COLUMBUS CITY UTILITIES
Combined Sewer Overflows
Sewers have existed in Columbus since the latter part of the 19th Century. When they were first constructed they had a simple task, to transport water from inhabited areas to the river where it would go away. No classifications were placed on these waters as to whether they were polluted or not since the science of the time made no distinction on how these waters were handled.
By the 1940's it became clear to most that the rivers and streams in Indiana had to be protected from pollution by community sewage. Columbus joined most Indiana communities and constructed a wastewater treatment plant to improve polluted waters and prevent harm to the waterways. From that point on, sanitary flows have been handled separately from rainwater flows.
However it was considered cost prohibitive and unnecessary then to reconstruct the old 'single pipe' sewers and overflow weirs were built to direct the heavy flows that occur during rains and that the treatment plant couldn't handle to the rivers. This is the system that remains in place today.
The City of Columbus is moving forward with development of a long-term control plan for the City's combined sewer system. One of the most important steps to this process is to get public input on existing uses of the Flatrock and East Fork White Rivers. These two rivers receive the overflows from the City's CSOs. The first public meeting was held on January 30, 2002, at City Hall.
In order to provide background information, following are answers to some frequently asked questions regarding combined sewer system overflows and the associated programs.
What is a combined sewer system?
When households dispose of wastewater from toilets, sinks, clothes washers, or dishwashers, it travels through underground pipes to a Wastewater Treatment Plant (WWTP). The WWTP treats the wastewater to State standards before discharging it to a local stream or river. In some cities, however, older sewer systems were designed to also accept stormwater run-off from the city during rain events. A Combined Sewer System (CSS) is then a system of pipes that carry both wastewater as well as stormwater during rain events.
What is a (CSO)?
During dry weather, combined sewers carry wastewater to the WWTP. However, during a heavy rain event, a combined sewer pipe can get too full. These combined pipes were designed with “safety valves” that allow the combined wastewater and stormwater to overflow into a stream or river during rain events. If combined pipes did not have overflows, untreated wastewater could back-up into homes and businesses, and cause flooding in the streets. When the untreated wastewater and stormwater do overflow into a stream, this is called a Combined Sewer Overflow or CSO. The point where the overflow enters a stream is a CSO outfall.
Why are combined sewer overflows a problem?
The combined sewage that overflows into a stream contains various water pollutants. This combination of raw sewage and stormwater can carry a variety of human disease-causing bacteria and viruses, oils, chemicals, or other wastes and debris. There are also pollutants that can take oxygen from the river, making it difficult for fish and other organisms to survive. Overall, an overflow event poses a threat to water quality, aquatic life, human health, and aesthetic property values.
How long should I avoid contact with the stream or river after a CSO event?
There are several factors that affect the length of time a stream or river is impacted, such as the size of the stream, the volume of the overflow, the amount of pollutants introduced during the overflow, and the overall area that drains into the stream. Most public health officials generally advise that these areas be avoided for at least 48 hours after a heavy rain event.
How much rain does it take for a CSO overflow to occur?
Whether or not a system will overflow will depend upon how the sewer system was designed and built. Some communities will have overflows during a moderate summer storm, while other communities require a significant rain event of 2 or 3 inches before an overflow will occur.
How will I know where the overflow points are in Columbus?
Two points of CSO are located near the WWTP on the East Fork of the White River near Water Street and a third is located on the Flatrock River near Noblitt Park [MAP] Columbus has posted signs along the Flatrock and East Fork White Rivers where the overflows can occur during heavy rain events.
![[MAP]](images/CSOmap.jpg){kind=link}
What is my community's short-term plan to control CSOs?
In all, there are 108 communities across Indiana working on CSO plans. There are two phases to the planning process. The first phase, or short-term plan, is to develop a CSO Operational Plan, which outlines nine minimum “technology-based” control strategies. These nine control strategies are measures that can reduce the frequency and impacts of CSO discharges by minimizing capital expenditures. These nine controls are:
1. Proper operation and regular maintenance of the sewer pipe system
2. Maximum use of the sewer pipe system for storage of excess flows
3. Review and modification of Industrial Wastewater Pretreatment programs
4. Maximization of flow to the wastewater plant for treatment
5. Prohibition of CSO discharges during dry weather
6. Control of solid and floatable materials in CSO discharges
7. Pollution prevention programs (source control or reduction)
8. Public notification to ensure that the public receives adequate notification of CSO occurrences and CSO impacts
9. Monitoring to characterize CSO impacts, identify problem CSO points, and identify the effectiveness of the previous 8 controls.
These short-term controls result in minimizing the effect of overflows on local streams and rivers.
What is Columbus' long-term plan to control CSOs?
Developing a Long Term Control Plan (LTCP) is much more complex than implementing the nine minimal controls. The U.S. Environmental Protection Agency (EPA) and the Indiana Department of Environmental Management (IDEM) require that communities put forth considerable effort in developing strategic, sensible, long term plans that will meet State and Federal water quality standards. The LTCP will include specific mapping of the combined sewer system, identifying existing uses of rivers and streams, addressing sensitive areas, developing computer models, developing and evaluating control alternatives from a technical and economical standpoint, and developing implementation priorities and schedules.
What can I do to get involved and help the City of Columbus?
The first of several public meetings was held on January 30 th . The discussion introduced the program, and heard public comments on existing issues and the uses of the Flatrock and East Fork White Rivers. Future meetings will discuss suggested corrective actions and implementation schedule. Listen to your local news (radio and/or newspaper) or check this web page regularly for notification. If you wish direct notification, you can be included on our [CSO NOTIFICATION LIST]
Why are documenting existing uses of the Flatrock and East Fork White Rivers important?
IDEM and the US EPA both require that combined sewer overflow communities, including the City of Columbus, obtain public input on several issues. One of the first issues is that of documenting existing uses along CSO receiving streams and rivers, including the Flatrock and East Fork White Rivers.
The State has established designated uses for all “Waters of the State”, including the Flatrock and East Fork White Rivers. The designated uses are that the river water be clean enough for swimming and fishing. However, the City needs to document what areas, of the Flatrock and East Fork White Rivers are in fact used for swimming, fishing, boating, wading, or other recreational activities. Documenting these existing uses makes a difference on what the City can and cannot do in the future to minimize or eliminate overflows from the combined sewers.
What can I do now to help keep the Flatrock and East Fork White Rivers cleaner?
Every citizen of a combined sewer community can help minimize the impacts of overflows to local streams and rivers. If you live in a part of the City that has combined sewers, remember that everything that goes down the drain in your home, or washes into storm grates along the streets, has a potential of ending up in local streams and rivers. Try to avoid dumping strong chemicals, solvents, or paints down household or business drains. Also be aware of outdoor contaminating activities near storm drains. This could include such activities as storing, oils, herbicides, pesticides, general garbage and even grass clippings in places where they could wash into the storm drains.
If you would like additional information on the CSO LTCP program, you are invited to contact Keith Reeves, P.E., Director of the City Utility Office, or you may log-on to IDEM's CSO information website at http://www.in.gov/idem/water