SRF is assisting Hennepin County, in cooperation with MnDOT and municipalities, in evaluating the conversion of the TH 252 expressway to include new interchanges in the Cites of Brooklyn Park and Brooklyn Center. The drainage systems along the TH 252 corridor are complex and relatively flat, with existing XP-SWMM hydrologic and hydraulic modeling indicating significant flooding in areas where little to no flooding has been observed. SRF was retained to evaluate the existing models and design stormwater infrastructure for the project. We implemented a data collection plan and validated and updated the existing models. The data collection plan included reviewing record drawings and surveys and deploying monitoring equipment to collect flow data for model calibration. SRF then created more accurate models for the design and properly sized stormwater infrastructure. This was key as increasing the size of trunk storm sewer in developed areas like the TH 252 corridor is expensive and could require additional right-of-way acquisition.