Page 275 - Trenchless Technology Piping Installation and Inspection

Pr oject Considerations for Pipe Replacement Methods 239

Pipe bursting has substantial advantages over open-cut replace-
ments; it is much faster, more efficient, and often less expensive than
open-cut, especially in sewer applications due to the large depths at
which gravity sewer pipes are typically installed. The large sewer
depth requires extra excavation, shoring, and dewatering which sub-
stantially increases the cost of open-cut replacement. The increased
depth has only a minimal effect on the cost per foot for pipe bursting,
as shown in Fig. 6.7. Specific studies carried out in the United States
have shown that pipe bursting cost savings are as high as 44 percent,
with an average savings of 25 percent, compared to open-cut
(Fraser et al., 1992). This cost saving could be much greater if the soil
conditions are difficult such as, hard rock. Furthermore, open-cut
excavation can cause significant damage to nearby buildings and
structures (Atalah, 2004).
In addition to the direct cost advantage of pipe bursting over
open-cut, pipe bursting, as a trenchless technique, has several in
social cost savings, including less traffic disturbance, road or lane
closing, improved productivity, less business interruption, and less

Average unit cost comparison between pipe bursting and
open-cut pipe replacement, a case study from U.K.
(modified to 2005 dollars)
$250

$200
Average costs (US dollar/ft) $150

$100

$50

$0
7 10 13 16
Depth (ft)

Open-cut replacement - heavy traffic
Replacement by pipe bursting
Open-cut replacement - average traffic

FIGURE 6.7 Cost comparison between pipe bursting and open-cut
replacements. (ASCE, 2007.)