THE STRUCTURAL PIPE LINING SOLUTION

The provision of an adequate quantity and quality of water is a constant concern of municipalities in Ontario and across Canada.  Certainly, the water main cleaning and Cement Mortar Lining is a very feasible alternative for water mains where the structural integrity of the existing pipe is adequate.  Traditionally, for water mains with structural problems, open-cut replacement was the only solution.  However, with advancement of trenchless technologies another alternative is now available to municipal engineers.  What is the alternative?  The Structural Pipe Lining Solution.

Unlined cast-iron pipe, ductile iron pipe or asbestos-cement (A-C) pipe was the material choice for water distribution systems from the beginning of this century to the mid 1970’s.

Although alternative products are being used, these water mains account for the majority of pipe in most distribution systems in Canada.  Structural integrity of the pipe and carrying capacity can be severely reduced due to many factors.

One factor is the corrosion of steel.  This is caused by the electrochemical process that requires the flow of an electric current as well as one or more chemical processes.  As the corrosion process occurs, the inside and outside walls of the pipe will develop pits and cracks as material is lost.  The formation of tubercules begins to form on the inside walls of the pipe.  This can be resolved with The Cement Mortar Lining Solution.  However, the deterioration of the outside pipe can only be effectively resolved using the open cut replacement or with the insertion of The Structural Pipe Lining Solution.

The Structural Pipe is a stand alone, structurally sound liner which can take the place of the host pipe if gradual deterioration leads to disintegration or destruction.

The Structural Pipe Lining Solution eliminates the factors of internal and external corrosion and tuberculation, restores carrying capacity, eliminates discoloured water, and decreases pumping and maintenance costs. More importantly, with restored flow and a stand alone structurally sound liner, the savings go on for many decades.

The Structural Pipe Lining Solution allows for the rehabilitation of damaged pipes such as cast iron, ductile iron, and asbestos cement pipe.  It is designed to structurally rehabilitate 150mm, 200mm and 250mm water distribution conduits by inserting a composite material liner into the host pipe.   The liner itself is made up of two (2) concentric, tubular, plain weave polyester jackets with the inner jacket bonded onto a polyurethane elastomer.  The polyurethane elastomer is potable water compatible and designed to maintain water tightness of the liner.

The jackets are impregnated with a curable polymeric resin that plays two important roles.  First the curable resin allows the tubular liner to adhere to the host pipe.  Second, the curable resin, once reticulated, completes the formation of the composite structural liner.  The resulting composite material liner has mechanical properties exceeding ASTM F1216 and ASTM F1743 recommendations for fully deteriorated pipe.

Construction procedures are similar to that of The Cement Mortar Lining Solution.  Prior to the insertion of the Structural Pipe liner the host conduit must be cleaned, removing accumulated scale and rust (tuberculation).  Locating and mapping of the service connections will also take place.

The excavation of individual water services is not necessary when the Structural Pipe liner has been cured in place.  A dimple forms around the water service which makes its location extremely evident.  A mechanical robot equipped with a camera is inserted into the rehabilitated conduit and activated by an operator using a remote control and television unit.  The robot is equipped with a drilling tool that allows the operator to drill a hole in the liner at the precise location of the connection.  Each location was previously recorded and mapped prior to the rehabilitation and insertion of the Structural Pipe liner.

Such drilling action on the wall of the liner will not affect the water tightness of the rehabilitated pipe.  The thermo-curable polymeric adhesive that surrounds the threaded cavities of the service connections preserves water tightness and corporation stops and assures a tight bond with the liner.

After opening the connections, the rehabilitated pipe is flush cleaned, chlorinated and service is restored.

THE REHABILITATION PROCESS

Some of the major advantages of this method compared to traditional open cut replacement are:

• the method facilitates an overall cleanliness of the project, as opposed to the excavation of entire road section,
• substantial economic savings can be realized,
• it can be applied to pipeline materials such as cast iron, steel or ductile iron,
• the pipeline can be rehabilitated while in place,
• the rehabilitated areas are supplied with water and fire protection via a temporary by-pass system with a minimal disruption of water service to residents,
• a minimal disruption of services and traffic because small excavation pits are used to access the pipe,
• individual water services do not have to be excavated,
• future deterioration of road beds and asphalt due to trenching are minimized.

THE PROVEN PROTECTION

Benefits After Structural Pipe Lining:

• prevention of water main breaks,
• increased hydraulic carrying capacity in rehabilitated system,
• makes previously lost water available for sale,
• improved fire flow from hydrants, which can reduce insurance rates,
• reduced pumping costs,
• savings in the cost of energy to pump water,
• curtailing of coliform bacteria regrowth,
• savings in the cost of chemical treatment,
• stabilization of chlorine residuals,
• clean, clear water free of odour, poor colour, unpleasant taste and turbidity,
• reduction in danger of undermined pavement,
• resistance to chemical attack,
• encasement of lead joints to reduce threat to water safety.