In-place pipe lining is not new, but better materials and processes continue to make jobs faster and more worker friendly. With current technology, putting new pipes inside old ones is easier than it may sound and is less disruptive and often cheaper than replacing pipes by traditional trenching methods. The lining process does require quality materials, a skilled crew and job-focused tools.

Among innovative lining systems is Blue-Tek cured-in-place lining technology from Reline America, Inc. The technology, which cures the installed liner with ultraviolet (UV) light, was developed in Germany. Reline America brought it to the United States nearly three years ago, and since then more than 100,000 linear feet of the liner has been installed nationwide and Canada.

Municipalities and utilities find that owning the lining system and implementing lining programs in-house saves money and lets them reline more feet of pipe each year.

A team from the Stoney Creek Sanitary District, based in Woodstock, Va., demonstrated the technology on July 23, 2009. The crew was in its first week of installations after a week of training at Reline America’s headquarters in Saltville, Va.

Observing and supporting the crew was Bradley Harper, lead trainer for Reline America. Also present were Reline America construction and technical supervisor Tom West and marketing coordinator Alicia Roland, and Stoney Creek director of public utilities Rodney McClain. The demonstration took place in a rugged and rural ski resort and vacation community near Basye, Va.

Walk-around

The Blue-Tek process uses UV light to cure the liner in minutes. Liners are fabricated at the Reline America facility in Saltville and arrive ready to install – no manual mixing of resins or wetting out of liner material is required. The process can be used in 6- to 48-inch pipes, and for runs of up to 1,000 feet between manholes.

Spiral-wound fiberglass liners are manufactured with a blend matched to the working environment and are quality-checked before shipping to assure batch-to-batch uniformity. The liner used for demonstration on a 10-inch sewer pipe resembled a thick, gray plastic ribbon about 14 inches wide and one inch thick.. It arrived in a wooden crate in which it could be stored for up to six months.

The liner has three layers. The outer gray plastic layer protects the UV-sensitive inner layer from sunlight, abrasion and premature solidification. Fiberglass ribbons, bonded the length of the outer layer, bear the forces encountered when the liner is pulled into the pipe.

The second layer is a malleable, spiral-wound fiberglass material that is expanded and cured to form the new pipe inside the old. An inner plastic film protects the soon-to-be-cured material from the passage of the UV light train, which can be pulled through the line at up to 10 feet per minute in 8-inch pipe. The film is removed as the final step at the end of the curing process.

The process requires two dedicated, purpose-built trucks and a two-wheeled winch trailer housing a dual-capstan cable winch. The trucks are deployed at two consecutive manholes. The winch trailer and cure truck are deployed at the manhole to which the liner will be pulled (pull manhole), and the service truck is positioned near the manhole through which the liner will introduced (introduction manhole).

The cure truck has an under-floor-mounted 25 kW Stadco generator to power the UV light train’s nine 600 watt bulbs, an entrained CCTV camera, and all other necessary electrical equipment. Additional outlets on the outside of the truck can power hand tools, lights, fresh air blowers or other equipment.

The light train operator’s control station is easily accessible and roomy. Via digital displays, the controls present real-time information on each bulb and its operating amperage. The computer that controls most light train functions is accessed through a touchscreen monitor, which is a central feature of the work station.

A small TV monitor presents the CCTV camera’s view. Nearby but out of sight are the computer and a digital recorder that captures video images and all cure-related data. All images and data can be burned to a DVD.

A powered CCTV cable retrieval reel with 500 feet of control cable fills a large share of the cure truck’s interior. The light train breaks down into three parts, stored in sections of 4-inch plastic pipe secured under the cable reel box.¬¬

The winch trailer is deployed between the cure truck and the pull manhole. This system manages up to 1,000 feet of 5/8-inch wire rope. An on-board diesel engine drives a hydraulic system that powers the dual-capstan winch, rated at five metric tons.

The winch system continuously measures, displays and stores cable and pulled-liner tension information, which the operator uses to prevent stretching or overstressing of the liner. An on-board printer can print out the tension data much as an EKG strip recording shows a medical patient’s heart data. The light train and cable winch operators can directly observe the pull manhole and directly communicate with each other.

The service truck is typically deployed near the introduction manhole. On board, a Gardner-Denver 550 cfm belt-driven blower provides air to inflate newly positioned liners and to maintain up to 8 psi during the curing process. A small generator serves electrical needs in the vicinity of the introduction manhole.

This truck also carries the third-man winch. When in use, this frame-mounted winch is positioned over the introduction manhole. Easily handled by two workers, it is frequently repositioned during the relining process. The service truck’s RV sized Guardian 5,500-watt gasoline-powered generator energizes the 220v winch motor, fresh air blower, and any other needed power hand tools or lights.

Operation

The sewer line had been cleaned the previous afternoon. Work began when a lightweight messenger line attached to a one-liter plastic bottle was washed downstream from the pull manhole to the introduction manhole. All flows from upstream sources were then stopped using inflatable plugs.

