WET LANDS OF SOUTHERN LOUISIANA. 



31 



Levees. 



On one side the embankment- of the Southern Pacific Railroad serves as a 

 levee, and on the side bordering the bayou an almost continuous ridge of silt, 

 averaging about 2 feet above ordinary water level, makes an excellent founda- 

 tion for the levee. This levee was built in two layers by a floating dredge 

 with material taken out of the bed of the bayou. The height is about 5 feet, 

 the top width from 6 to 12 feet, and the side slopes 1£ to 1. After the first 

 layer of material was placed in the levee a muck ditch about 3 feet deep was 

 dug along the inside toe of the slope, and when The second layer of material 

 was placed this ditch was filled with pure silt taken from the bottom of the 

 bayou. This made the levee free from seepage through the base. On the 

 other two sides the levee was located through softer land. Some years before 

 the building of the present levee a canal had been cut along these two sides 

 of the district. The spoil bank of this canal formed the base of the levee, 

 although it was necessary to cut a muck ditch along the inside slope to cut off 



Fig. 



PARISH DRAINAGE CANAL 



7. — Sketch map of Des Allemands Drainage District, La Fourche Parish, La., show- 

 ing arrangement of levee and ditches. 



possible seepage. This portion of the levee was built up in two layers to a 

 height of 4 feet, with a top width of from 4 to 6 feet and side slopes about 

 2| to 1. The berm varies from 5 to 10 feet. Except where , some old muck- 

 filled bayous were crossed, the levee is up to the above grade. Many layers of 

 material have been placed in these soft spots. The only method that seemed 

 to be effective in raising this levee was to bring material in wheelbarrows 

 from the solid banks of the bayou. After each layer w T as placed there was 

 some subsidence, but gradually the top of the leVee was raised. After the 

 solid material placed in the levee reaches the solid bottom of the old bayou 

 the levee should be free from further subsiding, except for the decay of the 

 vegetable material in the soil, which will cause a gradual subsiding in all 

 levees in this section. 



On a portion of the levee in the northwest corner of the district very severe 

 seepage conditions existed in 1912. Water appeared in springs as far as 100 



