Figure 1-10 illustrates a typical absorption trench layout for level ground. If the slope of
the field exceeds about 6 inches in any direction within the area, serial distribution may
be used. In serial distribution, individual absorption trenches (laterals) are laid level with
the long axis perpendicular to the slope. The laterals are then connected in series as
shown in Figure 1-11 so that the upper trench is filled first; then excess liquid is carried
by means of a closed line to the next succeeding or lower trench.
Figure 1-10. Absorption-field system for level ground.