Occoquan VA – Resilient Stormwater Assessment and Flood Mitigation Plan

Weston & Sampson was selected to evaluate the conditions of its stormwater system, assess the capacity of the system under current and future storm events, and develop a portfolio of high-priority actions to mitigate flood impacts in Occoquan, Virginia.

High-priority actions identified included green infrastructure, grey infrastructure, or stormwater system maintenance needs. The town had limited spatial data on the stormwater system, so the initial task included a field data collection effort to create a more comprehensive GIS layer of the system, its components, and the component sizes following the field investigation. Our team developed a hydraulic and hydrologic (H&H) model of the system to evaluate the current volumetric capacity and the anticipated capacity under the probabilistic conditions of climate change, accounting for increased rainfall events. Informed by site visits and the H&H model, our green infrastructure specialists and stormwater engineers identified high-priority actions to increase capacity of the system and reduce flood impacts throughout the watershed.