Front Street Interceptor Rehabilitation Project

When Capital Region Water set out to rehabilitate a century-old sewer interceptor beneath one of Harrisburg’s busiest public corridors, we delivered a trenchless design solution that overcame complex technical, logistical, and community challenges — preserving vital infrastructure with minimal disruption.

A century-old challenge

The Front Street Interceptor, constructed in 1911, is a critical component of Harrisburg’s wastewater infrastructure. Stretching nearly three miles beneath the Capital Area Greenbelt and adjacent neighborhoods, it collects and conveys combined sewage and stormwater from half of Harrisburg and all of Susquehanna Township. Over time, the reinforced concrete structure showed significant deterioration, including exposed rebar, cracking, and voids.

Capital Region Water (CRW) recognized the urgent need to rehabilitate the aging asset to ensure continued service reliability and environmental protection. However, its location beneath a popular public trail and its role in conveying over 20 million gallons per day during wet weather posed major design and construction challenges. CRW engaged AECOM to design a trenchless solution that extended the asset’s life while minimizing community and environmental disruption.

Innovating with non-circular CIPP design

We developed a bespoke rehabilitation strategy using cured-in-place pipe (CIPP) technology, tailored to the unique structural and hydraulic demands of each segment. The interceptor included a variety of non-circular shapes — such as 39″x36″ and 42″x42″ boxes with straight side walls but curved top and invert sections — requiring custom liners and advanced modeling to ensure structural integrity and long-term performance.

To guide the design, we applied ASCE’s Manual of Practice 145 (MOP145), a standard for structural design of flexible close-fit liners in non-circular pipes. This marked the first major U.S. project to use MOP145 for non-circular CIPP design. More than 2,000 design cases were analyzed to validate liner thickness, material properties, and installation parameters. By implementing MOP145 on a project of this scale and complexity, the Front Street Interceptor Rehabilitation Project set a new industry benchmark.

Project execution

Located beneath a narrow, tree-lined public trail, the interceptor was inaccessible to traditional open-cut methods. The 14-foot-wide corridor, shared with pedestrians and cyclists and bordered by environmentally sensitive parkland, imposed strict spatial constraints. Ensuring continuous public access and protecting the environment were essential.

The interceptor’s role in conveying high volumes of combined sewage and stormwater, particularly during wet weather, required a parallel 30,000-foot bypass system to safely divert flows during construction. The pipe’s non-circular geometry added further complexity, requiring bespoke liner designs and rigorous structural analysis.

Construction activities were meticulously coordinated to avoid disruption during community events, including concerts, marathons, and seasonal festivals. We worked closely with the contractor, Insituform, and Capital Region Water to develop a phased construction plan that balanced technical requirements with community needs. Cleaning and inspection crews prepared the pipe ahead of each lining phase, removing decades of sediment and debris. On-site, crews worked around the clock to complete installations within narrow timeframes, often coordinating with local authorities.

Outcomes and community impact

The successful rehabilitation of the Front Street Interceptor delivered far-reaching benefits:

Delivering lasting value

Delivering lasting value The Front Street Interceptor rehabilitation stands as a model for how complex infrastructure challenges can be met with innovation, collaboration, and care. Faced with aging assets, constrained access, and high community visibility, our trenchless design approach delivered a solution that was technically robust, environmentally sensitive, and socially responsible.

Project recognition

In acknowledgment of the project’s technical excellence, collaborative delivery, and community-focused approach, it has received the following awards: