chapter 4 bank protection erosion

8/13/2019 Chapter 4 Bank Protection Erosion

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USER MANUAL: GUIDELINES & STANDARDS FOR LAND USE NEAR STREAMS 4.65

INTRODUCTION AND PURPOSE OF THE DESIGN GUIDE

This Design Guide is intended to clarifythe Chapter 1 of the Water ResourcesInfrastructure Protection Manual, section

VIII, articles D-H (Outfalls, Pump stationsand Site Drainage). This Design Guidedescribes how to address streambankerosion problems, and how to usebioengineered methods of bank protectionand erosion repair.

This Design Guide is to be used by localpermitting agencies, property ownersand professionals who design projects onstreamside parcels (i.e. civil engineers, landuse planners, landscape architects, etc..) It isintended to:

Provide guidance for how to designa variety of bank protection projects,in places where streambanks are, have, ormay be eroding

Promote proactive approach to preventingand resolving serious erosion problems

This document is a guide, not an instructionmanual. Erosion repair activities within astream channel will impact water quality,flood protection, the stability of adjacentproperties, and the habitats of many stream-

dependant species. It is for these reasonsthat these activities require several state andfederal permits, as well as the involvementof qualified professionals to help design andconstruct the project in a way that addressesstability and long-term water resourceprotection. Examples of more detailedguidance manuals are listed at the end of

this document for reference.

MOVING TOWARD SOFT, MORE

SYSTEMIC METHODS OF BANK

PROTECTION/EROSION REPAIRTraditional methods of controlling erosionhave relied on hard structural practicessuch as covering banks with interlockingconcrete blocks and building retainingwalls. However, these techniques oftenhave negative impacts on streams. In many

BANK PROTECTION/EROSION REPAIR DESIGN GUIDE

cases, these methods are also expensive andineffective in the long run. Recommendedinstead are soft or bioengineered bank

stabilization methods. A bioengineeredapproach involves the planting of nativestreamside or riparian vegetation combinedwith the strategic placement of logs orminimal rock, where necessary, andregrading of steep slopes wherever possiblein order to produce living systems thatminimize erosion, control sediment, andprovide habitat. The natural attributes ofplants, when combined with stabilizedbank slopes, provide better dynamic streamsystems than stationary hard structures.

An objective of this Design Guide is toprotect, and where appropriate, restorestreambanks and related stream resources.Where suitable, it encourages a systemicapproach to streambank protection andstream restoration. This Design Guidestarts by describing how streams function,typical features of a stream and importanceof riparian vegetation. It then discussestypical causes of streambank erosionand recommends basic measures to beconsidered when planning and designing

a bank protection erosion repair project.Finally, alternative methods of protecting astreambank are presented, starting with howto treat a reach of a stream in a more ruralsetting where there is room to use a moresystemic approach, and continuing witha variety of treatments for smaller, urbanparcels, which include a small reach of astream.

GOALS/PURPOSE OF

STREAMBANK PROTECTION

ACTIVITIES

In general, the goals of any bank protection/erosion repair activity should be to:

Maintain or increase stream stability andfacilitate transport of sediment and water;

Avoid localized solutions that repaironly a single erosion site but reduce thestability of neighboring stream banks


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4.66 USER MANUAL: GUIDELINES & STANDARDS FOR LAND USE NEAR STREAMS

and cause erosion problems on upstreamor downstream properties;

Enhance and increase native vegetationboth in extent and diversity to providehabitat value and help ensure long-termbank stability.

With these goals in mind, this DesignGuide delineates some general guidelinesand issues to consider when embarkingon a bank-protection/erosion-repairproject, as well as a description of variouserosion-repair techniques. This guidancealso provides agency staff and streamsideproperty owners with a brief overview ofhow streams are formed, their commoncharacteristics and features, and typical

causes of streambank erosion

DESIGN GUIDE 19GUIDELINES AND STANDARDS I.V


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ORGANIZATION OF THIS DESIGN GUIDE

This Design Guide is organized into two parts and six subsections. The Technical Primer partincludes useful background information that explains the causes of erosion. Homeownersand project developers will likely refer to the Techniques and Guidance part more frequently,

because it outlines techniques and guidelines for erosion repair.

CONTENTS PAGE

Part I: Technical Primer on Stream Function and Form 4. 68

Section 1: How Streams Function 4.69

Section 2: Typical Causes of Streambank Erosion 4.74

Part II: Techniques and Guidance for Developing Your Erosion Repair Project 4.76

Section 3: Embarking on a Bank Protection/Erosion Repair Project 4.77

Section 4: Introduction to Appropriate Watershed-Friendly Design 4.80Section 5: Detailed Descriptions of Erosion Repair Techniques 4.83

Section 6: Helpful Hints on Obtaining Permits for Stream-bank Repair 4.110

Section 7: Reference Materials 4.116


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PART ONE: TECHNICAL PRIMER ON STREAM

FUNCTION AND FORM



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FIGURE 1: CROSS-SECTI ONAL VIEW OF A NATURAL STREAM

TYPICAL STREAM FEATURES

In a cross-sectional view, a stable naturalstream can be defined by two significantfeatures: the bankfull (or active channel)and the active floodplain.

See figure 1 below.The bankfull or active channel can bedefined by the elevation of the floodplain,which is formed by the most effectivechannel forming or dominant streamdischarge. It is the part of the streamwhere sediment is actively transportedand deposited, the part that is capable ofcontaining the most frequent flows.

The active channel is an important featurebecause it transports the majority of thewater and sediment in the stream system,and thus it influences the channel formationover time. As seen in Figure 1, the activechannel is usually distinguished from theactive floodplain by an abrupt change inthe slope of the stream bank, usually froma vertically-sloped plane to the horizontally-sloped plane on top of the floodplain.

Active floodplains are the low-lying areasbetween Top of Bank (See Figure 1) andadjacent to the active channel that aresubject to frequent inundation during

moderate and high flows. This area is wheresediment is deposited when the activechannels capacity is exceeded during high

flows. In urban settings, active floodplainsare often hard to identify, due to channelincision and erosion from increasedurban runoff. On rural streams, the activefloodplain normally fills approximately everyyear or two. Floodplain filling usually occurs

more often in urban areas. Vegetation istypically present in the floodplain area,as it will become established between thealternating seasonal periods of inundationand sediment deposition.

(Section 2 of the Guidelines and Standardsalso includes more detailed definitions andsketches showing these features in a varietyof settings).

Important Note: A streams active floodplainis not to be confused with the delineation

of floodplain used for flood insurancepurposes. The floodplain defined for floodinsurance purposes is the one percent(100-year) flood, or the area that has aone percent chance of being flooded toa depth of one foot or greater each year.For insurance purposes, this equates to a26 percent chance of suffering some flooddamage during the term of a 30-yearmortgage.



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FIGURE 2. DETERMINING TH E APPROPRIATE WIDTH TO DEPTH RATIO

STREAM BELTWIDTH AND

STREAM MEANDER WIDTH

A channel has a certain beltwidth withinwhich it naturally moves. This beltwidth canbe determined by studying: sections of thechannel which have not been straightened;pre-development photographs; or, adjacentsimilar channels. Levees should not, forexample, be constructed in a way that doesnot accommodate the beltwidth. Doingotherwise increases erosion potential andmaintenance costs.

Meander width is the amplitude of themeander within the beltwidth. It is smallerthan the beltwidth. At a minimum, theaverage meander width of a channel shouldnot be compromised in the lower flood

plains. In the mid to upper slopes above thevalley floor, where the natural channel maybe fairly straight, the beltwidth should alsobe respected.

