NASSCO Report – Spiral Wound in the Great Lakes
In spring 2022, the engineering staff at Macomb County Public Works Office (MCPWO) in Michigan began an extensive evaluation of an 800-lf stretch of an 84-in. diameter reinforced concrete pipe (RCP) sanitary sewer interceptor.
Macomb County officials grew concerned over the pipe’s location beneath the busy Garfield Interceptor. Over the years, the pipe had severely deteriorated due to age, heavy usage and the release of hydrogen sulfide H2S sewer gas. Macomb County determined that this pipe needed to be repaired. If the deteriorating pipe were left unattended, there would have been a significant threat of collapse, potentially resulting in the formation of a sinkhole that could jeopardize public safety and nearby infrastructure.
Rehabilitation utilizing trenchless technologies emerged as the superior choice compared to traditional dig and replace construction. The decision was made to rehabilitate the pipe using spiral wound lining. Other methods, such as sliplining and cured-in-place pipe (CIPP), were also considered for this project. Due to the pipe’s depth and the challenging access location for an insertion pit at a major intersection, sliplining was not considered feasible due to its potential impact on traffic. Additionally, the requirement for a full bypass, the size of the bag, shipping logistics and the overall construction footprint made CIPP an unsuitable solution, as well.
The implementation of the spiral wound trenchless method was preferred primarily due to the ability of the winding equipment to install the liner under live flow conditions. This ensured cost-savings by minimizing the need for extensive bypass operations during the rehabilitation project, and by using existing manholes for installation. The result was a fully structural and rehabilitated pipeline with a minimum service life of 50 years.
SAK Construction and Sekisui SPR Americas implemented an innovative solution to restore the sewer pipe by using a steel-reinforced machine-wound spiral lining technology; a 78-in. Sekisui spiral wound liner would be installed in the 84-in. host pipe.
One of the notable benefits of the usage of spiral wound technology for this project was the ability to utilize existing manholes to line the pipe, which resulted in significant cost savings for Macomb County. This approach eliminated the need to construct a new shaft, as would have been required with other rehabilitation methods or technologies.
Installation
To initiate the repair procedure, a comprehensive evaluation of the sewer pipe’s condition was conducted. This assessment successfully determined the extent of the pipe’s decay, potential hazards, as well as the most efficient repair strategies and action plan. Despite encountering unfavorable weather conditions on certain days, the technicians of this project resumed the installation process promptly whenever the weather permitted.
The spiral wound lining installation process followed essential steps to ensure a fully structural rehabilitation solution. The process began with thorough site preparation, followed by detailed pipe investigation and cleaning. Next began the process of winding the PVC profile and reinstating laterals as needed. Grouting the annulus further strengthened the lining, providing long-lasting durability. To ensure stability, the profile was braced, and end seals were installed. Once the installation was complete, the bracing was removed, and the final touches were implemented.
The Garfield Interceptor project involved two 42-in. laterals. The first lateral was located 10 ft from the winding starting point with live flow and the second was located three hundred feet downstream with significant live flow. The team was able to install the product with live flow and no disruption to the progress of the installation.
The installation process for the project in Macomb County began in January 2023 and the nearly 800 lf of spiral lining was completed in April 2023. During the installation an average of 44 ft were installed per day. As the advancing machine approached downstream, the power of the advancing machine increased which helped increase the production rates.
Conclusion
The execution of this project was successfully processed in a timely manner. This groundbreaking project marked Macomb County’s inaugural use of spiral wound technology to ensure a minimum service life of 50 years, with the potential for an even longer lifespan.
