Trenchless Vs. Traditional Sewer Repair

Experts say that it is a good idea to inspect a sewer line with a camera before you purchase a home. The last thing you want is to have a $3,000 to $5,000 sewer problem right when you move in. Cities around the nation have began requiring a camera inspection before selling a home, but this practice is not widespread.

Even if you have lived in your home for years, it’s worth hiring a professional to examine your line. That way you can budget for future repairs or replacement, without having to make snap decisions when an emergency happens. Inspection prices usually run between $250 to $350. Some Companies advertise free or reduced rate inspections. Make sure the contractor is reputable and there are no hidden fees.

If you would like to find out more, or want to schedule a camera inspection, call ACE HI PLUMBING, HEATING & AIR, INC. today at 970-667-0300.

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Trenchless technology is a type of subsurface construction work that requires few trenches or no continuous trenches. It can be defined as “a family of methods, material and equipment capable of being used for the installation of new or replacement or rehabilitation of existing underground infrastructure with minimal disruption to surface traffic, business and other activities”.

Trenchless construction includes such construction methods as

  • tunneling,
  • micro tunneling ,
  • horizontal directional boring,
  • pipe ramming,
  • pipe jacking,
  • moling,
  • horizontal augur boring

and other methods for the installation of pipelines and cables below the ground with minimal excavation. Large diameter tunnels such as those constructed by a tunnel boring machine, and drilling and blasting techniques are larger versions of subsurface construction. The difference between trenchless and other subsurface construction techniques depends upon the size of the passage under construction.

Trenchless rehabilitation includes such construction methods as

  • sliplining, (one of the oldest methods used to repair leaks or restore structural stability to an existing pipeline)
  • thermoformed pipe,
  • pipe bursting,
  • shotcrete,
  • gunite,
  • cured-in-place pipe (CIPP),
  • grout-in-place pipe,
  • mechanical spot repair (applied where damaged pipelines require the reinstatement of structural integrity)

and other methods for the repair, rehabilitation, or replacement of existing buried pipes and structures without excavation, or at least with minimal excavation.

Sliplining, cured-in-place pipe and thermoformed pipe lining involve pulling or inverting a new liner into an existing pipe and then applying heat and/pressure to force the liner to expand to fill the pipe. Other methods are primarily for fixing spot leaks. CIPP technologies combine a carrier (felt or fiberglass) impregnated with heat, ultraviolet light or ambient curable resign to form a jointless and seamless pipe-within-a-pipe, with the capability to rehabilitate pipes ranging in diameter from 0.1-2.8 meter (4″-110″). As one of the most widely used rehabilitation methods, CIPP has application in water, sewer, gas and chemical pipelines.

SLIPLINING

Pipe bursting consists of a torpedo-shaped metal bursting head, attached to a steel cable, being pulled through the existing sewer line to burst the pipe, breaking it up into little pieces. The existing line is just a conduit to pull the new pipe through. This is done via a heavy cable and a hydraulic pulling machine that pulls with 30 tons of force with and intermittent pneumatic hammering action to assist the bursting head in breaking the old pipe apart and out of the way.  With pipe bursting, the entire pipe is replaced with a new high density polyethylene pipe (HDPE). This method of sewer replacement requires only a hole at each end of the line rather than the entire length of the line, as required by more conventional methods.

Limitations of Trenchless Sewer Rehabilitation

 

Method                                                                    Limitations
Pipe Bursting Bypass or diversion of flow required

Insertion of pit required

Percussive action can cause significant ground movement

May not be suitable for all materials

Sliplining Insertion pit required

Reduces pipe diameter

Not well suited for small diameter pipes

CIPP Bypass or diversion of flow required

Curing can be difficult for long pipe segments

Must allow adequate curing time

Defective installation may be difficult to rectify

Resin may clump together on bottom of pipe

Reduces pipe diameter

Modified Cross Section Bypass or diversion of flow required

The cross section may shrink or unfold after expansion

Reduces pipe diameter

Infiltration  may occur between liner and host pipe unless sealed

Liner may not provide adequate structural support

Consider the Disadvantages and Risks of Trenchless Sewer Repair or Replacement

These methods we’ve gone over are referred to as “trenchless” because very little, or in some cases no excavation is required. These types of trenchless sewer repair and replacement are very common today because they are fast, economical and are not invasive. It used to be that the only way to repair or replace a sewer line was to excavate it, meaning tearing out driveways, porches, additions, landscapes or whatever might lay in the path of the existing sewer line. You should consider that this type of installation method might not pass inspection if water pools in a low spot in the line. Because the new line uses the old line as a conduit, this is a possibility. Generally, labor cost can be more expensive as the equipment that is used is expensive.

Another issue with pipe bursting, is the close proximity of other utilities. As the bursting head passes through the pipe, it splits the existing pipe and forces it outward as the new pipe is pulled through. If there are utilities close enough, the existing pipe being pushed outward can damage them. Water lines can be cut and gas leaks can result. Contractors must locate all utility crossings as well as close parallel utilities to determine if there is adequate room for this type of installation. It may also be necessary for the workers to do some hand digging in order to establish where these lines are located. Occasionally, it may also be necessary to remove some of the landscaping, but only if the root system of plants will cause future problems.

If you are considering trenchless sewer replacement, be sure to verify that the contractor has significant experience doing it and has been trained by both the trenchless equipment manufacturer and the pipe material manufacturer.

 

ACE HI PLUMBING, HEATING & AIR, INC. does not believe in doing these “trenchless” methods. We believe that traditional sewer repair and replacement is more effective.

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