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6 <br /> HDR Services <br /> 1. Meet with City to review and discuss the status of the existing InfoSWMM.hydraulic model. <br /> Items for discussion include: <br /> A. Status of sewer system basins conversion from the old MOUSE model, <br /> B. Status of basin modeling upgrades, . <br /> C. Model calibration/validation status, <br /> D. Flow monitoring data status/needs, <br /> E. Discussion of data file transfers and modeling tasks, <br /> F. Outline updated modeling plan including basin prioritization and level of detail desired. <br /> 2. Prepare a Modeling Plan that will describe the modeling process/procedures that will be <br /> used for both the combined and separated areas. The Modeling Plan will also include a <br /> summary of the assumptions made regarding basin prioritization, modeling of parameters <br /> and modeling of stormwater LID alternatives (as defined in Task 800). <br /> 3. Set up the existing model(s) on the HDR computer system. <br /> 4. Review and familiarize the appropriate members of the project team with the existing <br /> model(s). <br /> 5. Update model(s) to reflect: <br /> A. The improved understanding of the hydrologic conditions, through the model <br /> refinements, particularly in the combined area—soil conditions, impervious area, etc. As <br /> appropriate, the hydrologic parameters developed by OTAK will be extrapolated across <br /> the combined system model. <br /> B. Flow loading —evaluate the flow loading methods in the current model for the combined <br /> and separated areas. For the combined system, the sub-basin/catchment methodology <br /> used by OTAK will be extended to the other high priority basins. For the separated <br /> system, the most appropriate method to assign dry weather and wet weather flows will <br /> be determined. Diurnal patterns and peaking factors will be evaluated and updated, as <br /> needed for the separated basins. The flow loadingprocess will be described in the <br /> Modeling Plan. <br /> i. Current sanitary flow loading —update flow loads to reflect the current flows <br /> observed in the combined and separated portions of the system. Evaluate and <br /> update inflow and infiltration (I&I) assumptions in selected areas of the separated <br /> system based upon results of the Task 400 data review. <br /> ii. Future sanitary flow loading —define and load into the model projected buildout flows <br /> to be used in the evaluation of future combined and separated systems performance <br /> scenarios. Include City of Snohomish flows in this analysis. <br /> C. Current maintenance issues and operational procedures—modeled system will be <br /> reviewed and updated, as necessary, to include any recurring maintenance issues and <br /> reflect current operating procedures. <br /> 6. Work with City on prioritized basin model updates. <br /> 7. Use available data to validate the model within selected prioritized combined and separated <br /> sewer basins. If the model results do not fall within reasonable flow and volume ranges as <br /> compared with the observed system performance, then the model will be adjusted to better <br /> conform to existing system performance. <br /> City of Everett Comprehensive Sewer Plan Update 7 s Scope of Services April 2011 <br />