Quantifying Effectiveness of Cathodic Protection in Water Mains: Case Studies

Abstract

Cathodic protection is a viable measure to extend the residual life of water mains and thus defer capital investments in their rehabilitation and renewal. The effectiveness of cathodic protection varies with the unique set of conditions under which it is applied and is therefore difficult to quantify. Consequently, reported case histories have been largely anecdotal and most often based on the observed reduction of water main breaks following the application of cathodic protection. Models to assess the impact of cathodic protection programs were proposed in a previous companion paper “Quantifying the Effectiveness of Cathodic Protection in Water Mains: Theory.” This paper describes the application of these models to five groups of water mains from two water utilities that have had on-going programs of hot spot and retrofit cathodic protection. The case histories show that cathodic protection programs (hot spot and retrofit strategies) have had a significant effect on reducing breakage rates, however, in some cases it appears that the much cheaper hot spot strategy is sufficiently effective and there is no need to retrofit as well. The proposed analytical methods should assist water utilities to optimize the implementation and scheduling of future cathodic protection programs.