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Walnut Creek WWTP Update Shay Ralls Roalson, PE Charles Celauro, PE Rebecca Vento, PE May 11, 2022 Presentation Outline  Walnut Creek WWTP Overview  Capital Improvement Program Summary  Notable Projects  Conclusion  Questions WALNUT CREEK WWTP OVERVIEW AW Wastewater by the Numbers  Gravity Lines ≈ 2,900 Miles (15.3 Million Linear Feet)  Manholes ≈ 59,000  Lift Stations ≈ 135  Force Mains ≈ 78 Miles (411,800 Linear Feet)  Decentralized Package WWTPs = 8  Wastewater Treatment Plants = 2 Walnut Creek WWTP & South Austin Regional WWTP  Biosolids Plant = 1 Hornsby Bend Biosolids Management Plant Current Permit & Flows  Permitted flow • Average = 75 MGD • 2-hour peak = 165 MGD  History • Original plant 1977 • Two major expansions in 1980s • Major expansion in 2005 2022 Walnut Projections (for "10 year" data set) Walnut Historical Influent Projection using 10 year avg gpcd Walnut Creek Permitted Capacity Projected Flows Reach Capacity 100% of Permitted Capacity (75 MGD) 90% of Permitted Capacity (67.5 MGD) 75% of Permitted Capacity (56.25 MGD) 100 90 80 70 60 50 40 30 20 10 ) D G M ( t n e u l f n I 0 1990 1995 2000 2005 2010 2015 2020 2025 2030 2035 2040 Updated February 2022 Capital Improvement Program Summary Strategic Investments  Rehabilitation projects upgrade and modernize the existing facilities and equipment to extend the life of the treatment plant.  Growth projects expand the treatment capacity to support the growth in Austin and meet new regulatory requirements.  $370 Million FY23-27 CIP (all categories) Project Summary Project Phase Construction Cost Upcoming Commission Actions Tertiary Filter Rehabilitation Substantially Complete $25 Million (contract value) Sludge Thickener Rehab Substantially Complete $10 Million (contract value) Secondary Process Improvements Construction $25 Million (contract value) Pumping System Improvements Construction $14 Million (contract value) Controls & Network Upgrades Construction $6 Million (contract value) --- --- --- --- --- Gas Scrubber Systems Renewal $3 - 4 Million (estimate) 2022 – Construction Contract Influent Lift Station Headworks Improvements $9 - 10 Million (estimate) 2024 – Construction Contract $37 - 40 Million (estimate) Design Design Design Primary Clarifier & Flow Equalization Basin Rehab Design $32 - 35 Million (estimate) Expansion to 100 Million Gallons Per Day Preliminary Engineering $500 - 600 Million (estimate) 2024 – Construction Contract & Construction Phase Services July 20, 2022 – CMAR Contract July 20, 2022 – Design Phase Services Construction is underway Rehabilitated Gravity Thickener New Diffusers in all Aeration Basins Replacement of Main Plant Lift Station Pumps Notable Projects Walnut Creek WWTP Expansion to 100 MGD  Capacity: • Existing Capacity = 75 MGD • Capacity After Expansion = 100 MGD  Capital Cost: • Estimated Construction Cost: $500 - 600 million  Project Milestones: • Preliminary Engineering 2022 • Final Design: 2024 • Construction NTP: 2024 • Substantial Completion: 2028  RCA Commission Actions: • July 20, 2022 – Final Design Phase Services Project Features  Expansion from 75 MGD to 100 MGD  More stringent effluent quality  Major Elements: • Conversion of Existing Plant to Biological Nutrient Removal (BNR) • New 25 MGD Treatment Train Including BNR • Wet Weather Facilities • Site Improvements  Bid packaging, phasing options, and delivery method are under consideration Atlas 14 Impacts • Anticipated solution is flood wall around perimeter of site Primary Clarifier & Flow Equalization Basin Rehab  Capital Cost: • Construction Cost : $32 - 35 million  Project Milestones: • Final Design: December 2023 • CMAR Packages: 2023 • Substantial Completion: October 2027  RCA Commission Actions: • July 20, 2022 – Construction Manager at Risk (CMAR) Contract  CMAR Delivery: • Primary clarifiers and FEBs located in underground structures, making access and overall constructability challenging • CMAR delivery will allow the project team to bring in a contractor during design phase to collaborate on construction methods and release equipment earlier than traditional “low bid” Conclusion Conclusion  $370 Million in FY23-27 CIP  Major expansion moving to design phase  Community engagement ongoing • Community meeting on May 24 • Future community meetings anticipated as Expansion project continues QUESTIONS