construction and refurbishment of earthen irrigation channel banks

More documents

Recommendations

Info

Some irrigation authorities use one roughness coefficient (n) for design of allearthen channels irrespective of size. While a single figure may be adequate for arange of situations, a more careful consideration of the roughness coefficient isrecommended to reduce life-cycle costs and achieve the most economic outcome.Section 12.11.1 considers the selection of appropriate roughness coefficients.Detailed design of channel cross sections that provide satisfactory velocities andadequate capacities are determined principally by the topographic and geologicconditions along the channel alignment. Topographic conditions determineavailable grades and depths of excavation, and geologic conditions determine mostof the other details of design.A careful study should be made of the materials forming the channel section orderto determine the appropriate velocity for the required capacity. Section 12.11considers the channel velocity aspects of design.For open channels, the semicircle is theoretically the most hydraulically efficientshape, ie the maximum area for the minimum wetted perimeter, but the constructionand maintenance of a semicircular earthen channel presents particular difficultiesand costs. One major issue is the instability of the circular side slopes.Close approximations to the semicircular shape can be made without sacrificing toomuch hydraulic efficiency, and trapezoidal cross sections are commonly used forearthen irrigation channels since they are usually the most practical shape toconstruct and maintain.The proportions of the trapezoidal sections vary depending on the size of thechannel, the grade, and the soils through which the channel is to be constructed.Trapezoidal earthen channels often became naturally rounded at the bottoms as aresult of gradual scouring and silting. A section constructed with rounded toesbetween the bed and batters is better than a strictly trapezoidal section, as it is morestable.Deep narrow sections are desirable when feasible, since they provide higherhydraulic efficiency than wide shallow sections. However, this section is seldompractical for earthen channels because flatter batter slopes are required due to soilstability conditions.Once the batter slopes have been determined, the trapezoidal shape with the greatesthydraulic efficiency can be determined. For batter slopes of 1:2, a bed width equalto about half the water depth is the most hydraulically efficient section.However, economic considerations and certain practical construction, operationaland maintenance requirements, usually make necessary considerable departure fromthe most theoretically efficient cross-section, and bed widths are generally threetimes the water depth for small channels and up to eight times the water depth forlarge channels.The costs of construction needs to be considered, where the excavation cost of achannel may be reduced by adopting a wide shallow section instead of a moreefficient deep narrow section.Construction and Refurbishment of Earthen Channel Banks August 2002 - Edition 1.0 12-36
