Technical Manual: Conduits through Embankment Dams (FEMA 484)

More documents

Recommendations

Info

Conduits through Embankment Dams• Design modifications.—The new conduit can be designed to provide increaseddischarge capacity to meet current or future operational and emergency releaserequirements.The disadvantages of removal and replacement of an existing conduit through a highembankment dam include:• Cofferdam.—Unless the reservoir can be drained, the construction of acofferdam is generally required. Inflows into the reservoir will need to bediverted. In some special cases a downstream cofferdam may also be required.• Costs.—Construction costs for removal and replacement are generally higherthan for other renovation methods. Construction costs rapidly rise as theheight of the embankment dam increases.• Reservoir operations.—Construction may impact reservoir operations and add riskto the downstream community.• Seepage paths.—If proper compaction of the embankment closure section is notobtained, potential seepage paths may exist along the junction of the closuresection and existing embankment13.1 Embankment excavation slopes.An excavation transverse to an existing embankment dam centerline increases thepotential for hydraulic fracture of the replacement embankment material fromarching. Because hydraulic fracture poses special hazards when the reservoir issubsequently refilled, special care is required for designs that involve excavationtransverse to the existing embankment dam. The excavation should be wide enoughto accommodate motorized compaction equipment, and the side slopes should beflat to reduce differential strain.The guidance for excavation discussed in chapter 5 applies equally to constructioninvolving removal and replacement of existing conduits. Excavations for conduits insoil foundations should be wide enough to allow for backfill compaction parallel tothe conduit using heavy rolling compaction equipment. Equipment used to compactalong the conduit should be free of framing that prevents its load-transferring wheelsor drum from working against the structure (USACE, 2004a, p. 6-6).332
Chapter 13—Replacement of Conduits13.2 Removal of the existing conduitThe first step in removal and replacement of the existing conduit is usually toexcavate the embankment dam to the invert of the conduit and remove it. Removalof the entrance structure (figure 186), terminal structure, or other structures may berequired due to age or deterioration, or to ease construction of the replacementstructures. Occasionally, where removal of the existing conduit is difficult andexpensive, the existing conduit may not be removed, but will be abandoned bybackfilling the conduit with grout and installing a new conduit at a separate location.See section 14.3 for guidance on abandonment of conduits. Excavations should bewide enough at the bottom to ensure adequate working room for removal of theexisting conduit and replacement with the new conduit, and compaction of earthfillmaterials.A qualified professional engineer or engineering geologist should carefully observeand document the excavation required for the removal of the existing conduit toverify that any damaged embankment or foundation materials have been fullyremoved and/or treated prior to construction of the new conduit and replacement ofembankment materials. For an example of the replacement of a conduit, see thePablo Dam case history in appendix B.13.3 Design and construction of the conduitFor