The evaluated properties include water entry into the pipe, water-table drawdown, drain spacing, and cost effectiveness. The bulletin also compares the properties of three 4-inch diameter pipes: sock-wrapped, 8-row sand-slot, and 4-row sand-slot pipes. This bulletin describes the condition where sock-wrapped and sand-slot pipes are needed. For more information about regular-perforated pipes, see Ghane (2023). Other pipes can also be wrapped with a knitted sock to give the same drainage performance. Typically, a regular-perforated rectangular-slotted pipe is wrapped with a knitted-sock envelope. A sand-slot pipe has a narrow slot width of about 0.015 inches to keep sediment out of the drain pipe. A sand-slot pipe is also known as narrow-slot, knife-cut, or fine-slot. If drain sedimentation is a problem, use either sock-wrapped or sand-slot pipe (Figure 1).
If fine sand or silt gets into subsurface (tile) drain pipes, it can remain near the entry point, build up over time, and cause drain clogging. Overview of sock-wrapped and sand-slot pipes For the pdf version of this bulletin, click here.
