DEVELOPING A LIFE-CYCLE COST ANALYSIS FRAMEWORK TO EVALUATE THE COST-EFFECTIVENESS OF HYDROELECTRIC PENSTOCK CORROSION CONTROL STRATEGIES

摘要

The Bureau of Reclamation utilized protective coatings to maximize reliability and useful life for its water infrastructure. Steel hydroelectric penstock pipes received long-lasting coatings during construction. These coatings are reaching the end of their service life and require recoating. Stricter regulations shifted today's recoating specifications to less harmful systems, which vary in initial coating costs, periodic maintenance, and service life. For expensive penstock recoating projects, the challenge is in determining the most cost-effective coating system. A life-cycle cost (LCC) analysis framework was developed for cost comparison of competing coating systems. This analysis is particularly suitable for determining whether the higher initial cost of a coating system is economically justified by reductions in future costs, e.g., maintenance, repair, or replacement costs. The theoretical framework shown here includes a spreadsheet tool designed to accommodate all unique inputs and accounts for the time-value of money. It offers several output options, including the equivalent uniform annual cost, to aid decision makers in selecting coating systems. A sensitivity analysis is also provided to demonstrate the effect of modifying principal variables, such as discount rate and coating service life.