Close attention needs to be paid to the design of cross sections for earthen channelson steep hillside locations, as channel seepage may cause failure of the downhillbank. Whenever feasible, water surfaces should be kept below the natural surfacelevels along the downhill sides. Where downhill banks are required, special designand construction precautions may be required.The dimensions of a channel section needed to carry a specified flow depend on thetypes of section, roughness factor, available grades and permissible velocities.Some typical cross-sections for channels are shown in Figure 12-10, Figure 12-11and Figure 12-12.Slope variable,not steeperthan 1 in 1.5freeboard1 in 40 1 in 40Natural surfaceCompactedBankCompactedBankFigure 12-10Typical Trapezoidal SectionMin msetbackMin msetbackSpoilbankBermDrainage1 in 40SteepeststableslopeAccessTrackberm12freeboardNatural surface211 in 40Steepeststable slopeSpoilbankBermDrainageFigure 12-11Typical Trapezoidal section in cutNatural surfaceSlope variable,not steeperthan 1 in 1.51 in 40CompactedBank1freeboard221berm11.5Break inslopeBermDrainageFigure 12-12Typical trapezoidal section on hillside locationConstruction and Refurbishment of Earthen Channel Banks August 2002 - Edition 1.0 12-37
Page 3 and 4:
Your comments on the format and con
Page 5 and 6:
During the course of this project,
Page 7 and 8:
AcknowledgmentsThese Guidelines rep
Page 9 and 10:
FundingFunding of this project was
Page 11 and 12:
Table of ContentsBook 1SubjectPage
Page 13 and 14:
1. Introduction1.1 GeneralGood asse
Page 15 and 16:
(iv) provide proven practice approa
Page 17 and 18:
3. Research Procedure3.1 Terms of R
Page 19 and 20:
4. How to use these Guidelines4.1 W
Page 21 and 22:
6. Units of MeasurementQuantity Uni
Page 23 and 24:
8. Earthen Irrigation Channels8.1 D
Page 25 and 26:
8.3 ReferencesAustralian National C
Page 27 and 28:
9.1 IntroductionA key input to adva
Page 29 and 30:
Data from Goulburn-Murray Water’s
Page 31 and 32:
General 1 2 3 4 5 6DescriptionRisk
Page 33 and 34:
Channel BankSequential Deterioratio
Page 35 and 36:
9.2 ReferencesGutteridge Haskins &
Page 37 and 38:
10.2.3.1 Dispersive layer of materi
Page 39 and 40:
Causes ofSpecific factorDeteriorati
Page 41 and 42:
10.1.2.5 BendsA bend in the channel
Page 43 and 44:
10.1.4.1 Construction techniqueIrri
Page 45 and 46:
10.1.5.4 Overtopping of banksIn ade
Page 47 and 48:
In the past maintenance techniques
Page 49 and 50: Maintenance is a continuing require
Page 51 and 52: 10.1.7.4 Yabbies/fresh water crayfi
Page 54 and 55: Direct removal ofmaterial by entrai
Page 56 and 57: Figure 10.10 shows longitudinal cra
Page 58 and 59: 10.2.3.3 Irregular compaction - bri
Page 60 and 61: 10.3 ReferencesEmerson W (1996), pe
Page 62 and 63: 11.1 GeneralThe Investigation and P
Page 64 and 65: iv) Available fill materials and, w
Page 66 and 67: 12.15 Radius of Bends .............
Page 68 and 69: There are several ways a channel ca
Page 70 and 71: • Land acquisition extent and typ
Page 72 and 73: The investigation should generally
Page 74 and 75: • Backfill: 10% compaction factor
Page 76 and 77: 1. Flow Area, A, is the cross-secti
Page 78 and 79: after ageing and weed growth. If an
Page 80 and 81: elationships may be the controlling
Page 82 and 83: These maximum velocities should be
Page 84 and 85: Thus channels are usually designed
Page 86 and 87: Some of the design issues that shou
Page 88 and 89: 12.12.1.3 Best PracticeEither of th
Page 90 and 91: 12.13.2 Channel MaintenanceIncrease
Page 92 and 93: along a channel. The depth of the w
Page 94 and 95: 12.13.4.7 Change of AlignmentThe in
Page 96 and 97: 12.15 Radius of Bends12.15.1 Flow A
Page 98 and 99: 12.16 Channel Cross SectionThe cros
Page 102 and 103: 12.16.2 BanksChannel cross sections
Page 104 and 105: Unless the bank is very high, the s
Page 106 and 107: The stability of channel batters ca
Page 108 and 109: drop bars become difficult and time
Page 110 and 111: Both the height above the bed and t
Page 112 and 113: • enable maintenance of the chann
Page 114 and 115: - Access agreementsA description of
