To CIPP or Not to CIPP: CCTV, Laser Profiling, and Core Sampling Assessment of a 66” and 72” RCP Sanitary Sewer

Jefferson County AL ESD owns and operates over 3,100 mi of gravity sanitary sewer and has been actively assessing and improving its sanitary sewer collection system. This case study will provide a detailed discussion of the inspection of 54” to 72” reinforced concrete pipe (RCP) sanitary sewers using closed circuit television (CCTV), sonar, laser profiling, core sampling, structural analysis, and field testing. The core sampling and lab testing were especially effective at understanding the remaining useful life of some of the RCP sewers that were observed with CCTV and laser profiling to have hydrogen sulfide (H₂S) microbial induced corrosion and concrete wall loss. The results of these assessments allowed the program to efficiently develop prioritized O&M and structural solutions. This project provided an immense benefit of delaying a proposed expensive sewer rehabilitation project for at least 7 years and this money can be reallocated to higher risk pipes and other projects that will have a much higher benefit to reducing overflows and increasing the useful life of degrading assets.