Following survey collection, we completed a desktop analysis using GIS data on existing stormwater infrastructure, impervious surfaces, and known drainage concern locations. This analysis identified stormwater points of investigation and associated drainage areas for additional field evaluation.

Field investigations assessed the condition and performance of stormwater infrastructure and existing best management practices. The team documented maintenance concerns, structural deficiencies, and potential restoration opportunities, while also capturing any unmapped infrastructure to update the city’s stormwater GIS database.

To further evaluate flood risk, our team developed a hydrodynamic model using the personal computer stormwater management model (PCSWMM). The model combined one-dimensional and two-dimensional flow components to simulate underground pipe systems and overland flooding during 10-year and 25-year storm events under both existing and future climate conditions.

Working closely with the City of Gaithersburg, we developed a prioritization matrix to evaluate project opportunities based on a combination of social, environmental, and economic metrics, including public safety, flood mitigation potential, water quality benefits, and cost effectiveness. This process incorporated field observations, modeling data, survey input, and feedback collected through three community meetings held throughout the study.

Ultimately, the team advanced 14 projects for concept development, including stormwater infrastructure upgrades, retention and detention basins, and green infrastructure solutions such as bioswales and bioretention systems. Projects were organized into three watershed-based concepts to maximize cumulative benefits and were supported by preliminary cost estimates and conceptual designs for phased implementation through the city’s CIP.

To learn more about the study, head to the project’s interactive storymap developed by the project team.