Alternative Methodsfor Storm-water Drainage and Erosion Control

Lois Balin, Urban Wildlife Biologist

Texas Parks and Wildlife Dept.

A holistic approach to channel systems must consider the vegetation as a key component

Influences: • Channel morphology• Flow hydraulics• Sediment erodibility.

The Human Factor

• Arroyos are dynamic living systems• Unknown spatial and temporal effects of a

structural approach• Land use planning that adjusts and adapts

• Arroyos undergo major flooding• In general, they remain wide and braided• Structurally impervious areas increase peak

flows, preventing the natural functions performed by native plants

Erosion

Rill erosion

Rain splash erosion

Sheet erosion

Surface runoff erosion

Preserving Flow Corridors• Provides for systematic drainage infrastructure• Minimizing future flood hazards• Off-site development impacts are lessened

– Maintains existing flow paths– Optimizes system sediment balance – Provides continuity for wildlife corridors

Traditional Stream Management

• Dams• Channelizing• Concrete walls• Culverts• Building on floodplain

• Expensive to build and maintain• High failure rates, leads to more problems• Aesthetically unappealing

Effects of Traditional Stream Management on Dry land River Ecosystems

• Attempts to confine a dynamic system• Creates erosion, incision, and other problems• Disrupts natural balance and ecology

Loss of habitat leads to:– Declining water quality– Invasive plant monocultures– Loss of wildlife

Bioengineering

• Restores critical areas with severe erosion• Plans are hydrology / geomorphology site-specific• Bioengineering combines biological, mechanical,

and ecological concepts to control erosion and stabilize soil using construction materials and or vegetation

Caltrans Erosion Control New Technology Report—Practices User’s Guide App

• Bank/channel armoring• Biostimulants• Biotechnical Headcut Repair• Brush Barrier• Compost Soil Amendment and Mulch• Contour Furrows• Fiber Roll Anchoring with Rope Restraint• Fiber Soil Reinforcement• Filter Wedge• Fiber Reinforced Earth Fill • Furrow Planting

Partial List of Practices

•Loose Rock Headcut Repair•Micro Soil Nailing•Mycorrhizal Soil Innoculant•Rock with Interstitial Fill•Serrated/Stepped/Terraced Slope with Top soil•Top soiling•Top soiling /Cellular Confinement•Turf Reinforcement Mat with Perennial Vegetation•Wood Chip Berm

Bio-engineering Control TechnologyProcesses that Counteract Degrading Arroyos and Slopes

· Biological Activity Stimulant· Bonded Fiber Matrix . Geotextiles· Cell Confinement System· Fiber Roll/Wattle· Flocculates· Hydraulic Soil Stabilizers· Hydromulch· Hydroseed-Mulch Additive· Rolled Erosion Control

Products· Sediment Barrier· Soil/Plant Amendment. Turf Reinforcement Mat

Storm water, Arroyos, and Slope Stabilization

• Seeding / Hydroseeding• Mulching / Hydromuching • Swales / Contour Swales• Sponges• Berms• Linings• Mats• Cobbles• Gabions / Riprap• Fabric Concrete

Design Criteria

Rainfall runoff / flow must be considered when evaluating erosion control solutions:

•Flow velocity•Flow depth•Bank slope angle•Flood / storm duration•Water course geometry•Adherence of the protection to the slope

Seed With Native Xeric Grasses for Permanent Erosion control

• Xeric species with variable timing of germination• Native viable seeds

• Indian ricegrass (Achnatherum hymenoides)

• Black grama (Bouteloua eriopoda)

• Sideoats grama (Bouteloua curtipendula)

• Sand dropseed (Sporobolus cryptandrus)

• Spike dropseed (Sporobolus contractus)

• Mesa dropseed (Sporobolus flexuosus)

• Giant dropseed (Sporobolus giganteus)

Seeding Techniques for Erosion Control

• Broadcast seeding - scattering seeds by hand or mechanically

• Hydroseeding - spraying a slurry of seeds, fertilizer, tackifier, and water onto exposed soils

Mulch

• Holds slope• Intercepts water flow• Slows water flow and direction• Benefits organisms & soil profile

Mulch Application After Seeding

• Native grass hay • Wood chips• Gravel mulch• Hydromulch wood fiber• Erosion control blankets

Hydromulch and Erosion Control Blankets Effective mulch alternatives for steep slopes

• Hydromulch reduces soil loss by 50-60%• Tackifiers glue the hydromulch in place• Combine hydroseeding (native seeds) and hydromulching • Cost-effective and durable

Hydro-Blanket Bonded Fiber Matrix

• Greater erosion control on steep slopes / heavy rains• Less expensive, more effective and easier to install• Dries a breathable, built-in-place blanket that protects

soils and provides medium for seed germination

• Intercept and slow surface water on a slope • Direct water laterally across a slope instead of

vertically• Allows water infiltration • Creates moisture for planting environment

Slowing Water Velocity - Swales and Contours

Swale Without Mulch

• A depression or ditch dug on contour

• Slows and moves surface water to a desired location

• Soil from swales used for berms down slope

Contour Swales

Sponges

• Buried organic matter (straw-bales/flakes, mulch, compost, phonebooks, etc.)

