Columbus, Ohio
900,000 population
Clean streams.
Strong neighborhoods.
EPA Region 5
The Scioto River with Columbus Skykline.
Photo courtesy of City of Columbus.
Columbus is the capital of Ohio and has a population of nearly 900,000. The
city operates separate sanitary, combined, and storm sewers that discharge to
the Scioto and Olentangy Rivers. The separate sanitary and combined sewer
systems connect to two wastewater treatment facilities that discharge into
the Scioto River. The river runs through the middle of downtown Columbus. In
2015, Columbus opened the "Scioto Mile"—a massive project to rehabilitate
the river that included habitat restoration, miles of trails, and 33 acres of new
Columbus agreed to eliminate SSOs and basement backups and to address CSOs in two separate consent orders,
filed with the Ohio Environmental Protection Agency (EPA) in 2002 and 2004. To meet all the consent order
requirements, the city developed a combined Wet Weather Management Plan (WWMP) in 2005, which had an
implementation cost of $2.5 billion over 30 years.
During heavy storms, stormwater and groundwater enter Columbus's sanitary
sewer system through cracks and improper connections (i.e., infiltration and
inflow). This leads to sewage releases in the form of sanitary sewer overflows
(SSOs) and backups into basements. In addition, large storms cause combined
sewer overflow (CSOs) and bypasses at the wastewater treatment facilities.
These overflows and bypasses lead to the discharge of sewage and partially
treated wastewater into the Scioto and Olentangy Rivers. Both wastewater
treatment facilities have permits that require the city to control these
discharges. Columbus also has a stormwater permit that requires the city to
implement a management plan to improve stormwater quality. All three permits
implement total maximum daily loads (TMDLs) for bacteria, nutrients, sediment,
and total suspended solids.
Integrated Planning in Action
In 2012, the city began an integrated planning process to update the 2005 WWMP and consider more beneficial
and cost-effective solutions to address SSOs, CSOs, and stormwater pollution. Columbus used a city-wide
engagement approach, called Blueprint Columbus, to educate residents about sewer overflows, get feedback on
proposed options, and improve outreach to homeowners. The city also created a community advisory panel to
provide guidance during the development of the plan. Planners developed and analyzed two options for updating
the 2005 WWMP:
¦ A "Blueprint" option that focused on reducing the sources of infiltration and inflow and implementing green
infrastructure in certain areas of the city (see box on below).

¦ A "gray" option that focused on managing a likely
increase of flows overtime. This option would use
tunnels for excess storage, increase the size of
sewer pipes, and clean and line pipes to transport
and minimize sewer overflows.
Columbus first compared how well the options could
achieve compliance goals, additional water quality
improvements, regional economic benefits and job
creation, neighborhood benefits, and sustainability.
In addition to meeting all water quality compliance
obligations, green infrastructure in the Blueprint option
would achieve a greater reduction in overflows and
remove an estimated 342 tons of sediment each year.
Columbus also estimated that the city's investment in
maintaining private laterals would save homeowners
$453 million, and that the Blueprint option would create
more than 700 jobs over 20 years.
Next, Columbus evaluated how the cost of the two
options would affect water and sewer bills, particularly
for households with lower income. Analysis showed
that even with a faster 20-year implementation
schedule, the Blueprint and gray options would require
lower rate increases than the 2005 WWMP, which had
a 30-year schedule.
After considering implementation schedules, Columbus
tabulated how much each option would cost in total
over 20 years. The city determined that the Blueprint
option would be more expensive than the gray option.
However, it chose to invest the additional funds
because of the stormwater quality benefits and the
larger reduction in overflows that the Blueprint option
would achieve.
Columbus estimated that revising the 2005 WWMP
using the Blueprint option would require capital
costs of $1.74 billion, with an estimated operation and
maintenance cost of $60 million over 20 years (through
2035). The capital cost estimate includes $400 million
for some projects identified in the 2005 WWMP,
including adding a process to partially treat bypasses
at the wastewater treatment facility, and $1.3 billion
for new green infrastructure and infiltration and inflow
reduction projects.
In 2015, Columbus finalized its Integrated Plan and
2015 WWMP Update Report. The Ohio EPA approved
the plan that same year and incorporated it into one
of the city's existing wastewater treatment facility
permits. Columbus has made significant progress
in implementing the plan's "pillars," which include
installing more than 400 rain gardens along roadways
and parking lots, more than 30,000 square feet of
porous pavement, and 350 private sump pumps—along
with assessing more than 670 homes (25 percent of the
target number) for improvements to reduce infiltration
and inflow. As a result, the city experienced 30 percent
fewer SSOs in 2019 than in the previous year, despite
above-average precipitation.
Four Pillars of the Blueprint Option
¦	Installing green infrastructure (rain gardens and porous pavement) to
help slowly filter water
¦	Redirecting downspouts so runoff from roofs goes into the storm sewer
¦	Installing sump pumps to direct excess groundwater to the storm sewer
and keep it from getting into the sanitary sewer
¦	Lining pipes (specifically, "laterals" that connect homes to the sewer
main) to reduce infiltration through cracks
For more information, visit EPA's integrated planning Report to Congress webpage at:
EPA-832-F-21-020 I June 2021