A cured-in-place pipe (CIPP) is a trenchless rehabilitation method used to repair existing pipelines. It is a jointless, seamless pipe lining within an existing pipe. As one of the most widely used rehabilitation methods, CIPP has applications in sewer, water, gas, chemical and district heating pipelines ranging in diameter from 0.1 to 2.8 meters (2–110 inches).
The process of CIPP involves inserting and running a felt lining into a preexisting pipe that is the subject of repair. Resin within the liner is then exposed to a curing element to make it attach to the inner walls of the pipe. Once fully cured, the lining now acts as a new pipeline.
A resin impregnated felt tube made of polyester, fiberglass cloth, spread tow carbon fiber or another resin-impregnable substance, is inserted or pulled through a damaged pipe. It is usually done from the upstream access point (manhole or excavation). It is possible to insert the liner upstream (e.g. from the downstream access point) but this carries greater risk. It is possible to install a liner from the downstream access point, upstream to a blind end; however, this carries the highest risk of all the CIPP installation methods. CIPP is considered a trenchless technology. Little to no digging is involved in this trenchless process, making for a potentially more cost-effective and less disruptive method than traditional "dig and replace" pipe repair methods. The liner can be inserted using water or air pressure. The pressure required for insertion can be generated using pressure vessels, scaffolds or a "chip unit". Hot water or steam can be used to accelerate the curing rate of the resin. If a fiberglass tube is used, the curing of the resin can be triggered though the use of UV light introduced into the tube. As the resin cures, it forms a tight-fitting, joint less and corrosion-resistant replacement pipe. Service laterals are restored internally with robotically controlled cutting devices called cutters in the larger-diameter pipe. Smaller diameters (100 mm) can be opened remotely using smaller cutters designed for small diameter pipe. The service lateral connection can be sealed with specially designed CIPP materials, sometimes referred to as a 'top-hat'. The resin used is typically polyester for mainline lining and epoxy for lateral lines. Since all resins shrink (epoxy resins shrink far less than poly and vinyl ester versions) and it is impossible to bond to a sewer that has fats, oils, and grease an annular space exists between the new CIPP liner and the host pipe. The annular space exists in all installations just some are larger than others and depending on the severity may need additional rehabilitation. There are multiple ways to prevent water from tracking in the annular space and entering back into the waste stream including: water swelling material (hydrophilic), lining of the entire connection and host pipe with a continuous repair (YT repair) gaskets, and point repairs placed at the ends of the host pipe.
In 1971, Eric Wood implemented the first cured-in-place pipe technology in London, England. He called the CIPP process insitu form, derived from the Latin meaning "form in place". Wood applied for U.S. patent no. 4009063 on January 29, 1975. The patent was granted February 22, 1977, and was commercialized by Insituform Technologies until it entered the public domain on February 22, 1994.
The process began to be used in residential and commercial applications in Japan and Europe in the 1970s and for residential application in the United States in the 1980s. [1]
As a trenchless technology, CIPP does not require excavation to rehabilitate a pipeline that is either leaking or structurally unsound. Depending upon design considerations an excavation may be made, but the liner is often installed through a manhole or other existing access point. Liner is installed as it is wet out on site in these instances. In the case of sewerlines, lateral connections are also restored without excavation via a remote controlled device that drills a hole in the liner at the point of the lateral connection. If larger than 24" and it is safe to do so someone will reinstate laterals by hand. CIPP has a smooth interior and no joints. While CIPP can repair a pipe with bends, special design considerations must be taken into account to prevent wrinkling and stretching. CIPP can effectively reduce infiltration and leaks in pipeline systems without digging.
