Technical Manual: Conduits through Embankment Dams (FEMA 484)

Conduits through Embankment Damsimpacts of a theoretical release of the stored water during a dam failure. However,the most common problem with all of these classification systems is the lack of clear,concise, and consistent terminology. The Federal Emergency Management Agency(FEMA) has a hazard classification system that is clear and succinct, and this systemwas adopted for the purposes of this document. The reader is directed to FEMA333, Federal Guidelines for Dam Safety: Hazard Potential Classification Systems for Dams(1998), for a complete version of their system. The FEMA document uses threehazard potential levels to classify embankment dams. These levels are summarizedas follows:• Low hazard potential.—Embankment dams assigned the low hazard classificationare those where failure or misoperation results in no probable loss of humanlife and low economic and/or environmental losses. Losses are principallylimited to the owner’s property.• Significant hazard potential.—Embankment dams assigned the significant hazardclassification are dams where failure or misoperation results in no probable lossof human life, but can cause economic loss, environmental damage, ordisruption of lifeline facilities, or can impact other concerns. Significant hazardpotential classification dams are often located in predominantly rural oragricultural areas, but could be located in areas with population and significantinfrastructure.• High hazard potential.—Embankment dams assigned the high hazardclassification are those where failure or misoperation will probably cause loss ofhuman life.Hazard potentialEconomic, environmental, lifelineclassification Loss of human life lossesLow None expected Low and generally limited to ownerSignificant None expected YesHigh Probable—one or Yes (but not necessary for thismore expected classification)Embankment dam hazard classifications are assigned based on their potential forcausing downstream damage, but these classifications do not reflect in any way onthe likelihood that the dam may fail. An embankment dam might be classified ashaving a low hazard potential based on the impacts a failure would have on thedownstream area, but have a high probability of failure if it were in very pooriv