Executing an Asset Management Plan for Large Diameter PCCP

Large diameter water transmission mains are the backbone of the Baltimore Metropolitan Water District (BMWD) system. These mains transport water from three treatment plants to pumping stations, ground storage reservoirs, elevated tanks, surrounding counties, and finally to smaller distribution mains to customers in Baltimore County and Baltimore City. Approximately 86 miles (454k lf) of these transmission mains are large prestressed concrete cylinder pipe (PCCP). When PCCP fails, the results are devastating to the water system and surrounding areas. After several catastrophic failures of PCCP, the BMWD determined that PCCP water mains 36-inches and larger are critical to the overall integrity of the metropolitan water system and should therefore be a top priority for condition assessment. In the late 2000s, The BMWD established Project 953 to create the groundwork for an inspection, assessment, and preventive maintenance and monitoring program for raw and finished water mains. This project also included a pilot inspection of a 54-inch PCCP water main to demonstrate the technology that could be utilized for future inspections. In 2016, Pure Technologies (Pure) was tasked by the BMWD to develop a more comprehensive condition assessment plan or pipeline risk prioritization (PRP) predicated on the preliminary work done in Project 953 for the next 10-years based on the BMWD’s budget restrictions. A factor-based prioritization model was utilized with pipe attribute failure factors and a set of rules to weigh and calculate the combined risk for segments of large diameter PCCP. These segments were combined into “Data Acquisition Unit (DAQ) Zones”. Each DAQ zone was assigned a priority based on calculated risk factors. Pure began inspections on the highest priority water mains using visual and sounding methods, innovative tools for locating leaks and gas pockets using acoustic based technology, and electromagnetics for identifying broken pre-stressing wires. Three years after the completion of the PRP plan, the BMWD and Pure have inspected 4 of the 14 DAQ Zones and made repairs to the pipelines. It was also during this time that the asset management plan and risk factors underwent revisions due to changes in key personnel. This paper will provide an overview of the PRP, the lessons learned during the last three years of the execution of the program, and showcase how the BMWD in partnership with Pure continues to mold and create a strong asset management plan based on an improved risk management system while mitigating various project challenges.