Sewer pipe renewal options
Why did I experience a sewer back-up?
A sewer back up can be a traumatic event. Homes suffer damage, personal property is destroyed, claims are filed, capital is lost and inconveniences are experienced. There are a variety of reasons why a sewer system can back up, ranging from objects being accidentally placed into the private plumbing system to complete collapse of the sewer pipe.
Quite often, persistent tree roots extend through the joints of old vitrified clay sewer pipes while searching for nutrients and moisture during the dry summer months. The Sewers Operations Branch spends considerable time and resources clearing sewer mains and house connections free from tree roots.
Why should I replace my sewer?
There are thousands of older homes in Vancouver, many with the original sewer pipes still in use. Much like the roof of your home, a sewer connection has a "life span". Unlike a roof, however, it is difficult to determine the condition of a buried pipe. Often sewer renewal isn't considered until repeated blockages and back-ups occur.
Prior to 1984, most sewer connections in Vancouver were installed using vitrified clay pipe. Altogether, this material is relatively durable and can last over a hundred years in the ground. On average, it is anticipated that vitrified clay pipe maintains a 60 to 80 year life expectancy.
The most common failure attributed to older vitrified clay pipe is tree roots penetrating the joints of the pipe. In past years, joints were placed together and stopped up with a twine-like substance referred to as "oakum". Over an extended period of time, the oakum disintegrates allowing in some cases for roots to grow into the sewer pipe as they search for moisture.
How is a sewer repaired or replaced?
When sewer pipes fail, the conventional means of repair is to excavate the ground, find the pipe and perform the mend or renewal. Roads, sidewalks, yards, driveways, and landscaping may be disturbed when locating and repairing sewer pipes. This typical means of repair is referred to as "open trenching".
Sewer connections can sometimes run directly underneath other utilities and large trees with extensive and sensitive root systems. In these situations, repairs can be difficult and expensive because they require hand digging around the utility or roots.
Sewer Operations have been successfully using a trench-less form of technology referred to as "Pipe Bursting" to renew selected sewer-lines and main-lines within the City.
Pipe bursting is one trench-less method available today to replace failing sewer service lines. A launch pit is dug at one end of the failed sewer pipe, usually near the home, and an exit pit is dug at the other end, usually near the sewer-main. Constant tension is placed on the bursting tool from the exit pit by operating a hydraulic puller.
The pulling cable is fed through the old sewer connection and is attached to a steel bursting head positioned on the old pipe at the launch pit. A roll of seamless high-density polyethylene pipe is fed from the launch pit and is pulled behind the bursting tool.
As the bursting tool pushes forward, it employs the tension from the hydraulic puller and makes use of the alignment of the old sewer connection to guide the new pipe into place. The bursting component of the work takes relatively little time to complete.
Not every failed sewer connection can be pipe-burst. Primarily the old pipe must be relatively straight, free of dips and bends and unblocked. Furthermore, there must be sufficient area on private property to dig a launch pit and feed the new polyethylene pipe.
What is relining?
Pipe relining is a seamless way of repairing pipes with very little excavation involved. Damaged pipes with cracks or root infiltration can be fixed by inserting a long cloth sleeve into the existing pipe. The sleeve is treated with epoxy resins and molded to the inner wall of the host or existing pipe with compressed air. The liner cures or cooks to the wall of host pipe and after several hours, it is ready to stand alone. When everything is complete, you have a pipe within a pipe.
The City is beginning to look at using relining technologies to repair and rehabilitate sewer-line connections. We hope to have a relining program started by 2008.
How would I qualify to have my sewer-line replaced?
For the City to consider sewer-line replacement options, there firstly must be a documented history of sewer-line blockages of which the City is fully or partially responsible for. Secondly, there needs to be an indication that a City managed sewer-line maintenance program is no longer effective or has become exhaustive.
Homeowners are expected to make the necessary repairs to remedy pipe blockage problems by making the private portion of the sewer-line better, primarily by installing approved plastic root resistant pipe. If you have fully replaced the private portion of the sewer-line and the City portion is in poor condition, then please give us a call at 604-326-4694 and we can visit the home and consider City replacement options.
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