An OptiSurface 2Way is a Surface Type in OptiSurface which can drain in two opposite directions (2Way). This suits crops grown in furrows or even minor wheel tracks where water needs to drain along the furrows or direction of travel but it can drain out to either end of field or at some distance along the furrow using cross drains or taildrains.
The location of the high point in the field is defined using a subzone with the Subzone Type setting of 'Ridge'. This subzone is placed where the Existing Topography already has the high point to reduce earthworks.
Taildrains are added using subzones at the ends of the field and defining the cross slope to force water to drain and exit to the desired location.