History
A 19-square mile area of Atlanta, with Downtown as its center,
is served by a combined
sewer system. In a combined system, a single large sewer
pipe carries both sewage and stormwater
to a water reclamation center for treatment.
Combined sewers were built from the late-1800s until the mid-1900's
in many major metropolitan areas. The practice has since largely
been discontinued.
During heavy rains, storm flows often exceed the capacity of
the combined sewer pipe. The Atlanta sewer system was upgraded
so that combined flow is diverted to one of seven CSO
control facilities. When the rains exceed the treatment capacity
of the CSO control facilities,
screened and disinfected flows are discharged to a nearby stream
or creek.
The City currently operates four CSO treatment facilities on
the West side of Atlanta and three on the East side. The East
Area facilities, installed in the mid-1980s, currently use storage
(a tunnel at the Custer Avenue facility and a vault at the McDaniel
facility) and treatment designed to eliminate trash and disinfect
all overflows to reduce bacteria. The West Area facilities,
installed in the early 1990s, treat overflows using screening
and disinfection also designed to remove trash and reduce bacteria.
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