Technical Manual: Conduits through Embankment Dams (FEMA 484)

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Conduits through Embankment Damscommon for repair of leaking joints and cracks in conduits. Polyurethanegrouts are generally viscous liquids which react with water to form a solid orsemisolid material. The properties of common chemical grouts are described inthe USACE’s Chemical Grouting (1995a).Chemical grouts are classified as hydrophobic or hydrophilic depending on howreactive they are when mixed with water. Hydrophilic grouts can incorporate alarge amount of water into the cured products, and may shrink substantially ifallowed to dry out completely. Therefore, hydrophilic grouts should be used inlocations which are not kept wet at all times. Hydrophilic grouts cure withlower strengths than epoxy types of grout and are not considered to produce astructural bond in the area being grouted. Hydrophilic grouts form aclosed-cell flexible foam barrier to stop the seepage of water through the joint.These grouts are usually injected when the ambient air temperatures in theexisting conduit is above 32 °F. Figure 196 shows an example of resin injectionequipment used for small repair projects.For examples of grout cracks in an existing conduit see the case histories forPablo and Ridgway Dams in appendix B.14.3 Conduit abandonmentWhen the existing conduit deteriorates to a point where it can no longer serve itsintended design purpose, a decision must be made to renovate, remove/replace, orto abandon it. In some cases, the designer may find it technically and economicallymore feasible to abandon the conduit by grouting it closed and leaving it in place.For instance, abandonment has some advantages over removing the conduit becausea large trench is not required to be excavated transverse to the embankment dam.Backfilled excavations in an existing embankment are a source of differentialsettlement and potential hydraulic fracture. If abandonment is selected, a filterdiaphragm or collar should be part of a design to intercept any flow that couldpotentially occur through defects in the grouted conduit or along the interfacebetween the existing conduit and earthfill. For guidance on the design of filterdiaphragms and collars, see sections 6.4 and 6.5, respectively. At embankment damswith small reservoirs, abandonment of a conduit may be done in conjunction withthe installation of a siphon. See section 11.4.1 for guidance on the design andconstruction of siphons. For an example of a conduit abandonment, see the casehistory for St. Louis Recreation Lake Dam in appendix B.354
Chapter 14—Repair and Abandonment of ConduitsFigure 196.—An example of resin injectionequipment used for small repair projects.Components are pumped independently andmixed at the nozzle for injection.The advantages of abandoning an existing conduit through an embankment daminclude:• Reservoir operation.—Abandonment can in some cases be done while thereservoir is full. See section 14.3.1 for precautions involving drilling from thesurface of the embankment dam.• Costs.—Costs are generally less than other renovation and replacementmethods.The disadvantages of abandoning an existing conduit through an embankment daminclude:• Grouting.—Difficulties may exist trying to grout the existing conduit full.355
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Technical Manual:Conduits throughEm
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PrefaceTens of thousands of conduit
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Prefacecondition. The hazard classi
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PrefaceLakeLine MagazineMaryland Da
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Conduits through Embankment Dams11.
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Contents23 Precast concrete pipe be
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Contents81 On first filling, a high
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Contents117 This conduit was severe
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Contents158 An example of a histori
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ContentsFigures in the AppendicesNo
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ContentsB-33 Aerial view of Como Da
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ContentsB-81 Cross section of Wiste
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ContentsMASW, multichannel analysis
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Symbolsc, cohesionE', modulus of so
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ContentsD 3350D 4221D 4253D 4254D 4
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IntroductionConduits convey water f
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IntroductionFigure 3.—A 15-inch d
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Introductionunstable. When seepage
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IntroductionAn embankment dam with
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A vortex may form at the location w
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IntroductionWater from the reservoi
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IntroductionFlowing water from the
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IntroductionThe process of dislodgi
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Introductionbe observable at the su
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IntroductionFigure 11.—Example of
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Introductionwhere conduits were ass
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Introduction• Conduits within lev
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IntroductionFigure 12.—An example
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Introductionmore recent practiced h
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IntroductionThe “best practices
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Chapter 1GeneralConduits have been
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Chapter 1—GeneralFigure 14.—Ant
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Chapter 1—GeneralFigure 17.—Fai
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Chapter 1—Generalmeans the condui
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Chapter 1—Generalfacilitate futur
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Chapter 2Conduit MaterialsVarious m
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Chapter 2—Conduit MaterialsFigure
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Chapter 2—Conduit Materials• Co
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Chapter 2—Conduit MaterialsSteel
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Chapter 2—Conduit Materials2.3.2
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Chapter 3Hydraulic Design of Condui
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Chapter 3—Hydraulic Design of Con
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Chapter 4Structural Design of Condu
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Chapter 4—Structural Design of Co
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Chapter 5Foundation and Embankment
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Chapter 5—Foundation and Embankme
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Chapter 6Filter ZonesZones of desig
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Chapter 6—Filter Zonesseepage or
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Chapter 6—Filter ZonesFigure 87.