• Improves water absorption & and soil retention• Increases water adhesion & cohesion• Decreases evaporation

Detention Basin• High-volume capacity depressions in ground

• Stores water for a limited time• Receives and slows high-velocity flows before overflowing

• Geo-synthetic fabric lining prevents soil undercutting• Rocks absorb energy

Berms

Straw Wattle Technology for Slopes

• Fiber rolls/wattles with bio and photodegradable netting• Slope intercepts - reduce travel distance of surface waters • Sediment catchment barriers• Fiber Roll Anchoring and Fiber Soil Reinforcement

Liners

• Cobbles• Riprap• Gabions• Turf reinforcement mats / mattresses• Fabric-formed concrete

Cobbles

Reno Mattress

Cobble/Rip Rap

Gabions

• Check dams / drop structures• Water filters through stone• Drain with non-erosive velocity

Permanent Soil Erosion Control Mat

• 3 D mats composed of UV stabilized, non-degradable synthetic fibers • Secures channel linings, slopes and embankments • Provide immediate protection of exposed areas • Creates setting that enhances plant growth through the mat• Reinforces the root system • Reduces velocity and volume of run-off flow • Superior retention of hydroseeding,

MacMat®

Mechanically Stabilized Earth SystemTerramesh

Las Vegas, NV

Terramesh

Fabric-formed Concrete Erosion Control and Armoring Systems

• Protects against high flow in drainage ditches, upper slopes of channels, and other water courses

• Physical barriers used to hold soil in place

• Enviromat Linings are comprised of concrete-filled and unfilled areas that allow for the establishment of vegetation

• Protects against periodic heavy flows, embankments subject to heavy run-off and channel lining

The Advantages of Fabric-formed Concrete:

• Outperforms conventionally-formed concrete slope paving, gabions or rip rap

• Greatly reduces costs• Has greater hydraulic stability-

Soil Bioengineering

• Amendments such as compost, mycorrhizae fungi, biostimulants, flexible growth medium, bacteria inoculations, etc.

• Promote living soil and functional soil ecology• Uses plant matter to stabilize stream banks• Replaces traditional methods of bank stabilization

(concrete, riprap and channelization)• Improves water quality, bank stability, wildlife habitat,

urban aesthetics

• Arroyos over and above that requited for drainage will be responsibility of the City. Dedication of arroyo right of way as open space or parks or the granting of recreational easement are the preferred methods of acquisition.

City of Albuquerque: Major Open Space Arroyos

• Major Open Space Arroyos are to remain in a “natural” or ”semi-natural” condition with native vegetation and channel stabilization consisting primarily of naturalistic treatments such as un-grouped riprap and gabions.

• Tinted concrete or soil cement may be used in limited applications such as in low-flow channels or as needed to control erosion at points where developed runoff enters the arroyo.

• The existed open space characteristics of these arroyos will be preserved to the greatest extend feasible in order to provide visual and psychological relief from urbanization and to protect the natural drainage process.

• Acquisition and maintenance of the public right-of-way associated with Major Open Space .

• Arroyos over and above that requited for drainage will be responsibility of the City. Dedication of arroyo right of way as open space or parks or the granting of recreational easement are the preferred methods of acquisition.

City of Albuquerque: Major Open Space Arroyos

• Major Open Space Arroyos are to remain in a “natural” or ”semi-natural” condition with native vegetation and channel stabilization consisting primarily of naturalistic treatments such as un-grouped riprap and gabions.

• Tinted concrete or soil cement may be used in limited applications such as in low-flow channels or as needed to control erosion at points where developed runoff enters the arroyo.

• The existed open space characteristics of these arroyos will be preserved to the greatest extend feasible in order to provide visual and psychological relief from urbanization and to protect the natural drainage process.

• Acquisition and maintenance of the public right-of-way associated with Major Open Space .

Facility Plan for ArroyosMultiple Use of Albuquerque’s Arroyos and Their Floodplains

Number of terrestrial and aquatic wildlife crossingsin North America

References• Amole Arroyo Corridor Plan, Albuquerque, NM 2003• Basic Guidelines for Seeding Native Grasses in Arid and Semi--Arid Ecoregions,

David R. Dreesen, Agronomist , USDA-NRCS Plant Materials Center , Los Lunas, NM . 2009

• Bear Canyon Arroyo Corridor Plan, Albuquerque, NM 1991• CALTRANS EROSION CONTROL NEW TECHNOLOGY REPORT, CTSW-RT-

03-049 California Department of Transportation, June 2003• Dry land Rivers, Hydrology and Geomorphology of Semi-arid Channels.2002. L.J.

Bull and M.J. Kirkby• Facility Plan for Arroyos, Multiple Use of Albuquerques Arroyos and Their

Floodplains, Albuquerque, NM 1986• Geostar Corporation, HYDROTEX™ and HYDROCAST™ Fabric-formed

Concrete Erosion Control and Armoring Systems. • Maccaferr, Permanent Soil Erosion Control Mats MacMat Brochure Part 1of2.pdf• Maccaferri, Permanent Soil Erosion Control Mats MacMat Brochure Part 2 of

2.pdf• Maccaferri, CASE HISTORY Ref: USA031—Rev:00, Issue Date 12.12.2004

RIVER BANK PROTECTION MSE STRUCTURE SUPPORTS DEVELOPMENT LAS VEGAS, NV, USA

• US Army Corps of Engineers, Technical Report EL-97-8, April 1997, Bioengineering for Streambank Erosion Control Report 1 Guidelines, by Hollis H. Allen, James R. Leech