construction and refurbishment of earthen irrigation channel banks

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17. Protective CoverTable of ContentsSubjectPage No.17.1 Introduction ........................................................................................................... 17-217.2 Cracking................................................................................................................ 17-217.3 Dispersion Failure.................................................................................................. 17-317.4 Proven Practice Options......................................................................................... 17-317.5 Specifications ........................................................................................................ 17-517.5.1 Gravel............................................................................................................................................... 17-517.5.2 Sand ................................................................................................................................................. 17-517.5.3 Topsoil ............................................................................................................................................. 17-617.5.3.1 Chemical Treatment of Material available on Site ................................................................. 17-617.6 Establish Vegetation Cover.................................................................................... 17-717.6.1 Benefits of Vegetation Cover on Channel Banks............................................................................. 17-717.6.2 Disadvantages of Vegetation Growth on Channel Banks ................................................................ 17-717.6.3 Vegetation to be encouraged on Channel Banks.............................................................................. 17-717.6.4 Issues to consider before vegetating a channel bank...................................................................... 17-1017.7 Methods of Establishing Vegetation Cover .......................................................... 17-1017.7.1 Propagation From Seed And Vegetative Matter Contained In Topsoil.......................................... 17-1017.7.2 Rope Wick Application.................................................................................................................. 17-1117.7.3 Vegetative Propagation.................................................................................................................. 17-1117.7.4 Sowing Seed .................................................................................................................................. 17-1117.8 Decision Process.................................................................................................. 17-1317.9 Maintenance ........................................................................................................ 17-1317.10 Australian Standards............................................................................................ 17-1517.11 References ........................................................................................................... 17-15Construction and Refurbishment of Earthen Channel Banks August 2002 – Edition 1.0 17-1
17.1 IntroductionIt is important that the finished surface of the compacted earthen bank be covered as soonas possible after construction is completed. This Protective Cover is required over theexposed crest and outside batter of the compacted bank to maintain moisture content andto minimise deterioration caused by:• drying and surface cracking of the compacted bank• piping or tunnelling failure of dispersive soils• sheet erosion or rilling caused by rainfall runoff• stock, vehicles and farm operationsPhysical damage to the bank by stock and farm operations can be controlled bylongitudinal fencing of banks, however this is not always practical. A protective coverover the channel bank may reduce damage that is caused by these activities.crestprotective coverNaturalSurfaceoutsidebattercompacted bankFigure 17-1Protective CoverThis section addresses the crest and outside batters of channel banks. For Inside BatterTreatment refer to Section 18.17.2 CrackingDuring periods of dry weather it is common for some minor surface cracking to occur aschannel banks dry out. This is a normal cyclic occurrence and these minor cracks shouldseal up during the next period of wet weather.However, some material types are more prone to cracking than others, and where theseexpansive (fat) clays are used in compacted banks, deep cracking that extends below thewater level can occur as the compacted bank dries out during long dry periods. Refer toSection 10.2.2, Cracking and Section 15.5 Shrinkage.Low shrinkage material will experience less cracking problems and no special protectivecover or treatment required.Many irrigation systems report increased number of channel bank leaks and bank failuresduring long periods of extreme dry weather. These leaks typically occur in the topsection of the bank, where cracks have opened up across the bank and extend downbelow the water line.Construction and Refurbishment of Earthen Channel Banks August 2002 – Edition 1.0 17-2
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Your comments on the format and con
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During the course of this project,
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AcknowledgmentsThese Guidelines rep
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FundingFunding of this project was
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Table of ContentsBook 1SubjectPage
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1. Introduction1.1 GeneralGood asse
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(iv) provide proven practice approa
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3. Research Procedure3.1 Terms of R
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4. How to use these Guidelines4.1 W
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6. Units of MeasurementQuantity Uni
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8. Earthen Irrigation Channels8.1 D
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8.3 ReferencesAustralian National C
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9.1 IntroductionA key input to adva
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Data from Goulburn-Murray Water’s
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General 1 2 3 4 5 6DescriptionRisk
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Channel BankSequential Deterioratio
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9.2 ReferencesGutteridge Haskins &
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10.2.3.1 Dispersive layer of materi
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Causes ofSpecific factorDeteriorati
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10.1.2.5 BendsA bend in the channel
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10.1.4.1 Construction techniqueIrri
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10.1.5.4 Overtopping of banksIn ade
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In the past maintenance techniques
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Maintenance is a continuing require
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10.1.7.4 Yabbies/fresh water crayfi
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Direct removal ofmaterial by entrai
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Figure 10.10 shows longitudinal cra
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10.2.3.3 Irregular compaction - bri
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10.3 ReferencesEmerson W (1996), pe
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11.1 GeneralThe Investigation and P
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iv) Available fill materials and, w
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12.15 Radius of Bends .............
