Trae L. Miller III on Inspecting centuries-old pipes to improve the safety of cities

What did this project require and involve?

Applus+, through its Engineering Business Unit, successfully completed several rounds of public testimony before the Illinois Commerce Commission (ICC), presenting for approval an independent engineering report which analysed cast-iron and ductile-iron pipes installed many decades ago in the City of Chicago.

Some of the pipes that were analysed predated the American Civil War and were installed when Abraham Lincoln was President. Cast and ductile-iron pipes pose unique hazards to gas delivery systems because of the way they were manufactured, as well as the materials’ brittle nature.

The U.S. Pipeline and Hazardous Materials Safety Administration (PHMSA) has issued a Call to Action stipulating that operators must have a plan in place to remove these pipes in a safe and effective manner. The ultimate goal of this project was to ensure that the replacement was both necessary and not premature.

Tell us about the team’s responsibilities in this project

The Applus+ team of experts was responsible for all aspects of the study. Before starting the complex engineering work, the team was required to be on-site in the Chicago area to take samples from the pipelines for return to the materials laboratory in Columbus, Ohio. Then, the samples were properly cleaned and underwent an array of material and mechanical testing to determine the condition and properties of the pipe samples. Because it was not feasible to excavate all of the pipes, we ran probabilistic studies to evaluate the nature of the samples’ locations, so to be certain that the samples represented a statistically significant representation of the system, which included different ages, external pipe diameters, and nominal pipe sizes.

What was the main challenge of this project?

The main challenge of this project was the large number of stakeholders affected by the outcome of this report. Firstly, the city of Chicago deserves a safe pipeline distribution system. Conversely, paying for the replacement of these pipes by the end-consumer could cause economic hardship in areas that cannot afford higher utility-service costs. Applus+ managed this in two ways. First, we placed a team member

in the offices of the utility provider to be a point of contact from within the operator’s operations, from the government, the media, etc., providing status updates on our work. Second, we simply stuck to the data, calculations and known facts, which ultimately provided sound independent engineering judgment that always prioritised the safety and wellbeing of the public.

What has the team who led the project discovered during the process?

The PGL cast-iron and ductile-iron system is one of the oldest and largest in the United States, with the installation of some segments dating back to the 1860s. The report’s findings were summarised in Pipeline and Gas Journal, as “an extensive independent study that found the People’s Gas programme to replace ageing natural gas pipes will increase public and customer safety.” The article further highlights the report’s success in stating, “the approval came after nine months of staff review and input from customer advocates and environmental groups [….] The study by Kiefner and Associates, […], found that more than 80% of the iron pipes in the People’s Gas delivery system have an average remaining life of less than 15 years.”

What are the conclusions of the project?

Because of findings by Applus+, all remaining cast-iron and ductile-iron pipe systems in the city of Chicago will ultimately be replaced as each pose unique hazards to the long-term safe and reliable operation of these assets. This study has assisted in prioritising which pipe sizes and wall thicknesses need to be handled first.

Which are the next steps of the project?

While Applus+ has completed our part of the study, the pipeline operator must now work to remove and replace the pipes. Many pipes intersect with roads or railroads, others go through neighbourhoods and under buildings. Although time will be needed to replace all of the components of this complex system, the study by the team at Applus+ will help prioritise those replacements, contributing to costs controls and improved safety.

What has the successful completion of this project meant for Applus+?

With the successful completion of this project, the Applus+ Engineering Business Unit in the United States has demonstrated going beyond standards and is now one of the leading global providers for engineering assessments of cast-iron and ductile-iron pipeline systems.