WSP Water Solutions

Flood Protection 

Southwestern Illinois Levee Flood Risk Reduction Southwestern Illinois Flood Prevention District Council (SWILFPDC) | Illinois

Flood Risk and Dam Rehabilitation for Natural Resources Conservation Service (NRCS) Structures Natural Resources Conservation Service (NRCS) | Nationwide ■ Extensive dam assessments across 16 states ■ Integrated planning and feasibility studies ■ Dam rehabilitation design and review Since 2009, WSP has supported the NRCS dam-related task orders across 16 states, focusing on flood risk reduction and infrastructure resilience. We have completed 212 dam assessments, including inspections, breach studies, hazard classification reviews, hydrologic and hydraulic (H&H) analyses and cost estimates for rehabilitation alternatives. Our team conducted 20 planning and feasibility studies, which involved on-site evaluations, ecosystem and cultural resource investigations, preliminary geotechnical and H&H assessments, and benefit-cost analyses to guide future investments. WSP also delivered six full dam rehabilitation designs, incorporating engineering analyses, construction plans, permitting, and operation and maintenance manuals. Additionally, we performed five independent technical reviews to ensure design integrity and regulatory compliance. These efforts have helped NRCS strengthen dam safety, improve flood risk mapping and support long- term planning for critical water infrastructure. geologic investigations, soil mechanics testing, detailed

Rocky Carter Levee in the Yazoo River Watershed Natural Resources Conservation Service Mississippi | Yazoo City, Mississippi

■ Design update and rehabilitation for 65 miles of levee ■ FEMA accreditation achieved ■ Installation of cutoff walls, relief wells and seepage berms The Southwestern Illinois Levee Flood Risk Reduction project is an infrastructure initiative protecting 174 square miles of land, over 4,000 businesses, and 56,000 jobs along 65 miles of levees and floodwalls near the Mississippi River. In 2007, the Federal Emergency Management Agency (FEMA) announced that the levees no longer met federal flood protection standards, threatening the region with development restrictions and increased flood risk. WSP was selected to lead the rehabilitation effort, delivering a full suite of services, from geotechnical investigations and design optimization to environmental permitting and construction oversight. The project navigated complex challenges including complex and variable stratigraphy, industrial development, hazardous materials, cultural resource issues involving the Cahokia Mounds and overlapping federal jurisdictions. WSP designed engineering solutions such as relief wells, seepage berms and America’s largest cutoff wall to mitigate underseepage and ensure long-term resilience. Through more than a decade of engineering and by leveraging existing infrastructure, WSP helped the SWILFPDC complete the project decades ahead of schedule and tens of millions under budget.

■ 45-mile flood protection corridor ■ Targeted flood risk reduction ■ Section 401/404/408 permitting and watershed planning

The Rocky Carter Levee is a critical flood risk reduction initiative located in the Yazoo River Watershed of Mississippi. Designed to protect farmland, homes and infrastructure from recurring Mississippi River backwater flooding, the project spans a 45-mile corridor upstream of the Yazoo-Mississippi confluence. WSP provides comprehensive levee engineering services, including a National Environmental Protection Agency analysis, geotechnical analysis, levee design and levee risk analysis in coordination with the USACE and Natural Resources Conservation Service. The team has conducted extensive wetland and stream delineations across 1,800 acres, identifying 42 wetlands and 21 other “waters of the state.” WSP also supports Section 401/404/408 permitting and watershed work plan development. The project addresses urgent flood vulnerabilities in Yazoo and Humphreys counties, where prolonged inundation has caused significant agricultural and economic losses. By integrating hydraulic modeling, environmental permitting and stakeholder coordination, WSP offers consistent and resilient levee infrastructure in one of the nation’s most flood-prone regions.

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