be used to intercept or control surface water. These
should be dug by bulldozers, scrapers, backhoes, or
motor graders, depending on circumstances. Culverts
are constructed to drain water across a construction
site. Subdrains to drain groundwater are usually
excavated with ditchers or backhoes. The drains used
are french drains (perforated or open-joint tile
pipes). Figure 15-65 shows typical covered and
Runoff water from rain or melted snow is removed
from the area by constructing an adequate transverse
slope or crown. This runoff is collected in ditches and
drained into the nearest natural drainage channel.
Drainage for construction sites can be provided by
building the ends of the site sloping towards the
middle or sloping from one end to the other. These
types of drainage construction are shown on the
runways in figure 15-66.
Figure 15-65.Typical sections of covered and french drains.
Figure 15-66.Longitudinal drainage of runways.