Miami-Dade Water & Sewer Department (Miami-Dade) operates one of the largest public utilities in the United States – serving the highest population in Florida. The water system is over 100 miles of 48-inch diameter, and larger, pre-stressed concrete cylinder pipelines.
Condition Assessment Program is implemented
After a series of high profile failures, Miami-Dade implemented a comprehensive asset management program for their large diameter pipeline system. The program consists of scheduled inspections of the pipeline inventory on a rotating basis. Once inspections are completed, risk factors and priority classification are given for repair and maintenance.
Since Miami-Dade’s pre-stressed concrete pipe system runs through densely populated areas and under busy streets, there are several challenges to consider when performing a condition assessment and implementing repairs and maintenance.
A trenchless method widely used across the country for high pressure large diameter pipelines is carbon reinforced polymer. This lightweight high strength material is installed on the interior of distressed pipeline segments and provides a full structural upgrade able to resist all internal pressure and internal loads.
Rapid Mobilization Begins for Pipeline Upgrade
Structural Group Companies STRUCTURAL TECHNOLOGIES and STRUCTURAL help Miami-Dade with their pipeline repair needs. STRUCTURAL TECHNOLOGIES’ V-WrapTM system is an approved system for pipelines, while STRUCTURAL provides specialty contracting services as part of the Miami-Dade’s emergency response team.
One project STRUCTURAL was contracted for recently included carbon fiber repairs at 13 segments of 54-inch diameter pre-stressed concrete pipe. The 13 segments were spread out over a 3½ mile stretch of road in the Miami-Dade area. Upon finalizing the exact work scope and technical submittal, STRUCTURAL began a rapid localization to begin pipeline upgrade operation. Due to safety and other challenges associated with summer’s high daytime temperatures, along with traffic flow in the repair area, STRUCTURAL crews completed the project working night shifts to minimize risks.
Once the pipeline was properly isolated, STRUCTURAL completed the dewatering process so repair work could begin.
Upon entry into the designated pipe segments, surface preparation was the first step in the V-WrapTM installation process. Preparing the concrete and joint areas properly is critical for ensuring water tightness of the repair, as well as ensuring the long-term performance of the pipeline upgrade. The carbon fiber fabric was then conveyed through the saturation machine which displaces the appropriate amount of epoxy into the fabric. Once the fabric was properly saturated, it was then lowered into the pipe for installation.
For the Miami-Dade project, V-Wrap™ was installed in multiple layers to meet design requirements. In addition, as the installation took place quality control inspections were also conducted simultaneously. The carbon fiber system was installed safely, successfully and within the allocated budget for the project.
Delivering Innovative Solutions
As part of the project STRUCTURAL TECHNOLOGIES also worked with Miami-Dade to implement a pilot installation of the StrongPIPE® Hybrid FRP System to rehabilitate three (3) segments of 54-inch PCCP. The StrongPIPE® system was developed to address extended runs of large diameter pressure pipe with a low-profile, fully structural repair system. As a leader in asset management, Miami-Dade seeks out innovative solutions which enhance the reliability of their pipeline system. With the StrongPIPE® system, there is an alternative to slip lining - which causes a reduction in the diameter of the pipe section.
The StrongPIPE® system consists of high strength steel wires installed in combination with FRP layers, custom designed to meet pressure and loading requirements. StrongPIPE® is 100% trenchless, so the installation took place utilizing only manhole access to complete the 54-inch segments.
STRUCTURAL completed surface preparation and the initial layer of longitudinal FRP was installed, followed by placement of the high strength steel wire placement utilizing the automated system developed by STRUCTURAL TECHNOLOGIES. Following wire installation, the steel was encapsulated in specialized thickened epoxy and the final layer of FRP and top coat was installed per the approved design.
The collaborative services of STRUCTURAL and STRUCTURAL TECHNOLOGIES combined with state-of-the-art production solutions – V-Wrap™ Carbon Fiber and StrongPIPE® – resulted in the successful and on-time completion to the repairs of the high risk pipe segments. With continued prioritization of inspection and rehabilitation efforts for their large diameter water mains, along with their desire to continue using cutting edge technology, Miami-Dade will continue to be one of the most proactive water agencies in the United States.