Figure 11.8: field in seepage pit sections(b) Drainage trenches: the disposal of the large quantity of
effluent from septic tanks is often effected in trenches,
which disperse the flow over a large area, reducing the
risk of overloading at one place. The effluent is carried in
pipes, which are normally 100 mm in diameter with a gap
of about 10 mm between each pipe. For detail section of
this see figure 11.9.