Failure Analysis Helps Sanitation District No. 1 of Northern Kentucky Improve Its Continuous Sewer Assessment Program

Sanitation District No. 1 of Northern Kentucky (SD1) is the second largest public sewer utility in Kentucky, serving more than 290,000 residents and maintaining 1,600 miles of sanitary sewer. During implementation of its Capacity, Management, Operation, and Maintenance (CMOM) Program, SD1 developed a Continuous Sewer Assessment Program (CSAP) to develop a logical approach to prioritizing inspection, cleaning, and other maintenance of the collection system. This program was commenced in 2008 and has been effective in reducing operation and maintenance (O&M)-related overflows in the system. SD1 is now refining the program to become more efficient and to improve the likelihood of detecting pipe problems before they result in failures. As part of this program update, SD1 evaluated the historical sewer inspection and failure records since July 1, 2009, to determine if re-inspection triggers could be further refined and return frequencies lengthened without significantly increasing risk of failure and to make further data-driven recommendations.Separate lists of pipe structural failures and O&M failures were developed from an extensive data set and analyzed with a data visualization software. The results of this evaluation helped SD1 to better understand the historical behavior of the sewer system. This information will be used to revise and improve CSAP processes with the goal to better assess infrastructure condition and life cycle, cost-effectively minimize O&M related spills, and implement system renewal and rehabilitation in a way that targets dollars where they have the highest benefit.