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• <br /> • <br /> 2. One modeling kick-off meeting to discuss the status of the existing model and aspects .6 <br /> modeling plan.The meeting will include HDR (up to three)-and City staff, and may also <br /> include staff from OTAK—8 hours. <br /> 3. The existing InfoSWMM model is in "ready to run"condition but needs updating and <br /> refinement of prioritized basins. Combined sewer basins will be updated to a similar level of <br /> detail as those areas modeled by OTAK. <br /> 4. OTAK has already adequately modeled approximately one-half of the combined sewer <br /> basins that will not require any significant modifications. <br /> 5. City staff will update the model infrastructure and geometry as needed. <br /> 6. I&I model parameters for selected and prioritized separated sewer basins will be updated <br /> using available flow meter data. <br /> 7. The InfoSWMM model data is coordinated and linked with system GIS shape and data files. <br /> 8. The model workshop will be held at the end of the project and be no longer than 4 hours in <br /> length. Attendees will include HDR staff (up to two) and City staff. <br /> Deliverables <br /> 1. Draft and final technical memorandum describing the Modeling Plan—emailed PDF. <br /> 2. Electronic modeling files upon completion of the project (CD-ROM) <br /> 3. Draft and final text and exhibits describing the results of the model analysis —establishing <br /> LOS and results of alternatives analysis —will be developed under Task 1700. <br /> Task 600 — Determine Design Flow Events and Current LOS <br /> Objective <br /> To determine controlling design storm/flow events to be used in the determination of levels of <br /> service and for use in analyzing collection and conveyance system alternative improvements. <br /> These design flow events will be determined using historical flow information that is adjusted for <br /> potential influences on storm patterns and volumes due to climate change. <br /> HDR Services <br /> 1. Using information from Task 1800 and information already developed by MGS for the City <br /> for OTAK north end modeling, develop a long-term rainfall time series to be representative <br /> of the rainfall patterns experienced in combined sewer area of the City of Everett. The series <br /> will be for approximately 20 years in time increments of 5 to 15 minutes. <br /> 2. Collect and evaluate publicly available rainfall data from rain gage stations in the vicinity. <br /> 3. Based on a review of City rainfall data and rain fall data within the public domain, assess the <br /> potential differences in rainfall patterns across the City service area provide <br /> recommendations of adjustments to rainfall time series that will be used in the modeling <br /> analysis. <br /> 4. In the modeling Task 500, apply the rainfall time series to combined sewer basins within the <br /> calibrated model. Determine the return frequency of the model predicted flows and establish <br /> the collection system level of service at selected points within the system. <br /> 5. Identify specific historical storm events that generate flows for varying levels of service. <br /> City of Everett Comprehensive Sewer Plan Update 7 710 Scope of Services April 2011 <br />