guidance on design and construction of the conduit, see chapters 3 and 4.13.4 Design and construction of the filterFor guidance on the design and construction of the filter, see chapter 6. The newfilter should be designed to extend upstream into the embankment dam. Frequently,the filter installed in this situation is larger than that used for first time constructionof an embankment dam. The filter should extend to both sides of the new conduitand key into the existing embankment dam. If the existing embankment dam has achimney filter, the filter should be designed to be a part of that system wherefeasible.13.5 Design and construction of the replacement embankment damThe following sections discuss aspects of design and construction that the designershould consider for the replacement portion of the embankment dam.333
Page 1:
Technical Manual:Conduits throughEm
Page 5 and 6:
PrefaceTens of thousands of conduit
Page 7 and 8:
Prefacecondition. The hazard classi
Page 9:
PrefaceLakeLine MagazineMaryland Da
Page 16:
Conduits through Embankment Dams11.
Page 19 and 20:
Contents23 Precast concrete pipe be
Page 21 and 22:
Contents81 On first filling, a high
Page 23 and 24:
Contents117 This conduit was severe
Page 25 and 26:
Contents158 An example of a histori
Page 27 and 28:
ContentsFigures in the AppendicesNo
Page 29 and 30:
ContentsB-33 Aerial view of Como Da
Page 31 and 32:
ContentsB-81 Cross section of Wiste
Page 33 and 34:
ContentsMASW, multichannel analysis
Page 35 and 36:
Symbolsc, cohesionE', modulus of so
Page 37 and 38:
ContentsD 3350D 4221D 4253D 4254D 4
Page 39 and 40:
IntroductionConduits convey water f
Page 41 and 42:
IntroductionFigure 3.—A 15-inch d
Page 43 and 44:
Introductionunstable. When seepage
Page 45 and 46:
IntroductionAn embankment dam with
Page 47 and 48:
A vortex may form at the location w
Page 49 and 50:
IntroductionWater from the reservoi
Page 51 and 52:
IntroductionFlowing water from the
Page 53 and 54:
IntroductionThe process of dislodgi
Page 55 and 56:
Introductionbe observable at the su
Page 57 and 58:
IntroductionFigure 11.—Example of
Page 59 and 60:
Introductionwhere conduits were ass
Page 61 and 62:
Introduction• Conduits within lev
Page 63 and 64:
IntroductionFigure 12.—An example
Page 65 and 66:
Introductionmore recent practiced h
Page 67 and 68:
IntroductionThe “best practices
Page 69 and 70:
Chapter 1GeneralConduits have been
Page 71 and 72:
Chapter 1—GeneralFigure 14.—Ant
Page 73 and 74:
Chapter 1—GeneralFigure 17.—Fai
Page 75 and 76:
Chapter 1—Generalmeans the condui
Page 77 and 78:
Chapter 1—Generalfacilitate futur
Page 79 and 80:
Chapter 2Conduit MaterialsVarious m
Page 81 and 82:
Chapter 2—Conduit MaterialsFigure
Page 83 and 84:
Page 85 and 86:
Chapter 2—Conduit Materials• Co
Page 87 and 88:
Page 89 and 90:
Chapter 2—Conduit MaterialsSteel
Page 91 and 92:
Chapter 2—Conduit Materials2.3.2
Page 93 and 94:
Page 95 and 96:
Chapter 3Hydraulic Design of Condui
Page 97 and 98:
Chapter 3—Hydraulic Design of Con
Page 99 and 100:
Page 101 and 102:
Page 103 and 104:
Page 105 and 106:
Page 107 and 108:
Page 109 and 110:
Page 111 and 112:
Page 113 and 114:
Chapter 4Structural Design of Condu
Page 115 and 116:
Chapter 4—Structural Design of Co
Page 117 and 118:
Page 119 and 120:
Page 121 and 122:
Page 123 and 124:
Page 125 and 126:
Page 127 and 128:
Page 129 and 130:
Page 131 and 132:
Page 133 and 134:
Page 135 and 136:
Page 137 and 138:
Page 139 and 140:
Page 141 and 142:
Page 143 and 144:
Page 145 and 146:
Page 147 and 148:
Page 149 and 150:
Page 151 and 152:
Chapter 5Foundation and Embankment
Page 153 and 154:
Chapter 5—Foundation and Embankme
Page 155 and 156:
Page 157 and 158:
Page 159 and 160:
Page 161 and 162:
Page 163 and 164:
Page 165 and 166:
Page 167 and 168:
Page 169 and 170:
Chapter 6Filter ZonesZones of desig
Page 171 and 172:
Chapter 6—Filter Zonesseepage or
Page 173 and 174:
Chapter 6—Filter ZonesFigure 87.
Page 175 and 176:
Page 177 and 178:
Page 179 and 180:
Chapter 6—Filter Zones3. Upstream
Page 181 and 182:
Chapter 6—Filter Zonesbedrock sur
Page 183 and 184:
Chapter 6—Filter Zoneszones, and
Page 185 and 186:
Chapter 6—Filter Zonesfiltering t
Page 187 and 188:
Chapter 6—Filter Zonessoil. This
Page 189 and 190:
Chapter 6—Filter Zones6.8 Specifi
Page 191 and 192:
Chapter 6—Filter ZonesVarious deg
Page 193 and 194:
Chapter 6—Filter Zones• For pre
Page 195 and 196:
Chapter 7Potential Failure Modes As
Page 197 and 198:
Chapter 7—Potential Failure Modes
Page 199 and 200:
Page 201 and 202:
Page 203 and 204:
Page 205 and 206:
Page 207 and 208:
Page 209 and 210:
Page 211 and 212:
Page 213 and 214:
Page 215 and 216:
Chapter 8Potential Defects Associat
Page 217 and 218:
Chapter 8—Potential Defects Assoc
Page 219 and 220:
Page 221 and 222:
Page 223 and 224:
Page 225 and 226:
Page 227 and 228:
Page 229 and 230:
Page 231 and 232:
Chapter 9Inspection and Assessment
Page 233 and 234:
Chapter 9—Inspection and Assessme
Page 235 and 236:
Page 237 and 238:
Page 239 and 240:
Page 241 and 242:
Page 243 and 244:
Page 245 and 246:
Page 247 and 248:
Page 249 and 250:
Page 251 and 252:
Page 253 and 254:
Page 255 and 256:
Page 257 and 258:
Page 259 and 260:
Page 261 and 262:
Page 263 and 264:
Page 265 and 266:
Page 267 and 268:
Page 269 and 270:
Page 271 and 272:
Page 273 and 274:
Page 275 and 276:
Page 277 and 278:
Page 279 and 280:
Page 281 and 282:
Page 283 and 284:
Chapter 10Evaluation by Geophysical
Page 285 and 286:
Chapter 10—Evaluation by Geophysi
Page 287 and 288:
Page 289 and 290:
Page 291 and 292:
Page 293 and 294:
Page 295 and 296:
Page 297 and 298:
Page 299 and 300:
Chapter 11Appropriate Emergency Act
Page 301 and 302:
Chapter 11—Appropriate Emergency
Page 303 and 304:
Page 305 and 306:
Page 307 and 308:
Table 11.2.—Potential problems an
Page 309 and 310:
Page 311 and 312:
Page 313 and 314:
Page 315 and 316:
Page 317 and 318:
Page 319 and 320: Chapter 11—Appropriate Emergency
Page 327 and 328: Chapter 12Renovation of ConduitsThe
Page 329 and 330: Chapter 12—Renovation of Conduits
Page 369: Chapter 13Replacement of ConduitsGe
Page 373 and 374: Chapter 13—Replacement of Conduit
Page 383 and 384: Chapter 14Repair and Abandonment of
Page 385 and 386: Chapter 14—Repair and Abandonment
Page 401 and 402: ReferencesThe following references
Page 403 and 404: ReferencesBureau of Reclamation, De
Page 405 and 406: ReferencesCooper, Chuck, E. Wesley
Page 407 and 408: ReferencesJacobsen, S., “Buckling
Page 409 and 410: ReferencesNatural Resources Conserv
Page 411 and 412: ReferencesU.S. Army Corps of Engine
Page 413 and 414: ReferencesWooten, R. Lee, Peter S.
Page 415 and 416: Additional ReadingThe following ref
Page 417 and 418: Additional ReadingCarter, Brent H.,
Page 419 and 420: Additional ReadingJohnson, Brian, J
Page 421 and 422:
Additional ReadingNatural Resources
Page 423 and 424:
Additional ReadingU.S. Army Corps o
Page 425 and 426:
Additional ReadingVan Aller, Hal, R
Page 427 and 428:
GlossaryThe terms defined in this g
Page 429 and 430:
Glossary• Backward erosion piping
Page 431 and 432:
GlossaryCathodic protection system
Page 433 and 434:
GlossaryConsequences (FEMA, 2004):
Page 435 and 436:
Glossarymalfunction or abnormality
Page 437 and 438:
GlossaryDrawdown (FEMA, 2004): The
Page 439 and 440:
GlossaryFailure mode (FEMA, 2004):
Page 441 and 442:
GlossaryGate chamber: An outlet wor
Page 443 and 444:
GlossaryImpervious: Not permeable;
Page 445 and 446:
GlossaryLeakage (FEMA, 2004): Uncon
Page 447 and 448:
GlossaryOpen cut: An excavation thr
Page 449 and 450:
GlossaryPolyvinyl chloride (PVC): A
Page 451 and 452:
GlossaryResistivity: A measure of t
Page 453 and 454:
GlossarySettlement (FEMA, 2004): Th
Page 455 and 456:
GlossaryStandard Proctor compaction
Page 457 and 458:
GlossaryThermoset (ASTM F 412, 2001
Page 459 and 460:
GlossaryReferencesAmerican Concrete
Page 461 and 462:
IndexAAbandonment of conduits, 225,
Page 463 and 464:
IndexCompaction of backfill, 6, 10,
Page 465 and 466:
IndexDDamembankment, 113-130, 333-3
Page 467 and 468:
IndexExisting conduit, 23, 31, 45-5
Page 469 and 470:
IndexHydraulic fracture, 4-11, 17,
Page 471 and 472:
IndexMechanical caliper, 246Metal c
Page 473 and 474:
IndexPressure flow, see Conduit, pr
Page 475 and 476:
IndexSliplining, 39, 45-47, 51, 164
Page 477 and 478:
IndexUUltrasonic pulse-echo, 245, 2
Page 479 and 480:
Appendix AHistory of Antiseep Colla
Page 481 and 482:
Appendix A—History of Antiseep Co
Page 483 and 484:
Page 485 and 486:
Page 487 and 488:
Appendix BCase HistoriesIndexDam Lo
Page 489 and 490:
Appendix B—Case HistoriesDam Loca
Page 491 and 492:
Page 493 and 494:
Page 495 and 496:
Appendix B—Case HistoriesProject
Page 497 and 498:
Appendix B—Case HistoriesFigure B
Page 499 and 500:
Page 501 and 502:
Page 503 and 504:
Page 505 and 506:
Appendix B—Case Historiesproject,
Page 507 and 508:
Appendix B—Case Historieswatersto
Page 509 and 510:
Page 511 and 512:
Appendix B—Case HistoriesLessons
Page 513 and 514:
Page 515 and 516:
Page 517 and 518:
Page 519 and 520:
Appendix B—Case HistoriesThe cond
Page 521 and 522:
Page 523 and 524:
Page 525 and 526:
Appendix B—Case Historiesroadway.
Page 527 and 528:
Page 529 and 530:
Appendix B—Case Historiesentire c
Page 531 and 532:
Page 533 and 534:
Page 535 and 536:
Page 537 and 538:
Appendix B—Case Historieshauled i
Page 539 and 540:
Page 541 and 542:
Appendix B—Case Historiescoal tar
Page 543 and 544:
Appendix B—Case Historieshistory
Page 545 and 546:
Page 547 and 548:
Appendix B—Case Historiesarea, a
Page 549 and 550:
Page 551 and 552:
Page 553 and 554:
Page 555 and 556:
Page 557 and 558:
Appendix B—Case Historiespipe. Du
Page 559 and 560:
Appendix B—Case Historiesinvert o
Page 561 and 562:
Page 563 and 564:
Page 565 and 566:
Page 567 and 568:
Appendix B—Case Historiesdownstre
Page 569 and 570:
Page 571 and 572:
Page 573 and 574:
Page 575 and 576:
Page 577 and 578:
Page 579 and 580:
Page 581 and 582:
Page 583 and 584:
Page 585 and 586:
Page 587 and 588:
Appendix B—Case HistoriesThe caus
Page 589 and 590:
Page 591 and 592:
Page 593 and 594:
Page 595 and 596:
Page 597 and 598:
Page 599 and 600:
Page 601 and 602:
Page 603 and 604:
Appendix B—Case Historiesof sever
Page 605 and 606:
Page 607 and 608:
Appendix B—Case HistoriesThe down
Page 609 and 610:
Appendix B—Case Historieshose and
Page 611 and 612:
Page 613 and 614:
Appendix B—Case HistoriesADownstr
show all

Technical Manual: Conduits through Embankment Dams (FEMA 484)

Create successful ePaper yourself

Delete template?

Save as template?