FACTORS THAT AFFECT STREAM

STABILITY

Several factors affect stream stability. Theyinclude stream topography, the width-to-depth ratio, and extent of channel incision

The quantity and movement of both waterand sediment in a stream are two of theprimary influences on the topography ofa stream. These materials tend to balanceeach other within the confines of the streamchannel. For example, erosion on one bank

is typically balanced by sediment depositionon the other. While the location and extentof the erosion and resulting deposition maychange over time, the width and depth of astable stream does not change much. Thus,any type of erosion repair project must be

designed to maintain width-to-depth ratio inorder to ensure long-term stream stability,while also allowing the streambed to erodeand fill naturally.

A channels width-to-depth ratio iscalculated by dividing the width of thestream channel (at the bankfull level) by themean channel depth. Width-to-depth ratiois part of a more complicated concept calledentrenchment ratio, which is importantbecause it calculates a channels stability.Generally speaking, it calculates its stability

in terms of its floodplainthe larger thefloodplain, the higher the entrenchmentratio. Specifically the entrenchment ratio isequal to the width of the stream channel(at twice the maximum bankfull depth)divided by the width-to-depth ratio ofthe bankfull channel. In order to preventchannel incision and maintain a stablestream, the ratio of the width of the channelat 2 bankfull heights (see Figure 2) to thebankfull width should be a minimum of 2where the channel is constrained. It should

be a 3 to 4 ratio at other locations, bothupstream and downstream. This providessufficient relief, and thus prevents excessiveerosion of streambed and bank. It alsoprevents damage to bankside propertiesduring 1 year10 year storm events.



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EFFECTS OF WATER AND

SEDIMENT TRANSPORT ON

BANK STABILITY

Streams adjust themselves to transport, asefficiently as possible, water and sediment

from higher elevations to lower elevations.If the amount of sediment available to acreek is significantly increased or decreased,the creek adjusts its channel area or crosssection to handle the change in sediment.In a normally-functioning gravel bed stream,for example, it is not uncommon for thestream channel (or portions of the streamchannel) to downcut and refill significantlyfrom a few inches to 10 feet or more in asingle storm event. This is one way streamstransport their sediment loads, cleanthemselves, and temporarily increase theirflow capacity.

With the expanded development in SantaClara County, the time it takes for runoffto reach the streams has decreased, whichleads to the increase in the amount of waterin most streams. Some of the specificfactors that have led to this increase in waterflows are:

Substantial increases in impervioussurfaces such as pavement and roof tops.

The routing of storm water runoff directlyinto streams through piped storm drainsystems.

Removal of large areas of streamsidevegetation that would otherwise formbuffers for runoff, and promote infiltrationinto the soil.

The stormwater management programs oflocal municipalities have efforts underwayto address these long-term issues. Inthe interim, however, it is important that

armoring the channel be avoided onindividual properties whenever possible,for several reasons. First bank armoringprevents channels from adjusting to highflows, and can increase the probabilityof flooding. Bank armoring also causesaccelerated flow velocities and turbulencealong banks, which then induces moreerosion on unarmored banks.

Finally, because armored banks cannotadjust to changing stream conditions, theyare prone to undercutting.

IMPORTANCE OF VEGETATION

AND RIPARIAN BUFFERS

The roots of well-established vegetation notonly protect the surface of stream banks,but also penetrate deeply into the ground,helping to stabilizing it. Lack of vegetationclose to a creek bank can contribute toslope instability and failure due to overbankdrainage or soil saturation. In additionto providing bank stability, streamsidevegetation filters pollutants; shades andcools the stream; increases infiltration;reduces flash runoff; and provides habitatfor wildlife. A variety of scientific studies

of the minimum and optimum width of avegetated buffer along a stream indicatethat a width of 10 feet is not enough toprovide adequate filtration or habitat. Astudy by U.S. Fish and Wildlife indicates thatin order to effectively remove pollutants, abuffer of 50 feet is needed. Other sourcesrecommend a vegetated buffer that is 2 to5 times the width of the stream channel.While there is ongoing discussion aboutthe most appropriate width for vegetatedbuffers, it is conclusive that at least some

adequate buffer is necessary to protectstream resources. In terms of erosion repairprojects, the use of live plants, either aloneor in combination with dead or select rockmaterials, can be sufficient to preventerosion, control sediment, and providehabitat.

STREAM FEATURES THAT ARE

IMPORTANT TO FISH HABITAT

The movement of water through astreambed creates certain natural

characteristics or that benefit fish habitat.Some of these important features are riffles,runs, glides and pools. Riffles are located inshallow areas or bends in a stream wherewater flows over rocks. Runs are the straightsections between riffles. Glides are thetransition areas between the downstreamend of pools and a run or riffle. Pools areusually formed on the outside of bends in a



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stream. Deep pools are particularly important in providing critical fish habitat andrefuge areas. When the flow in the streamdecreases in drought, fish can retreat tothese pools to wait for the return of higherflows.

These stream features described abovediffer from stream to stream dependingon a streams geometry and location. Forexample, at higher elevations, streamchannels are steeper, narrower, and dropat faster rates, and may contain series ofstep-pool cascades. At a lower elevation,however, a channel tends to be less steep,wider, and more sinuous, making riffles andpools more common. The combination ofriffles, runs and pools is extremely importantfor fish because it provides different feeding,

spawning and/or nursery areas. Thesestream characteristics should be preserved,restored, and enhanced where possible, asappropriate to the stream topography, inany type of erosion repair effort.



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All streams erode to some extent as a partof natural processes. Natural erosion istypically caused by:

1) Hydraulic forces that remove bankmaterial;

2) Geotechnical instabilities;

3) Or, most commonly, a combination ofboth these two forces.

HYDRAULIC FAILURES

Hydraulic failures occur when the force orvelocity of the water is greater than thenatural cohesion of the soil. In other words,the forces that bind the soil together are

overcome by the water. Some visible featuresof hydraulic failures are erosion near thebottom, (or at the toe,) of a stream bank,or alteration of the streambed. Changes inthe direction of flow, constrictions, increasesor decreases in the amount of sediment, andincreased amount and duration of flow fromimpervious areas can all accelerate erosionof the stream bank or alteration of thestreambed, and in turn, hydraulic failure.

Some of the sediment that is introducedinto the stream will naturally deposit on

the bottom of the stream. Over time, thismay raise the bottom of the stream andreduce the capacity of the active channel,forcing the water to spread out laterally.This causes erosion and steepening of thestream banks. This can also occur when astream is starved of sediment (typically bydams or erosion control structures) and theexcess energy that would have been used totransport sediment is now free to erode bedand banks. This condition typically occurswith the construction of hardened channel

linings, or with the addition of other typesof instream debris, sediment, or detentionbasins that trap sediment. In this case, theerosion (down-cutting and steepening) ofthe streambed and banks occurs belowthe lined section (or instream basin),causing the eroded sediment to settle fartherdownstream. Nonetheless, the impact on thestream is similar. Thus, for hydraulic failures,

the most effective erosion repairs areaccomplished by addressing the root causeof the failure, which may include installationof measures to redirect flow, increasing the

erosion resistance of the bank, by plantingvegetation on the bank or adding protectionto the toe of the stream bank.

GEOTECHNICAL FAILURES

Geotechnical failures occur whengravitational forces are greater than thestrength of the soil. These failures areusually caused by over steepened banksand/or excess moisture in the soil. Thisresults in the movement of earth, betterknown as a landslide. Near a stream, the

likely causes of this type of failure are ahigh groundwater table, poorly designedsurface drainage systems (such as those thatdrain surface runoff directly over the top ofthe stream bank), leaking swimming pools,and leaking septic systems or water lines(which saturate the stream bank). Thus, formost geotechnical failures, what must beaddressed is the source of the water thatscausing excess moisture in the vicinity of thestream bank.

