Lesson 7 - nptel

Horizontal Filter
It collects the seepage from the inclined/vertical filter or from the body of the dam, in the
absence of inclined/vertical filter, and carries it to toe drain. It also collects seepage from
the foundation and minimizes possibility of piping along the dam seat.
Inner Longitudinal and Inner Cross Drains
When the filter material is not available in the required quantity at reasonable cost, a
network of inner longitudinal and inner cross drains is preferred to inclined/vertical filters
and horizontal filters. This type of drainage feature is generally adopted for small dams,
where the quantity of seepage to be drained away is comparatively small. A typical
arrangement of longitudinal and cross drains is shown in Figure 37.
Version 2 CE IIT, Kharagpur