Except for very common sizes, liners are not usually stocked and must be made specifically for each project. [2] CIPP requires bypass of the flow in the existing pipeline while the liner is being installed. The curing may take from one hour to 30 hours depending on pipe diameter and curing system (steam, water or uv) and must be carefully monitored, inspected, and tested. Obstructions in the existing pipeline, such as protruding laterals, must be removed prior to installation. Cost should be compared with similar methods such as Shotcrete, thermoformed pipe, close-fit pipe, spiral wound pipe and sliplining as these other methods can provide a similar design solution for similar or less cost in certain situations. CIPP must also be carefully monitored for release of chemical agents utilized in the reaction process for contamination downstream of rehabilitated pipes. The liner material used for common sizes is normally a felted fabric (non-woven) and does not go around bends well without wrinkling and going out of round on corners. Liners used for pipes with bends (particularly 100 mm pipes) are made from a woven fabric allowing it to go around bends with minimal wrinkling. The more flexible the liner, the more care needs to be taken during inversion to ensure the liner remains on the correct alignment. Once a line is repaired with the CIPP method, that line can no longer be cabled or snaked with a machine, it must be cleaned by method of Hydro jetting (AKA high-pressure water blasting)
Testing of CIPP installations is required to confirm that the materials used comply with the site and engineering requirements. Since ground and ambient installation conditions as well as crew skills can affect the success or failure of a cure cycle, testing is performed by 3rd party laboratories in normal cases and should be requested by the owner.
Samples should be representative of the installation environment since the liner is installed in the ground. Wet sandbags should be used around the restraint where the test sample will be extracted from. As with any specimen preparation for a materials test, it is important to not affect the material properties during the specimen preparation process. Research has shown that test specimen selection can have a significant effect on the CIPP flexural testing results. A technical presentation [3] at the CERIU INFRA 2012 Infrastructures Municipales Conference in Montreal outlined the results of a research project which examined the effects of test specimen preparation on measured flexural properties. Test specimens for ASTM D790 flexural testing must meet the dimensional tolerances of ASTM D790.
The North American CIPP industry has standardized around the standard ASTM F1216 which uses test specimens oriented parallel with the pipe axis, while Europe uses the standard EN ISO 11296–4 with test specimens oriented in the hoop direction. Research has shown that flexural testing results from the same liner material are usually lower when determined using EN ISO 11296-4 as compared to ASTM F1216.
Testing conducted by the Virginia Department of Transportation [4] and university researchers [5] from 2011 to 2013 showed that some CIPP installations can cause aquatic toxicity. [6] A list of environmental, public health, and infrastructure incidents caused by CIPP installations as of 2013 was published by the Journal of Environmental Engineering. [7] In 2014, university researchers [5] published a more detailed study in Environmental Science & Technology [8] that examined CIPP condensate chemical and aquatic toxicity as well as chemical leaching from stormwater culvert CIPP installations in Alabama. [9] In this new report additional water and air environmental contamination incidents were reported not previously described elsewhere.
In 2017, CALTRANS backed university researchers [10] examined water impacts caused by CIPPs used for stormwater culvert repairs. [11]
In April 2018, a study funded by six state transportation agencies (1) compiled and reviewed CIPP-related surface water contamination incidents from publicly reported data; (2) analyzed CIPP water quality impacts; (3) evaluated current construction practices for CIPP installations as reported by US state transportation agencies; and (4) reviewed current standards, textbooks, and guideline documents. [12] [13] In 2019, another study funded by these agencies identified actions to reduce chemical release from ultraviolet light (UV) CIPP manufacturing sites. [14]
With proper engineering design specifications, contractor installation procedures, and construction oversight many of these problems can likely be prevented.
