Sewer System
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Stewart Creek West Wastewater Treatment Plant Expansion to 15 MGD and Plant I Improvements; Project No. 309-0621-23 Engineering Services Agreement - Preliminary Engineering
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SUBJECT
recommendation
Authorize funding in the amount of $2,961,650 to Hazen and Sawyer for an engineering services agreement for preliminary design of the Stewart Creek West Wastewater Treatment Plant Expansion to 15 MGD and Plant I Improvements project.
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PURPOSE
The action will authorize preliminary engineering to expand the Stewart Creek West Wastewater Treatment Plant (WWTP) capacity by 5 million gallons per day (MGD) and improve the reliability and regain capacity of the existing Plant I to accommodate the growth in the City of Frisco service area.
RECOMMENDATION
The Executive Director and NTMWD staff recommend the Board of Directors authorize the Executive Director to execute an engineering services agreement (ESA) as follows:
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Consultant: |
Hazen and Sawyer |
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Scope: |
Preliminary Engineering |
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Project: |
No. 309-0621-23 Stewart Creek West Wastewater Treatment Plant Expansion to 15 MGD and Plant I Improvements |
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Amount: |
$2,961,650 |
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Committee: |
This will be an item on the October 21, 2026, Wastewater Committee meeting agenda |
DRIVER(S) FOR THIS PROJECT
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Strategic Objective: |
1.4 Reliable and Resilient System Capacity |
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☐ Regulatory Compliance |
☒ Asset Condition |
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☒ Capacity |
☐ Redundancy/Resiliency |
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☐ Relocation or External Requests |
☐ Operational Efficiency |
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☐ Safety |
☐ Administrative |
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☐ Policy |
☐ Other _____________ |
BACKGROUND
• The Stewart Creek West WWTP, located in the City of Frisco, Texas, has a permitted capacity of 10 million gallons per day (MGD) annual average daily flow (AADF) and a 35 MGD peak 2- hour flow (P2HF). Stewart Creek West WWTP has two 5 MGD Plants. Plant I was built in 1992 and expanded in 1999, and Plant II was bult in 2015.
• The City of Frisco has attracted several significant entertainment venues and businesses resulting in increased flows to the Stewart Creek West WWTP. Based on the data provided by the City of Frisco, the facility will require expansion to 15 MGD AADF with a 52.5 MGD P2HF. Current flow projections indicate the construction is needed to be complete between 2031 and 2034 with construction anticipated to take 3-4 years to complete. Therefore, it is necessary to begin preliminary design of the expansion in 2026. The actual construction schedule of the expansion is dependent on actual flows and growth in the service area and will be evaluated as design progresses.
• In addition to the projected increase in flows, Plant I has experienced aging infrastructure and a steady increase in biochemical oxygen demand (BOD) loading over the years, which have limited its overall functional capacity. The project will focus on critical components to address aging infrastructure and equipment, regain lost treatment capacity, and improve operational reliability.
• The conceptual design analysis, approved via Administrative Memorandum No. 5913 in April 2023, evaluated alternatives and determined that construction of a new 5 MGD wastewater treatment plant utilizing package plant technology and critical improvements at Plant I is the recommended alternative to support the City of Frisco’s growth.
• Recommendation to proceed with Preliminary Engineering was presented to the City of Frisco City Council on August 18, 2026, and was approved to proceed with the Preliminary Engineering phase.
PROJECT PURPOSE
• Expand Stewart Creek West WWTP to the permitted 15 MGD AADF with a P2HF of 52.5 MGD between 2031 and 2034 to meet City of Frisco growth in the service area.
• Address critical improvements within the existing Plant I facility to enhance its reliability, regain lost functional capacity, and ensure continued compliance with discharge permit requirements.
Construction Manager At-Risk (CMAR) delivery method will be considered to prioritize improvements, improve cost assurance, and phase construction activities to meet project objectives. Recommendation of the CMAR delivery method will be a separate, future item for board consideration.
• The planning level estimated construction cost is approximately $266 Million.
PROJECT COMPONENTS
• 5 MGD preliminary, secondary with package plant technology, and tertiary treatment train, including supporting facilities
• Evaluation and preliminary design of the necessary improvements to Plant I to improve reliability and regain lost function capacity
• Additional solids handling to support increased hydraulic and organic loading
BASIC SERVICES
• Project Management, stakeholder coordination and design review workshops
• Structural condition assessment and evaluation of Plant I
• Construction Manager at Risk procurement support
• Basis of Design Report and 30% plan development
• Opinion of probable construction cost estimate
The proposed preliminary engineering approach advances the project to a 30 percent design level, shifting effort from exploratory evaluation to a detailed, constructable design that establishes firm technical criteria, layouts, and cost basis. This level of development improves cost certainty, supports early contractor engagement, and materially reduces downstream design revisions, construction risk, and schedule uncertainty for the District.
SPECIAL SERVICES
• Topographic survey
• Geotechnical engineering
• Laser scanning of Influent Pump Station
• Structural testing at Plant I
ENGINEERING SERVICES FEE
Description Amount
Basic Services $2,662,400
Special Services $299,250
Requested Amount $2,961,650
FUNDING
Funding in the amount of $2,961,650 is to be made available in the Stewart Creek Wastewater Treatment Plant Capital Improvement. The City of Frisco was invoiced on October 7, 2026.