The City of Akron’s Long Term Control Plan (LTCP) update required the construction of a single storage basin (known as the “Hazel Storage Basin”) to achieve zero overflows within the adjusted typical year.
When the LTCP was updated, the minimum required storage volume to achieve this goal was approximately 2.5 million gallons.
Since the LTCP update, the recalibration of Akron’s hydraulic model of its sewer system has increased the required size of the basin to 3.6 million gallons.
After recent work with Akron’s Integrated Plan, the volume further increased to 4.5 million gallons. This increase optimizes the available capacity within the downstream Little Cuyahoga Interceptor (LCI).
Because of the size increase, the originally proposed area was not large enough to accommodate the increase in basin volume.
Seven locations were evaluated to select a new site. Alternative conveyance methods, such as gravity sewers, remote pump stations, siphons, and influent pumping at the basin were all considered. Each alternative configuration was then numerically rated to determine the best site for the project based on a number of factors. Considerations included impacts to local businesses, traffic and the community, as well as design, construction, and operational considerations.
Ultimately, a hybrid basin configuration was selected. The hybrid basin configuration allows the basin to partially fill by gravity for 27 of the 33 events during the Typical Year that the City’s LTCP model predicts that the basin will be activated.
Additionally, two 300-horsepower screw pumps have been designed to fill the basin completely during the larger storm events.
New sewers were also required as part of the Hazel Storage Basin project. The new sewers convey flow from the existing collection system to the basin, and eventually to the Little Cuyahoga Interceptor sewer. The new sewer system includes the construction of 78-inch, 48-inch, 36-inch, and 30-inch diameter sewers.
The Hazel Storage Basin project also includes rehabilitation of the existing sewers related to the Hazel Storage Basin and lining the Little Cuyahoga Interceptor sewer.
The Opinion of Probable Construction Cost (OPCC) for the Hazel Storage Basin Project is approximately $35 million and the project is on schedule to meet all of its Consent Decree milestones.