo 44 Brushmattress establishing Photo 43 Brushmattress Installation

105 LIVE CRIBWALL Definition: A vegetated cribwall consists of a hollow, interlocking arrangement of logs or timbers, soil, rocks and live cut branches. Purpose: Vegetated cribwalls protect eroding streambanks, prevent formation of a split channel or act as a gravity wall at the bottom of a slope. Applications: Stabilizes the toe of a slope, protecting it against scouring and undermining. Useful where space is limited because it is a vertical or near vertical structure. Useful where a less intrusive more natural appearance is desired in a highly steepened area. The upper area may be used as a walking trail. 105

106 Design Considerations: Vegetated cribwalls typically use untreated timbers; therefore they are not resistant to large lateral earth stresses. Live cribwalls need to be placed below the channel bed in a stream setting below the scour depth and on a competent foundation. Drawing 27 Cross Section of Live Cribwall Live Cut Branches Rock Backfill Timbers or Logs Existing Soil NOTE: Rooted/leafed condition of the plant material is not representative at the time of installation. 106

107 Installation: The logs or timbers for a live cribwall have a diameter of mm (4-8 in). Installation begins at the base of the slope, typically below the bed and scour depth in a stream environment. The live cribwall must be constructed on a stable competent foundation. Place the first course of parallel logs or timbers at the front and back of the excavated foundation. The logs should be meters (4.5-6 ft) apart and parallel to the slope contour; with the back log or timber mm (6-8 in.) lower than the front one. Place the second course of logs or timbers perpendicular to the first course. These logs or timbers overhang the front and back of the first course by mm (3-6 in.). Secure the second course to the first course with nails or reinforcing bars. Install filter fabric in the bottom, up the back and front, ensuring enough material is available to cover the top of the rock. Fill the bottom of the crib structure with rock and compact. This is done below the streambank channel and approximately mm (12-28 in.) above the flow elevation. Above the rock, fill and compact with soil. Place live cut branches on the soil cribfill perpendicular to the slope, and then cover branches with soil fill and compact. The growing tips of the branches extend mm (6-12 in.) beyond the front face of the cribwall. Incline the live cribwall 10 to 20 degrees from the vertical or step it back. 107 Repeat the preceding steps until cribwall reaches the desired height. Ensure that the ends are well keyed into the bank 1 to 3 meters (3-10 ft).

108 REFERENCES 1. Akzo Nobel Geosynthetics, Enkamat Distributor Manual (1997). 2. Brunet, Ghislain, Bank Stabilization with Ecological Engineering (1999). 3. Gray, Donald H. and Sotir, Robbin B., Biotechnical and Soil Bioengineering Slope Stabilization (1996). 4. IECA, Bioengineering Techniques for Streambank and Lake Shore Erosion Control. 5. Maccaferri Canada Ltd., MacMat Brochure. 6. Maccaferri Canada Ltd., Green Terramesh Product Specifications (1999). 7. Salix Applied Earthcare, Erosion Draw Schiechtl, H.M. and Stern, R., Water Bioengineering Techniques (1994). 9. Sotir, Robbin B., Soil Bioengineering Short Course Notes from Natural Stream Channels Conference (1999). 10. Terram Data Sheet, Geogrid Reinforced Soil Slopes Installation Guidelines (1997). 11. United States Department of Agriculture (Natural Resources Conservation Service), Engineering Field Handbook, Chapter 16 Streambank and Shoreline Protection (1996). 12. United States Department of Agriculture (Soil Conservation Service), Engineering Field Handbook, Chapter 18 Soil Bioengineering for Upland Slope Protection and Erosion Reduction (1992) 13. U.S. Army Corps of Engineers, Bioengineering for Streambank Erosion Control (1997). 14. U.S.D.A., Stream Corridor Restoration Manual (1998). 108

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