Pay special attention to the joints so roots
do not grow into the piping. The depth of
the piping should be below the frost line.
Also, you should encase the piping with
concrete or sleeve it with a metallic material
when laying piping under roadways.
It may be necessary to install the
building sewer and the water-service pipe in
the same trench (fig. 7-1). If so, use the
Figure 7-1.Building sewer and the water-service
pipe in the same trench.
Ensure the bottom of the water pipe is at
least 12 inches above the top of the
Place the water pipe on a solid shelf at the
side of the trench.
Use hot lead when joining cast-iron pipe
for a building sewer; use a hot-poured
compound in joining bell-and-spigot clay or
concrete sewer pipe.
After installation, test the building sewer
with a 10-foot head of water, or equivalent
Install sanitary drainage piping on a uniform
slope. This slope, pitch, grade, or drop per foot
decides the flow velocity of liquid within the pipe.
Piping with a diameter of 3 inches or less
requires a slope of not less than 1/4 inch per foot.
Pipe 4 inches or larger slopes no less than 1/8 inch
per foot. This allows a velocity of not less than 2
feet per second, that provides the scouring action
necessary to keep a pipe free from fouling. Sewer
mains may have slopes of less than 1/8 inch per
foot, as long as there is a cleaning velocity of 2 feet
per second or greater. See table 7-1 (A) for code
Table 7-1 (A).Discharge Rates and Velocities of Sloping Drains