WSP Water Solutions

System Modeling and Analysis 

Knox County Stormwater Modeling

City of Naples Stormwater System Modeling and Lake Restoration City of Naples | Naples, Florida ■ Stormwater system improvement ■ Coordination and public engagement services ■ Design and permitting WSP provided comprehensive engineering services for the City of Naples’ Lake Manor Restoration project, aimed at improving stormwater system performance and water quality. The project included the design, permitting, public engagement and construction administration for dredging and dewatering approximately 16,000 cubic yards of sediment from Lake Manor. WSP coordinated with local agencies to identify beneficial reuse options for the removed sediment and conducted homeowner meetings to ensure community alignment with project goals. During the design and permitting phase, WSP prepared technical specifications, cost estimates and bid packages for state, federal and local regulatory approvals. The firm also led construction administration and inspection services, including weekly site visits and monthly progress meetings to ensure compliance with the contract schedule. This project exemplifies WSP’s expertise in stormwater modeling, permitting and stakeholder coordination. It reflects a commitment to sustainable water infrastructure and community- focused restoration.

Carolina Sewer Trunk Rehabilitation City of Portland | Portland, Oregon

Knox County | Knox County, Tennessee

■ Watershed modeling ■ Flood risk analysis ■ Infrastructure level of service analysis ■ Strategic planning ■ Regulatory and grant funding objectives support WSP developed detailed stormwater models for eight watersheds in Knox County, Tennessee, using PCSWMM for dynamic urban hydrologic and hydraulic analysis. Models focused on areas with extensive closed conduit stormdrain systems and were calibrated with historical high water marks, stream gage data and field observations at sinkholes during major storms. This effort supported Knox County’s floodplain management, mitigation planning and capital improvement priorities. The project began with an evaluation of the County’s storm drain database to identify gaps, followed by field surveys integrated with LiDAR and ground cover data using GIS tools. Results helped identify flood vulnerable properties, evaluate conveyance improvements and prioritize resilience projects. The project scope included eight watersheds totaling 60 square miles, 59 miles of open channels, 12 miles of storm drains, 40 detention basins and 25 sinkholes. Surveys covered over 100 bridges, 260 stream channels and 70 conduit runs identified during gap analysis.

■ Advanced hydraulic modeling ■ Design optimization and cost savings ■ Energy dissipation and overflow reduction

WSP led the rehabilitation design of the Carolina sewer trunk in Portland, Oregon. Throughout this project, we focused on reducing combined sewer overflows through storm sewer separation. A key feature of the design was the implementation of vortex drop structures on both storm and combined sewer lines. This better managed significant elevation changes and dissipated energy more effectively. To validate the hydraulic performance, WSP developed a 3-D computational fluid dynamics model using FLOW-3D HYDRO. A one-fluid simulation assessed water pressures and velocities, revealing that minimum flows did not produce a vortex regime. Force calculations at the outlet pipe informed support design under maximum flow conditions. A two-fluid model evaluated air entrainment and venting, confirming negative pressure within the drop pipe and guiding vent pipe design. The modeling process revealed a short-circuit in the preliminary design. This insight allowed the team to refine the layout by reducing pipe pressure,

improving airflow through the vent and ultimately lowering construction costs.

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