On July 26, 2017, Purdue University researchers published a peer-reviewed study in the American Chemical Society's journal Environmental Science & Technology Letters about material emissions collected and analyzed from steam cured CIPP installations in Indiana and California. [15] To further make the study accessible to the public and CIPP worker community, the study authors established a website and made their publication open-access, freely available for download. Purdue University professors also commented on their study and called for changes to the process to better protect workers, the public, and environment from harm. [16]
On August 25, 2017, the National Association of Sewer Service Companies, Incorporated (NASSCO), which is a (501c6) nonprofit dedicated to "improving the success rate of everyone involved in the pipeline rehabilitation industry through education, technical resources, and industry advocacy", posted a document on its website [17] bringing up several important concerns and unanswered questions regarding the study, and its messaging. NASSCO then sent a letter to the researchers who then responded. [18]
On September 22, 2017, NASSCO announced it would fund and coordinate an assessment of previous data and studies, and an additional study [19] and analysis of possible risks related to the CIPP installation and curing process. Later in September, the NASSCO posted a request for proposals to “review of recent publication(s) that propose the presence of organic chemicals and other available literature relating to emissions associated with the CIPP installation process, and a scope of services for additional sampling and analysis of emissions during the field installation of CIPP using the steam cure process.” The request specifically identified the project would review studies conducted by the Virginia Department of Transportation, California Department of Transportation, and Purdue University.
At the federal and state levels in September 2017, on September 26, the US Centers for Disease Control and Prevention (CDC) National Institute for Occupational Safety and Health (NIOSH) published a Science Blog contribution regarding Inhalation and Dermal Exposure Risks Associated with Sanitary Sewer, Storm Sewer, and Drinking Water Pipe Repairs. [20] In September 2017, the California Department of Public Health issued a notice to municipalities and health officials about CIPP installations. One of several statements in this document was that "municipalities, engineers, and contractors should not tell residents the exposures are safe." [21]
On October 5, 2017, the National Environmental Health Association sponsored a webinar about the hazards involved for workers and residents associated with cured-in-place pipe repair. The video can be found here. [22] Several questions [23] about the webinar, and the study have been raised, and feedback noted by industry members.
On October 25, 2017, a 22-year old CIPP worker died at a sanitary sewer worksite in Streamwood, Illinois. [24] The U.S. Occupational Safety and Health Administration (OSHA) completed their investigation April 2018 and issued the company a penalty. Chemical exposure was a contributing factor in the worker fatality.
In 2018, NASSCO funded a study on chemical emissions from six CIPP installations. [25] In 2020, the study was completed. [26] A few locations and worker tasks were identified of potential chemical exposure concern and worksite recommendations were provided.
In 2019 and 2021, the U.S. National Institute for Occupational Safety and Health published a safety evaluations ofUV, steam and hot water CIPP worksites. A UV CIPP company was the first to engage NIOSH. Study results indicated several worker chemical exposure conditions that exceeded recommended limits, and this US federal agency recommended several actions to reduce worker exposures. [27] Two years later, the NIOSH published results of a steam and hot water CIPP worksite study. [28] Results indicated several worker chemical exposure conditions that exceeded recommended limits. The US federal agency recommended several actions to reduce worker exposures.
In 2020, the Florida Department of Health issued their own factsheet about CIPP to municipalities and health departments. [29] The document explained the CIPP process, health concerns, chemicals used and created, how persons living nearby can protect themselves from exposure, and biomonitoring and blood testing considerations after exposure.
In 2022, researchers made several additional discoveries. In the Journal of Hazardous Materials, a study funded by the National Institute of Environmental Health Sciences and National Science Foundation revealed CIPP pressure makes blowback from sinks and toilets in nearby buildings possible and provided recommendations for emergency responders and health officials. [30] Later that year, a study in the Journal of Cleaner Production revealed that by modifying the initiator loading, an ingredient in thermal based CIPP resins, pollution potential of the process could be reduced by 33-42%. Though, also found was that non-styrene CIPP resin contained styrene due to handling at the resin processing facility. [31] In October, researchers discovered that steam based CIPP creates and emits nanoplastics into the air during plastic manufacture. [32] Results of these investigations help better understand the occupational safety, bystander safety, and environmental pollution risks associated with current practices, and also improve technology and practice to reduce undesirable consequences.