With a more or less dry work environment, the messenger was returned with a heavier working line in tow. At the introduction manhole, crew member Ron Miller and maintenance construction supervisor Rick Moomaw attached the heavier working line to a plastic slip sheet.

Pulled from a large roll, threaded through the introduction manhole and into the pipe, this sheet conforms to the pipe’s internal circumference. Once in place, the slip sheet becomes a solid, low-friction lubricating film through which the liner will be pulled.

Using the working line and the third-man winch, the wire rope cable was pulled from the winch trailer through the slip sheet to the introduction manhole. After unpacking the liner from its delivery crate, the crew prepared the liner’s end for attachment to the wire rope, using two heavy nylon straps, two ratchet-tightening nylon tie-downs, and a clevis pin. During this process, the fiberglass ribbons in the outer liner layer are firmly secured to the wire rope, as well.

Three crew members guided the liner from the crate, across the ground, over the introduction manhole’s edge, and into the pipe. To eliminate liner damage, the liner slides on a section of slipsheet placed on the ground and over the manhole’s lip.

At the pull manhole, crew member Doug Richman operated the winch on the trailer, gradually increasing the pull to a continuous 15 feet per minute. While the liner was being pulled, Miller assembled the UV light train on grass near the cure truck. He plugged the components together, then mechanically secured each joint with a twisting quick-fitting that had a watertight seal. At the train’s front end is a CCTV camera.

Miller next inserted roller-tipped standoffs into sockets along the light train. These standoffs assure smooth passage of the train through the uncured liner and position the UV lamps in the center of the pipe. This assures uniform illumination and curing.

At each manhole, a crew member using confined-space precautions entered and prepared the liner ends for the next steps. At the introduction manhole, a worker slipped the protruding liner over a metal packer and secured it. This packer has a 3-inch quick-connect air hose fitting outside the connected liner.

When in place, another crew member, Clinton Hawkins, started the blower to partially inflate the liner, enabling insertion of the light train. After the light train was introduced and the control and retrieval cables were threaded through a pulley-protected hole in the opposite packer’s end, the packer was secured to the liner.

The air pressure in the liner was then increased in a prescribed series of steps. After the liner was fully inflated, the light train was pulled toward the introduction manhole using the third-man winch, operated by crew members Joe Montz, Jr. and Mike Barrick. In the cure truck, Miller inspected the still uncured liner. With the inspection complete, the UV lights were brought on line as sensors monitored bulb performance. The worker in the introduction manhole verified successful U-V curing by conducting a “tap test” that verified solidification. When a proper cure was validated the cable winch was engaged. The UV train was pulled through at 5.5 feet per minute.

After the curing pull, the liner had to cool. The packer was removed from the liner at the pull manhole and the light train was removed . The blower continued moving air through the pipe. When the liner was cooled, the working rope was attached to the plastic inner liner, which was pulled back through the pipe and wrapped onto the third man winch.

Workers again entered each manhole and, using electric side-cutting grinders, trimmed off excess liner material and dressed the ends where they entered the manhole from the sewer pipe. The plugs were then removed to restore flow.

Observer comments

The Blue-Tek process appeared straightforward. No unusual wastes or odors were generated in the relining process. Crew members must master a broad set of skills for the various tasks, but none are physically challenging or difficult to learn. The Stoney Creek crew appeared at ease with the materials and machinery.

Cross-training of crew members would add variety to the work and keep all members’ skills sharp. Confined-space entry precautions are essential, and this crew was attentive to the well being of co-workers inside the manholes.

Effective and prompt communication between access points may be the most challenging part of coordinating a Blue-Tek relining project. Dust from trimming of the cured liner, the ordinary unpleasantries of working in a manhole, and the blower’s noise appeared to be the only negatives for workers.

Owner’ comments

McClain, of Stoney Creek, observed, “We know that relining the problem spots in our approximately 300,000 linear foot collection system will cut, perhaps by half, the cost of a new treatment plant. Our use of refurbished military surplus trucks cuts nearly $80,000 from the total price to deploy Reline America technology. Rick Moomaw saw the opportunity and worked with Reline’s representatives to make this happen.”

“Selecting this technology and using our crew to do the work will ultimately pay for itself through lower per-foot installation costs and avoided treatment charges.”

Manufacturer comments

“Our two-part, two-week training process acquaints every crew member with the manufacturing and installation processes,” says West, of Reline America. “Trainees’ understanding and skill-building experiences start in the factory and are refined in their home environment using their equipment.”

“By changing the blend of ingredients in the liner, the factory can match each liner’s characteristics with the liquid material being carried. We work with each customer to outfit their trucks, and while Stoney Creek’s surplus army trucks were a first for us, they meet the client’s needs.

Harper notes, “The U-V cure is completely contained. Because there is no on-site mixing of liner materials, the crew never comes into contact with hazardous materials or wastes. There are no regulated air-quality issues, either.”