DRAINAGE 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 lie 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 construe^ 
tion as applicable to this district are taken up. 
45582°— Bull. 114—14 2 