COMBINATION FAILURES

The third type of failure is a combinationof hydraulic forces and geotechnicalinstabilities. Hydraulic failures often leadto geotechnical failures. As the toe of thestream bank erodes, or the channel cutsdownward because of hydraulic forces,the bank effectively increases in heightand becomes too steep and unstable.Sometimes, the upper portion of thestream bank fails from lack of support, andslides into the stream. This process is well

described in the document MaintainingCorte madera Creek: A Citizens Guide toCreek-side Property Protection, which wasprepared by Phil Williams and Associatesin Collaboration with H. T. Harvey andAssociates for the San Francisquito CreekJoint Powers Authority. They write, Thehigher a bank is, the flatter the angle mustbe to prevent slumping. For example, most

SECTION 2 - CAUSES OF STREAM BANK EROSION



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soils will support a three-foot high verticalbank, but if the river cuts a deeper channel(say five feet) the bank will collapse underits own weight. A five-foot tall bank wouldneed to be graded to a lower gradient tobe as stable as a three-foot vertical bank,

and a ten-foot high bank would have to beexcavated to an even lower gradient to bestable. The higher the bank, the lower thestable gradient becomes. The best remedyfor this problemthe problem of an over-steepened bank experiencing both hydraulic

FIGURE 3: LAYING BACK A STREAMBANK TO INCREASE STABILITY

and geotechnical failurescombines severalsteps. The first step involves regrading theslope to a more stable angle, which is why itis called laying it back.

The second step involves reinforcing thetoe, where necessary, with biotechnicalmethods such as logs and rocks. The thirdstep involves reducing erosive energy on thebank by planting the bank, so that it doesnot become over-steepened again.

For an illustration, see figure 3 below.



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PART TWO:

TECHNIQUES AND GUIDANCE FOR DEVELOPING

A WATERSHED-FRIENDLY EROSION REPAIR PROJECT.



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STEP 3. IDENTIFY THE SOURCE

OF THE PROBLEM

It is important to identify and, if possible,address that the source of streambank orbed erosion. If it is not addressed, theerosion repair project may either need tobe repeated or expanded in the future, orcause other erosion problems upstream,downstream, or across the stream. Toidentify a potential source, one should lookfor:

Flow constrictions like bridges or debristhat increase downstream velocities andshear stress,

Existing hardscape, or paved overareas, that may be increasing velocitiesdownstream,

Natural or non-natural debris that mayhave redirected the flow into the bank,

Drainage features that may be directingflow onto, or saturating, the bank,

Watershed-wide increases in amount andduration of runoff that may be causingsystematic degradation of the creekchannel (incision), which leads to toefailures and bank slumps.

These underlying causes of erosion could

be natural features or constrictions, butmost likely, they are non-natural, i.e.,human-made. Oftentimes, the source of theproblem is an earlier effort to address anerosion problem upstream or downstream.Depending on the extent of the problem, itmay be worthwhile for the property owner toconsider a collective effort with neighboringproperty-owners, perhaps even includinggovernment and/or public agencies whoown land or rights-of-way in or near thestream.

Because actions taken to address erosion inone place can cause problems elsewhere,permit applicants should consider thepotential impacts on both the downstreamand upstream streambed and banks whendetermining the type of erosion repairmeasure to use. To this end, property ownersmay be asked to provide professionalanalyses of stream geomorphology and/or

hydraulics to determine potential negativeimpacts, and recommend ways to preventthem.

STEP 4. SEEK ASSISTANCE

FROM THE SANTA CLARA

VALLEY WATER DISTRICT(SCVWD)

For SCVWDs assistance in conductingrepair or maintenance, contact the SCVWDsWatershed staff at 408.265.2600. Thereare three different scenarios related toownership and easement that determineassistance eligibility:

SCVWD RIGHT OF WAY: If theDistrict owns the property where the streamis located, District staff will visit the site to

inspect the erosion, determine if and how itshould be addressed, and then, if need be,take appropriate measures to do so.

SCVWD EASEMENT: If the Districthas an easement on the section of thestream needing repairs, District staff will visitthe site to inspect the erosion. Easementsgenerally provide the District with thenecessary rights to perform the work.The District can make repairs within aneasement after assessing the extent of theerosion, the infrastructure affected, the

available funding, and the need to conductother work on District property.

PRIVATE OWNERSHIP:If the streamis under private ownership, District staff isgenerally available for a visit to the site,however this availability will depend onthe number of requests received and staffresources. Staff can provide advice on anapproach to use but, the District will notdesign or construct the project.

Requests for technical assistance for minor

erosion repair work can be submitted tothe District via their web site at http://www.valleywater.org/Water/Watersheds_-_streams_and_floods/Taking_care_of_streams/Service_request_form.cfm. Tonegotiate an agreement for assistance ona substantial repair project, contact theDistricts Watershed staff at 408.265.2600.



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This section provides some tips for streamcare during construction. Proper use of best

management practices (BMPs) can have atremendously beneficial impact on aquaticspecies and other wildlife, human health,environment, property, and public services.

CONSTRUCTION BMPS:

When restoring a damaged sectionof a streambank, imitate naturalstream features, such as channelmeanders, appropriate width and depth,and vegetation. This will stabilize thechannel. Details of this concept areincluded in Section 5 of this Design Guide.

Observe work windows. In-channelwork should generally be conductedduring the dry season, betweenJune15th and October 15th, tominimize negative impacts to plantand wildlife. Sometimes these dates willvary depending on the wildlife speciesin the area. Do not use heavy equipmentduring spawning or migration seasons,as it can destroy fish habitat.If construction during periods of stream

flow can not be avoided, include measuresto separate area of disturbance fromstream flow to minimize turbidityin stream.

Avoid removing in-stream gravel.Avoid disturbing the creek bed,particularly spawning gravel. After projectcompletion, replace or restore any gravelthat was moved or removed to maintainspawning areas for fish.

Take special care when establishing

stream access points, because these pointscan contribute undesirable sediment to thestream. So

Use established access pointwherever possible.

If it is necessary to createa temporary access point forconstruction, do so as close

to the work area as possible inorder to minimize adverseimpacts. When the project iscomplete, restore the access Pointto as natural and stablecondition as possible.

Prevent soil at constructionentrances from beingtracked onto streets nearwork sites.

Control dust. Dust can be a nuisance,and have an adverse impacton water quality.

To control dust: Water active maintenance areas

so that they are sufficiently moistto prevent dust.

Sweep any paved access roads ofvisible soil material.

Cover trucks hauling sediment,ensure that their tailgates areclosed, and brush off anyexcess dirt.

Store and secure materials.Remove all building materials, debris,lumber, et cetera within 2 days ofcompleting the project.

Be wary of mercury and othercontaminants. Disturbed or excavatedsoils in areas where soils are known tocontain mercury or other contaminantsshould be removed or properly cappedif the soil will be exposed to flood flows.In areas whose soils are known tocontain mercury, remediate the disturbed

or excavated soils if they are exposed toflood flows. Wear protective equipment.Consult the Santa Clara Valley WaterDistrict for disposal guidance.

WATERSHED-FRIENDLY DESIGN: BESTMANAGEMENT PRACTICES



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FOLLOW-UP MAINTEN ANCE:

Do not neglect stream-bank repair afterconstruction is over. Minor maintenanceactivities help ensure a projects success.

Remove trash and debris.Sometimes,

the accumulation of debris in the channelcauses erosion on nearby banks. So:

Regularly remove debris such astrash and human-caused debris.

Do not put yard waste in thecreeks or on the banks, whereleaves and clippingscan wash into the stream.

If mulching:

Use biodegradable erosion

control blankets on bareslopes or if it is too latein the season to establishvegetation. The blanketswill last for 1 to 3 yearswhile natives reseed.

Monitor the success of naturalrevegetation before takingaggressive action to revegetate.

Woody debris from the site mightmake for suitable mulch.

Use bark and other wood productsor fabric blankets above the highwater line to prevent erosion ofbare soil after constructionis completed.

Use weed-free certified mulch.

Do not use Eucalyptus, Walnut,or Tree of Heaven. They producean allelopathic compound that canbe toxic to plants and aquaticorganisms.

