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Figure 2: Cumulative probability of remaining service life (RSL) and remaining economic life (REL).

ry’s remaining economic life and allocate budgets for renewal programs that may include local repairs, replacement or rehabilitation. An approach to distinguish between the remaining service life and the remaining economic life was developed. This approach aligns with asset value depreciation with time, as an asset may lose its economic value, but may still operate below its strength capacity. Figure 2

summarizes the estimated remaining service life and economic life for the Thames Centre study. The pipe age at its end of economic life is estimated at 92 years, when the pipe will lose its ability to resist the pressure rating of 350 psi. However, the pipe may continue to function at a working pressure plus surge allowance for a total combined pressure of 150 psi, with failure estimated at 101 years. Given the

pipe’s current condition, this pipe was not recommended to be included in the 10-year capital renewal plan. Rabia Mady, P. Eng., is with CIMA+ Canada Ltd. Email:

The author would like to thank the Municipality of Thames Centre and especially Carlos Reyes, director of environmental service at the Municipality of Thames Centre for providing the inspection results.









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