A 200-foot section of 8" sewer main in Gwinnett County had
been awaiting installation of a CIPP (cured in place pipe) lining
for several months. Installation was delayed due to a crack in
the PVC pipe close to a lateral connection that allowed large
amounts of ground water to infiltrate the pipe. The engineers
on the project did not know how long this pipe had been leaking
but were guessing the leak to be as old as 20 years. The location
of the pipe made it impossible to excavate to make the appropriate
repairs. Prime Resins discussed the issue with the county engineers
and suggested probe grouting as a solution.
The first step required drilling several 1" access holes
through the concrete patio. Then the 3/8" steel probes were
driven down into the ground to a depth of about 14 feet. Inside
the pipe was a CCTV camera, allowing the contractor to monitor
repair process. The injection grout chosen for the repair was
Prime Flex 920 Hydrophobic Resin. This resin was selected due
to its fast reaction time and its high expansion rate. The inflow
of water through the crack at various times was several gallons
per minute and over many years had caused a substantial void around
the pipe.
Once the material started to be injected into the ground, several
of the surrounding voids started to fill with resin. The resin
mixed with the water and was carried to the crack in the pipe.
As the resin reacted with the water, foam was created. As the
foam began to expand, the flow of water began to decrease. At
that point, the contractor placed the next injection probe closer
to the pipe, adding more resin to the leaking area, completely
stopping the water leak.
The contractor that was performing the CIPP lining was able to
start their repair process 15 minutes after the grouting repair
was complete.
Click here to watch
the CCTV video of this repair.
