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<br />\ <br />OJG231 <br /> <br />GLOSSARY <br /> <br />Dam Terminology <br /> <br />Structural Height. - Distance between the lowest point in the excavated <br />foundation (excluding narrow fault zones) and the top of dam. <br /> <br />. The structural height of an embankment (earth or rockfill) dam is the <br />vertical distance between the top of the embankment and the lowest point <br />in the excavated foundation area, including the main cutoff trench, if <br />any, but excluding small trenches or narrow backfilled areas. The top <br />elevation does not include the camber, crown, or roadway surfacing. <br /> <br />. The structural height of a concrete dam is the vertical distance between <br />the top of the dam and lowest point of the excavated foundation area, <br />excluding narrow fault zones. <br /> <br />Hydraulic Height. - Height to which the water rises behind the dam, and is the <br />difference between the lowest point in the original streambed at the axis or the <br />centerline crest of the dam and the maximum controllable water surface. <br /> <br />Volume of Dam. - The total space occupied by the materials forming the dam <br />structure computed between abutments and from top to bottom of dam. No deduction <br />is made for small openings such as galleries, adits, tunnels, and operating <br />chambers withi n the dam structure. The volume incl udes all mass concrete <br />appurtenances not separated from the dam by construction or contraction joints. <br />Where a powerplant is located at the downstream toe of a concrete dam, the limit <br />of concrete in the dam should be taken as the downstream face projected to the <br />general excavated foundation surface. <br /> <br />Length of Dam. - The distance, measured along the axis or centerl ine crest of the <br />dam at the top level of the main body of the dam or of the roadway surface on the <br />crest, from abutment contact to abutment contact exclusive of an abutment <br />spillway; provided that, if the spillway lies wholly within the dam and not in <br />any area especially excavated for the spillway, the length includes the spillway. <br /> <br />Top of Dam. - The elevation of the uppermost surface of a dam, usually a road or <br />walkway, excluding any parapet wall, railing, curb, etc. <br /> <br />Crest of Dam. - On embankment dams, the crest of the dam is the top of the <br />embankment, not including camber, crown, or roadway surfacing. <br /> <br />Crest Length. - See Length of Dam. <br /> <br />Left or Right Designation. - The designation of left or right is made with the <br />observer looking downstream. <br /> <br />1 <br />