POND CONSTRUCTION 



for use as outlets and tlie most 

 easily installed are spiral-welded 

 steel pipe and asbestos-cement cast 

 pipe. Spiral-welded pipe is light- 

 weifjht, lontj lasting if properly 

 installed, and comes in long 

 lengths. Asbestos-c e m e n t pipe 

 comes in shorter lengths but can 

 be cut with a saw, and the joints 

 have considerable flexibility. Not 

 subject to corrosion, its period of 

 utility is indefinite. Standard fit- 

 tings can be used with both kinds 

 of pipe, and they can be utilized 

 for both drainage and waterlines. 

 In ponds i/4 ^^^'^ or less in area, 

 the drainline should be not less than 

 inches in diameter; and in ponds 

 of 1/4 to 114 acres, the line should 

 be not less than 8 inches. Use of 

 large drainlines has a number of 

 advantages, including savings in 

 time and labor and frequently a 

 saving in fish (which may be lost 

 otherwise because of high temper- 



ature, suffocation, muddy water, 

 or other causes, in the draining 

 process). 



Every pond should be equipped 

 with an outlet structure of some 

 type. This outlet, or kettle, serves 

 a number of purposes. It acts 

 as an o\'erflow Avhen rain or other 

 inflow of water raises the pond 

 level above normal. In the proc- 

 ess of draining the pond, the out- 

 let holds back the fish so that they 

 can be removed when the water 

 level has fallen to a depth that the 

 operator can wade. 



In small impoundments which 

 are to be drained infrequently, one 

 of a number of outlets may be 

 used. The Canfield outlet is the 

 type most commonly used (fig. 6). 

 It consists merely of a pipe cut 

 to the proper length so that it will 

 act as an overflow and control the 

 pond level. This pipe is inserted 

 in a 90° ell attached to the drain- 



WoUr Surfoce 



e 



Pischarc^t P>pc 



Figure 6. — Canfield pond outlet. Commonly used in small impoundments that are 



drained infrequently. 



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