E-5: Oakdale CSO Storage Basin
(Area in purple is the Oakdale CSO Storage Basin)
Beginning 10/26/2011, there is a 30-day period to provide comments/responses to this Public Notice fact sheet.
City Contact for Questions
David Selhorst at (419) 727-2615
Background
The Toledo Waterways Initiative (TWI) is a federally mandated program to protect area waterways by reducing sewer discharges that typically occur during wet weather. TWI consists of three major components:
- Doubling the capacity of the Bay View Wastewater Treatment Plant (WWTP) to eliminate all bypasses of partially treated sewage
- Eliminating all known sanitary sewer overflows (SSOs)
- Significantly reducing all combined sewer overflows (CSOs)
TWI’s first component was completed in 2007, and the second is well on the way toward completion. The third component, reducing CSOs, was initiated in 2008 and is now well underway with completion planned in 2020. The work included in this final component is covered by the CSO Long Term Control Plan (LTCP), which was approved by the USEPA in 2009. It consists of 25 projects, including the Oakdale CSO Storage Basin (See accompanying map).
Existing Conditions
The area to be serviced by the Oakdale CSO Storage Basin is located in southeastern Toledo, near the City’s border with Wood County. The combined sewers (carrying both sanitary and storm flows) in this area were mostly constructed between 1900 and1930. These sewers drain into a 93-inch diameter trunk sewer, which originally discharged all flows into the Maumee River.
In 1927, the Oakdale Regulator, located at Miami Street and Oakdale Avenue, was constructed to divert dry-weather flows in the 93-inch trunk sewer through a return line to the newly constructed Eastside Interceptor. This interceptor conveys the flows to the Bay View WWTP. Wet-weather flows, exceeding the capacity of the return line, overflow a weir wall in the regulator and are discharged into the Maumee River. These permitted CSOs occur on average 25 times per year.
Planning – Consent Decree and LTCP
The design criteria established by the LTCP requires that CSOs through the Oakdale Regulator be reduced to an average frequency of 2.6 overflows per year by constructing a new storage basin, estimated at 4.5 million gallons (mg) capacity. Once the wet-weather event is over, the overflow captured by this storage basin will be released to the Eastside Interceptor for treatment at Toledo’s Bay View WWTP. After the LTCP was written, additional flow monitoring and hydraulic modeling indicated an 8.0 mg basin would be required to meet the 2.6 overflows per year requirement.
Alternatives Evaluation
The LTCP initially identified Pilkington North America’s (PNA) unused treatment lagoon, Pond 5D, as a potential site for the Oakdale Basin. The site is low-lying, near the Maumee River and in close proximity to an existing CSO outfall. Subsequently, PNA began to re-use the pond for daily treatment of its industrial-process wastewater flows.
An alternatives analysis was performed to evaluate the cost-effectiveness of still siting the basin in Pond 5D, with provisions to address PNA’s use of Pond 5D, versus siting the basin at an alternate location. A total of four locations, including Pond 5D, were evaluated.
In the final analysis, it was determined the Pond 5D site has sufficient space to construct the basin and is the lowest-cost option, even with provisions to accommodate PNA’s current use of the pond.
Use of Pond 5D as the storage basin location will require the City to obtain approximately 40 percent of the pond, with the remaining 60 percent retained as the treatment lagoon for PNA processes. An analysis shows Pond 5D has sufficient capacity to handle both TWI and PNA’s needs.
Proposed Oakdale CSO Storage Basin
The proposed CSO control project will consist of an 8.0 mg, offline CSO storage basin located in the southeast corner of the PNA Pond 5D. A diversion structure will be constructed on the existing 93-inch CSO outfall pipe to divert flows to the storage basin via a new 108-inch sewer. Once the basin is at its 8.0 mg capacity, excess flows will overtop an overflow weir in the diversion structure and empty into the Maumee River via the CSO outfall pipe.
After the wet-weather event has passed, capacity will become available in the downstream interceptor sewer, pump station and WWTP. At that point, the basin will be dewatered via a 5.3 mgd dewatering pump station, conveying stored flow to the Eastside Interceptor for treatment at the Bay View WWTP.
Construction Related Impacts
Construction of the basin will temporarily require PNA to use its Pond 5C for daily treatment of process flows. Increased construction related traffic will be experienced on Miami St. and Oakdale Ave. The contractor will be required to clean construction related dust/debris that accumulates on these streets. Construction of utilities serving the site and connecting the new facility to the Eastside Interceptor will temporarily impact traffic flow along Miami St. However, most of the construction will occur on the current Pond 5D site that is located away from both residential and commercial areas. Construction-related noise is not expected to be a nuisance.
Schedule and Cost
The current schedule for this project has construction contract bidding in January 2012 with construction beginning in the spring of 2012 and initiation of operation of the facility scheduled for the fall of 2014. The current estimated construction cost for the Oakdale CSO Storage Basin is $20,180,000.