Be careful when trying to controlrodents. Burrowing rodents maybe a nuisance and can damage levees onstreams, but do not use rodenticides.Their effect on the local habitat is toodestructive. Instead, consult CountyVector Control.

Revegetate. In areas that have beenrevegetated, replace dead or dying plantsand weeds. Remove non-native plantcolonizers. Ensure that all plants receivesufficient water.



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SECTION 5 - DETAILED DESCRIPTIONS OFEROSION REPAIR TECHNIQUES

Described in this section are 16 differenttypes of erosion repair methods. Each

description contains a brief overview ofthe repair method, the circumstances inwhich it is most appropriate, its anticipatedenvironmental value, its relative costs,and its potential impacts. Descriptions arenot exhaustive, and should only be usedin conjunction with consultation from aqualified erosion repair professional, theSanta Clara Valley Water District, andrelevant regulatory agencies.

Even the most well-meaning erosion repairdesigns can have negative impacts on a

stream if they are not planned, designed,and constructed properly. Poorly placedrocks or woody material can cause bed andbank scour/erosion, excessive sedimentdeposition, and/or decreased channelcapacity. For this reason, it is essential thatthe project is designed to accommodatethe sites particular geomorphic location,channel form and depth, flow velocity, andsite constraints. This typically requires aphysical, or geomorphic assessment by atrained professional.

To protect both your property and its value,the goals of any streamside bank protectionor erosion repair project should be torestore stability and leave the site in a betterecological condition than it was before.The first erosion repair method, the modifiedflood plain, will provide the best long term,ecologically friendly and most stable results.Methods 2 through 8 use bioengineeringmethods. Bioengineered bank stabilizationmethods typically involve two components:

Regrading the upper streambank toestablish or re-establish a floodplain,with terraces where possible.

Planting native riparian vegetation onthe streambank and terraces in order torestore and provide long-term stability.

If soft methods of protection are not feasibledue to highly erosive forces, then there is

probably a channel dimension, hydrologyand/or morphology problem.

Hard bank protection can cause moreerosion and damage in the channel, alongthe downstream and/or upstream banks,as well as on the opposite bank of therepair site. Any consideration of the use ofhardened materials should be with cautionand with an assessment of the impacts thatmay occur.

Erosion repair methods 9 thorough 11,

incorporate bank armoring which shouldbe avoided. The use of log and rockflow deflecting structures as described inmethod 1 is less expensive and a moreenvironmentally friendly way of protectingbanks from erosion. Detailed guidance ofthese methods is beyond the scope of thisDesign Guide but should be considered bythe design professional.

Erosion repair methods 12 through 16 areNOT recommended. However, they maybe necessary when the site is constrained,

or where the water volume, velocity, banksteepness, and resultant erosive forcesnecessitate the use of more extrememethods



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Appropriate Water Velocity

1. Modifiedfloodplain

Varies Varies Positive Low

2. Slope Gradingwith Vegetation

2:1 or flatter for vegetationsection, 1.5:1 or flatter for

boulder section.

Low typically up to 6 ft/sec Positive Low

3. Erosion Mats 2:1 or flatter for erosion

mat section, 1.5:1 or flatter

if boulders used.

Generally 1-7 ft/sec but can go

up to12ft/sec if vegetated.

Positive, if planted. Low

4. ContourWattling

Low Positive Low

5. BrushMattresses

2:1 or flatter for erosion

mat section, 1.5:1 or flatter

if boulders used.

Low Positive Low

6. Brush Layering 2:01 Medium Positive Low

7. VegetatedGeogrids or SoilLif ts

Up to 1:1 Medium Positive Low

8. Root wads andboulders

Medium: (10 ft/sec or less) Positive, if planted High

9. Boulder/ RockRevetment

Up to 1:1, preferably 2:1. High: up to 15 ft/sec; less where

voids in boulders are planted.

Negative.

Negative to

Neutral, if planted

Medium

10. CellularConfinementSystem

Up to 0.5 to 1 Medium to High:5-21 ft/secdepending on vegetation)

Neutral Medium

11. Live Log CribWalls

Up to 0.25:1 Medium: up to 12 ft/sec or less Neutral to High, if

planted

High

Repair Method Appropriate Slope Environ Value Cost

TABLE 1: PREFERRED EROSION REPAIR METHODS



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#1 MODIFIED FLOODPLAIN

HOW TO CREATE A MODIFIED

FLOODPLAIN

The modified flood plain design provides theoptimum solution for long-term, ecologically-

friendly, and less expensive stability. Inurban areas property owners typically haveshort stretches of stream running throughtheir property and often only on one sideof the stream. The cooperative enlistingof neighbors to affect this approach iswell worth the effort. The typical steps increating a modified floodplain are:

Step 1: Identify the appropriate channelwidth and depth, at bankfull level. The activechannel will contain flows resulting fromsmall frequent rainfall events.

Step 2: Identify the appropriate elevationfor the floodplain area, and determine howmuch space is available and appropriate forwidening the banks.

Step 3: Regrade or lay back the existingbank above the floodplain to a flatter, morestable angle (usually a 2 horizontal to 1vertical slope, or greater);

Step 4: Create terraces above the activefloodplain to accommodate vegetation

Step 5: Plant the terraces with appropriatelocal, native, riparian vegetation to stabilizethe bank(s) and create habitat.



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HOW TO CREATE A MODIFIED FLOODPLAIN IN DEEPLY INCISED

CHANNELS

A watershed-friendly design that recreates a natural floodplain is depictedin Figures 4 and 5 below:

FIGURE 4: STREAM CHANNEL WITH DEEPLY INCISED STREAMBANKS

FIGURE 5: THE SAME STREAM CHANNEL AS FIGURE 4, BU T STREAM

BANKS HAVE BEEN REGRADES TO CREATE TERRACES WHERE

VEGETATION CAN BE PLANTED



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FLOODPLAIN IN BROAD FLAT

STRETCHES WITH SEDIMENT

DEPOSITION

In some cases, a stream may have

experienced heavy sediment deposition overthe years. In contrast to the deeply incisedchannels, with heavy sediment depositiontend to be wide, shallow and rather straight.Although there may have been fish presentat one time, the shallow flows make itdifficult for them to return. Where there isroom, it is important to restore the naturemeanders if possible.

Figures 6 below shows a stream prior toa stream restoration project. As you cansee, the channel was wide, shallow andrather straight. The bottom drawing showsthat the channel was made narrower andconstructed with a proper width/depth ratio

at the bankfull level. This helped assurethe proper transport of sediment throughthe area by increasing velocities in theactive channel. The active channel wasmoved away from the right bank and intothe center of the channel corridor, creatingdeep pools for steelhead trout and salmon.Brush rolls were used on the top of the rightfloodplain to accumulate fine sediment andthe right vertical stream bank was slopedback and vegetated.

FIGURES 6: STREAM CHANNEL CROSS SECTION VIEW



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POSSIBLE VARIATIONS ON THE FLOODPLAIN APPROACH:

RESTORING NATURAL STREAM MEANDERS

Where there is sufficient room in the stream channel, it can be very helpful to modify thechannel in a way that restores natural stream meanders. The diagram below shows how acreek channel can be narrowed and reformed with more meander. As noted earlier, a proper

width/depth ratio at the bankfull level is created and a modified floodplain can be constructed.In this example, three J-Hook rock structures were installed with brush rolls on the right bankfloodplain to divert the water away from the bank and into the center of the channel.

construct

narrower

meandering

channel

brushroll

flood

plain

fill

brush

roll

3 rock J-hook

weirs

pool

pool

pool

brush

roll

fill

cut, slope back

and vegetate

fill



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ADDITIONAL TOE AND BANK PROTECTION FOR HIGH FLOW

VELOCITIES OR CONFINED AREAS

In the uncommon situations where water velocities are especially high, or where astructure isthreatened by its proximity to the bank, additional protection or a hybrid approachmay be desired.

