Calculate Required Underdrain Lateral Spacing

Permeability rate of soil (K)

Recovery time of the system (t)

Depth to the drainage pipe from the natural ground elevation (dp)

Depth from the natural ground elevation to the water table (c)

Depth from the natural ground elevation to the impermeable layer (D)

Result

Where: drainage coefficient, q

m/hr

Height of water table above drain, m

Height of drain above impermeable barrier, a

Lateral Spacing, S

K - Permeability rate of soil
t - Recovery time of the system
dp - Depth to the drainage pipe from the natural ground elevation
c - Depth from the natural ground elevation to the water table
D - Depth from the natural ground elevation to the impermeable layer
q - Where: drainage coefficient
m - Height of water table above drain
a - Height of drain above impermeable barrier
S - Lateral Spacing