Drain Design Procedure

Determine if and where an adequate outlet can be installed

Estimate hydraulic conductivity (K) based on soil type

Select drainage coefficient (Dc) based on crop and soil type

Select suitable depth for drains

• Typical range 3 to 6 ft.

• Cover greater than 2.5 ft.

• Depth / Spacing balance to minimize cost

Determine spacing

• Use soil textural table guidelines

• Use NRCS Web calculator

Size laterals and mains to accommodate the design flow

• Maintain minumum velocity to clean pipe

  • (0.5 / s - No slit: 1/4 ft / sec - w/slit​

• Maintain pipe size to design flow​

  • (telescoping the size of the main)​

• Properly design outlet​