PHOTOGRAPH 1: ROCK CROSS VANE STRUCTURE:

PHOTOGRAPH 2: ROCK J-HOOK STRUCTURE:



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FLOODPLAIN IN BROAD F LAT

STRETCHES WITH SEDIMENT

DEPOSITION

In some cases, a stream may have

experienced heavy sediment deposition overthe years. In contrast to the deeply incisedchannels, channels with heavy sedimentdeposition tend to be wide, shallow andrather straight. Although there may havebeen fish present at one time, the shallowflows make it difficult for them to return.Where there is room, it is important torestore the nature meanders if possible.

Figures 6a and 6b below show a streamprior to a stream restoration project. Asyou can see, the channel was wide, shallowand rather straight. The bottom drawingshows that the channel was made narrowerand constructed with a proper width/depth

ratio at the bankfull level. This helpedassure the proper transport of sedimentthrough the area by increasing velocities inthe active channel. The active channel wasmoved away from the right bank and intothe center of the channel corridor, creatingdeep pools for steelhead trout and salmon.Brush rolls were used on the top of the rightfloodplain to accumulate fine sediment andthe right vertical stream bank was slopedback and vegetated.



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#2: SLOPE GRADING WITH VEGETATION AND FLOODPLAIN

TERRACES SPACE PERMITTING

This is perhaps the least engineered, and often most effective, method of long-term bankrepair, because it restores the natural contour and vegetative cover of the stream bank. If thebank is undercut or has slumped to a vertical face, consider matching the grade of a nearby

stable slope. Usually a 2 horizontal to 1 vertical slope is considered stable for many soil types,and if space allows, a 3to 1 slope would be even better. Regrading the channel to createterraced banks (as described in Section 4) in order to include an active channel and floodplainarea is appropriate wherever a more holistic approach to stream restoration is possible. Asnoted earlier, the stream bank should always be revegetated with appropriate native plants.

FIGURE 9A: SLOPE GRADING WITH VEGETATION

FIGURE 9B: CROSS SECTION OF SLOPE GRADING WITH

VEGETATION AND ROCK

TOE PROTECTION



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#3: EROSION MATS

This method consists of securing geotextileblankets made of biodegradable materialslike jute or coconut fiber to channel banksusing stakes or staples. Biodegradablefabrics are preferable to plastic because theydo not inhibit plant growth, or act like a netif they are dislodged during a storm. Theerosion mats provide soft armor protectionagainst erosive forces and are combinedwith live staking and direct seeding.Abrasive sediment, debris, foot traffic, andsunlight will slowly wear, snag, and tearthese fabrics, potentially undermining thestructure. Thats why erosion mats areintended to be only the foundation of avegetated erosion control system. In otherwords, the establishment of vegetation is

crucial to the long-term success of erosionmats.

DESIGN CONSIDERATIONS:

Toe protection may be required wheresignificant toe scour is anticipated.

The bank must be smooth before installingblankets to ensure adequate contact andprevent subsurface erosion.

The erosion mats must be installedaccording to manufacturers instructions in

order to prevent failure.

#3A: EROSION MATS WITH

BOULDER OR LOG TOE

PROTECTION

This method consists of grading the lowerportion of the eroded slope at a maximum

of 1.5:1. The upper portion of the slope isthen graded at a minimum slope of 2:1 andsmoothed to ensure that the whole erosionmat contacts the soil. Appropriately-sizedboulders are placed at the toe of the rebuiltbank up to the bankfull discharge waterelevation, or even slightly higher. Voidsbetween the boulders can be planted usinglive stakes.


Best for bank slopes of 3:1 or steeper

Boulders must be keyed in (min. 3 feet) atthe toe of the bank.

Boulder placement must not constrict thechannel cross section or reduce the width-to-depth ratio. Otherwise, the repair willlikely destabilize the channel.

The placement of boulders or armoringalong the bank may increase turbulencein the area and other areas downstream.

This could increase erosion.



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FIGURE 10: CONTOUR WATTLING



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#5: BRUSH MATTRESS

First, the bank must be prepared. Theeroded slope is graded and smoothed toensure that all willows are in contact withthe soil. Then, a deep trench (2 ft. min) is

dug at the toe of the bank for the butt endsof the willow branches. Wood, steel, or livewillow stakes are partially driven into thesoil in rows, on three foot centers, in thearea that will be covered by the mattress.After the stakes have been placed, livewillow branches are put on the bank withtheir butt ends in the trench. Straightbranches no shorter than four-feet in lengthand .5 to 1 in diameter are used. If thebranches are not long enough to reach theupper end of mattress, several layers may be used; however, it is necessary toshingle the layers by lapping each newlayer over the one below by at least 18.

Once the bank is covered by a thick layerof willows, cross branches are placedhorizontally over the bottom layer. Thesebranches are placed against the stakes andthen tied to the stakes using wire or string.The stakes are then driven into the bank atleast two feet deep. After the completionof the mattress, the toe trench is filled withappropriately-sized boulders and rocks to

anchor the butt ends of the branches. Thebrush mattress should be covered with anamount of soil sufficient to ensure a goodcontact surface between the mattress andthe soil, leaving some buds and twigsexposed.

This method forms an immediate protectivecover over the stream bank, capturessediment during flood flows, and rapidlyrestores riparian vegetation and streamsidehabitat. This measure is not appropriatewhere toe scour is anticipated, in which case

boulders may need to be added at the toe.

DESIGN CONSTRAINTS AND

CONSIDERATIONS:

Branches should be tamped down beforetying to create a good contact surfacebetween the soil and the mattress.

Butt or basal ends of branches must becovered with soil so they can root and toprevent them from drying out.

Branches should be partially covered withsoil.

This method should not be used onslopes that are experiencinggeotechnical failures or other slopeinstability.



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FIGURE 11: BRUSH MATRESS



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#7: VEGETATED GEOGRIDS OR

SOIL LIFTS

This method is similar to brush layering,but adds even more stability by wrappingengineered soil lifts in biodegradable

erosion control fabric or geotextiles betweenlayers of live branches. This method isuseful where site constraints dont allow theslope to be laid back. Boulder or log toe-protection can also be incorporated into thedesign where site conditions warrant.


Boulder placement must not constrictthe channel cross-section or reduce thewidth-to-depth ratio. Otherwise, therepair will likely destabilize the channel.

Armoring or the placement of bouldersalong the bank will increase turbulence inthe area andother areas downstream,which could increase erosion.

FIGURE 14: VEGETATED GEOGRIDS OR SOIL LIFTS



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#8: ROOT WADS AND

BOULDERS

This method consists of using a combinationof boulders, logs, and live plant materialto armor a stream bank. It enhances fish

habitat, and creates a natural-looking bankstabilization structure 1. Footer logs areset in a toe trench below the thalweg line(the line of maximum depth in a stream),with the channel end pointed downstreamand the butt end angled 45 to 60 degreesupstream. A second log (with a root wad)is set on top of the footer log diagonally,forming an X.

The root wad end is set pointing upstreamand the butt end lying downstream 45 to 60degrees. The apex of the logs are anchored

together using boulders, re-bar or cables.Large boulders are placed on top andbetween the logs at each apex. After allthe logs and boulders are set in place, liveplant material, such as willows, is placedwithin the spaces of the structure behindthe boulders. Excavated gravel and streammaterials can then be placed over the bankend portion of the structure1.

This method will tolerate high boundaryshear stresses if logs and root wads arewell anchored. This method should, where

appropriate, be used in conjunction withsoil bioengineering or live vegetationplantings in order to stabilize the upperbank and ensure a regenerative source ofstreambank vegetation. The enduranceof the structure depends on the speciesof logs used; it might need replacement ifvegetative colonization does not take place.


