The ditch's corner sectors were all assumed to have a square base and all be the same size in the calculations. In order to do this, the sector was considered a rectangular
prism. The volume of the prism was calculated using the volume formula: height * width * length. Then the volume of the remaining dirt was subtracted from the total volume using formulas,
(1/2) * B * H * n and (1/3) * H * B^2, where n is the average length of one of the sides.
Volume of Corner = H * L * W  2[(1/2) * B * H * n]  3[(1/3) * H * B^2]
L  Total Length
W  Width  side on the right of the length
B  base
H  Height
n  average length of one side

Minimum Estimate 
Maximum Estimate 
H 
4.8 
5 
L (average) 
7.4 
10.3 
W (average) 
9 
10.3 
B 
3.4 
4.1 
N (length) 
4 
6.2 
Volume 
994.96 
1596.5 