Laserfiche WebLink
• Comments on Draft Chapter 2 <br /> Deliverables <br /> • Draft Chapter 2 —Existing Collection & Conveyance Sewer System <br /> Task 7 — Sewer System Evaluation <br /> Objective <br /> Analyze the major components of the City's sewer collection and conveyance system, including <br /> collector and trunk lines,flow diversions, pump stations, and force mains. Identify deficiencies and <br /> improvements associated with system capacity and condition, infiltration and inflow, and planned <br /> growth.The sewer system evaluation consists of three main components that build off the findings <br /> of Tasks 3, 4, and 5: hydraulic analysis, condition assessment, and system resiliency analysis. <br /> Work Tasks <br /> 7.1 Hydraulic Modeling <br /> Review the City's existing hydraulic model including set up of existing lift stations, regulator <br /> stations, and CSO outfalls. Compare model to City's GIS hydraulic information for pipes and <br /> manholes and make updates as necessary. Incorporate information from recently completed <br /> models used for PGSF Plan and Sewer 0 project as appropriate. Set up model hydrology including <br /> informed by the sewer drainage basins established in Task 4. Set up dry weather flow parameters <br /> using ADWF determined in Task 4. The hydraulic resolution of the model to include all major <br /> interceptors and collector pipes at a similar resolution to the existing City hydraulic model. <br /> Calibrate the updated model to flow monitoring data collected in Task 4. Use peak flow and total <br /> flow volume as the calibration metrics. Flow depth to be used in the event flow data is not available <br /> at a meter location. Propose the acceptable level of accuracy and determine the agreed upon <br /> accuracy with City staff prior to model calibration. <br /> Develop and submit the H/H modeling Technical Memorandum discussing model update and <br /> calibration to be appended to the Plan. <br /> 7.2 Rainfall Timeseries Review and Update <br /> Review available rainfall and climate change information, and timeseries used for deficiency <br /> analysis, Combined Sewer Overflow (CSO) outfall compliance, and climate change, and update to <br /> facilitate the objectives of the Plan. Provide Summary of updates to the rainfall timeseries. Provide <br /> recommendation to City for updates, as necessary, and use recommendations in system analysis. <br /> City of Everett MURRAYSMITH 2023 Comprehensive Sewer Plan <br /> March 2021 12 <br />