Fiberglass or fibreglass is a common type of fiber-reinforced plastic using glass fiber. The fibers may be randomly arranged, flattened into a sheet called a chopped strand mat, or woven into glass cloth. The plastic matrix may be a thermoset polymer matrix—most often based on thermosetting polymers such as epoxy, polyester resin, or vinyl ester resin—or a thermoplastic.
Sewerage is the infrastructure that conveys sewage or surface runoff using sewers. It encompasses components such as receiving drains, manholes, pumping stations, storm overflows, and screening chambers of the combined sewer or sanitary sewer. Sewerage ends at the entry to a sewage treatment plant or at the point of discharge into the environment. It is the system of pipes, chambers, manholes, etc. that conveys the sewage or storm water.
Water pollution is the contamination of water bodies, usually as a result of human activities, so that it negatively affects its uses. Water bodies include lakes, rivers, oceans, aquifers, reservoirs and groundwater. Water pollution results when contaminants mix with these water bodies. Contaminants can come from one of four main sources: sewage discharges, industrial activities, agricultural activities, and urban runoff including stormwater. Water pollution is either surface water pollution or groundwater pollution. This form of pollution can lead to many problems, such as the degradation of aquatic ecosystems or spreading water-borne diseases when people use polluted water for drinking or irrigation. Another problem is that water pollution reduces the ecosystem services that the water resource would otherwise provide.
A sanitary sewer is an underground pipe or tunnel system for transporting sewage from houses and commercial buildings to a sewage treatment plant or disposal. Sanitary sewers are a type of gravity sewer and are part of an overall system called a "sewage system" or sewerage. Sanitary sewers serving industrial areas may also carry industrial wastewater. In municipalities served by sanitary sewers, separate storm drains may convey surface runoff directly to surface waters. An advantage of sanitary sewer systems is that they avoid combined sewer overflows. Sanitary sewers are typically much smaller in diameter than combined sewers which also transport urban runoff. Backups of raw sewage can occur if excessive stormwater inflow or groundwater infiltration occurs due to leaking joints, defective pipes etc. in aging infrastructure.
Trenchless technology is a type of subsurface construction work that requires few trenches or no continuous trenches. It is a rapidly growing sector of the construction and civil engineering industry. It can be defined as "a family of methods, materials, 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."
High-density polyethylene (HDPE) or polyethylene high-density (PEHD) is a thermoplastic polymer produced from the monomer ethylene. It is sometimes called "alkathene" or "polythene" when used for HDPE pipes. With a high strength-to-density ratio, HDPE is used in the production of plastic bottles, corrosion-resistant piping, geomembranes and plastic lumber. HDPE is commonly recycled, and has the number "2" as its resin identification code.
Crumb rubber is recycled rubber produced from automotive and truck scrap tires. During the recycling process, steel and tire cord (fluff) are removed, leaving tire rubber with a granular consistency. Continued processing with a granulator or cracker mill, possibly with the aid of cryogenics or by mechanical means, reduces the size of the particles further. The particles are sized and classified based on various criteria including color. The granulate is sized by passing through a screen, the size based on a dimension or mesh. Crumb rubber is often used in artificial turf as cushioning.
Pipe bursting is a trenchless method of replacing buried pipelines without the need for a traditional construction trench. "Launching and receiving pits" replace the trench needed by conventional pipe-laying.
Engineered stone is a composite material made of crushed stone bound together by an adhesive to create a solid surface. The adhesive is most commonly polymer resin, with some newer versions using cement mix. This category includes engineered quartz (SiO2), polymer concrete and engineered marble stone. The application of these products depends on the original stone used. For engineered marbles the most common application is indoor flooring and walls, while the quartz based product is used primarily for kitchen countertops as an alternative to laminate or granite. Related materials include geopolymers and cast stone. Unlike terrazzo, the material is factory made in either blocks or slabs, cut and polished by fabricators, and assembled at the worksite.
