height. On the downstream side the slope is generally, 

 2 to 1. However, if the soil contains more than the 

 recommended amount of sand or gravel, the slope should 

 be increased to as much as 5 to 1, depending upon the 

 nature of the construction materials used. This simply 

 means that if the top is 7 feet wide and the height is 

 10 feet, the base will be 57 feet wide. 



The site of the crest of the dam should be laid out 

 •first, then stakes set along the inside and outside toe 

 or limits of the dam. Stakes should also indicate the 

 limits of the water level in the pond. The dam should 

 be high enough to allow 2 to 3 feet of freeboard; that 

 is, the top should be 2 or 3 feet above the normal 

 water-level of the pond (fig. 2). 



The first step is to cut do\N?n all trees and bushes. 

 These should be removed from the site or stacked and 

 burned. All stumps should be removed from the pond 

 site, particularly if the pond is to be drained for 

 the removal of minnows, in which case it is also 

 desirable to grade the bottom so that no low spots or 

 pockets will be left after the pond has been drained. 

 Every piece of wood or stump should be removed from 

 the site where the dam is to be located. If this is 

 not done, it may cause trouble when the wood decays. 



The next step in construction of the dam is to 

 form a tight bond between the dam and the base upon 

 which it rests. If the surface is covered with a layer 

 of organic matter, this should be removed and stored 

 for later use in covering sections of the dam which 

 will be seeded with vegetation. The area covered by 

 the base of the dam should then be plowed. 



No structure is better than its foundation. To 

 assure a good pond, a section should be removed from the 

 middle, parallel to and directly under what will be the 

 highest portion of the dam, down to solid-clay soil. 

 If clay soils are underlaid with sand or gravel, do not 

 dig through the clay into the sand, as this will cause 

 the pond to leak. Excavation for the clay core may be 

 accomplished with equipment commonly used, but under 

 certain conditions may be done more rapidly with dyna- 

 mite. Dynamite is particularly effective where the 

 earth is saturated with water — the wetter, the better — 

 and where it would be impossible to use other methods. 

 Holes, 12 to 20 inches apart, should be driven down to 

 solid earth (rarely more than 16 inches below the 

 surface). These holes should be charged with dynamite 

 made of 50 percent straight glycerine, to be set off 

 with an electric battery in order to obtain the greatest 