This method may cause channel scour anderosion of downstream and opposite banksif a modified floodplain is not constructedalong the opposite bank. It may also causeupstream scour. 2.

1 Source: California Department of Fish and Game,

California Salmonid Stream Habitat Restoration

Manual

2Source: Natural Resources Conservation Service,

Stream Corridor Restoration Principles, Processes

and Practices



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#9: BOULDER/ROCK

REVETMENT

Rock rip-rap is a method for armoringstream banks with boulders that preventbank erosion. Rock riprap can be used at

the toe of the slope in combination withother vegetative methods on the upperportions of the bank. Rock can also be usedfor drainage outfall structures. Rip-rapfooting is laid in a toe trench dug alongthe base of the bank. The size of the rockis determined according to the expectedvelocity in the channel, and can vary from6 to 18 for velocities up to 10 feet persecond up to 24 minimum for highervelocities. Large angular boulders are bestsuited for this purpose because they tendto interlock. The rocks specifications mustmeet certain standards in order to assurethat it is structurally sound.

A gravel blanket that is at least one footthick should be placed under the rockrip-rap on slopes of 1:1 or greater. Thisprevents underlying soil from beingwashed out, which leads to slope slumpand failure during periods of high flow.Geotextile fabrics should be avoided, sincethey prevent the natural establishment ofvegetation1.

This method should, where appropriate,be used with soil-bioengineering systems,or live vegetation, to stabilize the upperbank and ensure a regenerative source ofstreambank vegetation. A major benefitof this method is that the components areflexible and their function is not impaired byslight movement from settlement or otheradjustments2.

DESIGN CRITERIA AND

CONSIDERATIONS:

Rock should be keyed in approximatelythree feet below the bed elevation.

Rock can be graded from larger at the toe

to smaller at the upper banks.

This method may cause channel scour anderosion, especially downstream and alongopposite banks, if a modified floodplain isnot constructed along the opposite bank.It may also cause upstream scour.

#9A: BOULDER REVETMENT

WITH SOIL AND REVEGETATION

This method consists of placing soil over theboulders and installing vegetation by staking

and/or direct seeding. Biodegradableerosion control mats are placed over thesoil to help control erosion until vegetationestablishes itself. Special care must betaken while driving live stakes betweenboulders to avoid damage to the cambiumlayer of the woody material and to ensuregood soil/water/stake contact. Thick rip-rap layers may require special tools forestablishing staking pilot holes.2


Woody material can be placed using abackhoe with an auger attachment, or bydriving a steel bar between boulders, or byplacing rock around durable plantingtubes.

This method may cause channel scourand erosion of downstream and oppositebanks if a modified floodplain is notconstructed along the opposite bank.It may also cause upstream scour.

1 Source: California Department of Fish and Game,

California Salmonid Stream Habitat Restoration

Manual

2 Source: Natural Resources Conservation Service,

Stream Corridor Restoration Principles, Processes and

Practices



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FIGURE 16: BOULDER REVETMENT WITH SOIL AND REVEGETATION



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#10: CELLULAR CONFINEMENT

SYSTEM

Soil cellular confinement system (geocell)is a polyethylene plastic cellular systemwhere structural strength is developed by

the composite design of soil, plant roots,and the plastics cellular configuration.This system is available in eight-inch deephoneycomb mats that can be installed inoffset vertical layers to create terracedplanting areas. The honeycomb cells arefilled with soil, moderately compacted, andplanted with woody vegetation and grasses.The structure functions similarly to a cribwall structure. This method can also beused in combination with slope grading andvegetation on the upper slopes.

This method can foster the development ofvegetation.

#11: LIVE LOG CRIB WALLS

Live log crib walls are used to reducesediment input and protect banks in areaswhere logs are available and boulders arenot practical1. These temporary structuresare designed to rot and degrade afterlive plant material has established itself.Cribbing provides protection in areas withnear-vertical banks where bank sloping

options are constrained by adjacent landuses.

In this method, two rows of base logsare placed parallel to the bank, intrenches below stream grade, to minimizeundercutting of the structure. Tie-backlogs are notched into the base logs andplaced at regular intervals (typically 6 to8 feet) along the base logs. Tie-back logsare attached to the base logs using re-barpins or cables. There should be at leasttwo tie-back logs connecting each pair of

base logs. Once the first row of tie-backlogs has been connected, a second set offace logs is placed on top of the tie-backs.This procedure is repeated until the desiredlevel of bank protection is achieved. Aseach lift is constructed, the face logs andtie-backs are filled with a mix of gravel andcobbles to the top of the face log. It is notnecessary to use topsoil in the fill material;

but there should be sufficient fine-grainmaterial to insure vegetation growth. Livecuttings are then laid in to form a completecover layer. These live branches should belong enough to have their butt ends in thesoil behind the crib wall. The tips should

stick out of the crib wall no more than aquarter of the cutting total length. Thebranches are then covered with the gravel/cobble mix to the top of the tie-backs, andthe next layer is continued.

This method is effective on the outside ofbends where high velocities are present,and in situations where a low wall may berequired to stabilize the toe and reduceslope steepness2. The use of crib wallsin a specific location must be consideredcarefully in the context of the streams

function. If placed incorrectly relative to theactive channel, the bends in a meanderingstream can induce considerable damagedownstream or on the opposite bank. Thismethod does not adjust to toe scour andshould be used in combination with soilbioengineering systems and live plantings tostabilize the upper slopes2.

DESIGN CRITERIA AND

CONSIDERATIONS:

This method may cause channel scour

and erosion of downstream and oppositebanks if a modified floodplain is notconstructed along the opposite bank.It may also cause upstream scour.

As the logs rot, the crib wall can beundercut and eventually fail. If thestructure fails, hazardous rebar and steelcable can be deposited in the riveralong with the logs and other debris of thestructure.

1Source: California Department of Fish and Game,

California Salmonid Stream Habitat Restoration Manual

2 Source: Natural Resources Conservation Service,

Stream Corridor Restoration Principles, Processes and

Practices



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FIGURE 17: LIVE LOG CRIB WALLS



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TABLE 2: EROSION REPAIR METHODS THAT ARE NOT RECOMMENDED:

Repair Method Appropriate Slope Appropriate Water

Velocity

Environ

Value

Cost

12 Concrete Crib

Walls

Up to 0.25:1 High: up to 15 ft/sec;

depending on size of cribwall openings.

Negative High

13: Articulated

Concrete Blocks

Up to 1:1 High: up to 15 ft/sec; for

closed cell ACBs, low to

medium for open cell

ACBs.

Negative High

14: Gabions From 0.75:1 up to

3:1

High: up to 15 ft/sec;

lower velocity if planted,

depending on size andnumber of planting

pockets.

Negative High

15: Sacked

Concrete

Up to 0.5:1 High: up to 15 ft/sec; Negative High

16: Gunite Slope

Protection

Up to 1:1. High: up to 15 ft/sec Negative Medium

#12: CONCRETE CRIB WALLS

Concrete crib walls consist of stackedinterlocking concrete frames that form aretaining wall. Its structural strength isdue in part to the composite design of aconcrete frame with compacted backfill.Crib walls are constructed with open facepanels that are planted by live staking.This method restricts plant growth to thesize of the panel opening. As the crib wallslope is flattened and the lattice becomesmore open, the vegetation potentialincreases, and the allowable velocitydecreases because of the exposed soil andvegetation. Concrete crib walls performsimilarly to live log crib walls. Becausethe crib wall is a rigid structure, it is moreprone to massive failure in the event ofundercutting or settlement.

All crib walls tend to cause channel bedand bank erosion both in the immediate

area and other areas downstream, and mayalso cause erosion upstream. Most cribwalls eventually fail because they attemptto resolve a symptom of erosion, not itscause. The use of concrete crib walls isdiscouraged. This method is mentioned onlyfor reference.