A pipefitter or steamfitter is a tradesman who installs, assembles, fabricates, maintains, and repairs mechanical piping systems. Pipefitters usually begin as helpers or apprentices. Journeyman pipefitters deal with industrial/commercial/marine piping and heating/cooling systems. Typical industrial process pipe is under high pressure, which requires metals such as carbon steel, stainless steel, and many different alloy metals fused together through precise cutting, threading, grooving, bending, and welding. A plumber concentrates on lower pressure piping systems for sewage and potable tap water in the industrial, commercial, institutional, or residential atmosphere. Utility piping typically consists of copper, PVC, CPVC, polyethylene, and galvanized pipe, which is typically glued, soldered, or threaded. Other types of piping systems include steam, ventilation, hydraulics, chemicals, fuel, and oil.
Directional boring, also referred to as horizontal directional drilling (HDD), is a minimal impact trenchless method of installing underground utilities such as pipe, conduit, or cables in a relatively shallow arc or radius along a prescribed underground path using a surface-launched drilling rig. Directional boring offers significant environmental advantages over traditional cut and cover pipeline/utility installations. The technique is routinely used when conventional trenching or excavating is not practical or when minimal surface disturbance is required.
Insituform Technologies, Inc. is a worldwide provider of trenchless technologies for gravity and pressure pipelines. Insituform is a subsidiary of Aegion Corporation..
Plastic pipe is a tubular section, or hollow cylinder, made of plastic. It is usually, but not necessarily, of circular cross-section, used mainly to convey substances which can flow—liquids and gases (fluids), slurries, powders and masses of small solids. It can also be used for structural applications; hollow pipes are far stiffer per unit weight than solid members.
Sliplining is a technique for repairing leaks or restoring structural stability to an existing pipeline. It involves installing a smaller, "carrier pipe" into a larger "host pipe", grouting the annular space between the two pipes, and sealing the ends. Sliplining has been used since the 1940s.
Michels Corporation is a family owned and operated energy and infrastructure construction company. Headquartered in Brownsville, WI, where it was established in 1959, Michels is one of the largest contractors in North America. It performs work throughout the world.
The National Association of Sewer Service Companies or NASSCO is a not-for-profit North American trade organization, established in 1976 "to increase the awareness of aging underground infrastructure and to provide viable solutions through education, technical resources and industry advocacy". NASSCO's intent is to research, train and educate members and non-members on rehabilitation of underground utilities using trenchless technology. Ultimately, NASSCO is committed to set the "industry standards for the rehabilitation of underground pipelines, and to assure the continued acceptance and growth of trenchless technologies".
CIPP may refer to:
The East Side Big Pipe is a large sewer line and tunnel in Portland in the U.S. state of Oregon. It is part of a combined sewer system of pipes, sumps, drains, pumps, and other infrastructure that transports sewage and stormwater run-off to the city's Columbia Boulevard Wastewater Treatment Plant. The East Side Big Pipe project, begun in 2006 and finished in 2011, was the largest of a 20-year series of projects designed to nearly eliminate combined sewer overflows (CSO)s into the Willamette River and the Columbia Slough. The combined projects were completed on time, and they reduced CSOs into the river by 94 percent and into the slough by more than 99 percent.
Sprayed in place pipe (SIPP) technologies is a trench-less rehabilitation method used to repair existing pipelines, that involves a robotic lining system that develops and manufactures proprietary lining polymeric. SIPP is a jointless, seamless, pipe with in a pipe with the capability to rehabilitate pipes ranging in diameter of .1 to 2.8 meters. SIPP can be applied in water, sewer, gas, and chemical pipelines.
HDPE pipe is a type of flexible plastic pipe used for the transfer of fluids and gases. It is often used when replacing aging concrete or steel mains pipelines. Constructed from the thermoplastic HDPE, it has low permeability and robust molecular bonding, making it suitable for high pressure pipelines. HDPE pipe is often used for; water mains, gas mains, sewer mains, slurry transfer lines, rural irrigation, fire system supply lines, electrical and communication conduits, stormwater pipes, and drainage pipes.
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