Page 351 - Facility Piping Systems Handbook for Industrial, Commercial, and Healthcare Facilities

SITE UTILITY SYSTEMS

SITE UTILITY SYSTEMS 6.73

run full. This method uses a foam dispenser that is run through the sewer pipe, producing a
chemical foam having the consistency of thick soapsuds. Since roots do not occur in a pipe
full of water, the foam adheres to the roots and pipe above the water line, killing the roots
and retarding future growth for approximately 3 years. This chemical does not remove the
roots immediately, but is very effective in about 3 to 6 months. If the roots must be removed
immediately, the use of an HJR is necessary. In addition to being used alone, this chemical
can be added to the grout used to repair cracks.

REPAIR OF CRACKS AND JOINT
SEPARATIONS IN PIPING

In many cases, cracks have appeared in pipes and joints have separated due to uneven
settlement of the earth surrounding the sewer pipe. When this occurs, the pipe will leak,
washing away the supporting earth fill and also allowing roots to enter the pipe. Repair of
these deficiencies is of the highest priority.
The most common method used for the repair of piping up to 24-in diameter is called
chemical grouting (CG). This method uses a polymer adhesive with the viscosity of water
that hardens into a solid in a period of time determined by the mixture of ingredients. It is
applied from inside a pipe by a device called a packer, which is, in essence, a 2 1/2 -ft length
of pipe, slightly smaller than the pipe being repaired, with an inflatable donut at either end.
The packer must be positioned correctly by the use of a video camera. Once in position, the
donuts inflate creating a seal, and the adhesive is injected under pressure between them.
The adhesive is forced out of the pipe into the surrounding soil, where it hardens, forming
a tough elastic and waterproof barrier to inhibit further leakage. If the rooting chemical is
added to this adhesive, any roots growing toward the hardened soil will die. This is con-
sidered a permanent repair. If any adhesive hardens on the inside of the pipe, it must be
cleaned, generally with an HJR with a rotating blade.

REPAIR OF MANHOLES

Manholes are generally repaired using a waterproof epoxy cement or other hydraulic coat-
ing applied to all areas of the manhole until a smooth finish is achieved. This is very labor
intensive.

PREVENTIVE MAINTENANCE

After the piping network is initially cleaned and repaired, the following scheduled preven-
tive maintenance program is recommended:
1. After the initial vapor rooting procedures, a second application is recommended after
1 year and again every 3 years. This should be applied only where there are trees. The
price would be the same as for VR cleaning.
2. A regularly scheduled cleaning using the HJR once every 2 years is recommended.
3. A video inspection of the piping system once every 5 years is recommended to see if
any problems have developed in the piping network.
4. The cleaning of residential and commercial lines in usually done with flexible rods
ranging from 5/16" to 1-1/4" in diameter.

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