When a force main suffered a major failure in Valley Forge National Park in Pennsylvania, Tredyffrin Township pledged to immediately repair or replace the pipeline.
Assessment of the 18,000 ft. force main, a prestressed concrete cylinder pipe (PCCP) built in the 1970s, determined that external corrosion had degraded the strength of the wire rope inside the 30-inch pipeline, rendering it unable to handle the system’s operating pressure.
Working with the engineer, CH2M HILL, on the project the method of repair chosen was a thermoplastic close-fit lining system from Aegion Corporation known commercially as the Tite Liner® system. The Tite Liner® system is a high-density polyethylene liner that can provide a fully-structural solution when pulled into place in the existing pipeline.
The Tite Liner® system was selected because maintaining maximum flow was a top priority for the pipeline. The trenchless Tite Liner® system and United Pipeline System’s unique installation method helped minimize disruption and lower material costs compared with similar rehabilitation methods.
Running through Valley Forge National Park, a National Historic Site, protected habitats and crossing the Schuylkill River, the emergency rehabilitation required the support and cooperation of several different entities including Tredyffrin Township, the National Park Service, CH2M HILL, the general contractor and United Pipeline Systems.
The project was completed on time and on budget with zero safety incidents. A total of 31 sections were installed using DR26 and DR32.5 HDPE, the longest section topping 1,500 LF. In addition, two of the installation sections crossed beneath the Schuylkill River, requiring complex cofferdams. The completed Tite Liner® system was engineered and custom made to be slightly larger than the host pipe (liner OD was 30.05 inches) and installed utilizing the Tite Liner® roller compression system.