Trenchless Technology Center
Louisiana Tech University

Water Environment Research Foundation

Rehabilitation of defective sewer laterals restores impaired structural integrity and reduced hydraulic capacity of these pipes, as well as improves the leak-tightness of pipes and connections and hence eliminates or minimizes groundwater infiltration into the sewer system and/or exfiltration of wastewater into the surrounding soil. Rehabilitation also prevents root intrusion through defects into the pipes, which is a serious problem for many agencies.

Sewer laterals can be repaired or replaced either over their entire length or only in selected parts.

A number of trenchless rehabilitation methods have been developed for the purpose of lateral repair—the principal methods in use today being cured-in-place (CIP) relining products, replacement by pipe bursting, chemical grouting, and flood grouting. Robotic repairs are a relatively new method, whereas mechanical repair sleeves for sectional repair of laterals are less frequently used.

The lateral rehabilitation methods shown below are included in our database. Click on the link to see details.
CIP Relining
  CIP, Standard Liners
  CIP, Remotely Inverted Standard Liners
  CIP, T-Liners
  CIP, Short T-Liners
  CIP, Top Hats
Pipe Bursting
  Static Pull
  Pneumatic Bursting
Lateral Chemical Grouting
  Grouting, Mainline Packers
  Grouting, Push Type Packers
Flood Grouting
Robotic Repairs
  Robotic, Pressure Applications
  Robotic, Non-Pressure Applications
Mechanical Repair Sleeves
CIP Relining

CIP relining is a method in which a resin-saturated material is inserted into the sewer and the resin is subsequently cured. The main components of a CIP relining system are a fabric tube and a resin. A plastic protective coating is often added to enable handling of the resin impregnated tube, holds the vacuum if used during resin impregnation, protect the resin from water during installation/curing, and take abrasion from sewage over the years when the lateral is in service.

In some CIP systems, a second coating is used to encapsulate the resin and fabric so that the liner can be pulled into place rather than being inverted into place.

Minimal on no excavation is typically needed for the installation and the disturbance to homeowners is small. The duration of installation depends mostly on the resin cure time and is much shorther when hot-air or steam are applied then with resin ambient cure.

Laterals need good cleaning before product installation. As laterals are small diameter pipes and typically have bends along their length, the inversion may become difficult, especially if there are 90-deg short radius bends or even worse back-to-back 90-deg bends. Furthermore, inversion in cast iron pipes is more difficult than in other pipe types.

The method eliminates infiltration and restores or enhances the structural integrity of pipes lost over time. Hydraulic capacity of aged, deteriorated pipes is also generally improved. Root problems are less likely to reoccur in the future.

Lateral CIP relining includes (1) standard liners, (2) remotely inverted standard liners, (3) T-liners , (4) short T-liners, and (5) top hat liners. Numerous systems on the market differ in materials used and type of resin cure.

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