Green & Gray Infrastructure vs CSOs

Many American cities have a problem hidden beneath their paved streets. Approximately 860 communities in the U.S. have combined sewers that carry commercial and residential sewage along with storm runoff. On dry days these aged sewer systems, parts of which may date back to the 1800s, route soiled water to treatment facilities. However, rain or melting snow can easily overtax the sewer systems, which causes the waste to spill into a local body of water. These spillages, called combined sewer...