I-405 South Bellevue Widening

Huitt-Zollars completed drainage and landscape designs to widen four miles of interstate freeway in a congested urban area, through this $124 million design-build project. The drainage system included five wetland facilities along with water quality media filtration embankments and a water quality monitoring basin. Improvements included stormwater drainage and control structures, rehabilitation of culverts and pipes, water quality monitoring facilities, slope drainage behind retaining walls, and a new 2.5-acre off-site wetland mitigation site. Roadway restoration plans were prepared. All work complied with a detailed Quality Management Plan and required daily coordination with the design-build team.