GPM Inc

By: Guildner  09-12-2011
Keywords: Rehabilitation, hdpe, Sliplining

We have rehabilitated approximately 300,000 linear feet of various type and size pipe using HDPE.

Sliplining is a popular and trusted trenchless method that allows the rehabilitation of deteriorating pipe by inserting a smaller pipe into an existing pipe. As a trenchless method, sliplining can be applied to either pressure or gravity pipelines.  Water, sanitary and storm sewers can be renewed with minimum excavation.  When done properly, sliplining ensures that the rehabilitated pipe and lateral connections are leak-tight, corrosion resistant and capable of even greater flow rates.

In the sliplining process, a winch cable is inserted through the existing line and then attached to the front of the new liner pipe.  The new pipe is then pulled into the existing  pipe and reconnected to the system.

Benefits:

  • Sliplining can be used on most types of pipe and is suitable for potable water.
  • Installation is rapid and causes little disturbance to other utilities.
  • Hydraulic performance is improved due to an improved friction coefficient.
  • Installation can be completed in live lines without bypass pumping.
  • Structural strength and life expectancy is added to existing systems.
  • Service connections are replaced with new taps to ensure proper connection.
  • Sliplining is a cost-effective alternative to excavation, replacement and CIPP methods.

A typical sliplining project consists of the following steps:

  1. The pipe is cleaned to remove tuberculation or any debris that may be present.  It is then televised for proper measurements and to make sure there are no obstructions or protrusions from service taps or broken or separated pipe.
  2. The excavation points are located at connections that would have to be excavated anyway.  The HDPE is then pulled through from the downstream manhole.  The configuration of the excavation at the insertion end is important because the trench's length-to-depth ratio must be large enough to minimize the bending stress on the HDPE to be inserted and on the welds between sections.  The actual ratio depends on the diameter of the HDPE pipe; 10:1 ratios are not uncommon.
  3. Workers then butt weld sections of HDPE together if they haven't already done so, and attach a tapered nosepiece to the front of the  HDPE.  This piece is fitted with a winch hook to pull the HDPE through the host pipe.
  4. The HDPE is inserted into the host pipe and pulled through by the winch.  Care is taken to avoid damage to the HDPE at the point of insertion.
  5. Service connections are then reestablished and the void between the HDPE and existing pipe are grouted in at the man holes.

With proper planning, sliplining is a cost effective method for the rehabilitation of aging sanitary and storm sewer collection systems, extending the service life of these systems for many decades to come.

Keywords: hdpe, Rehabilitation, Sliplining