. Bulletin of the Department of Agriculture. Agriculture; Agriculture. DRAINAGE OF IRRIGATED SHALE LAND. 29 comer 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,. 0 100' 200' 300' " 400 Fig. 5.—Typical profiles across tr
. Bulletin of the Department of Agriculture. Agriculture; Agriculture. DRAINAGE OF IRRIGATED SHALE LAND. 29 comer 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,. 0 100' 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. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original United States. Dept. of Agriculture. [Washington, D. C. ?] : The Dept. : Supt. of Docs. , G. P. O.
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