Trenchless Rehabilitation in Downtown Mexico City

In a city with a population more than 20 million people, the infrastructure takes a beating. Historically, repairing a deteriorated sewer pipe under a busy street in downtown Mexico City meant closing down the street for weeks at a time to dig up the old pipe and replace it with a new pipe. The effect on the people living along that street was significant.

Without a functional sewer line in place, alternate means of disposing waste had to be considered and implemented over a period of weeks or even months. Traffic had to be rerouted; parking had to be adjusted. Social complications were dramatic.

With the advent of trenchless methods of renovating a deteriorated pipe, an alternate method became available to limit the negative social impact of this repair. In a matter of days instead of weeks or months, the renovation could be completed. Minor disruptions to traffic and parking would be the norm and sewer services would be disrupted only for a short period of time. This was the scenario for the largest renovation to date of deteriorated sewer lines in downtown Mexico City completed by INBODE.

The project began in late 2014 when the Sistema de Aguas de la Ciudad de Mexico (SACM) requested proposals for the renovation of approximately 800 m (2,625 ft) of deteriorated concrete sewer pipe on a street in downtown Mexico City. Since this street is directly off of a main artery in Colonia Roma, approximately seven miles from the downtown center of Mexico City, the minimal disruption offered by trenchless rehabilitation made it more appealing than digging and replacing the lines. The SACM clearly saw all the benefits and made the bold decision to move the project forward with the total support of Ramon Aguirre, the general director of the Mexico City Water Authority.

INBODE was awarded the project and began work in early 2015. Initially, five lines were scheduled for renovation using cured-in-place pipe (CIPP). All lines were gravity pipes running under existing roadways with manhole accesses, making CIPP an ideal choice. The renovated lines were concrete pipes more than 80 years old and had deteriorated due to age, traffic loading and corrosion from sewer gases in the line. The earthquake of 1985 also significantly damaged the concrete pipes. Sections of the existing pipe had cracked and some pieces had separated.

The existing pipe was approximately 60 in. in diameter and carried about 500 L (132 gals) of waste per second. These lines served both residential and industrial customers. Sand, dirt and non-wastewater infiltration were all entering the existing pipe through cracks and broken or missing sections of pipe. Because of the age and condition of the existing pipe, the flow was constricted due to the rough pipe wall and previously mentioned issues.

INBODE started in 2010 as a distributor of equipment for infrastructure renovation. The company also rented maintenance equipment, pumps, desilting trucks, CCTV cameras and more. More recently, INBODE entered the arena as a contractor for trenchless technologies, specifically CIPP work. The company works in partnership with Ferratex Inc., a CIPP liner supplier in the United States. INBODE owner Daniel Posadas started his career in infrastructure remediation in 2001. He has worked with CIPP systems for industrial and municipal projects.

Since the project would require long lengths of large diameter liner, INBODE chose to wet out and install the CIPP liner onsite or over-the-hole (OTH). During the initial phase of the project, the existing lines were cleaned with high pressure water, service connections were identified and current pipe conditions were assessed with closed circuit TV (CCTV) cameras run through the cleaned lines. As this process commenced, INBODE began setting up the jobsite on the street. The set-up included a conveyor belt system, on which the felt tube would be saturated with resin; a static mixer, to mix the resin system components and accurately dispense this system; bypass pumps, to permit flow of wastes from upstream of the project site; a large bulk storage tank to hold the resin; and various pieces of equipment for cleaning, CCTVing and heating and pumping the process water.

Using CIPP in Mexico

It is important to note that there were some significant differences in using the CIPP process in Mexico City than most contractors face in the United States or Canada. One significant difference was the lack of street fire hydrants as a source of water for the process. Water for inversion of the liner and curing of the liner had to be brought in tankers. At one time during the project, more than 10 tankers of water were lined up on side streets waiting to offload. Ordering additional tankers could result in delays to the process, making careful planning crucial. Another challenge not normally faced was the lack of all available initiators typically used in this process. INBODE worked with Interplastic Corp. to construct a resin specifically designed to cure with the initiators available in Mexico City.Since regulations for construction projects in Mexico City are very strict, all parties had to schedule to deliver product and work within the constraints of those regulations. With the massive population of the largest city in the world, congestion at all times of the day and days of the week was a significant consideration.

The resin for this project came from Interplastic Corp.’s Oklahoma facility. It was the first bulk delivery from Interplastic for a CIPP project in the interior of Mexico. The resin was a premium, corrosion-resistant, enhanced CIPP resin. Resin was loaded on a tanker in Oklahoma and delivered by the U.S. carrier to the Mexican border. A Mexican carrier in partnership with the U.S. carrier picked up the load at the border and delivered it to Mexico City. The tube material and technical assistance on the project was supplied by Ferratex Inc., located in McKenney, Va.
The process for lining the first section began on a Friday afternoon. The felt tube was laid on the conveyor. This tube was approximately 60 in. in diameter, 22.5 mm thick and approximately 510 ft long (about 165 m). Resin that had run through the static mixer to incorporate the appropriate amount of initiator was metered into the dry tube.

Several slugs of resin would be used, one after another, as each slug wet out a section of dry tube. Since this was an OTH project, the wet out tube was inverted and fed into the host pipe as each section was wet out. The inversion was facilitated with pressure from a head of cold water. This head pressure was calculated based upon the size and weight of the wet out tube. Once the liner was completely inverted into the host pipe, the water used to invert the liner was heated, by means of a boiler truck, to a water temperature of approximately 180 F (82 C). The water was kept at that temperature until the liner was cured. The water was then slowly cooled until it reached a temperature below 100 F (38 C). Once cured, the ends were cut out and services restored over a period of time.



Since this was newer technology in Mexico City, several news services, educational facilities, engineers and municipalities were present to witness portions of the wet out and installation. In addition, the project was located on a busy downtown street, meaning many onlookers at the project. INBODE, Interplastic Corp. and Ferratex all felt it was important to promote this technology and took time to answer any questions and explain the process and equipment being used.

The entire process of wetting out the tube, inverting the liner, cooking and curing the liner and restoring service took about 72 hours. The new liner had a slightly smaller cross section than the existing host pipe, but the smoother surface of the new liner provided a higher flow capacity than the old pipe. Samples were collected from the project and sent to a laboratory for physical testing. The testing will confirm that the liner as constructed meets the design requirements of the project.

This was the first large project attempted by INBODE and they have proven worthy of the trial. This new pipe within a pipe is projected to last a minimum of 50 years and based upon historical assessments on current CIPP liners, much longer.

An article in the Reforma newspaper in Mexico City on Feb. 15, advertised a summary of the process and the success of the project. Because of the success of the initial parts of the project, INBODE was given additional lines to renovate in Mexico City. Because of the success of this project, more CIPP lining projects will be used by our southern neighbor.

In the United States and Canada, the CIPP process has been a proven technology for many years and millions of feet of deteriorated pipes have been renovated. In Mexico and Central and South America, the CIPP process is just beginning to prove its worth. Successful projects like this will help the process gain credibility quickly.

Kaleel Rahaim is business manager for Remediation Polymers, Jason Schiro is product manager and Carlos Trujillo a sales representative at Interplastic Corp.