I shared a graph of Portland, Oregon’s CSO between the years 1990 and 2011. Between those years, it has been reduced from 6 billion gallons to about .3 billion gallons a year, because of work on the CSO control program, a set of cornerstone projects designed to remove millions of gallons of stormwater from the combined sewer system before construction started on large tunnel and other control facilities.
They constructed a pipeline that diverts Tanner Creek and smaller west hills streams from the combined sewer system to remove about 165-million gallons of stormwater annually from combined sewers, a tactic called stream diversion. About 3,000 stormwater sumps and sedimentation manholes in combined sewer areas throughout north, east and southeast Portland collect residential street runoff, trap sediment and pollutants, and allow water to soak into the ground. Residents in combined sewer areas disconnected roof drains from combined sewers removing more than 1.2-billion gallons of stormwater per year from the combined sewer system. Environmental Services eliminated combined sewers in key neighborhoods by installing new pipes to separate stormwater from sewage.
Seeing a successful project should give us hope that New York can accomplish this too. However, it took Portland almost 20 years to complete, so I think we should get a move on.