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Chapter 6—Filter Zones3. Upstream
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Chapter 6—Filter Zonesbedrock sur
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Chapter 6—Filter Zoneszones, and
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Chapter 6—Filter Zonesfiltering t
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Chapter 6—Filter Zonessoil. This
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Chapter 6—Filter Zones6.8 Specifi
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Chapter 6—Filter ZonesVarious deg
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Chapter 6—Filter Zones• For pre
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Chapter 7Potential Failure Modes As
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Chapter 7—Potential Failure Modes
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Chapter 8Potential Defects Associat
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Chapter 8—Potential Defects Assoc
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Chapter 9Inspection and Assessment
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Chapter 9—Inspection and Assessme
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Chapter 10Evaluation by Geophysical
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Chapter 10—Evaluation by Geophysi
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Chapter 11Appropriate Emergency Act
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Chapter 11—Appropriate Emergency
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Table 11.2.—Potential problems an
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Chapter 12Renovation of ConduitsThe
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Chapter 12—Renovation of Conduits
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Page 369 and 370: Chapter 13Replacement of ConduitsGe
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Page 383 and 384: Chapter 14Repair and Abandonment of
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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
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GlossaryImpervious: Not permeable;
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GlossaryLeakage (FEMA, 2004): Uncon
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GlossaryOpen cut: An excavation thr
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GlossaryPolyvinyl chloride (PVC): A
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GlossaryResistivity: A measure of t
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GlossarySettlement (FEMA, 2004): Th
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GlossaryStandard Proctor compaction
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GlossaryThermoset (ASTM F 412, 2001
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GlossaryReferencesAmerican Concrete
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IndexAAbandonment of conduits, 225,
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IndexCompaction of backfill, 6, 10,
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IndexDDamembankment, 113-130, 333-3
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IndexExisting conduit, 23, 31, 45-5
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IndexHydraulic fracture, 4-11, 17,
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IndexMechanical caliper, 246Metal c
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IndexPressure flow, see Conduit, pr
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IndexSliplining, 39, 45-47, 51, 164
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IndexUUltrasonic pulse-echo, 245, 2
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Appendix AHistory of Antiseep Colla
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Appendix A—History of Antiseep Co
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Appendix BCase HistoriesIndexDam Lo
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Appendix B—Case HistoriesDam Loca
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Appendix B—Case HistoriesProject
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Appendix B—Case HistoriesFigure B
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Appendix B—Case Historiesproject,
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Appendix B—Case Historieswatersto
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Appendix B—Case HistoriesLessons
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Appendix B—Case HistoriesThe cond
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Appendix B—Case Historiesroadway.
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Appendix B—Case Historiesentire c
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Appendix B—Case Historieshauled i
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Appendix B—Case Historiescoal tar
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Appendix B—Case Historieshistory
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Appendix B—Case Historiesarea, a
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Appendix B—Case Historiespipe. Du
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Appendix B—Case Historiesinvert o
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Appendix B—Case Historiesdownstre
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Appendix B—Case Historiesof sever
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Appendix B—Case HistoriesThe down
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Appendix B—Case Historieshose and
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Appendix B—Case HistoriesADownstr
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Technical Manual: Conduits through Embankment Dams (FEMA 484)

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