OUR BLOG: INSIDE THE LIFT

22Apr 2015

Sealing Annular Space in a Sliplined Pipeline

By Susan Albershardt

In the United States, billions upon billions of gallons of stormwater are transported through the local sewer systems every day.  The pipes that the water travels through have different degrees of structural integrity.  Some of the pipes are as small as 8 inches in diameter and some are as large as 120 inches.  The storm sewers can be made out of brick, metal, concrete, clay and plastic.  As communities grow and these sewer systems age, local governments are forced to incur costs far beyond the material and labor to rehabilitate or expand the pipelines.  Government officials must also figure out how to alleviate traffic delays, as well as business interruptions and disruption to neighborhoods, which can add to the cost of repairing the stormwater system.

One of the oldest and most cost effective methods of rehabilitating an existing drainage pipe is called sliplining.  With sliplining, a new, smaller “carrier pipe” is installed inside the old, larger “host pipe.”  Sliplining is an effective method for stopping the infiltration of adjacent soils and restoring the structural integrity of the existing pipe.

In a project for the Alabama Department of Transportation in Boaz, Alabama, URETEK Holdings was called in to fill the “annular” space between the carrier and host pipes with geotechnical polymer to anchor the two pipes together, avoiding future slippage.

URETEK team works to inject grout in between the pipes.
URETEK team works to inject grout in between the pipes.

During installation, the chemical grout also seeks out the deteriorated areas of the host pipe and travels outside the pipe to void-fill, stabilizing the host pipe. When installation of the chemical grout is complete, there is a tight seal between the two pipes, as seen below.  Typically, the end of the carrier pipe is trimmed so that it is flush with the culvert, but the DOT wanted to widen the road above and keep the longer pipe for a future connection.

The pipes are sealed tightly together.
The pipes are sealed tightly together.

For most projects, installation of the polymer can be completed within one hour after insertion of the liner.  URETEK is also able to provide a fixed cost for each project.