Various governmental, professional and private studies have shown that the replacement costs of underground pipeline infrastructure is excessive and that best practice approaches for infrastructure risk management promote condition assessment programs to understand the actual condition of individual pipe sections in order to best allocate limited capital replacement and rehabilitation funding. The key element to these programs is a physical inspection of the underground piping which provides the required data for planned renewal and replacement activities which costs significantly less than emergency mobilization repairs.
The Miami-Dade Water and Sewer Department (WASD) is one of the largest utilities in the United States and the largest user of Prestressed Concrete Cylinder Pipe (PCCP). A failure in one of their large diameter PCCP treated water mains precipitated a move by WASD to implement the Infrastructure Assessment And Replacement Program (IAARP) to find and implement the best available inspection and rehabilitation technologies to address potentially damaging deficiencies in the large diameter buried pipe of its water distribution system.
Using electromagnetic (EM) and acoustic technologies to evaluate distressed pipe and leak detection. Engineers at WASD have collected quantitative information for individual pipe sections in an effort to effectively manage and make the bestinformed decisions regarding capital planning and the sustainable operation of their pipeline infrastructure. Over the course of two years, WASD has assessed over 75 miles of PCCP mains. Results show pipelines with distress levels ranging from 0 to almost 20% of pipe sections inspected. The question faced by WASD engineers now is how to maintain pipeline reliability over the remaining life of the pipeline at an acceptable level of risk and most cost effectively.
The assessment technologies used by WASD assist in 1) identifying, localizing, and quantifying the presence of broken pre-stressing wires and leaks in individual segments of pipe along the pipeline and 2) providing risk analysis and repair prioritization for pipes identified with broken pre-stressing wires and leakage. As such WASD has been able to categorize the structural damage found, allowing it to prioritize its rehabilitation program and allocate funds accordingly in an emergency and/or an annual basis. The program demonstrates that by using quantitative data from EM and acoustic assessments, a customized pipe rehabilitation solution can be built that saves significant amounts of money for infrastructure renewal while minimizing services disruptions.