Trenchless Technology Center
Louisiana Tech University

Water Environment Research Foundation
http://www.werf.org
 
SEWER LATERAL REHABILITATION

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.
METHODS:
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
Lateral Chemical Grouting

Chemical grouting creates a sealing collar of material around the pipe by injecting a self-setting grout into an opening in a pipe wall, which is followed by the grout passing through the pipe wall into the surrounding soil and bonding of the grout with the soil. Chemical grouting is usually done as a “test-and-seal” procedure, in which an isolated segment of the pipe is pressure-tested for leak-tightness and, if the test fails, the segment is sealed by injecting the grout.

The method eliminates infiltration but does not provide structural enhancement and is intended for rehabilitation of structurally sound pipes only. No excavation is needed, access to private property is not required and the disturbance to homeowners is minimal. This is the least expensive of all lateral repair methods. In some situations, the isolated section can’t be pressurized and the test-and-seal procedure cannot be carried out. The installed grout may have limited longevity in some cases, e.g., when the groundwater table fluctuates above and below the grout seasonally. Access to private property is not required. The method is most suitable when an inexpensive and quick repair is needed in leaking structurally sound pipes.

Lateral chemical grouting can be carried out as (1) grouting from mainline, or (2) grouting along lateral pipe.

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