CIPP is a thermoset resin system (polyester, vinyl ester, or epoxy) that is installed into the existing pipeline to be rehabilitated, with either a polyester felt or fiberglass tube of the approximate thickness designed for the application. The resin-saturated tube is installed either by directly inverting the tube into position using water or air pressure, or by pulling the resin saturated tube into place and inflating the tube. Once in place and properly inflated the resin system is cured using either heat (hot water or steam) or ultraviolet light. Recent technology developments include tubes that are reinforced with various high tensile fibers capable of increasing the overall strength of the finished CIPP. Because CIPP does not bond to the host pipe in sewers, groundwater may track between the CIPP and the host pipe. Supplemental technologies that provide a watertight seal between the host pipe and the new CIPP should be employed wherever groundwater infiltration may enter the collection system, such as at laterals and manholes. Seal technologies have been developed that have hydrophilic properties that can be installed in conjunction with the CIPP product.
CIPP is available in sizes ranging from 2 ” through 120″. It is most cost-effective in sizes 8″ through 48″; though it is routinely used for larger diameters due to a project’s site-specific parameters. The resin-saturated tube can be installed in a variety of common shapes for sewer lines; round, egg, arch, and elliptical. Square or rectangular pipes can be lined, but can provide many challenges to fitting the CIPP tightly. Multiple bends up to 90° and transitions in size and shape have been accomplished successfully and can be accommodated by fabricating the tube accordingly.
Typically, the house service connections are reconnected robotically, requiring no excavation.
Hundreds of millions of feet of CIPP are in service throughout the world today, and it is considered the most widely accepted pipeline rehabilitation technology worldwide. CIPP has been installed successfully in continuous lengths of over 2500 LF
Sensors are strung via a cable, inside the pipe that is to be repaired, prior to insertion of the CIPP liner. Once the liner is inserted, and the heating process via steam or water has started, temperature readings from the sensors that are distributed all along the pipeline are transmitted to an on-site computer. Designed to monitor the CIPP wall temperature during curing of the pipe in the field, the technology is a CIPP cure measurement technique using a 3mm diameter probe that is pulled through the pipeline to be rehabilitated. Temperature is measured every 1.5 feet, displaying the average temperature across each 1.5-foot section of the liner. The sensor wire is pulled into the host pipe, then the liner is installed over the wire. Temperature readings are displayed on a computer connected at the end of the sensor wire.
The liner is typically winched into place using a constant tension winch, then inflated using air pressure. A special light train, including CCTV, UV lights, and infrared sensors is pull through the inside of the inflated liner before it is cured. The uncured liner is televised to determine if there are any defects before curing. The UV lights, on the light train, are turned on and the train is pulled back through causing the liner to cure. Infrared sensors record the entire cure process
Installation equipment for water and air installations has improved over the years. Newer equipment is more compact and is operated using pump pressure in lieu of static pressure.
Cured-in-place-pipe (CIPP) cured with ultraviolet light is expanding the market by offering an additional rehabilitation option. UV curing technology is widely used in Europe and its use is now gaining traction in North America.
This rehabilitation method uses a light train that emits ultraviolet light as it is pulled through the flexible, resin-impregnated liner. The UV light causes the liner to cure and harden forming a new tight-fitting, joint-free pipe.
Light trains with various configurations are now available to match the pipe diameter and profile. An integral video camera allows inspection of the pipeline while the train is initially pulled through the inflated liner. This ensures that the liner is properly fitted. Adjustments to the liner can be made before the curing process begins.
After the initial inspection, the UV lights are powered up and the train is pulled back through the pipe. A computer controls the speed of the train, predetermined by the diameter of the liner. The curing speed, liner pressure, ambient and liner wall temperature, and light settings are carefully regulated and monitored. The computer logs the inspection video and data to provide complete documentation.
Various UV curing systems are offered to meet application requirements. A portable unit can be trailer-mounted or retrofitted to an existing truck. This system, for lining pipe diameters from 6- to 18-inches, controls the light train speed and powers the UV lights on the light train. It includes a monitor, automatic cable feed and 100 m (328 feet) of cable.