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There are several ways a channel ca
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• Land acquisition extent and typ
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The investigation should generally
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• Backfill: 10% compaction factor
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1. Flow Area, A, is the cross-secti
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after ageing and weed growth. If an
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elationships may be the controlling
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These maximum velocities should be
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Thus channels are usually designed
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Some of the design issues that shou
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12.12.1.3 Best PracticeEither of th
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12.13.2 Channel MaintenanceIncrease
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along a channel. The depth of the w
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12.13.4.7 Change of AlignmentThe in
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12.15 Radius of Bends12.15.1 Flow A
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12.16 Channel Cross SectionThe cros
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Some irrigation authorities use one
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12.16.2 BanksChannel cross sections
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Unless the bank is very high, the s
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The stability of channel batters ca
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drop bars become difficult and time
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Both the height above the bed and t
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• enable maintenance of the chann
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- Access agreementsA description of
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13/08/02 19:2012.20 Channel Tenure
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13/08/02 19:20As with the damage to
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13/08/02 19:20Advantages of Protect
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- gates provide a better deterrent
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13/08/02 19:20When considering expo
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13/08/02 19:20A typical design draw
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13/08/02 19:20Sinclair Knight Merz
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13.1 IntroductionIn many irrigation
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For example, the initial constructi
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13.2.6 When to use Life Cycle Analy
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The timing of the life-cycle costin
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• assess cost of collecting missi
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Microsoft Excel has quite a good pr
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The costs used in these methods sho
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Life CyclePhaseInvestigationDesignC
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Life CyclePhaseMaintenanceRehabilit
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ReplacementProject managementInvest
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Residual valueLegal feesInsuranceAd
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13.4.6.2 Recurring CostsChannel con
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$1.00.80Percent ofValue of$1.00.60.
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13.4.11 Evaluate ResultsThe results
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13.6 Tipsthe way open to incur sign
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14. Risk AnalysisTable of ContentsS
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Consequences for irrigation authori
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15. Material Selection and TestingT
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c) Shrinkage - will the bank crack
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depth. For this reason, the soils o
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Natural moisture content should als
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The study identified some confusion
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15.4.2 Determination of the plastic
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1. Preparation of PatTake approxima
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EmersonClass No.Degree ofDispersion
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15.7.1 Coarse grained soilsIn this
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sufficient gravel for erosion resis
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Page 186 and 187: The uniform application and thoroug
Page 188 and 189: essential that the chemical is thor
Page 190 and 191: Where laboratory testing facilities
Page 192 and 193: Clays are the plastic fines. They c
Page 194 and 195: etween the soil sample and the wate
Page 196 and 197: 16. Compaction ControlTable of Cont
Page 198 and 199: 16.1 PurposeDuring this research pr
Page 200 and 201: All compaction equipment utilises s
Page 202 and 203: The soil density required for a cha
Page 204 and 205: In the past, a method specification
Page 206 and 207: Low permeability and high stability
Page 208 and 209: 16.10.1.1 Tamping Foot RollerTampin
Page 210 and 211: 16.10.1.5 Non-Circular Impact Rolle
Page 212 and 213: 16.10.3 Compactor OperationsAfter t
Page 214 and 215: 16.11.4 Moisture Content ControlBef
Page 216 and 217: 16.12 Density Control Tests and Pro
Page 218 and 219: Correlation with local materials an
Page 220 and 221: The main advantages of the Nuclear
Page 222 and 223: Figure 16.4Hilf Density Ratio Repor
Page 224 and 225: The location and test results for e
Page 226 and 227: 16.14.3 Reporting and RecordsTest r
Page 228 and 229: 16.16 Tests for small projectsThe s
Page 230 and 231: The advantages of the Drop Test are
Page 232 and 233: AS1289.6.3.2-1997AS1289.6.3.3-1997A
Page 236 and 237: The bank dries and cracks from the
Page 238 and 239: 17.5 Specifications17.5.1 GravelPar
Page 240 and 241: 17.6 Establish Vegetation CoverTops
Page 242 and 243: Species Growing Conditions Establis
Page 244 and 245: 17.7.2 Rope Wick ApplicationMuch of
Page 246 and 247: There are a number of fibre mats or
Page 248 and 249: 17.10 Australian StandardsAS1289.3.
