City of Akron Rack 14 CSO Basin
The City of Akron Combined Sewer Overflow (CSO) Long Term Control Plan (LTCP) Update required construction of a storage basin to store storm and sanitary flow tributary to CSO Rack 14 to achieve zero overflows within the adjusted typical year.
Rack 14 is one of 34 permitted CSOs within the City’s collection system and controls overflows from approximately 240 acres of tributary area. Rack 14 influent flow rates used for design of the storage basin and associated structures exceeded 200 MG for the 100-year/1-hour storm.
Originally, Rack 14 flows were conveyed in combined sewers to the existing CSO Rack 14 regulator structure. Dry weather flow passed through the rack, into an underflow pipe and were conveyed to the Little Cuyahoga Interceptor. During a wet weather event in which the capacity of the underflow sewer was reached, flow overtopped a weir and was con-veyed through an overflow sewer to the Little Cuyahoga River. The completed storage ba-sin stores wet weather flow up to the typical year storm in the basin until the storm passes and capacity is available in the interceptor. Once capacity in the interceptor is available, the basin dewatering process is initiated and stored combined sewage is directed by gravity to the Little Cuyahoga Interceptor. Flow rates equivalent to dry weather flow are contin-ually conveyed to the interceptor during dry weather events.
The design of the Rack 14 CSO Storage Basin was based on a consent decree agreement entered into between the City of Akron and the US EPA that all existing combined sewage that currently overflows into the Little Cuyahoga River be intercepted and stored in an above ground basin so that it can be redirected to sanitary-only sewers and be properly treated.