A METHOD FOR DETERMINING OPTIMAL REPLACEMENT TIMING OF WATER DISTRIBUTION PIPES BASED ON EVALUATION OF LIFE CYCLE COST

Abstract

 Water pipe networks had been expanded and a lot of new pipes had been introduced in the period of rapid economic growth in Japan. On the other hand, revenue has been decreasing due to decrease of water demand caused by population decrease. In such a budget condition, a crucial task with water utilities is to renew old pipes effectively at lower cost.
 We proposed a new pipe renewal method based on evaluation of life cycle cost and evaluated it using leakage incident and pipe data that water utilities possess. Life cycle cost consists of initial and running costs and respective costs are modeled by using above mentioned data. Optimal timing of pipe replacement was determined so that life cycle cost of each pipes was minimized. Optimal timing of pipe replacement was 40th to 50th year for pipes with material of VP and 45th and 50th year for pipes with material of SP. This timing is almost equal to the durable years designated by law.