AWWA ACE63259

AWWA ACE63259 Quantitative Results of EPS Model Calibrations with a Comparison to Industry Guidelines
Conference Proceeding by American Water Works Association, 06/01/2006

Edwards, Jerry; Cole, Scott; Brandt, Malcolm

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The concept for this paper originated with the question of how to define acceptablecalibration criteria for water distribution models. A 2001 report by the AWWAEngineering and Computer Applications Committee (ECAC) titled "Hydraulic and WaterQuality Modeling of Distribution Systems: What Are the Trends in the US and Canada"reported that only 48% of the 174 survey respondents considered their hydraulic model tobe calibrated. Respondents had various definitions of calibration, used various methods toachieve calibration, and accepted varying accuracies of calibration.The definition of calibration criteria will become increasingly important as a result ofincreasing regulatory focus on water quality in the distribution system. The recentlypromulgated Stage 2 Disinfection Byproducts Rule (Stage 2 DBP Rule) is the first U.S. Environmental Protection Agency (USEPA)regulation that specifically identifies computer modelling as a method for evaluatingmonitoring locations. It allows water age and source trace results from calibrateddistribution system models to be used as an alternative to extensive field measurements ininitial studies required by the rule.Prior to promulgation of the Stage 2 DBP Rule, a 1999 report by the ECAC titledCalibration Guidelines for Distribution System Modeling suggested that additionalmeaningful discussion is needed among the United States (US) modeling communityregarding the need and validity of calibration standards. To further that effort, this paperpresents extended period simulation (EPS) model calibration results for several mediumand large utilities across the US. The results of the calibrations are evaluated relative tothe guidelines in the ECAC report.In consideration of different practices and their impact on calibration accuracies,information on the development and calibration of a model in the United Kingdom (UK)is also presented. Includes 9 references, tables, figures.