Page 250 and 251: 18.1 IntroductionFor many earthen c
Page 252 and 253: When re-shaping the batters of exis
Page 254 and 255: LifeCrestOld bank lineBattered bank
Page 256 and 257: Photos\inside batter\CG7channel2arm
Page 258 and 259: 4. To help place the rock material
Page 260 and 261: False ToeFigure 18.8Protective laye
Page 262 and 263: The confinement system would be adv
Page 264 and 265: • Able to survive during non-oper
Page 266 and 267: 18.6 ReferencesHutchison D & Locke
Page 268 and 269: 19.20 Guidelines on Field Quality C
Page 270 and 271: Construction and Refurbishment of E
Page 272 and 273: • Figure 19.2)3. Temporary Bench
Page 274 and 275: The capabilities and limitations of
Page 276 and 277: 19.3.1 Construction EquipmentThe ba
Page 278 and 279: construction. The aim of scarifying
Page 280 and 281: Whether or not a front-end loader o
Page 282 and 283: The thickness of each layer will va
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distribution. The use of alternativ
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19.8 Construction RecordsAdequate r
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19.12 Protective Cover on Crest and
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19.21 Australian StandardsAS 1726-1
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20.1 ScopeAustralia’s earthen irr
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Bank re-construction normally requi
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•meter outlet locations and type
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In the case of channel bank refurbi
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20.4.1.1 StrippingWith outside bank
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All public roads to be used by truc
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5. Material is delivered by trucks
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Need to drain and de-waterEBM befor
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significantly and a more conservati
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Aim for crest width ofabout 2 metre
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Refer to Section 18, Inside Batter
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21.8.10 Re-alignment ..............
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Seepage is a complex hydrologic phe
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2. Seepage losses increase as the d
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Refer also to the following section
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21.4 Channel Seepage ConsequencesSe
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Channel seepage is one of the sever
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Seepage is proportional to soil per
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Methods based on vertical flow meas
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ainfallPumpingevapotranspirationIrr
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Flow NetsA flow net is a system of
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Data from indirect measurement proc
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(ii) EM SurveyElectro-magnetic (EM)
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The volume of waterloss from the dr
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21.7.3.2 Inflow-Outflow Method (Dyn
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Imperfect seal will cause the meter
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The groundwater level can then be d
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Stable IsotopesThe basis of testing
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To be most successful, there needs
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21.8.6 Surface interception drainag
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KeyWatertable before tree plantingW
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• The preparation of a best pract
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21.11 ReferencesAustralian National
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22. Channel LiningTable of Contents
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22.1 IntroductionThe conservation o
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The different types of channel lini
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Table 22-1Unlined Earthen Channels
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Lining of channels will not elimina
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To supply a given discharge, the cr
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22.4.5 Structural SafetyThe stabili
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soil pressures and under-drainage i
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Concrete linings are suitable for b
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22.5.12 Availability of Constructio
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esistance to erosion. To improve th
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Construction and Refurbishment of E
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22.7.1.2 General Design Considerati
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22.7.1.4 Lining ThicknessThe thickn
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particular problems, but in smaller
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Where the earth lining finishes abo
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control where the channel material
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sand requires about 5% cement by we
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22.7.6 Soil SealantsSoil sealants a
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22.7.7 Cost of Earth LiningsThe cap
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Although they can assist with shear
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22.8.2 Membrane Liner TypesGeomembr
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Polyethylene has also appeared in m
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FPP resistance to common chemical e
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The base coat and seal coat rates m
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A common and misleading argument is
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These thermal expansion and contrac
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Another factor is the ability to ha
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Some lining methods expand and cont
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22.8.9.1 Geomembrane ThicknessThe t
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Cover typeThickness ofEarth fill(m)
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22.8.9.5 Cover MaterialGeomembranes
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As well, velocities which are permi
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22.8.11 FencingWhen livestock, part
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22.10 ReferencesAlther GR (1987), T
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23. Measures to Reduce the Rate ofD
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Channel DesignBank MaterialDeterior
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Stock and VerminAdjacentlandholders
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To ensure that a channel bank has a
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Advantages of Draining• Allows fo
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To efficiently maintain a channel,
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Compared with other countries where
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23.4.7 LeaksTransverse cracks are t
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23.5 Reduction of Deterioration due
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Photo 23-1Channel bed showing mumbl
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Thus, control of carp by draining c
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The disadvantages of a biological c
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Carp have been blamed for erosion o
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Management Groups gives guidelines
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Organisation Contact Details Aims/A
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Chemical treatment is often recomme
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23.7 Reduction of Deterioration due
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Grey Parrot Pea - Dillaynia cineres
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Lodge G (1998), Review on Fish Barr
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cation exchange capacity (CEC) a me
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fetch the distance over which the w
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plant term used for construction eq
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supply level the supply level is a
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