A sewer main rehabilitation is featured in this case study, which showcases the value of a concrete protective liner (CPL) to help prevent concrete degradation from corrosives.
Context
The Water Pollution Control Facility (WPCF) in Cedar Rapids, Iowa, treats an average of 45 million gallons daily (MGD) of water from residential and industrial sources.
In January 2024, a video inspection of a vital 84-inch reinforced concrete pipe (RCP) suggested microbial-induced corrosion was the cause of pipeline failure, and sewer main rehabilitation was needed. MIC is a naturally occurring process typically caused by the chemical interaction between sewer pipes and the substances that flow through them (1). This process can significantly weaken the integrity of the pipes, reducing lifespan and effectiveness (2).
Opportunities
Although concrete is a strong, cost-effective material, it has a significant weakness when it comes to wastewater applications: corrosion. The city needed to replace about 900 feet of 84-inch concrete pipe, while implementing technologies to maximize the service life of the rehabilitated infrastructure.
Solution
While maintaining water flow by utilizing the intact portion of the pipe, the contractor installed sheeting to protect existing infrastructure and installed bypass pumps. The damaged pipe was replaced with 84-inch concrete pipe segments lined using AGRU HDPE concrete protective liner (CPL). This 2 mm high-density polyethylene (HDPE) liner protects concrete structures against corrosion, creating a long-term solution.
Additionally, approximately 3,000 ft2 of 5 mm HDPE Ultra Grip CPL sheeting was cast in place within existing concrete structures that had degradation due to MIC, significantly extending the design life of the municipality’s concrete structures.
Outcome
The sewer main rehabilitation project was completed in late March 2024, allowing the plant to return to normal operations within 17 days.
References:
- A. Schweitzer. “Corrosion-resistant linings and coatings.” CRC press. (2001).
- Ghafari. “Investigation of water transmissivity of water-resistant concrete with acrylic polymer modifier used for improvement of tunnel temporary support.” (2011).
Overview
- Completed: 2024
- 3,000 ft2 of 5 mm HDPE Ultra Grip Concrete Protective Liner
- Owner: City of Cedar Rapids
- Contractor: CH Langman Construction, Inc.
- Installer: Save Our Sewers, Inc.
- Pipe Manufacturer: American Concrete Products
- Liner Manufacturer: AGRU America, Inc.
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