2023-064 - Laserfiche WebLink

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Exhibit A IRC North County Inline Pump Station Evaluation ATKINS • New infrastructure added since the 2015 Wastewater Hydraulic Model update, including pipe and valves • GIS shapefiles of the collection system • Projected wastewater flows that are anticipated in the LS 203 basin such as planned unit developments, commercial/industrial developments and/or populations projections. • New lift station operations (pumps on/off) • Previous Geotechnical Reports, Condition Assessments, or other studies performed within the abandoned North WWTF site. • Operational SCADA data for all lift stations in Lift Station 203 basin showing pumping start times, durations, and flow rates (15 -minute intervals). Deliverables: Data request memo. Task 03 Hydraulic Evaluation The hydraulic model of the existing collection system will be updated to the latest software version and any new lift stations and piping will be added. Existing flows will be updated in the model based on geocoded water demands, pump station flows, and influent flows at the Central WWTF. Current peaking factors will be determined through evaluation of SCADA data. Future flows through 2045 for Lift Station 203 will be determined by review of anticipated future development and anticipated land use plans. The results of the modeling effort will be summarized and presented in a Workshop with the County for verification of results with actual field operations. Following the meeting, the model will be updated to address County comments. The model will then be utilized to determine the anticipated range of flows and pressures required for the new pump station. System curves will be created for use in pump selection. Along with Workshop meeting notes, tables and figures summarizing the results from the finalized model will be submitted to the County for their records. Deliverables: Workshop with County Staff to discuss and verify the results of the updated model. Workshop summary, including final model tables and figures. Task 04 Equipment Selection and Operations The Atkins Team will utilize the results of the hydraulic model to determine the capacity of the proposed lift station and determine if an emergency wet weather bypass system is required. To meet the anticipated need for bypass during extreme weather, a bypass to the equalization tank has been considered. Pending hydraulic model results, the volume and frequency of bypass operations will be better understood and the potential operations for bypass and recovery can be addressed. Atkins will facilitate a Workshop to discuss options with County Staff and finalize pump station operations. The results of the Workshop will be documented in a meeting summary. Atkins will contact pump vendors to discuss the intended 3