DRAINAGE OF IRRIGATED SHALE LAND. 29 
corner and extends to the center of the tract and thence south, where 
it is well defined. Along these ridges the water table always was 
nearest the surface. 
Several years prior to the draining of this tract a drainage system 
was installed on the tract south and east. Four-inch tile were used 
and branches were placed at frequent intervals, but the depth was 
not much over 4 feet. While the surface of the ground is not wet, 
100° 200° 300 400’ 
jt 
aes TN | ST Te a ee fe 
fp Pt ming 
OSS Pee ees HE A FS a FF a 
me Resa eee GGG eeceeea 
SUR SSS ESP eae ees 
PSRSSIE [Sse PELE PRSae EPP pe 
| TA 
105 
ea 
ea ae a |e ete | RTS 
es sf | ee [aed DS |S 
BBreeer Dem ee 
af ea et al | alia Tall 
M5 100’ 
CAS OSeee ec 
Scones Selene 
jsf | en S| 
BEER Me He 
ease teehee sla PeCGrnaa See Cer scer ecg 
Me Foe een ior em icles sicicin nis Ne Stree 
iaeietee EOE EEE nae 
100° 200’ 300’ 400 
Fig. 5.—Typical profiles across tract shown in figure 4. 
the trees are beginning to show the effect of a high water table and 
a number of them are already dead. One of these 4-inch tile branches 
was used as an outlet for the system under discussion in order to 
cut down expenses, but it would have been better if an outlet of larger 
tile had been constructed. 
The system was laid out as shown in figure 4, an attempt being 
made to follow the shale ridges. The depth of the system ranges 
from 6 to 7 feet. As nearly all of the trenches were in shale, very 
little difficult construction was encountered. In some places the 
banks of the shale trenches broke off in large pieces and it became 