The truck-mounted system provides a professional platform for lining pipe with diameters to 60 inches. The reel assembly contains 200 m (565 feet) of cable, with an option for 300 m (985 feet). The unit ensures that the light train is retracted through the pipe at the preset speed to exactly meet the prescribed curing time. The electronic panel inside the control room monitors and records the curing process, controls the UV lights on the train, and displays and logs the inspection video and data. An 80 kW diesel generator powers the mechanical systems, the CCTV camera and the UV lights. The blower system is sized to accommodate large lining for pipe diameters to 60 inches.
The complete system typically includes two light trains and two sets of packers with air couplings.
Main/lateral connection lining is a process that is commonly used to address structurally inadequate, broken, cracked or improperly installed conditions of the connection between a lateral pipe and the mainline pipe. It is also used to connect the mainline pipe with laterals.
Lateral connection CIPP is commonly used to repair broken service taps where they enter the mainline, and to connect mainline linings with lateral liners to establish a watertight connection between the two systems. They are also used to stop leakage between the installed liner and the host pipe from entering the sewer at the service connection. A sealing technology should be used together with the connection lining. The connection liner may be shaped like a hat or a structural full-circle repair, and typically consists of a polyester/fiberglass assembly which is impregnated with a curable liquid resin. These technologies may incorporate hydrophilic gasket or grout or resin paste injection sealing technology, ensuring a non-leaking connection, and are installed using ambient, heat or ultra-violet light curing techniques. Each type of sealing technology, must however, be evaluated and selected for its recommended application and proven long-term capability. Lateral connection lining installation can be performed with or without the use of a cleanout.
A number of different trenchless technologies are available that are specifically designed for the repair of pipe joints and/or localized pipeline defects. They can vary in length from several feet to 30 feet or longer and can be provided with O-ring-type seals installed at the ends of the sectional liner.
Inverted sectional liners are available in a variety of lengths, sizes and thicknesses to accommodate the needed structural repair. The liner tube is vacuum saturated with resin in the field with an approved thermoset resin and loaded into a flexible air inversion launcher. The launcher is pulled through the pipe to the point of repair; air pressure is applied causing the liner tube/bladder tube to invert through the defective pipe section. The liner is held under pressure until cured, approximately two hours at ambient temperatures, or the liner may be steam cured, reducing cure time from two hours to as little as 30 minutes.
Short sectional liners are saturated in the field, typically with an epoxy resin system, wrapped around an inflation packer and winched into the existing pipeline to the defective section. The packer is then inflated, and the resin is allowed to cure (typically two hours @ 75°F) depending on the temperature of the sewer. Heated packers can be used to speed up the cure time. The key to effective installations is to thoroughly understand the effects of temperature on the cure time for the short liner repair system. Some short liners use ultraviolet light cured systems. The short liner is installed in the pipe and positioned over the defective area. Once in place the ultraviolet light is switched on and the short liner is cured in less than 10 minutes. Short liners can be used for patching pipe joints, pipe leakage, mis-cut service connections and any defect that may need repair in the pipeline
Geopolymer coatings and linings are use in the restoration of highway culverts and drainage structures. The product is typically spun cast applied to provide a uniform lining for concrete and corrugated culverts
Shotcrete, which dates back to 1907 in the USA, is an all-inclusive term to describe the spraying of concrete or mortar that may be accomplished through either a dry- or wet-mix process. Gunite refers only to the dry-mix process in which the dry cementitious mixture is blown through a hose to the nozzle, where the water is injected immediately prior to application. Because complete mixing of the water and dry ingredients is not possible in the nozzle, mixing is completed as the material impinges on the receiving surface, through manipulation of the nozzle. This requires a very highly skilled nozzleman, especially in the case of thick or heavily reinforced sections. It is used for pipeline rehabilitation, slope stabilization, structure restoration and new construction.
As the concrete is centrifugally cast evenly around the interior of the pipe, the application head is retracted by a computer-controlled motor at the properly calculated speed to ensure an even thickness predetermined by the engineer. The spin caster can be started and stopped as needed without joints or gaps, resulting in a seamless, high strength, fully structural pipe.
