| What are Combined
Sewers and Combined Sewer Overflows (CSOs)? SANITARY,
STORM & COMBINED SEWERS
Three types of sewers exist in the City of Akron: separate
storm sewers, separate sanitary sewers and combined sewers. Separate storm sewers collect
rain water that falls on roads, parking lots and roof tops and sends the rainwater
directly to streams, rivers or lakes. Separate sanitary sewers are typically smaller in
diameter and collect domestic sewage and industrial waste from houses, schools, stores,
factories and other buildings. The sanitary sewers transport the waste to larger combined
interceptor sewers which sends the waste directly to the Akron Waste Water Treatment
Plant. The third type, Combined sewers, carries domestic sewage, industrial waste and
rainwater. Combined sewers are larger in diameter and make up the main sewage network of
the Akron Sewer System. When it is not raining, all the domestic sewage and industrial
wastewater goes through combined sewers and transports the waste directly to the Akron
Waste Water Treatment Plant. When it does rain significantly and the amount of collected
rain plus the domestic sewage and industrial wastewater exceed the capacity of combined
sewers, the combined sewers overflow into the Cuyahoga River, Little Cuyahoga River, Ohio
Canal and Camp Brook. Such an event is called a Combined Sewer Overflow, frequently
abbreviated to CSO. All interceptors are combined sewers. Thus, all separate sanitary
sewers must travel through a combined sewer interceptor to be treated at the Akron Waste
Water Treatment Plant.
Fully Separate Sanitary and Storm Sewer
System

Combined Sewer System

The majority of overflow from a CSO is rain
water. Although, the overflow does include a small percentage of the domestic sewage and
industrial waste. Different types of contaminants can be present in the overflow including
pathogens, oxygen-demanding pollutants, suspended solids, nutrients, toxics and floatable
matter.
Approximately 772 cities in the US, including the City of
Akron have combined sewers. |