AWWA ACE59989

This paper presents the results and methodologies used in the development of a unique cost model based on existing and/or planned membrane desalination plants. Data has been collected from existing and planned treatment plants and standardized to prepare curves for capital and operating costs. These curves can be used to provide order of magnitude cost estimates for Integrated Membrane Desalination Plants. It is expected to be an extremely useful tool for planners and engineers for evaluating costs for different treatment scenarios. Three water sources have been considered for this project including reclaimed water, surface water and groundwater. The use of real world costs for this model provides a connection to reality with regard to costs. Competitive bidding in recent years has caused the market prices to be disconnected from theoretical prices in recent years. Models for similar applications use standard curves for the other treatment processes, established 30 years ago but for membrane plants they are largely driven by user input and guestimates. The curves presented in this paper incorporate special membrane cost indices for low pressure and high-pressure membranes to standardize membrane costs from different sources to provide specific costs based on market data and not driven by user input. In addition, data gathered provides useful information with regard to the trend in historical market costs and improvement in productivity for membranes. This project was conducted as part of a research program initiated by the Desalination Research and Innovation Partnership, an organization of water purveyors in the Southern California region. The capital cost curves are based on widely used indices like the ENR - Construction Cost Index, ENR - Skilled Labor Wage Index, Marshall and Swift Equipment Cost Index, Chemical Engineering Plant Indices and on specially developed membrane indices which could be used to update the cost curves so that they remain current in the future. Operational costs present a challenge for cost models because of volatile cost components like power costs and sometimes, chemical costs. As part of standardization of operational cost data obtained from existing and planned treatment plants, a sliding scale of costs based on user input was found appropriate. This "sliding scale" is based on user inputs for chemical costs and power costs and will generate new curves every time these inputs are changed to provide "realtime" operational costs for the specific project. Another feature of the model is that it uses a separate curve for power costs as power is the most volatile component of the total cost and does not scale up similar to the other operational cost components. Includes tables, figures.