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Technical Manual: Conduits through Embankment Dams (FEMA 484)

Technical Manual: Conduits through Embankment Dams (FEMA 484)

Technical Manual: Conduits through Embankment Dams (FEMA 484)

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<strong>Conduits</strong> <strong>through</strong> <strong>Embankment</strong> <strong>Dams</strong>Scaling: The deposition and adherence of insoluble products on the surface of amaterial.Scarification: The process of roughening the surface of a previously compacted liftof soil before placement of the next lift. Scarification is accomplished with discs,harrows, and similar equipment. The purpose of scarification is to promote bondingof lifts and reduce interlift permeability. Scarification is usually required inconstruction specifications written by designers concerned over stratification ofearthfills.Scour: The loss of material occurring at an erosional surface, where a concentratedflow is located, such as a crack <strong>through</strong> a dam or the dam/foundation contact.Continued flow causes the erosion to progress, creating a larger and larger erodedarea.Seepage (ASTM D 653, 2002): The infiltration or percolation of water <strong>through</strong>rock or soil or from the surface.Seepage paths (ASCE, 2000): The general path along which seepage follows.Segregation: The tendency of particles of the same size in a given mass ofaggregate to gather together whenever the material is being loaded, transported, orotherwise disturbed. Segregation of filters can cause pockets of coarse and finezones that may not be filter compatible with the material being protected.Seismic activity: The result of the earth’s tectonic movement.Seismic tomography: A geophysical method that measures refraction andreflection of small, manmade seismic waves and high-level imaging software tocreate cross-sectional views of the internal portions of a structure, similar tocomputerized axial tomography (CAT) scans used in medicine.Self potential (or streaming potential): A geophysical method that maps fields ofelectrical potential (voltage) generated by water flowing <strong>through</strong> a porous material tolocate seepage areas in a dam or foundation.Self-healing: The property of a sand filter that reflects its ability to deform and fill acrack that is transmitted to the filter.Service life: Expected useful life of a project, structure, or material.Service spillway: See Spillway, service414

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