Options are severely limited when the challenge is rehabilitating an industrial sewer line, which carries highly corrosive chemical wastes.

  The traditional solution is dig up the old line and replace it with new pipe. The strategy is effective, but nobody ever called it cost-effective.

  An East Coast pharmaceutical company found a cost-effective method to rehabilitate 5400-feet of process sewer line, which serves the company's manufacturing and research facility.

  Due to environmental concerns, replacing the 5400-feet of process sewer line through the traditional open-trench methods would have cost millions of dollars. In addition, there would have been the cost of plant disruption for dozens of weeks. Not to mention the regulatory concerns associated with the handling and disposal of the soil.

  Using a combination of trenchless solutions the job was completed within 30 days for a cost of approximately $800,000 and with no regulatory or material disposal problems.

  The effluent being carried by the line had a temperature range of ambient to 175 degrees F and contain variable concentrations of solvents, including acetone, butanol, methanol, toluene, methyl isobutyl ketone, trtiethylamine, and acetonitrile.

  The various lines being rehabilitated were of varying lengths ranging from a few feet to a few hundred feet and diameters from 8 to 18 inches. The lines transport the chemical, and sanitary sewer wastes, to an on-site wastewater treatment facility. When processing at the on-site treatment facility is complete the wastes are tested and certified for the municipal system, which serves the plant's location.

  The pharmaceutical company's initial RFP specified a cured-in-place pipe (CIPP) liner system for the entire 5400 lineal feet of pipe. New Hope Pipe Liners, the New Jersey based installation contractor, responded to the specs but also proposed an alternative trenchless method, which offered significant cost savings when compared to an epoxy resin cured-in-place liner. The alternative, which was accepted by the client, is called U-Liner. It is a jointless, continuously extruded, structurally stand alone, high-density polyethylene pipeline renewal system. The pharmaceutical company and its consulting engineers, Parsons Engineering Sciences, Inc. of Syracuse, NY, evaluated U-Liner's chemical and temperature compatibility, structural strength and cost-effectiveness before accepting the liner system. New Hope had used U-Liner in several other pharmaceutical/chemical facility applications.

  U-Liner is factory-fabricated specifically for each installation. In the manufacturing process it is deformed into a "U" shape approximately one-half the diameter of the host pipe. At the installation site, the deformed pipe is pulled through the host pipe and then reformed by a heat/pressure method to securely fit the shape of the host pipe. The end result is a structurally sound "pipe within a pipe." No stretching of the liner or thinning of the wall occurs when the correct size U-Liner is intalled into a host pipe. The outside diameter of the U-Liner is manufactured to match the measured inside diameter of the host pipe.

  Al Conrad, New Hope Pipe Liners' Sales and Marketing Representative, said U-Liner was used to rehabilitate 4700 of the 5400 feet of clay pipe. Site conditions required the remaining 750 feet be lined with a cured-in-place system using an epoxy resin. U-Liner and the epoxy cured-in-place lining were the only two trenchless systems that could withstand the high temperatures and aggressive chemicals transported through the pipe. If the cured-in-place system had been used throughout the entire 5400 feet of clay pipe the cost would have been substantially more.

  Before recommending the U-Liner, Conrad also verified that the high-density polyethylene pipe met all standards regarding resistance to the chemical content and temperature ranges of the effluent.

  "If we had used CIPP with epoxy resins through all 5400 lineal feet the cost of the job would have been increased by approximately $600,000," says Conrad. The U-Liner savings result from the ease of installation as well as materials cost.

  The pipeline system, which was rehabilitated, contained dozens of manholes. The industrial nature of the job required that all workers wear full body protective clothing in addition to the normal following of OSHA confined space entry practices when entering the manholes.

  The installation of U-Liner usually results in an increase in flow capacity and overall line performance. A spokesman for the Pipeline Rehabilitation Systems Division of CSR/HydroConduit said the job demonstrates the suitability of U-Liner in pharmaceutical/chemical waste applications.

  In the past 12 years, more than eight million lineal feet of U-Liner have been installed in gas, water and sanitary sewer lines in the U.S. When used in gas line rehabilitation U-Liner is manufactured from Medium Density (MDPE) polyethylene. For water and sewer lines, high-density polyethylene (HDPE) is used. Its primary appeals are long service life, durability, abrasion and chemical resistance. U-Liner is manufactured in accordance with ASTM F-1533, utilizing pressure pipe grade high-density polyethylene categorized under ASTM D-3350 as cell 345434.

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