Technical Manual: Conduits through Embankment Dams (FEMA 484)

Chapter 9—Inspection and Assessment of Conduit-Related Problemsdam to safely convey seepage or leakage along the conduit to an exitpoint.6. Critical function of the feature.7. Any existing site conditions that may compromise the safety of the feature.The appropriate frequency and extent to which the normally inundated featuresare examined will vary based on available information. The review personneland decisionmakers will need to determine the appropriate frequency andextent based on the above factors. As an example, Reclamation has identifiedabout 6 years as an appropriate frequency for a “hands-on or equivalentinspection frequency” for inaccessible features, such as conduit.• Operation.—Certain problems may not normally appear when the feature is drythat appear when the feature is being operated. Also, when a feature isoperating during a period of higher than normal releases, additional informationmay be gathered that may not have been available during normal operations.The opportunity to optimize both access and operation during a single inspectiontypically is not possible. Inspection objectives may have to alternate from oneinspection to the next. This may necessitate the need for scheduling “special”inspections during unusual conditions, in addition to regular inspections to provide acomprehensive understanding of the conduit safety. Special inspections may berequired after floods, seismic activity, or other unusual or extreme events.9.3 Periodic inspections by selected organizationsThe frequency of periodic inspections varies among organization and embankmentdam owners. Emergency situations may require much more frequent inspections,such as daily or hourly. Situations can arise suddenly that cause serious damage in ashort period of time. Examples of these problems are operations at full dischargecapacity, seismic activity, or other special conditions. The need for specialinspections should be evaluated after occurrence of any of these situations.A sampling of periodic inspections as required by selected organizations:• Reclamation.—Reclamation employs the following process (Reclamation, 1998c,pp. 2-11) to monitor its significant and high hazard dams and attempt to detectany potential dam safety deficiencies:1. Annually.—Annual inspections are performed by inspectors who aregeneralist (as opposed to specialist) engineers very familiar with the199