Laserfiche WebLink
378-5 Pond <br />\J <br />• <br />I <br />aplllvay. The inlets and outlets <br />shall be designed to function satis- <br />factorily for the full range of floe <br />and hydraulic head anticipated. <br />Pipe conduits under or through the <br />dam shall meet the following require- <br />ments: <br />The pipe shall be capable of with- <br />standing external loading without <br />yielding, buckling, or cracking. <br />Pipe strength shall not be less than <br />that of the grades indicated in Table <br />1 for plastic pipe and in Table 2 for <br />corrugated aluminum and galvanized <br />steel pipe. The inlets and" outlets <br />shall be structurally sound and made <br />of materials compatible with chat of <br />the pipe. All pipe joints shall be <br />made watertight by the use of <br />coupling or gaskets or by welding or <br />caulking. . <br />For dams 20 feet or less in effective <br />height, acceptable pipe materials are <br />cast-iron, steel, corrugated steel or <br />aluminum, asbestos-cement, concrete, <br />plastic, vitrified clay with rubber <br />gaskets, and Last-in-place reinforced <br />concrete. Asbestos cement, concrete, <br />and vitrified clay pipe shall be laid <br />in a concrete bedding. Plastic pipe <br />that will be exposed to direct sun- <br />light shall be made of ultraviolet- <br />resistan[ materials and protected by <br />coating or shielding or provisions <br />made for replacement as necessary. <br />Connections of plastic pipe to less <br />flexible pipe or structures must be <br />designed to avoid stress concentra- <br />tions that could rupture the <br />plastic. <br />For dams more than 20 feet in effect- <br />ive height, conduits shall be rein- <br />forced concrete pipe, cast-Sn-place <br />reinforced concrete, corrugated steel <br />or welded steel pipe. The maximum <br />height of fill over any steel pipe <br />shall not exceed 25 feet. PSpe shall <br />be watertight. The points between <br />sections of pipe shall be designed to <br />remain watertight after point elonga- <br />tion or compression roused by founda- <br />tion consolidation. Concrete pipe <br />shall have either a concrete bedding <br />or a concrete cradle. Cantilever out- <br />let sections, if used, shall be de- <br />signed to withstand the cantilever <br />load. Pipe supports shall be provided <br />when needed. Other suitable devices <br />such as a SAF or impact basin may be <br />used to provide a safe outlet. <br />Cathodic protection shall .be provided <br />for welded steel and corrugated steel <br />pipe if the need and importance of the <br />structure warrant. Cathodic protec- <br />tion should normally be provided for <br />corrugated steel pipe if the saturated <br />soil resistivity is less than 4,000 <br />ohms-cm or the pH is lover than 5. <br />Practice standard 430-FF provides <br />criteria for cathodic protection of <br />welded steel pipe. <br />Zf corrugated steel or welded steel <br />pipe is used as a conduit through a <br />dam having an effective height of 25 <br />feet and storage of 50 acre-feet or <br />more below the lowest ungated spill- <br />way, the conduit shall be encased in a <br />minimum of eight (8) inches of con- <br />crete, reinforced with temperature <br />steel. <br />Antiseep collars shall be installed <br />around the pipe conduit or pond drain <br />in the nornal saturation zone (gener- <br />ally within the upstream two-thirds of <br />the dam) on all Livestock Slater Tanks <br />or Erosion Control Dams. On all dams <br />constructed for other purposes, anti- <br />seep collars are required if any of <br />the following conditions exist: <br />1. The effective height of the dam <br />exceeds 10 ft. <br />2. The conduit 'is of smooth pipe <br />larger Chan 8 ln. in diameter. <br />SCS, Colorado, April 1980 <br />