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What We Do
Combined Sewer Overflow Program
The Long-Term Control Plan
CSO Public Notification
CSO Map
What We Do
The Stormwater Process
Combined Sewer Overflow Program
Combined Sewer Overflow Program
What Is A Combined Sewer & How Does It Affect The Mississinewa River?
Almost every time it rains, raw sewage mixed with stormwater from combined sewers overflows into the Mississinewa River. Marion Utilities is currently addressing this problem, however, meeting Federal mandates may require significant financial expenditures that will affect the whole city.
CSO Public Notification
Long Term Control Plan
The sewer collection system consists of three kinds of sewers:
The theory behind the combination sewer was that during dry weather it could transport sanitary waste to the treatment plant. During wet weather, the sanitary waste would be flushed to the treatment plant by the influx of stormwater, and as the sewer reached capacity, the stormwater would overflow to the river. However, a large amount of sanitary waste also discharges to the river. This discharge is called a Combined Sewer Overflow (CSO).
Sanitary waste discharged to the river can have a drastic impact on the water quality of the river. High concentrations of metals from industrial discharges such as zinc, lead, copper, nickel, chromium, cadmium and mercury, low levels of dissolved oxygen due to the biological breakdown of organic waste and high levels of bacteria and pathogens can make the river unfit for recreational use, impair the rivers ecology, and in extreme cases, cause fish kills.
CSO Public Notification
Long Term Control Plan
The sewer collection system consists of three kinds of sewers:
- Storm sewers that carry only stormwater runoff.
- Sanitary sewers that carry only sanitary waste.
- Combined sewers that carry sanitary waste and stormwater runoff.
The theory behind the combination sewer was that during dry weather it could transport sanitary waste to the treatment plant. During wet weather, the sanitary waste would be flushed to the treatment plant by the influx of stormwater, and as the sewer reached capacity, the stormwater would overflow to the river. However, a large amount of sanitary waste also discharges to the river. This discharge is called a Combined Sewer Overflow (CSO).
Sanitary waste discharged to the river can have a drastic impact on the water quality of the river. High concentrations of metals from industrial discharges such as zinc, lead, copper, nickel, chromium, cadmium and mercury, low levels of dissolved oxygen due to the biological breakdown of organic waste and high levels of bacteria and pathogens can make the river unfit for recreational use, impair the rivers ecology, and in extreme cases, cause fish kills.
The History Of Combined Sewer Overflow Controls
The US EPA recognized the potential danger that CSO’s and other discharges posed to the nations water ways and passed the “Clean Water Act” in 1972. This Act no longer made it legal to construct combined sewer systems. However, this Act did not require CSO communities to reduce the number of combined sewers contained in their system, therefore communities continued to maintain and operate existing combined sewer systems. Realizing that more needed to be done to improve the water quality of the nations streams and rivers, the US EPA developed a national CSO Policy in 1989. With revisions in 1994, this policy set forth 9 controls which every CSO community must follow. These “nine minimum controls” are:
- Proper operation and maintenance of the collection system | This insures that each community has a preventative maintenance program to keep the system operating efficiently.
- Maximum use of the system for storage of excess flows | The more sewage that can be stored in the sewer pipes, the less that will be discharged to the rivers.
- Review and modification of industrial pretreatment programs | This involves working with the industries to reduce discharge volume and/or metal concentrations.
- Maximization of flow through the wastewater treatment plant | Most treatment plants are capable of handling more than their design capacity for short periods of time without affecting the quality of the effluent or harming plant operations. The more flow that can be brought through the treatment plant, the less that will be discharged to the river through a CSO.
- Prohibition of CSO discharges during dry weather | Some communities have combined sewer systems that are so hydraulically overloaded that overflows would occur without a rain event.
- Control of solid and floatable material in CSO discharge | This is mainly for aesthetic reasons to reduce the amount of trash and debris discharging to the river.
- Establishment of pollution prevention programs | Recycling, street sweeping, trash pick-up, and programs such as “Tox-away Day” all reduce the amount of trash that can eventually end up in the sewer system, cause maintenance problems, or be discharged to the river.
- Public notification of CSO occurrences/impacts | This involves public education on CSO impacts and possible dangers. Signage is placed at each CSO for identification with phone numbers to call if discharging is noticed during dry weather.
- Submission of a Stream Reach Characterization Evaluation Report (SRCER) to the Indiana Department of Environmental Management | This study measures the effectiveness of the first eight minimum controls, and identifies the impacts that a community’s CSO’s have on the river. After submission of the SRCER, each community must submit a Long Term Control Plan (LTCP) designed to reduce/eliminate the CSO’s.
What Are The Existing Conditions Of The City Of Marion’s Waterways
Sewer System?
Sewer System?
Marion’s sanitary waste collection system consists of approximately 75% combined sewers with 44 miles of sanitary sewer and 132 miles of combined sewers. Some of these sewers are over 100 years old. It should be noted that previous to the 1940’s, there was no Wastewater Treatment Plant in Marion and all sewers eventually discharged directly to the river. At one time the system contained over 15 CSO’s, however through a program of regular maintenance, and sewer separation, the collection system now contains only seven combined sewer overflows. It is estimated that, on average, 182 million gallons of raw sewage mixed with stormwater discharges from these on an annual basis.
Sampling along the Mississinewa River has indicated that the metal concentrations and other water quality parameters are within the normal standards with the exception of the E-coli levels. E-coli levels are higher than the acceptable standard (235 colonies/100mL) during dry weather and climb even higher during storm events.
Sampling along the Mississinewa River has indicated that the metal concentrations and other water quality parameters are within the normal standards with the exception of the E-coli levels. E-coli levels are higher than the acceptable standard (235 colonies/100mL) during dry weather and climb even higher during storm events.
What Is Being Done To Reduce CSO Events In Marion?
A study completed in 1988 showed that Marion discharged an average of over 1.1 Billion gallons of raw sewage mixed with stormwater runoff on an annual basis. With improved maintenance focusing of storage within the system and over $12 million in sewer separation and system improvements, it is estimated that Marion now overflows 55 million gallons in an average year.
The Long-Term Control Plan
The Long-Term Control Plan
More Information coming soon!
CSO Public Notification
CSO Public Notification
More information coming soon!
CSO Map
Combined Sewer Overflow Map
More information coming soon!
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