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Stantec August 6,2019 Page 7 of 14 produced upon conclusion of the capacity and alternatives analyses to be conducted in Tasks 500 and 600. Deliverables: • Site visit for Condition Assessment • Draft Condition Assessment TM • Workshop with City staff to review draft TM • Meeting agendas and minutes Task 400 Capacity Analysis Stantec will evaluate the capacity of the existing treatment plant with respect to hydraulic capacity, Biological Oxygen Demand (BOD)and Total Suspended Solids (TSS) removal, and nutrient removal under current conditions and under design influent flow and loading conditions.Stantec will use a biological process simulator to develop, calibrate, and validate treatment plant performance to approximate the actual performance of the Everett WPCF.The Process Simulator will be augmented with a hydraulic model and other specific process calculations where appropriate to evaluate plant capacity. Subtask 400.001 Data Collection,Sampling Plan,and Model Development Stantec will review plant record drawings and up to three years of reported sampling,operations,and compliance data. Stantec will also review any existing biological process simulator prepared as part of previous planning or design efforts. Based on available data,Stantec will develop a Sampling and Analysis Plan to guide the City's efforts in collecting and analyzing supplemental wastewater characterization data needed for model calibration. Stantec will prepare a model to simulate wastewater treatment plant performance. It is anticipated that the GPS-X simulator will be used as a process model. If the City determines that an existing biological process model BioWin model is available,Stantec will review the model and may use it as the basis for the process simulation. Before initiating model development 2 Stantec staff will conduct a 4-hour meeting with appropriate City and WPCF staff to review the plant configuration,operating scenarios, and calibration data so they are accurately reflected in the process model. Subtask 400.002 South Plant and North Plant Biological Process Analysis Using the calibrated process simulator,Stantec will evaluate the capacity of the South and North Plant under flow and loading conditions identified in Task 100 and under up to two alternative river water surface elevation conditions to simulate performance Subtask 400.003 Hydraulic Analysis Stantec will prepare a HADES model of the treatment plant based on existing as-built data.The hydraulic capacity of the existing treatment system will be evaluated under average and peak conditions (as identified in Task 100).To evaluate the potential impact of climate change on WPCF hydraulic operation, WEST Consultants will use the existing 1D HEC-RAS model to simulate a range of existing and future conditions including"existing", 2050,and 2080, "low"and "high" emission scenarios. Using the results of these scenarios,Stantec will work with the City and WEST to select two future conditions to be used as the basis of plant hydraulic capacity analysis. Stantec assumes the most current hydraulic profile for the WPCF will be provided to inform our evaluation. One 2-hour meeting is planned to discuss and select the future scenarios for climate change analysis.