Page 116 and 117: 13/08/02 19:2012.20 Channel Tenure
Page 118 and 119: 13/08/02 19:20As with the damage to
Page 120 and 121: 13/08/02 19:20Advantages of Protect
Page 122 and 123: - gates provide a better deterrent
Page 124 and 125: 13/08/02 19:20When considering expo
Page 126 and 127: 13/08/02 19:20A typical design draw
Page 128 and 129: 13/08/02 19:20Sinclair Knight Merz
Page 130 and 131: 13.1 IntroductionIn many irrigation
Page 132 and 133: For example, the initial constructi
Page 134 and 135: 13.2.6 When to use Life Cycle Analy
Page 136 and 137: The timing of the life-cycle costin
Page 138 and 139: • assess cost of collecting missi
Page 140 and 141: Microsoft Excel has quite a good pr
Page 142 and 143: The costs used in these methods sho
Page 144 and 145: Life CyclePhaseInvestigationDesignC
Page 146 and 147: Life CyclePhaseMaintenanceRehabilit
Page 148 and 149: ReplacementProject managementInvest
Page 150 and 151:
Residual valueLegal feesInsuranceAd
Page 152 and 153:
13.4.6.2 Recurring CostsChannel con
Page 154 and 155:
$1.00.80Percent ofValue of$1.00.60.
Page 156 and 157:
13.4.11 Evaluate ResultsThe results
Page 158 and 159:
13.6 Tipsthe way open to incur sign
Page 160 and 161:
14. Risk AnalysisTable of ContentsS
Page 162 and 163:
Consequences for irrigation authori
Page 164 and 165:
15. Material Selection and TestingT
Page 166 and 167:
c) Shrinkage - will the bank crack
Page 168 and 169:
depth. For this reason, the soils o
Page 170 and 171:
Natural moisture content should als
Page 172 and 173:
The study identified some confusion
Page 174 and 175:
15.4.2 Determination of the plastic
Page 176 and 177:
1. Preparation of PatTake approxima
Page 178 and 179:
EmersonClass No.Degree ofDispersion
Page 180 and 181:
15.7.1 Coarse grained soilsIn this
Page 182 and 183:
sufficient gravel for erosion resis
Page 184 and 185:
GroupSymbolsSuitability for Earthen
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 234 and 235:
17. Protective CoverTable of Conten
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
Page 284 and 285:
distribution. The use of alternativ
Page 286 and 287:
19.8 Construction RecordsAdequate r
Page 288 and 289:
19.12 Protective Cover on Crest and
Page 290 and 291:
19.21 Australian StandardsAS 1726-1
Page 292 and 293:
20.1 ScopeAustralia’s earthen irr
Page 294 and 295:
Bank re-construction normally requi
Page 296 and 297:
•meter outlet locations and type
Page 298 and 299:
In the case of channel bank refurbi
Page 300 and 301:
20.4.1.1 StrippingWith outside bank
Page 302 and 303:
All public roads to be used by truc
Page 304 and 305:
5. Material is delivered by trucks
Page 306 and 307:
Need to drain and de-waterEBM befor
Page 308 and 309:
significantly and a more conservati
Page 310 and 311:
Aim for crest width ofabout 2 metre
Page 312 and 313:
Refer to Section 18, Inside Batter
Page 314 and 315:
21.8.10 Re-alignment ..............
Page 316 and 317:
Seepage is a complex hydrologic phe
Page 318 and 319:
2. Seepage losses increase as the d
Page 320 and 321:
Refer also to the following section
Page 322 and 323:
21.4 Channel Seepage ConsequencesSe
Page 324 and 325:
Channel seepage is one of the sever
Page 326 and 327:
Seepage is proportional to soil per
Page 328 and 329:
Methods based on vertical flow meas
Page 330 and 331:
ainfallPumpingevapotranspirationIrr
Page 332 and 333:
Flow NetsA flow net is a system of
Page 334 and 335:
Data from indirect measurement proc
Page 336 and 337:
(ii) EM SurveyElectro-magnetic (EM)
Page 338 and 339:
The volume of waterloss from the dr
Page 340 and 341:
21.7.3.2 Inflow-Outflow Method (Dyn
Page 342 and 343:
Imperfect seal will cause the meter
