DBAINAGE OF BLACK AND BOGGY SWAMPS, S. C. 9 



year or more. Conditions in the Lyon Swamp district are practically 

 the same as at Chadbourn, and the chief difference, so far as run-off 

 factors are concerned, between that district and the Black and Boggy 

 Swamps drainage district lies in the character of the soil. The 

 drainage area of the Lyon Swamp district consists of 6,000 acres of 

 dark brown and black loam from 3 to 5 feet deep underlain by a coarse 

 sand, which gradually changes to a fine sand, and about 12,000 acres 

 of sand ridges and bays, the latter varying in size from 1 acre to 2,000 

 acres. The soil of the sand ridges consists of a very coarse white 

 sand, which absorbs the heaviest rainfalls with great rapidity. That 

 of the bays consists of a very fine white sand near the surface, which 

 also absorbs water quite readily. The entire area is underlain by 

 blue marl at a depth of from 15 to 20 feet below the surface. The 

 Lyon Swamp ditch was designed to remove one-half inch in depth of 

 water from the entire area in 24 hours. The soil in this district, taken 

 as a whole, will give a considerably lower run-off than that of the 

 Black and Boggy Swamps drainage district. 



From the preceding* description of the several districts it will be 

 seen that the chief difference is in the character of the soil, that of 

 the Black and Boggy Swamps drainage district being of such a char- 

 acter as to give a somewhat higher run-off than either of the other 

 districts. Therefore it would appear that the main outlet ditch for 

 Boggy Swamp should be designed to remove a run-off of three-fourths 

 inch depth in 24 hours from its entire watershed of 36,693 acres 

 and 1 inch depth from areas less than 20,000 acres. On the same 

 basis the main outlet ditch for Black Swamp should be designed to 

 remove 1 inch of depth of run-off from its entire watershed area, 

 18,490 acres. 



PLAN OF IMPROVEMENT. 



The plan recommended for reclaiming the lands of Black and 

 Boggy Swamps drainage district consists of a system of open ditches. 

 These ditches, as a general rule, are planned to He in the lowest parts 

 of the swamps and are as straight as can be made without leaving 

 the swamp. In only a few instances have the swamps been departed 

 from, the object in these cases being to make cut-offs across the 

 adjoining lands where they are low, thus reducing the distance. 

 The complete plan involves the construction of 68 miles of dredged 

 ditches and 98 miles of handmade ditches, a total of 166 miles for 

 the district. On the two lines located in the field all changes of 

 direction have been shown by angles, which in construction should. 

 be replaced by curves of suitable radius so that the flow of water 

 will not be retarded by abrupt changes of direction. In the fol- 

 lowing paragraphs some of the principal features of ditch construc- 

 tion as applicable to this district are taken up. 

 45582°— Bull. 114—14^—2 



