R2000-258 AUTHORIZING AGREEMENT - Laserfiche WebLink

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These statements are very open-ended. Determining the level of accuracy depends on the allowable error in the model. Since no such information is provided, the ISWS plans to test the "accuracy" of the existing model using the data available for the 84-day operation and then develop a map showing the difference between the actual drawdown observed and the simulated drawdown. This "error map" will allow the City of Decatur to visually analyze the error in the model results and determine, based on their actual needs, if the error in the model is acceptable. In other words,the City will be able to determine if the model is "accurate" or "not accurate" by the City of Decatur's standards. The ISWS will also provide an opinion about the quality of the model related to the error mapping and discuss the implications of the level of error found. Such opinion will be based on evaluation of the model and appraisal of the calibration of the model. Scope of Effort The project will include two parts, first an evaluation of the modeling results based on the existing model, and second, an evaluation of the model's ability to simulate water level declines as evidenced during the 84-day operation of the emergency well field. To complete these tasks, the City will provide the ISWS with all model input and output files, all data related to the I previous project that lead to the development of the digital flow model, all data available for the 84-day operation of the well field including data from the recovery of water levels after the , pumps were turned off, and information about the locations of wells impacted during the 84-days � of operation. The ISWS has data available related to water level declines that will be used in addition to the data provided by the City. ; The following tasks will be completed: '� Task 1. Appraisal of the pumping test results. The results from the original pumping I test conducted by LGI will be evaluated. The data collected from that test will be re- analyzed where any question arises about how the original analysis was completed. Task 2. Evaluation of the model. The assumptions in the design of the model will be assessed. There are standard assumptions and methods of developing boundary conditions for this type of model and their appropriateness will be reviewed. This will include an assessment of the boundary conditions, initial conditions, and the data used in the model. Task 3. Appraisal of the calibration of the model. The calibration steps, error analysis and decisions regarding the final calibration of the model will be reviewed and evaluated. Task 4. Testing of the model using the data from the 84-day operation of the emergency well field. The model will be ran to determine how it performs in simulating the water level declines observed during operation of the well field and the subsequent recovery of those water levels after the emergency well field was turned off. 3