32 BULLETIISr 502^ U. S, DEPARTMENT OF AGRICULTURE. 



The first point to be taken up in the reclamation of this tract is 

 the disposal of the waste water. The soil on the north half is mostly 

 Fresno fine sandy loam, and the conditions are fairly uniform. The 

 method of relief drainage should be used with six branches of 6-inch 

 tile, running east, about 400 feet apart. The drainage of the south 

 half is a more complex problem; a combination of the relief and 

 intercepting methods should be used. Branches " G " and " K " 

 (fig. 6) are intercepting drains. The peculiar arrangement of the 

 other lines is due to the irregularities in the seepage conditions and 

 to the fact that limestone is found near the surface in some places, 

 as an attempt w^as made to locate the lines so as to prevent rockwork 

 in the trenching. The average depth of the system should be not 

 less than 7 feet, and in no place should a line be less than 6 feet deep. 



EXAMPLE V. 



An investigation was made on this tract during the early part of 

 the year 1915. A large number of test wells were drilled and a topo- 

 graphic map of the underlying shale and water surface was made, 

 as shoAvn in figure 7. A pronounced shale ridge was found, and 

 there was a marked resemblance between the shale and water con- 

 tours (see figs. 7 and 8). As figure 8 indicates, the point of the shale 

 ridge was discharging water into the soil beyond. At the time of the 

 examination only a small portion of the alfalfa was affected between 

 the point of the underlying shale ridge and the south fence line. A 

 tile line reaching well into the shale point was staked out, as shown 

 on the map. The owner Avas unable to install the line at that time, 

 and the tract was visited again in the early part of 1916, when it 

 was found that the affected area had spread over the entire south 

 half of the tract. 



EXAMPLE VI. 



It is not known just when trouble first became apparent on the 

 40 acres shown in figure 9, but from all indications it must have been 

 at least three or four years before the time of making the preliminary 

 examinations in the spring of 1913. At that time about 20 acres, 

 extending north and south through the center of the field, were very 

 wet and badly alkalied (PI. VII, fig. 2). The whole 40 acres were at 

 one time in alfalfa, and on both sides of the alkali strip alfalfa was 

 still growing, with the stand about normal except immediately adja- 

 cent to the wet land, where it was thinner and more spotted. 



The land to the north and west is higher than the tract under 

 consideration, especially to the west, just across the road, where it 

 rises to an elevation some 20 or 30 feet higher and culminates in a 

 little ridge running north and south. Excessive irrigation on this 

 ridge has been one of the chief sources of the seepage water, al- 



