INLAND DRAINAGE 



105 



DRYING UP A SWAMP 



"In case No. 2, a more complicated situation is presented. Here the 

 seepage flow is from a large U-shaped bend in a hillside, resulting in a 

 swamp many acres in extent, with a small lake at the outer edge. The 

 water-table in this case extended clear across the swamp, but was con- 

 cealed along a slight elevation running down the middle. On account 

 of this elevation, it was necessary to drain the right and left halves of the 

 swampy area separately. As shown in the sketch, a ditch was put 



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F 1G eg. — Seepage outcrop, Case No. 2. (A/«er .1/V/z.) 



along the toe of the hill on each side at the upper margin of the outcrop 

 and then run off into the lake. But the water-table this time was too 

 deep to be intercepted entirely by one ditch, and it was necessary to dig 

 additional intercepting laterals at intervals lower down. On one side, 

 five such ditches, more or less parallel to one another and at right angles 

 to the seepage flow, were required to catch all of the water before it 

 came to the surface. 



"In case No. 3, an outcrop on a relatively steep hillside is represented. 

 Here it was necessary to dig several intercepting laterals parallel to one 

 another and only a few feet apart in order to catch all of the flow. 

 When this was done over the area in which the seepage water was actu- 



