Water/Wastewater Treatment Plant Field Device Wiring Method Decision Analysis

Abstract

The choice of field device wiring method for water and wastewater treatment plant design is extremely complex and contains many variables. The choice not only affects short-term startup and equipment costs, but also long-term operations and maintenance costs and attributes such as sustainability, water quality, and asset lifespan. The literature suggests several advantages and disadvantages to each available wiring method, though no industry standard wiring method exists since each client has their own unique situation and preferences. While it is true that the field device wiring method decision can many times be mandated by existing client standards or existing plant assets, new treatment plants or open-minded clients may benefit from an objective analysis, performed by subject matter experts, of the available wiring methods. This research report investigates the use of a dynamic decision analysis tool that utilizes the analytic hierarchy process. This process can utilize both objective data (like manufacturer quotes, bills of materials, or net present value calculations) and subjective data (like surveys) to weight alternative wiring methods based upon unique client preferences and engineering technical expertise. The resulting tool facilitates a standard process for making the complex field device wiring method decision.