WSP Water Solutions

Transportation Drainage 

State Road (SR)-9 Bridge Replacements

Willamette River Water Quality Improvements Oregon Department of Transportation (ODOT) | Oregon

North Houston Highway Improvement Plan Texas Department of Transportation (TxDOT) | Houston, Texas

over Yalobusha Floodplain and

Shutispear Creek Mississippi Department of Transportation (MDOT) | Calhoun County, Mississippi ■ Advanced hydraulic modeling across floodplains ■ Integrated stormwater and structural design ■ Phased recommendations with regulatory coordination WSP conducted a Phase A Bridge Replacement Analysis for four of eleven bridge crossings in Calhoun County, Mississippi—three over the Yalobusha River floodplain and one over Shutispear Creek. Key tasks included a pre-design meeting, field reconnaissance, data collection and conceptual bridge replacement evaluations. Advanced hydraulic modeling was central to the analysis. Hydraulic Engineering Center (HEC) River Analysis System (RAS) was used for all four bridges, while SRH-2D was applied to the ten Yalobusha floodplain crossings to simulate complex floodplain dynamics. WSP delivered conceptual and preliminary bridge recommendations, including layout drawings, stream stability assessments and two hydraulic reports (one for each floodplain). The preliminary analysis also addressed scour analysis, guide bank design, bridge deck drainage, and stream and scour countermeasure calculations. Final bridge recommendations were submitted following MDOT requested revisions.

■ Pump station design and installation ■ Roadway reconstruction ■ Stormwater modeling and analysis

■ Water quality flow improvements ■ Implementation of green stormwater infrastructure ■ Environmental services and review

As a subconsultant for Segment 3B of the NHHIP, WSP supported two major packages. Package #1 included pump stations, drainage outfall upgrades and roadway reconstruction, while Package #2 focused on reconstructing the State Highway 288/ Interstate 69 interchange and architectural bridges for Elgin, Tuam and McGowan streets. WSP designed a 207 million-gallon per-day (MGD) stormwater pump station (SWPS) and a 1.61 MGD dewatering pump station (Siphon PS). The SWPS featured 10 high-flow pumps, sump pumps, vortex energy dissipation and dual 108” tunnels with debris screens. These were optimized through computational fluid dynamics analysis and full scale modeling to ensure reliability and minimize impacts. The Siphon PS addressed unique siphon storm sewer conditions caused by utility conflicts, incorporating best practices for drawdown and trash screening. Both stations complied with all necessary regulatory requirements.

WSP partnered with ODOT to design 15 retrofit sites that improve the water quality flowing into the Willamette River. Our team used green stormwater infrastructure and advanced hydrodynamic separation to capture trash, oils, metals and other pollutants; this work reduced contaminants and improved ecosystem health. Our solutions enhanced fish habitats, protected public health and restored resilience to critical waterways. The sites manage runoff from multiple bridges and along US 30, demonstrating innovation at scale. WSP delivered comprehensive services, including design, permitting, environmental review, geotechnical, survey, traffic and public engagement. Completed within the $30-million programmed construction budget, this project reflects WSP's commitment to sustainable infrastructure and future ready communities.

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