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# 13: ARTICULATED CONCRETE

BLOCKS

Articulated concrete blocks (ACB) consists ofconcrete interlocking blocks that are cabledtogether to form mats that can be laid on

the channel slope and/or channel bottom.There are two styles of ACBs: open cell andclosed cell. The open cell style allows forvegetation to be recruited into the soil fillingeach cell. Vegetation growth is restrictedby the sizes of the cell openings and by thedisconnection caused by the cell walls. Inour arid climate, the long-term viability ofvegetation within the restricted cell openingsis problematic. However, open plantingareas can also be constructed into the ACBmats by creating an opening in the mat by

removing some of the blocks. The openareas can be revegetated with shrubs andtrees. Irrigation is necessary to aid plantestablishment.

This method will create channel andbank erosion both down and upstreamof protected areas. It is environmentallyunfriendly and prone to failure. When itfails, steel cables and stakes hazardouslyprotrude from the mats into the channel.This method is not appropriate for smallerosion repair sites, and is discouraged

because of the limited potential for bioticresources.

#14: GABIONS

This method consists of placing large wirebaskets filled with rocks on channel banks,either as mattresses or stacked in layers thatresemble steps. Gabions can sometimesnaturally revegetate if adequate water andsoil are available. Gabions can also berevegetated using planting boxes. (Plantingboxes are gabion cells that are left opento bare soil and revegetated with shrubsand trees.) Temporary irrigation may beprovided to the planted vegetation in orderto aid its establishment. But, wire basketscan deteriorate over time and may beharmful to fish.

Gabions are very hazardous and unfriendlyto native fish, especially salmonids, which

often try to spawn in gabions below thewater line. The basket wire deterioratesquickly, and the fish are injured on thebaskets sharp wire barbs.

Furthermore, the baskets used to line orarmor the banks of streams cause bedand bank erosion. They often undercut orfail due to slumping of the soil on whichthey are constructed. The use of gabionsis discouraged and are rarely permitted bythe Department of Fish and Game except inextreme situations. The material is included

here for information.



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#15: SACKED CONCRETE

Sacked concrete slope protection consists ofburlap bags filled with concrete and placedagainst channel banks. Sacked concretedoes not provide any revegetation potential.However, it offers the opportunity to contourwalls around existing vegetation such as treewells.

Sacked concrete should not be used becauseit causes erosion, degrades water quality,and destroys other beneficial uses. It isincluded here for reference. There may,however, be extreme circumstances wheresite constraints, vertical slopes, and highvelocities preclude all other options.


#16: GUNITE SLOPE

PROTECTION

Gunite slope protection consists of apressurized concrete mixture sprayedover an eroded bank. The gunite can be

textured, colored, and formed for aestheticsto mimic natural rock. Reinforcing steelmay be placed against the bank prior tospraying. This is not an acceptable methodof erosion repair, but is included herebecause it has been successfully used withsoil nails to stabilize vertical slopes onupper banks where land use constraintspreclude regrading of the slope. Sheet pileretaining walls have been used in a similarmanner. Vegetation can be placed on thelower portions of the bank to enhance bioticresources.

Gunite slope protection causes erosionproblems, degrades water quality anddestroys other beneficial uses. Therefore, theuse of gunite slope protection is discouragedand is included here only for reference.


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When in doubt, ask. If you are notsure whether your project needs a permitor whether it is regulated at all, ask.Going ahead without following the properguidelines will ultimately cost you time,money, and goodwill.

Keep good records. Keep notes ofconversations and meetings. Ask forinterpretations of rules to be written bythe agency representatives. An easy wayto do this is to confirm conversationsby E-mail. Remember, agency staff timeis limited; it is easier for them to reviewor comment on your understanding thanfor them to compose the correspondence.

PROHIBITED ACTIVITIES

Before you decide to do work near acreek or river, you should consider thatit is illegal to place, store, or dispose ofmaterials of any kind on the banks of, orinto, a watercourse. Prohibited materialsinclude dirt, soil, and concrete; pool andspa water; paints, solvents, and soaps;yard and animal waste; automobile andmachinery fluids; and firewood and buildingmaterials. Remember to comply withbest management practices that preventpollution from entering the waterway anddamaging the ecosystem.



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AGENCIES THAT MAY REQUIRE PERMITS

Use this chart to help you determine which agency may be involved in your project.A checked box indicates that an agency may be involved and should be contacted,but does not mean they definitely will be involved.

SantaClara

Valley

WaterDistrict

YourCitys

Planningor

Public

WorksDept

NOAA

CalEPADTSC

SWRCBWater

Rights

RegionalWater

QualityControl

Board

CaliforniaFish

andGame

ArmyCorps

of

Engineers

U.S.

Fish&

WildlifeService

Involve work on the bank of

a river, stream, or lake? X X X X X X

Involve excavation of the

bank? X X X X

Involve placement of piers? X X X X X X

stabilization or erosion

control? X X X X X Xequ re t e remova o

riparian or other wetland

vegetation? X X X X X X X

Involve planting riparian or

wetland vegetation? X X X X X X

Affect native plants, wildlife,

or fisheries? X X X X X

Result in stormwater

discharge into a creek or

wetland? X X X X X X

Divert or obstruct the

natural flow or change the

natural bed or bank of a

creek or wetland? X X X X X X

Involve repair,

rehabilitation, or

replacement of any

structure or fill adjacent to a


Involve placement of bank

protection or stabilization

structures or materials (e.g.,gabions, riprap, concrete

slurry/sacks)? X X X X X

Involve building any

structure adjacent to a

creek or wetland? X X X X X Xnvo ve s an w e

enhancement, attraction, or

harvesting devices and

activities? X X X X X


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SantaClara

Valley

WaterDistrict

YourCitys

Planningor

Public

WorksDept

NOAA

CalEPADTSC

SWRCBWat

er

Rights

RegionalW

ater

QualityCon

trol

Board

CaliforniaF

ish

andGame

ArmyCorps

of

Engineers

U.S.

Fish&

WildlifeSer

vice

Use materials from a

streambed (including but not

limited to boulders, rocks,

gravel, sand, and wood

debris)? X X X X X X X

Require the disposal or

deposition of debris, waste,or any material containing

crumbled, flaked, or ground

pavement with a possibility

that such material could pass

into a creek or wetland? X X X X X X X

Involve the removal of any

materials from, or add fill to,

a creek or wetland? X X X X X X X X

Involve grading or fill near a


Involve a bridge or culvert? X X X X X XInvolve utility pipe lines? X X X X

Involve a septic leach field

near a creek or wetland? X X X X

Require a water well near a

creek or wetland? X X X X

Involve work within historic or

existing coastal wetlands? X X X X X

Remove water from a creek

for storage or direct use on

non-riparian land? X X X X X X X XRequire that hazardous

materials be generated

and/or stored on site? X X X X

Take place in, adjacent to, in

a building adjacent to or

near a river that has been

designated as "wild and

scenic" under state or federal

law? X X X X X



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SantaClaraValley

WaterDistrict

You

rCitys

Plan

ningorPublic

WorksDept

NOA

A

CalE

PADTSC

SWR

CBWater

Righ

ts

RegionalWater

Qua

lityControl

Board

CaliforniaFish

and

Game

ArmyCorpsof

Engineers

U.S.

