Condition Assessment and Asset Preservation Rationalization for the St. Paul Regional Water Services (SPRWS) in St. Paul, MN

St. Paul Regional Water Services (SPRWS) supplies drinking water to nearly 415,000 customers in the city of St. Paul and neighboring communities. The primary source for this water is the Mississippi River at Fridley, where an intake pumping station with a capacity of 340 MLD (90 MGD) pumps water into the raw water system. The raw water system is comprised of 41 km (25.5 miles) of various pipe types and vintages including cast-in-place concrete (1924 and 1936), riveted steel (1924), welded steel (1958 (1960), reinforced concrete pipe (1958), and prestressed concrete pressure pipe (1989/1990). The diameters range from 1500 mm to 2250 mm (60” to 90”). The current day replacement value of the raw water conduit system is $1.2 billion. Given that 88% of the concrete pipe was over 90 years old and 99% of the steel was approaching 60 years and older, the condition of the pipes needed to be understood with greater certainty. In 2016/2017, SPRWS initiated a large scale condition assessment program to determine the condition of all 41 km (25.5 miles) of pipe. Using a vast array of condition assessment techniques over 98% of the system was inspected and assessed. Using risk-based programing techniques a very innovative $24 million rehabilitation program was developed; phased in over a 15 year period to extend the projected service life of the raw water system for another 100 years or more.