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Item 4F-4G Item 4F and Item 4G Page 1 of 4 M E M O R A N D U M (May 17, 2023) To: Shana Yelverton, City Manager From: Rob Cohen, Director of Public Works Subject: Item 4F: Approve an engineering services agreement with Freese and Nichols, Inc. (FNI) to provide engineering services to update the City’s water model and master plan in an amount not to exceed $202,400. Item 4G: Approve an engineering services agreement with Freese and Nichols, Inc. (FNI) to provide engineering services to update the City’s Denton Creek/Grapevine Lake wastewater model and master plan in an amount not to exceed $169,800. Action Requested: Item 4F: Approve an engineering services agreement with Freese and Nichols, Inc. (FNI) to provide engineering services to update the City’s water model and master plan in an amount not to exceed $202,400. Item 4G: Approve an engineering services agreement with Freese and Nichols, Inc. (FNI) to provide engineering services to update the City’s Denton Creek/Grapevine Lake wastewater model and master plan in an amount not to exceed $169,800. Background Information: The purpose of items 4F-4G is to approve engineering services agreements with FNI to update the City’s water and wastewater models and master plans. As required by charter, the City of Southlake updates certain master plan documents every four years. The last comprehensive update to the City’s water model was performed in 2012, including modeling and analysis to identify needed improvements for current and future capacity. The last comprehensive update to the City’s wastewater model was performed in 2009, identifying needed improvements for current and future capacity. Recommendations from both updates were adopted into the City’s Southlake 2030 plan in 2012. Subsequent master plan updates have taken a more focused approach but have not reviewed system modifications or addressed the change in demand and demographics of the Item 4F and Item 4G Page 2 of 4 previous ten years. In 2021, Public Works and Planning & Development Services began preparations for a master plan update to review and reprioritize projects remaining on the master plan. During this process, several questions and information shaped the basis for the evaluation of updated studies and modeling to inform plan recommendations. Updates to the water model requires specialized software and system monitoring equipment, resulting in the City Staff to engage an engineering consultant to assist in the master plan revisions. Water Due to the interdependency of the elements of the water system, an update to the complete model will be necessary. Current knowledge of the water system is largely based on the 2012 study, of which many concerns have been raised by engineering and operations. Other more focused studies have been performed since (2017 Water Quality Study, 2014 & 2019 Water Conservation Plan, 2021 AWIA Risk and Resiliency Assessment (AWIA) and 2022 Texas Senate Bill 3 (SB3) Emergency Preparedness Plan). These studies focused on delivery optimization, water quality, conservation, risk reduction, system redundancy and emergency preparedness. The water update will address these concerns and verify recommendations from the most recent studies by building a complete water model, calibrate the model based on field-verified pressure and flow readings, review remaining 2030 CIP projects, and recommend new CIP projects for implementation. The following highlights major scope items for the water update. Existing and future conditions are considered for performance and recommended improvements. AWIA/SB3 items requiring the study from the model update are noted: • Water demand projections • All pipes water model rebuild and calibration • Average, max, fire flow and regulatory demand analysis (SB3) • Pressure plane analysis and delineation (SB3) • System improvement analysis and alternatives • Water age modeling (AWIA) • Source trace modeling (AWIA) • Alternate feed to high pressure plane from TW King Pump Station (SB3) • Updated CIP project costs and phasing recommendations Wastewater Unlike the City’s water system, the wastewater system contains sub- basins that operate independently from each other. The most recent Wastewater Master Plan was adopted in 2012 and utilized modeling from 2009 that identified needed improvements for current and future Item 4F and Item 4G Page 3 of 4 capacity. Since that time the City has conducted flow monitoring with the Town of Westlake for the N-1 interceptor in 2016, and flow monitoring along with smoke and dye testing in 2017 - 2018. The majority of growth within the wastewater system since 2009 has occurred in the Denton Creek/Grapevine Lake watershed, identified as the North Service Area. Near-term growth is also anticipated to remain concentrated in the North Service Area. Coupled with its dependency upon lift stations for final conveyance for treatment, it has been identified as requiring a comprehensive update. Similar to the water update, the wastewater master plan process will update the future flow projections, update the hydraulic wastewater model, and provide an updated Capital Improvements Plan (CIP) for the North Service Area, including a review of current CIP project recommendations. The existing model from 2009 includes all 10-inch and larger wastewater mains and limited 8-inch mains, accounting for some 40% of the 2009 infrastructure. The revised model will map and evaluate all wastewater mains within the North Service Area. The following highlights major scope items for the North Service Area wastewater update. Existing and future demands are considered for performance and recommended improvements. AWIA/SB3 items are noted: • Wastewater demand projections (existing and future) • All pipes wastewater model rebuild • Sub-basin remapping • Dry and wet weather calibration and modeling • Performance analysis • System improvement analysis and alternatives • Lift station assessment (AWIA/SB3) • Updated CIP project costs and phasing recommendations Model and Master Plan Updates As the City approaches its ultimate buildout conditions, projects will be identified that will help the City to direct resources toward correcting issues with current capacity and building out our system to manage remaining growth. Recommendations from the City’s Risk and Resiliency Assessment and Emergency Preparedness Plan will be analyzed to confirm feasibility and project elements are incorporated into the CIP. The master plan updates will focus more on operational optimization, water quality measures, and long-term sustainability rather than growth or facility expansion drivers. Financial Item 4F and Item 4G Page 4 of 4 Considerations: Funding for this agreement is budgeted as part of the approved Capital Improvement Program. This agreement is within the project budget. Strategic Link: These items link to the City’s Strategy Map by delivering on the focus area of Infrastructure & Development. It provides this by focusing on Financial Objective F2: Investing to Provide & Maintain High Quality Public Assets. Citizen Input/ Board Review: None. Legal Review: The proposed agreement is a standard agreement that the City Attorney has reviewed and approved. Alternatives: The City Council may approve or deny the agreement. Supporting Documents: Attachment A: Water Master Plan Modeling Memo Attachment B: Wastewater Master Plan Modeling Memo Attachment C: Water Agreement Attachment D: Wastewater Agreement Staff Recommendation: Item 4F: Approve an engineering services agreement with Freese and Nichols, Inc. (FNI) to provide engineering services to update the City’s water model and master plan in an amount not to exceed $202,400. Item 4G: Approve an engineering services agreement with Freese and Nichols, Inc. (FNI) to provide engineering services to update the City’s Denton Creek/Grapevine Lake wastewater model and master plan in an amount not to exceed $169,800. Staff Contact: Rob Cohen, P.E., Director of Public Works Lauren LeNeave, Deputy Director of Public Works - Administration Jeff Ginn, P.E., Deputy City Engineer