Fish&

Wild

lifeService

Require water to be

diverted from a river,

stream, or lake for the

project or activity? X X X X X X X

Affect water quality by the

deposition of silt, an

increase in water

temperature, a change in

the pH level, or in some

other way? X X X X X X

Occur in an area whereendangered or rare plant

species are thought or

known to occur? X X X X X

Occur in an area where

endangered or threatened

fish, bird, or animal species

are thought or known to

occur? X X X X X X

SAN FRANCISCO BAY AREA

JOINT AQUAT IC RESOURCEPERMIT APPLICATION

As discussed earlier, projects in or nearcreeks and even intermittent streams canbe regulated by many agencies, the localcity government, local agencies, such asthe Santa Clara Valley Water District, stateagencies, such as the San Francisco BayRegional Water Quality Control Board,and California Department of Fish andGame, and federal agencies, such as theArmy Corps of Engineers and U.S. Fish andWildlife Service, to name a few. For projectswith an aquatic component, such as worknear a creek or stream, a single applicationcalled the San Francisco Bay Area JointAquatic Resource Permit Application (JARPA)has been designed to replace individualapplications for state, regional, and federalagencies. As suggested earlier, considertaking advantage of this consolidated

application to streamline the project permit

application process.If a project requires local approval, suchas that of the local city government orSanta Clara Valley Water District, be sureto check with these agencies about what toinclude in the application, since the JARPAdocument does not consider local agencyrequirements.

CALIFORNIA ENVIRONMENTAL

QUALITY ACT

Prior to obtaining permits for a project, a

California Environmental Quality Act (CEQA)review will be required if the project isundertaken by a public agency or if a publicagency needs to issue a permit for a project.CEQA is found in Section 21000 et seq.of the Government Code, and the CEQAguidelines are found in Section 1500 et seq.of the California Code of Regulations.



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if the project will have no significantimpact on the environment without theneed for mitigation measures to reducea project impact to a less than significantlevel. A public hearing to adopt thefindings and the Negative Declaration

is required.

Hint: If, at any time along thepermitting or review process,you find that your proposedproject can have a significant impacton the environment, and byredesigning your project, theimpact can be eliminated orreduced to insignificant, youwill save yourself time and money byredesigning your project.

3. A Mitigated Negative Declarationis issued for the project. This meansthat there are significant impacts fromyour project on the environment,but mitigation measures duringimplementation can be adoptedto reduce these impacts to a less thansignificant level. A mitigation monitoringand reporting plan is required to identify,what, who, when and where for eachmitigation measure, thus ensuring that allmitigation measures are implemented.A public hearing is required.

4. An Environmental Impact Report(EIR) is required to study the significantimpacts of your project on theenvironment. Various alternatives to yourproject must be identified andevaluated and the environmentallypreferred alternative must be selectedunless there are overriding circumstancesthat make the project desirable, eventhough there are significant unmitigatedimpacts. This finding must be made by

the approving body of the lead agency,along with the findings and MMRP.Because there are more alternatives toevaluate, there is a slightly longer reviewperiod and a requirement to specificallyrespond to comments. For this reason, anEIR can be the most time-consuming andcomplicated scenario.

The Guidelines have the force of law, andlay out the way CEQA is administered.

(See http://ceres.ca.gov/topic/env_law/ceqa/)

The purpose of the CEQA review is to

inform project decision-makers of the issuesassociated with the project, to identifysignificant environmental impacts andreduce them, and to disclose to the publicthe rationale for the decision to approvea project. The agency responsible for theCEQA review is called the lead agency,and it is usually the agency with the mostinvolvement in the project. The localmunicipalitys planning department usuallyhandles the CEQA review, however, CDFG isalso a lead agency for purposes of issuing a

Streambed Alteration Agreement.Once the lead agency is identified, allother agencies that require a permit tobe issued for the project, whether state orlocal, become responsible. Responsibleand trustee agencies must consider theenvironmental document prepared by thelead agency and do not, except in rareinstances, prepare their own environmentaldocuments.

THERE ARE FOUR POSSIBLE

SCENARIOS REGARDING CEQAREQUIREMENTS:

1. The project is exempt from CEQA.Exemptions are listed in theCEQA Guidelines. Specific rulesshould be consulted, but essentially,a categorical exemption cannotbe used if the project has the potentialfor an individual or cumulativesignificant effect on the environment.Documentation of exemptions shouldbe obtained from the lead agency.

Unless a public hearing is requiredby the local agency for the project, acategorical exemption does not require apublic hearing. The document is simplyfiled at the county for a specified period.

2. A Negative Declaration is issuedby the lead agency for the project.A Negative Declaration can be issued



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There is a wide body of literature thatprovides more detailed information onthese bank protection repair techniques.

We have identified several of the morecomprehensive documents. A morecomplete list can be found athttp://www.4sos.org/wssupport/ws_rest/rest_con.asp.

A CITIZENS STREAMBANK

RESTORATION HANDBOOKThis 171 page handbook is a guide torestoring eroding streambanks usingvegetation and flexible systems. It, featuresinstallation guidelines, sample budgets,case studies and tips on choosing the bestrestoration solution. $20 plus $5 shipping.To order call 800/284-4952 or [email protected].

HOW TO HOLD UP BANKS:

USING ALL THE ASSETS An informative, well-illustrated booklet oncontrolling stream erosion. Produced by theBoquet River Association (BRASS), a smallnonprofit group with extensive experiencein stream monitoring and restoration, thebook helps citizen groups tap community

resources and find success with low-costtechniques. Techniques covered includestreambank shaping; grass, seedling, andlive posts planting; log cribbing and stoneriprap installation. To order send $8 to

BRASS, c/o Essex County GovernmentCenter, Box 217, Elizabethtown, NY 12932,or call 518/873-3688.

SECTION 7 - REFERENCE MATERIALS

STREAM CORRIDOR

RESTORATION: PRINCIPLES,

PROCESSES, AND PRACTICES

Developed by an interdisciplinary teamof stream and watershed managementspecialists, hydrologists, engineers andother EPA, federal agency, and privategroup representatives. A printed documentis available for $71, a CD-ROM versionsells for $60. Available through theCenter for Watershed Protection. athttp://www.cwp.org

THE PRACTICE OF WATERSHED

PROTECTION: TECHNIQUES FOR

PROTECTING AND RESTORINGURBAN WATERSHEDS -- At $80,150 articles are included on all aspects ofwatershed protection. Drawn from pastissues of Watershed Protection Techniques aswell as a wealth of other Center papers andreports, this 800-page book is organizedaround the eight tools of watershedprotection, and indexed for easy reference.Available through the Center for WatershedProtection. at http://www.cwp.org.

URBAN STREAM RES TORATION

PRACTICES: AN INITIAL

ASSESSMENT This assesses theperformance of 24 urban streamrestoration practices from sites around theMid-Atlantic and Mid-west, and providesrecommendations for improving theirapplication in a variety of urban streamenvironments. It costs $20. Availablethrough the Center for WatershedProtection. at http://www.cwp.org.



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STREAM-BANK REPAIR

GUIDANCE MANUAL FOR

THE PRIVATE LANDOWNER -

- GUADALUPE AND ALAMITOS

CREEK This focuses on erosion repairin mercury-contaminated streams, but itis relevant to a broad range of erosionrepair projects. Some of the most relevantinformation from this document is containedin this Design Guide. This publication canbe obtained from the Santa Clara ValleyWater District.

MAINTAINING CORTE MADERA

CREEK: A CITIZENS GUIDE

TO CREEK-SIDE PROPERTY

PROTECTION Created for the Town ofPortola Valley and its residents to help guide

bank stabilization and revegetation effortsalong Corte Madera Creek, a tributaryto San Francisquito Creek. The reportwas created to facilitate communicationsbetween the Town and private propertyowners who wish to address erosion andproperty loss. The document can be found athttp://www.cityofpaloalto.org/public-works/jpa-projects.html.

GUIDELINES FOR BANK

STABILIZATION PROJECTS: IN

RIVERINE ENVIRONMENTS OFKING COUNTY Produced by theKing County Department of Public WorksSurface Water Management Division,Seattle, Washington in 1993. This reportis an exceptional manual that clearly andcomprehensively describes the planning,design, permitting, and constructionaspects of bank erosion repair. From atechnical perspective , it is very applicable toCalifornia streams. This resource, includingsome of its illustrations, was used to help

prepare this Bank Protection Design Guide.


chapter 4 bank protection erosion

Documents