Effective Point Repair Of Laterals

Laterals – 4th In A Series
January 2011 Vol. 66 No. 1

Rehabilitating sanitary sewer laterals was the subject of a recent series of articles that focused on legal issues regarding ownership of laterals and the emergence of trenchless methods for lateral rehabilitation.

However, another key element in dealing with laterals involves point repairs that effectively address inflow and infiltration (I&I) problems that are structurally sound and do not require rehabilitation.

In such instances, point repair often is the solution. Grouting also is necessary for reinstated laterals following relining of mainline pipe.

“A common misconception in the sewer rehabilitation industry is that lining the mainline in a sewer will stop infiltration,” said Daniel Magill, president, Avanti International, a leading provider of high-quality chemical grouts for sewers, storm drains, other underground structures and applications in a variety of industries.

laterals4art1.jpg

“When a lining system is installed,” Magill continued, “an annular space is created between the lining system and the host pipe. When the lining is bored to reinstate the laterals, the groundwater/infiltration will flow through the annular space and enter the sewer system at the reinstated lateral connections. When lining is required in mainlines or laterals due to non-structurally sound pipe conditions, the use of chemical grout to seal lateral/mainline connections and the annular space between the host pipe and liner is necessary.”

Technology is available that allows grouts to be applied to buried pipes trenchlessly.

“Flexible packers to seal lateral pipe joints can be inserted from above ground access and pushed/pulled into position to apply grout,” said Marc Anctil, president, Logiball Inc. Logiball is a leading provider of test and seal lateral grouting packers that operate from the mainline sewer and as far as 30 feet into the lateral from the mainline access. The company also provides packers that can be inserted from an above ground access to seal lateral pipe joints above the mainline lateral connection.

Common repair location
Anctil said the most common repairs needed are usually found at the connection (main to lateral) and the first five feet of the lateral from the connection.

“This is where most of the infiltration is found, as this part of the service lateral is subject to being below the groundwater table,” he said.

Magill said acrylamide gels are the most widely used chemical grout for lateral repairs. Others are acrylic gels, acrylates and urethanes.

He provided these descriptions of grouting products: