PSA - Long-Termed Control Plan Stantec Consulting Services

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Stantec Consulting Services Inc. 9 of 16 TO1 – Randolph-Sampson RTB PER Task 3 – Update and Validation of Hydrologic and Hydraulic Model During the development of the South Bend CSO LTCP, Cognitive Hydraulic Response System (CHRS) nodes were used to provide the typical year hydrograph inputs to the CSO 022 main interceptor at the regulator structure. CHRS inputs were developed using a proprietary regression algorithm based on historic data collected under the system conditions during the data collection period. It provided a simplified approach to simulating the system conditions for high-level planning purposes. For design of the RTB facility and associated hydraulic modifications, STANTEC will refine the existing H&H model to include the sanitary and combined sewer network in the service area represented by the CHRS node for more accurate simulation of the design flow conditions such as design storms and select historical events. Additional flow monitoring data will be collected to validate the refined H&H model. Subtask 3.1- Update of H&H Model STANTEC will expand the LTCP H&H model in PCSWMM by including the sanitary and combined sewer network in the CSO 022 drainage area currently represented by the CHRS node. The expanded model will include pipes 15 inches and larger. The pipe network information will be based on the latest GIS data provided by the CITY. The survey information collected under Subtask 2.1 for sewer in the vicinity of the proposed RTB site will also be integrated into the model. Subtask 3.2 – Analysis of Historic Flow Data (by others) Historic flow data gathered by the CITY through its network of sensors can provide valuable information regarding conditions in the existing combined sewer system during real-world rain events. To support design of the proposed Randolph-Sampson RTB, STANTEC requests that CITY have its consultant, Hydro- Digital, compile and analyze data collected over the last five years from existing rainfall, flow, and level sensors in the CSO 022 basin and provide results of the analysis to STANTEC. STANTEC will prepare and provide to the CITY a detailed scope of the analysis to be performed once services have been initiated. However, it is anticipated that the analyses will include tasks such as: • Analysis of historic rainfall and regulator level/flow data to identify up to twenty rain events for which consistent, reliable data are available, • Generation of time series plots of rainfall, level, and flow from the sensors for the selected rainfall events, • Evaluation of the time series data for trends, patterns, or changes in flow conditions associated with certain rainfall events, • Preparation of a technical memorandum summarizing observations from the analyses related to typical level and/or flow responses and evaluation of factors that may impact level and/or flow responses in the system, and • Submittal of digital files (Excel format) containing rainfall, level, and flow data for the analyzed storms. The technical memorandum and digital data files produced by Hydro-Digital under contract with the CITY will be provided to STANTEC for its use in RTB design analyses. The memorandum will be included as an attachment to the Preliminary Engineering Report.