Good Engineering Practice for Northern Water and Sewer Systems

2.5.2 Individually Insulated Pipes
Recommended.
The wall area is minimized by insulating just the pipe.
Photo 2.6 – Recent Utilidor in Inuvik Using
Individually Insulated Pipes
2.5.3 Pipe
Welded steel pipe is recommended
for utilidors.
2.5.4 Pipe Support
Pile supports are recommended.
2.5.5 Lateral Pipe Movement on
Supports
Pipe supports must allow lateral
movement.
2.5.6 Thermal Expansion/Contraction
Suitable expansion loops or
expansion joints are
recommended.
Welded steel provides the continuous beam strength
needed to span between supports.
Piles spaced at approximately 6 m intervals provide
sufficient support for welded steel utilidor piping.
Properly installed piles are not subject to seasonal
movement as would be surface-mounted supports.
Thermal expansion and contraction forces should not
be transmitted to the support piles.
Thermally induced movements must be controlled.
Generally, certain points are fixed so all expansion
occurs toward the expansion loops or expansion joints.
2.6 PIPE BEDDING
Buried pipes rely on the subgrade and the pipe bedding to withstand both the load of the backfill
and, at shallow depths, the live load of vehicle traffic. Further, where pipes are installed in the
active layer, the bedding must also work to resist freeze-back forces. Figure 2.3 indicates how
pipe deformation mobilizes resistance of bedding material. Figure 2.4 shows a typical GNWT
cross-section. Designers should refer to pipe sizing guidelines, GNWT and community standards
for appropriate bedding configurations.
GOOD ENGINEERING PRACTICE 2-11 Apr-04
Piping