Chicago tackles reline of sewer beneath busy train station

Applied Felts has supplied a 120 inch cured-in-place pipe (CIPP) liner for the rehabilitation of an ageing sewer underneath a train station in busy Chicago, Illinois.

Wilson Station, which was built in 1923, underwent extensive renovations to provide – among other benefits – disability access and a better passenger experience.

The Chicago Transit Authority’s US$203 million Wilson Station Reconstruction Project – one of the largest in its history – was designed to replace a badly deteriorated train station. Built in 1923, it required renovation to provide a better overall experience for travellers, and to accommodate for people with disabilities, which was absent from the original structure.

Applied Felts’ CIPP liner ready to be connected to the inversion platform.

The project attracted considerable interest from local businesses, residents and public transport users; but perhaps the most impressive aspect was what happened beneath the ground, away from the public’s eye.

Located in a busy Chicago corridor, at the corner of Wilson and Broadway, considerable pre-construction work had to be completed before the construction could begin. Arcadis, the Wilson Station Reconstruction Project engineering firm hired for the evaluation of the reconstruction needs, discovered a large sewer running directly underneath the train tracks.

During the investigation, defects including cracks and fractures, which needed to be repaired prior to construction of the station, were also identified. Due to the numerous fractures and cracks, the sewer contained excessive deposits which required man-entry for removal. Access to the sewer also required the relocation of multiple utilities, including a 480 KV electrical duct. Effective traffic management was also a critical factor and a dig and replace method would have caused major disruptions to train traffic and the city’s inhabitants.

The City of Chicago considered all available technologies for the repairs, including slip lining, spray lining and CIPP. Due to the nature of the combined sewer and foot print it was imperative to maintain cross-sectional size and these factors, as well as many others, resulted in the City selecting CIPP technology for the project.

CIPP was selected for the rehabilitation in order to minimise disruption to Chicago’s inhabitants.

It hired Kenny Construction Company (Kenny), a wholly owned subsidiary of Granite Construction Company, based on its expertise and impressive CIPP proposal. Kenny assembled a team of industry experts including National Power Rodding, Applied Felts, AOC, LLC, and The Midas Companies.

The project used an over-the-hole wet-out method. Due to the size of the 120 inch pipe and the complicated logistics of the project, meticulous care was necessary to successfully perform all aspects of the liner installation. The project included the construction of two access shafts for the installation of the CIPP liner, and a third access shaft for the bypass discharge of 150 million litres per day.

The repair of the aboveground facility and the sewer line were not exclusive; in fact, the activities involved with one deeply affected the other, resulting in a high level of collaboration during this process.

For example, the sewer runs underneath the Chicago Transit Authority’s elevated tracks that are currently being replaced, and the city needed to strengthen the sewer to stabilise it during the construction of the new facility.

The size of the liner, the busy environment, combined sewer flows and the need for efficient coordination of logistics to minimise disruptions to residents, businesses and other above-ground construction work on the facility made this project challenging, if not memorable. Due to the length and size of the CIPP liner, it was necessary to engineer the construction of specialty material handling equipment to work within the construction site constraints, which included bridles to move the liner materials, a conveyor to impregnate the liner, and flow control in liner termination.

Applied Felts’ multi-stage production process includes testing of criteria such as density, thickness, fibre distribution, strength, and weld-ability of the finished product.

The tube used for the installation was manufactured by Applied Felts at its manufacturing plant in Martinsville, Virginia. Everything from the selection of the raw material, to the manufacturing and testing of the product, to preparing the logistics of delivery was conducted under one roof for the custom project.

“The liner was manufactured with the same precision as all of our liners,” says Applied Felts Technical Sales Manager Paul Green.

“The exception is that it was shipped as an oversized load that needed to be permitted with restrictions through five different states, each requiring special coordination with local jurisdictions in populated areas, with no schedule interruptions. The sequencing and execution of the installation was imperative for the successful installation of the liner.”

The rehabilitation of the line had to be performed without interrupting the reconstruction of the Wilson Street Station, as well as minimising interruption to the combined sewer flows. The ability to perform the work during the windows of opportunity, on account of the weather, was also imperative due to the nature of the combined lining system.

The project, which was successfully completed in March 2016, was finished ahead of schedule and with no interruptions to the active commuter rail system. Due to the trenchless nature of the technology chosen, the rehabilitation of the massive pipe did not negatively impact the ongoing train station project above-ground, no safety incidents were reported, and the community, surrounding businesses and traffic flow near the project were not impacted.

This article was featured in the Summer edition of Trenchless International. To view the magazine on your PC, Mac, tablet, or mobile device, click here.

For more information visit the Applied Felts website.

If you have a project you would like featured in Trenchless International contact Assistant Editor Nick Lovering at nlovering@gs-press.com.au

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