State-of-the-art self-propelled, remote operated cutting tools are specifically engineered to remove protruding taps, trim off-set joints smooth prior to CIPP lining, and quickly reinstate service connections. These grinding/cutting robots are outfitted with a pan/tilt camera that includes a lens washing device, allowing one single unit to perform pipe rehab work by accessing only one single manhole, and ensuring the operator has a clean, clear view of the robotic work being performed. These robots are also capable of cutting straight forward and 360-degrees, enabling the robot to grind and crawl through collapsed cured-in-place pipe linings. Robots today are outfitted to insert mechanical plugs up into service lateral connections, grind, trim, reinstate, chisel, video inspect and install main to lateral CIPP connection seals.
The saddle tee connection is a three-piece compression fitting designed to give the installer a water-tight, air-testable connections to any type of mainline pipe. Lateral connections are available in 2” through 30” in size for virtually any type of commonly used pipe. Installation of the tee requires that a hole be cut into the mainline to match the size of the lateral. The hole-saw must be ordered from the manufacturer, as they are size specific to the fittings. They are available in all configurations, depending on the type of material being cut. Once the hole is cut, the rubber sleeve is installed into the host pipe. There are guide lines and installation instructions supplied with every fitting. After the sleeve is installed, the PVC hub is installed using a small mallet. This part of the installation gives the fitting the necessary compression against the side wall of the host pipe, ensuring the water-tight seal. A stainless-steel band is installed last, before the fitting is ready for backfill.
Manhole end seals for pipe liner installations provide a water-tight seal of the liner pipe at the manhole wall. Some end seals are constructed for the mainline and manhole connection in the shape of a low-profile sleeve consisting of a hydrophilic neoprene material that swells upon contact with water, creating a compression gasket seal similar to that of new pipe installation.
Other designs include an internal rubber seal that is installed over the liner and the host pipe. This unique design captures the rubber and compresses it against the host pipe and new CIPP liner creating a permanent mechanical seal.
Folded Pipe Liners are thermoplastic materials that can be used in gravity sewers, culverts, industrial pipelines, sewage force mains and water lines.
Folded high density polyethylene (HDPE) is commercially available in sizes ranging from 6″ through 24″. The most common sizes used for sanitary sewer lines are 6″ through 12″. The larger diameters are typically used to renovate pressure pipelines and culvert piping. Folded HDPE is extruded in a round shape, folded and coiled on reels for delivery to the project site. In the field the folded pipe is winched into place and then un-folded to fit tightly within the host pipe. The un-folding process is accomplished by the application of air pressure and steam. In order to ensure a tight fit and no post-installation movement of the liner, a precise re-rounding procedure, to anneal any residual installation stresses and stretch of the HDPE pipe, is performed by the contractor. The liner is typically sized 2-2.5% smaller than the host pipe to ensure a tight fit, which limits the amount of stretching required, providing a consistent wall thickness. Typically, the house service connections are reconnected robotically requiring no excavation.
Folded polyvinyl chloride (PVC), depending upon the manufacturer, is available in size ranging from 6″ through 24″ and in some cases up to 30”. For sanitary sewer applications it is typically installed in sizes 6″ through 15″. Bends up to 90° can be accommodated. Folded PVC is extruded in a round shape, deformed, and coiled on reels for delivery to the project site. In the field the coil of pipe is placed into a steam cabinet to soften the material to allow it to be winched into place. The folded PVC is then reformed to tightly fit the host pipe using air pressure and steam. Typically, the house service connections are reconnected robotically requiring no excavation.
Materials are shelf-stable and able to be reprocessed. Thermoformed liners have been installed successfully in continuous lengths up to 1500 LF.
Injection grouting is a soil sealing process with a two-component chemical grout injected under low pressure through pipe defects into soils and voids around mainline pipe, laterals, lateral connections, manhole structures and into lined pipe annulus to stop leaks, stabilize soils and control infiltration. The non-structural sealing is achieved by filling voids between the soil grains on the exterior of the structures. Grout mixes, additives and grouting techniques provide long lasting repairs.
