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7.6 Pipe Plugging or Bypass Pumping
Bypass pumping of the existing fluid is required for the installation of
CIPP. With most small diameter pipelines, plugging may be adequate,
but must be monitored on a regular basis to prevent flow backups.
Service connections in the residential systems typically do not require
bypass pumping. The homeowners are notified usually a week or
two in advance and again 24 hours in advance to refrain from heavy
use of water while the CIPP installation process is underway. A small
amount of water from the service connection typically will not affect
the installation of the CIPP. In commercial and industrial applications
it may be necessary to bypass flow from each individual service con-
nection, since flow interruption may not be an option. In these cases,
individual cleanouts are identified and a small pump is set-up direct-
ing the flow to the mainline bypassing. In most cases, the project
owner will require a pumping capacity that is equal to the anticipated
peak flow (either recorded or anticipated) for the line section, plus
50 to 100 percent redundancy in the event the primary system fails
to function. Most pump rental suppliers will determine bypass
pumping suction and discharge configurations and setup require-
ments at the jobsite. However, pumping operations for the duration
of the project is typically the responsibility of the general contractor.
Figure 7.7 illustrates typical bypass pumping setup for a large vol-
ume of existing flow.
FIGURE 7.7 Typical bypass pump setup for a large volume of existing fl ow.