Hansen and Ryckman CSO Abatement and Flood Mitigation
Hansen Alley and Ryckman Alley have historically experienced flooding and system surcharging issues, resulting in frequent and substantial damage claims. The residences were constructed at a lower elevation than the alleys resulting in driveways that grade down to the buildings, potentially conveying flows and inundating basements and garages during flash flood conditions. Storm Water Management Model (SWMM) modeling results indicated that the alleys effectively had no outfall to drain the areas during high flow periods.
The project was designed to improve collection system efficiencies up-gradient of the two flood-prone zones and incorporate real-time controls to allow for the maximum reduction of runoff by promoting infiltration, evapotranspiration, and stormwater harvesting. To provide for abatement of system surcharging and flooding in Hansen Alley and streets surrounding the Hansen Alley area, CHA recommended that flow collected along Hansen Alley be diverted to an underground infiltration gallery and stormwater harvesting facility constructed using StormTech® chambers in Woodlawn Park. To provide proper system maintenance, the design incorporated an “isolation row” of chambers to provide pretreatment for stormwater flows.
Project Services:
- Water and Wastewater
- Stormwater Management
- Environmental Planning
- Landscape Architecture
- Green Infrastructure
- Wayfinding and Interpretive Signage