In the ultra-urban setting, such as Philly, NYC, Baltimore, etc., we know that the sweet spot for having a meaningful impact on CSO's is managing ~50-55% of the impervious surface areas within the area tributary to an outfall. We also know that only ~25% of that area is area available in the public ROW, ...
Matthew - I would be curious to hear more about what you are doing in D.C. You gave examples in other cities, but how is DC Water focusing their green infrastructure plan. I know you are working on a couple P3's, but to what extent have you engaged the private sector in maintaining GI installations. ...
I may be just repeating what others have already stated, but the consistent theme in this thread is that GI is a tool in the suite of solutions to be considered and depending on your definition of green may or may not get you to your goal alone. The definition is highly variable by locality where geometry ...
The point of contaminating groundwater with salts actually is a much broader consideration during design for all pollutants that are expected to run off the area of interest. There are means and design methods, even for salts and other soluble pollutants, to remove these before the infiltration stage, ...
Are you looking to simply reduce CSOs or improve water quality? It can't hurt to look at GI to improve water quality but TBL/ancillary benefits should be accounted for as well for a more accurate comparison. Philadelphia has done a good job with this. Depending on your ultimate goals (what % reduction ...
I want to caveat again - infiltrating water at the ground level and including runoff from streets and sidewalks in northern climates risks infiltrating deicing salts into groundwater. I believe this issue requires more consideration in project planning than it currently receives. Rooftop water is generally ...