While many pipelines appear structurally sound, the joint integrity (water-tightness) has probably been lost due to deterioration of the joint seal material. As a result, infiltration and fines will find their way into the pipeline. Infiltration is the root cause of structural decay, and grouting is most cost-effective prior to structural demise of the collection system. Injection grouting has been used successfully for more than 50 years by many utilities across the U.S. Key to the successful use of injection grout is in choosing the right grout mixes and pumping procedure to ensure that the void in the soil surrounding the joint is properly filled. A common myth or misunderstanding of injection grout is that it lasts only two or three years; that it dehydrates, cracks, and/or disintegrates. When acrylamide or acrylic grout is mixed and injected properly, and injected in a soil that has a relative humidity of 72%, it will not dehydrate. Almost all sanitary sewer piping is installed at depths where the soil meets this criterion. In areas subject to some seasonal drying out, additives such as ethylene glycol and latex can be added to the grout mixture to retard the dehydration of the grouted soil.
As the first defense against infiltration, a holistic approach with injection grouting at all four points of entry will extend the service life of the underground assets, reduce flow to WWTP, improve capacity and minimize the frequency and cost of sewer jetting or cleaning.
The connection is prepared for sealing by a cutting/milling robot operated remotely from a truck above ground. Broken or damaged pipe wall is removed by milling, opening larger pathways for injected resin and exposing new pipe free of grease and debris. After milling preparation, a mainline packer is positioned at the connection from inside the sewer main. From the mainline packer a lateral bladder is launched up into the lateral 18-24”. Both mainline packer and lateral bladder are inflated isolating the prepared connection for injection. A two-component resin or epoxy material is injected under pressure into the isolated area. Resin permeates into the soils and voids surrounding the lateral pipe connection to structurally re-establish bedding and springline support for the connection. Simultaneously, the resin bonds with cleaned, new pipe surfaces exposed during the milling preparation stage.
Pipe bursting is referred to, by many, as trenchless technology whereas it really is “less trench” technology. Translated this means that there is some excavation required but significantly less than traditional dig and replace methods. Pipe bursting, mostly applicable to replacing “friable” or “brittle” materials, is also sometimes referred to as “Pipe cracking”. “Pipe splitting” more correctly refers to replacing such materials as ductile iron, plastic and steel pipes.
Unlike lining system technologies, pipe bursting is a pipe replacement system. The existing host pipe is fractured or displaced with a new pipe, manufactured from a variety of factory produced materials. These new pipe materials are designed to sustain the full loading conditions encountered in a pipe replacement project.
Pipe bursting is a unique pipe replacement system. Unlike most pipe renewal technologies, pipe bursting allows the customer to replace an existing pipe not only with a new pipe using a number of different pipe materials, but also a larger pipe, with higher flow capacity.
Pipe bursting has been used commercially since the 1970s in Europe. In the early 1980s pipe bursting became more popular and was used to primarily burst thousands of miles of defective, cast iron gas main for British Gas in England.
Until the late 1970s and early 1980s sewer renewal in the United States was accomplished primarily by digging the old deteriorated pipeline and replacing it with newer pipe materials. With directional drilling developed in the U.S. as an effective tool for the replacement of small diameter gas mains, the need for pipe bursting was not immediately apparent.
Initially pipe bursting was primarily used in the replacement of friable type pipe materials that would crack or shatter to allow for insertion of a replacement pipe material such as cast iron, concrete, cement, clay and others. Over subsequent years the pipe bursting technology has expanded to include the replacement of such materials as ductile iron, steel and plastic pipe materials. The pipe bursting technology can be applied to water mains, water service connections, sewer mainline, sewer laterals, gas mains, gas service connections, industrial, telephone and other applications.
Pipe reaming technology incorporates the use of directional drilling equipment together with an aggressive pipe grinding head that pulverizes the existing pipe. Using appropriate fluids, the operation produces a liquid slurry, which then is pumped from a receiving manhole during the installation operation. During the reaming operation the existing pipe is ground out and not expanded into the surrounding soil making it an ideal method for tight utility locations and pipelines constructed through encasements, near non-compressible structures and soil and for pipe previously constructed in a rock trench.