Page 344 and 345:
The groundwater level can then be d
Page 346 and 347:
Stable IsotopesThe basis of testing
Page 348 and 349:
To be most successful, there needs
Page 350 and 351:
21.8.6 Surface interception drainag
Page 352 and 353:
KeyWatertable before tree plantingW
Page 354 and 355:
• The preparation of a best pract
Page 356 and 357:
21.11 ReferencesAustralian National
Page 358 and 359:
22. Channel LiningTable of Contents
Page 360 and 361:
22.1 IntroductionThe conservation o
Page 362 and 363:
The different types of channel lini
Page 364 and 365:
Table 22-1Unlined Earthen Channels
Page 366 and 367:
Lining of channels will not elimina
Page 368 and 369:
To supply a given discharge, the cr
Page 370 and 371:
22.4.5 Structural SafetyThe stabili
Page 372 and 373:
soil pressures and under-drainage i
Page 374 and 375:
Concrete linings are suitable for b
Page 376 and 377:
22.5.12 Availability of Constructio
Page 378 and 379:
esistance to erosion. To improve th
Page 380 and 381:
Construction and Refurbishment of E
Page 382 and 383:
22.7.1.2 General Design Considerati
Page 384 and 385:
22.7.1.4 Lining ThicknessThe thickn
Page 386 and 387:
particular problems, but in smaller
Page 388 and 389:
Where the earth lining finishes abo
Page 390 and 391:
control where the channel material
Page 392 and 393:
sand requires about 5% cement by we
Page 394 and 395:
22.7.6 Soil SealantsSoil sealants a
Page 396 and 397:
22.7.7 Cost of Earth LiningsThe cap
Page 398 and 399:
Although they can assist with shear
Page 400 and 401:
22.8.2 Membrane Liner TypesGeomembr
Page 402 and 403:
Polyethylene has also appeared in m
Page 404 and 405:
FPP resistance to common chemical e
Page 406 and 407:
The base coat and seal coat rates m
Page 408 and 409:
A common and misleading argument is
Page 410 and 411:
These thermal expansion and contrac
Page 412 and 413:
Another factor is the ability to ha
Page 414 and 415:
Some lining methods expand and cont
Page 416 and 417:
22.8.9.1 Geomembrane ThicknessThe t
Page 418 and 419:
Cover typeThickness ofEarth fill(m)
Page 420 and 421:
22.8.9.5 Cover MaterialGeomembranes
Page 422 and 423:
As well, velocities which are permi
Page 424 and 425:
22.8.11 FencingWhen livestock, part
Page 426 and 427:
22.10 ReferencesAlther GR (1987), T
Page 428 and 429:
23. Measures to Reduce the Rate ofD
Page 430 and 431:
Channel DesignBank MaterialDeterior
Page 432 and 433:
Stock and VerminAdjacentlandholders
Page 434 and 435:
To ensure that a channel bank has a
Page 436 and 437:
Advantages of Draining• Allows fo
Page 438 and 439:
To efficiently maintain a channel,
Page 440 and 441:
Compared with other countries where
Page 442 and 443:
23.4.7 LeaksTransverse cracks are t
Page 444 and 445:
23.5 Reduction of Deterioration due
Page 446 and 447:
Photo 23-1Channel bed showing mumbl
Page 448 and 449:
Thus, control of carp by draining c
Page 450 and 451:
The disadvantages of a biological c
Page 452 and 453:
Carp have been blamed for erosion o
Page 454 and 455:
Management Groups gives guidelines
Page 456 and 457:
Organisation Contact Details Aims/A
Page 458 and 459:
Chemical treatment is often recomme
Page 460 and 461:
23.7 Reduction of Deterioration due
Page 462 and 463:
Grey Parrot Pea - Dillaynia cineres
Page 464 and 465:
Lodge G (1998), Review on Fish Barr
Page 466 and 467:
cation exchange capacity (CEC) a me
Page 468 and 469:
fetch the distance over which the w
Page 470 and 471:
plant term used for construction eq
Page 472:
supply level the supply level is a
show all

construction and refurbishment of earthen irrigation channel banks

Create successful ePaper yourself

Delete template?

Save as template?