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<br /> <br /> <br /> <br />5 <br />Figure 1: Inspection methods typically follow a zigzag or parallel <br />method. <br />What Should I Look For? <br />Safety inspections will cover every visible portion of <br />the upstream and downstream slopes, crest, auxiliary <br />spillway, outlet conduit, outlet structures, and <br />reservoir rim. Although all inspections are <br />comprehensive in nature, the scope of the inspection <br />depends on the type of inspection being performed <br />(e.g., formal vs. intermediate vs. emergency). For <br />inspection tips and guidelines specific to outlet <br />conduits, see the previous article titled, You Con-du-it; <br />How to Fix a Leaky Pipe. <br />The following sections present some typical <br />deficiencies noted during dam safety inspections and <br />possible causes and consequences. <br />Upstream and Downstream Slopes <br />Slide/Slump/Slip (Deep or Shallow): <br /> Causes: Originated as cracking excessive erosion, <br />over steepened areas, saturation, rapid <br />drawdown <br /> Consequences: Crest loss and overtopping; <br />shortened seepage path <br />Photo 5: Shallow slide, slump, and slips on a slope (ASDSO) <br />Photo 6: Deep slide, slump, and slips on a slope (ASDSO) <br />Sinkhole: <br /> Causes: Embankment material carried through <br />erosion pipe, collapse of material into animal <br />burrow <br /> Consequences: May represent a serious piping <br />problem in embankment or foundation <br /> <br />Figure 2: Sinkhole on slopes (AECOM) <br /> <br />Photo 7: Sinkhole on downstream slope (AECOM) <br />Broken Down/Missing Riprap and Slope Erosion: <br /> Causes: Poor quality riprap has degraded, <br />undersized riprap displaced by wave action <br /> Consequences: Erosion, loss of crest, overtopping <br />Top of Slide