This has similarity to rain storms that cause sewage to overflow into the river in Portland, Oregon. Portland uses a combined sewage overflow system (CSO). Whe

This has similarity to rain storms that cause sewage to overflow into the river in Portland, Oregon. Portland uses a combined sewage overflow system (CSO). When there is a heavy rain, it used to be sewage would pour into the Willamette river. However, for the past 10 years the city has been installing rain gardens that contain water storage devices that allow flash rain to be collected like a capacitor and then slowly drain into the ground after. [1] These have had a big impact, not only in reducing or eliminated sewage spills into the river, but also reducing the amount of storm water being processed by sewage treatment plants. [1] https://www.portlandoregon.gov/bes/78921 https://www.portlandoregon.gov/bes/78921