Page 95 - Trenchless Technology Piping Installation and Inspection

62 Cha pte r T w o

2.3.8 Point Source Repair or Localized Repairs
Point source repairs are considered when local defects are found in a
structurally sound pipeline. Remote-controlled resin injection to seal
localized defects in the range of 4 to 24 in. (100 to 600 mm) in diameter
are available. Four specific applications can be addressed with these
methods:

1. To maintain the loose and separated pieces of unreinforced
existing pipe in alignment to ensure load-bearing equivalent
of the masonry arch.
2. To provide added localized structural capacity or support to
assist the damaged pipes to sustain structural loads.
3. To provide a seal against infiltration and exfiltration.
4. To replace missing pipe sections.
Figure 2.12 presents a localized repair technique.
Chemical grouting can be used in cases where compression
rings are used, to stop the leakage when grout is “injected” or
“forced” into the defective joint. Chemical grouting can also be
done from the surface above the repair area via probe grouting.
This process not only seals the leak, but also stabilizes the surround-
ing soils behind the pipe. It should be noted that a new liner in a
pipe cannot be considered complete if the soil surrounding the pipe
still contains voids potentially creating an unstable and shifting
environment.

FIGURE 2.12 Internal seal point repair. (Source: Miller Pipeline Corporation.)