Technical Manual: Conduits through Embankment Dams (FEMA 484)

Conduits through Embankment DamsConduitConcrete(reinforcement not shownFigure 19.—Conduit constructed in a trench infirm rock.Concrete(reinforcement not shown)Conduit1H:10VFigure 20.—Conduit cast against excavatedrock slope.38• Limit number of conduit penetrations.—Designs should use only one conduit, whenfeasible, to minimize problems associated with penetrations of the embankmentdam. Installing several conduits, particularly near one another, compounds theconstruction difficulties and increases the likelihood of problems associatedwith conduits through the embankment dam. However, the designer should beaware that with only one conduit, if problems develop that limit the ability tocontrol the release of water, this may result in a dam safety concern. Therefore,the design should be robust using proven methods.• Avoid locating conduit joints at discontinuities.—Locate joints for the conduit whereunderlying discontinuities do not occur. If the conduit alignment intersects aslurry trench cutoff or vertical drainage zone, the conduit should be designedwhere these discontinuities are not at a joint, but near the midway pointbetween joints. For guidance on conduit joints, see section 4.3.• Consider seismic deformation.—Seismic activity can result in significant deformationof the embankment dam. Deformations, such as settlement and spreading canopen conduit joints and cause cracking and displacement of the conduit.• Avoid the use of bends.—Locate the conduit so that bends in the alignment orprofile are not required for the portion under the embankment dam. This will