Understanding Combined Sewer Overflows (CSO's) in Small Communities

WHAT IS A COMBINED SEWER SYSTEM?

When households dispose of wastewater from toilets, sinks, clothes washers, and 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 runoff 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 your 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 MY COMMUNITY?

Your community has posted signs along the receiving stream or river where the overflows can occur during heavy rain events.

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 collection system 2. Maximum use of the collection 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 MY COMMUNITY'S 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 MY COMMUNITY?

Each community will be holding several public meetings to discuss your community's specific combined sewer system. Input from the general public is very important in developing accurate and reasonable long-term plans. Plan on attending your community's public meetings, and getting involved in productive discussions. Another way you can become involved is to serve on a Citizens Advisory Committee or CAC. The responsibility of the CAC members is to help the decision-makers in your community, select long-term controls that best achieve the environmental goals of the community in an economically and responsible manner.

WHAT CAN I DO NOW TO HELP KEEP OUR STREAMS AND RIVERS CLEANER?

Every citizen of a combined sewer community can help minimize the impacts of overflows to local streams and rivers. 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 your 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.

WHO CAN I CONTACT FOR ADDITIONAL COMBINED SEWER OVERFLOW (CSO) AND WATER QUALITY INFORMATION?

FEDERAL

U.S. Environmental Protection Agency Office of Wastewater Management Water Permits Division
MC 4203M
1200 Pennsylvania Avenue, NW
Washington, D.C. 20460
(202) 564-0717
www.epa.gov/npdes/

STATE

Indiana Department of Environmental Management Office of Water Quality Compliance Branch, Wet Weather Section Government Center North
100 N. Senate Avenue
P.O. Box 6015
Indianapolis, Indiana 46206-WI 5
(317) 233-0473
www.in.gov/idem/water/

Indiana Dept. of Natural Resources Government Center South
402 W. Washington Street
Indianapolis, Indiana 46204
(317) 232-4020
www.in.gov/dnr/

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TOWN OF LOWELL

COMBINED SEWER OVERFLOW (CSO) COMMUNITY NOTIFICATION

As required by 327 IAC 5-2.1-6(1) (Combined Sewer Overflow Public Notification Rule), the Town of Lowell offers local media sources, affected public and other interested persons in and around the Lowell area information concerning the frequency of overflow events that may be triggered by precipitation. Any entity or individual desiring such information is requested to contact Greg Shook, Public Works Director at the Lowell Town Hall at (219) 696-7794 or, in writing, to the Lowell Town Hall, 501 E. Main Street, P.O. Box 157, Lowell, Indiana, 46356.