74 IRRIGATION FARMING. 



one-inch board doubled. An apron should be put on 

 the dam to receive the overflow. 



A masonry dam should be built on a foundation of 

 concrete, laid on solid rock over piles driven close to- 

 gether, and both sides protected by sheet piling. The 

 piles should be left to protrude into the concrete foun- 

 dation. Except for waterworks, or an irrigation con- 

 duit, there should be no outlet in the bottom of the dam ; 

 but the work should be of the most solid character. A 

 waste channel for overflow should be made on the top 

 large enough to carry off any possible flood, and the ends 

 of the dam should be carried up with solid masonry as 

 high as may ever be needed to prevent the cutting out of 

 the ends by floods. A large dam should be constructed, 

 regardless of expense, .to secure safety in every direction, 

 and the small details of construction are very often the 

 most important parts of the work. 



Storage Ponds. These are classified as those arti- 

 ficial embankments that are made on the flat surface of 

 the ground and are used mostly in connection with a 

 pumping plant. In staking out, it will be best for the 

 convenience of graders to drive stakes on the outer and 

 inner base lines of the proposed bank. If the land on 

 which the reservoir is to be built be of fresh sod it will 

 be necessary to plow up or remove all of the sod from 

 the ground on which the embankments are to be con- 

 structed, otherwise there would remain a seam through 

 which the water would escape from the reservoir, as sod 

 i- not a suitable material upon which to build embank- 

 ments, nor should it be used when building them up to 

 their required bights. AVhen the outlines of the em- 

 bankments are established and the sod removed, then 

 plow within lines of the proposed embankments, and 

 with a scraper draw tin- earth from the inside of the res- 

 ervoir, with which to form the walls. These should not 

 be less than five feet in liight, ineasiirini: on the outside, 