Pipe splitting technology is a system that uses static pressure to cut and split the existing pipe, expand it out and insert a new structural replacement pipe material. The system is designed to allow upsizing of existing mains thereby improving capacity and flow characteristics
A variety of materials can be used with the technology including HDPE, ductile iron, steel and plastic pipe. Service taps are typically excavated and re-connected to the newly installed pipe.
One of the older technologies, continuous sliplining pipe is available in sizes ranging from 4″ through 60″. Continuous sliplining is installed using a number of different materials including HDPE, fused PVC, restrained joint PVC, ductile iron and steel. HDPE is still one of the more popular materials installed using the sliplining technique. In the case of HDPE, lengths of round pipe are fused together to make up the length of the pipeline being rehabilitated. The fused liner is winched into place and the ends sealed. Sliplining results in a smaller pipe being pulled into the existing pipe and some final capacity loss should be anticipated. In some cases, the annulus is grouted. Service re-connections are typically accomplished by excavation.
Segmental pipe is available in sizes ranging from 12″ to 102″ and is accomplished using short lengths of profile wall PVC or GRP. Profile wall PVC is applicable to round pipe restorations while the GRP systems can accommodate round, egg, arch, and elliptical shaped host piping. The annulus is grouted and the ends sealed. Bends and transitions in size can be accommodated by the GRP systems, as well. Service re-connections are typically accomplished by excavation.
Sectional pipe sizes range from 12” to 120” (or larger) with panel systems for the larger sizes. This process is generally accomplished by inserting short lengths of PVC or GRP pipe or panels through existing manhole openings. The panel systems typically have two or more pieces making up a “ring” that is assembled inside the pipeline. After these systems are put into place, a non-shrink grout is pumped into the annulus. These systems are applicable to round, rectangular, egg, arch and elliptical shaped host piping. Bends and transitions in size can also be accommodated by the panel systems. Service re-connections are typically accomplished by excavation.
Spiral wound pipe is manufactured in narrow continuous strips of PVC. The PVC strip is manufactured with an interlocking edge which, when installed, locks the strips together as they are machine wound into the host pipe. The material has a ribbed structure and can be reinforced with steel rings for greater strength. PVC spiral wound-in-place systems can be installed in sizes starting as small as 8″.
Spiral wound trenchless pipeline renewal process is designed for and used primarily in large diameter pipelines, typically worker entry. This process is unique as it can provide a customized structural solution to aging pipelines.
A GIPLS is typically composed of a thin sheet of plastic, either PVC or HDPE, which is bonded to a structural grout layer. The GIPLS is a composite structure with the original pipeline. Owing to its method of installation (forms are typically constructed to support the grouting operation), it is typically limited to worker-entry size piping. The exception to this is the PVC spiral wound-in-place system, which can be installed in sizes starting as small as 8″.
Segmental panel systems are a series of molded or translucent PVC panels, that when assembled, form a new pipe or culvert within the existing damaged structure. A structural grout may be used to fill the annular space between the new segmental panel pipe and its host. This restores the structural strength of the original pipe, as well. The unique see-through walls allow visual monitoring the grouting proces
These type repair systems can be installed either using a crawler-deployed inflation type packer or by worker entry. Joint seals can vary in size from as small as 6” to over 200” in diameter. These seals typically require trained and experienced personnel to insure proper installation of the products. Some of these technologies have been available in the market for over 30 years with a long installation history for both water and sewer applications. Materials will vary including stainless steel, PVC and rubber. PVC systems can be installed in a variety of shapes and sizes.
The internal joint seal is typically manufactured of EPDM or polyisoprene rubber and the expansion bands used to compress the rubber against the pipe wall are 14 gauge 304 or 316 grade stainless steel. In this manner, it provides both structural repair and abatement of infiltration. Unlike other rehab technologies, a mechanical sleeve requires no digging, resin mixing, cure time, or bypass pumping; has no pot life; and can be installed amidst active infiltration without the risk of wash-out. Mechanical sleeves are ideal for addressing infiltration, offset joints, root intrusion, abandoned laterals, and longitudinal and circumferential cracks. ain