U.S. Fish & Wildlife Service Low Hazard Dams - Association of State ...

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U.S. Fish & Wildlife Service Low Hazard Dams - Association of State ...

STANDING OPERATING PROCEDURESFigure 5-9: Photos Showing Cracks in an Embankment DamThese cracks should close as climatic or soil moisture conditions change. If they do not,it may be necessary to backfill the cracks to prevent entry of surface moisture, whichcould result in saturation of the dam. The cracks may be simply filled with earth that istamped in place with hand or tools. It is also recommended that the crest of a dam begraded to direct runoff waters away from areas damaged by drying cracks.Repair ruts or settlement on any of the roads. In the event of any repairs, a description ofthe earthwork, estimated labor and cost, and sketches should be provided to the RDSO toassess the required work.5.4.6 Animal Damage and ControlBurrowing animals are naturally attracted to the habitats created by dams and reservoirsand can endanger the structural integrity and proper performance of embankments andspillways. The burrows and tunnels of these animals generally weaken earthenembankments and serve as pathways for seepage from the reservoir.Beavers usually construct their tunnels and dens in the banks surrounding the reservoir orin the dam. The main entrance to a beaver’s den is generally 4–10 feet below the normalwater level of the reservoir. The tunnel systems become very extensive as the colonygrows, and embankment material located above these systems will eventually settle orcollapse. Tunnels occasionally extend through a dam where pools of water are allowedto collect along its toe, and provide pathways for water to pass through the embankment.5-16Revision No. 0October 2008

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