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

damsafety.org

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

STANDING OPERATING PROCEDURESProblemProbable Cause andPossible ConsequencesRecommended ActionsPoor configuration of stilling basinarea. Highly erodible materials.Absence of cut-off wall at end ofchute.Structural damage to spillwaystructure; collapse of slab and walllead to costly repair.Dewater affected area; clean outeroded area and properly backfill.Improve stream channel below chute;provide properly sized riprap instilling basin area. Install cutoff wall.Poor workmanship; unevensettlement of foundation; excessiveearth and water pressure;insufficient steel bar reinforcementof concrete.Minor displacement will createeddies and turbulence in the flow,causing erosion of the soil behindthe wall. Major displacement willcause severe cracks and eventualfailure of the structure. SeeFigure 5-5 for examples.Reconstruction should be doneaccording to sound engineeringpractices. Foundation should becarefully prepared. Adequate weepholes should be installed to relievewater pressure behind wall. Useenough reinforcement in the concrete.Anchor walls to present furtherdisplacement. Install struts betweenspillway walls. Clean out and backflush drains to assure properoperations. Consult an engineerbefore actions are taken.RDSO NOTIFICATION REQUIREDConstruction defect; localconcentrate distress; local materialdeterioration; foundation failure,excessive backfill pressure.Disturbance in flow patterns;erosion of foundation and backfill;eventual collapse of structure. SeeFigure 5-5 for examples.Large cracks without largedisplacement should be repaired bypatching.Surrounding areas should be cleanedor cut out before patching material isapplied. Installation of weep holes orother actions may be needed.Revision No. 0B-19 October 2008

More magazines by this user
Similar magazines