by Larry Powell, Schneider Electric Water Wastewater Competency Center

Pumps & Systems, February 2009

When the City of Delaware, Ohio, expanded its wastewater treatment plant, it looked to increase more than just capacity. It also wanted to increase its efficiency and automation capabilities to benefit the plant's operators and taxpayers. 

Known as the Upper Olentangy Water Reclamation Center (UOWRC), the plant increased its capacity from 5.5-mgd average flow and 10 million gallons storm flow to 10-mgd average flow and 30 million gallons storm flow. The expansion was completed in September 2007.

Greg Doubikin, assistant wastewater manager, said the improvements also provided a considerable upgrade to the utility's monitoring and control capabilities.

"We went from being able to take some simple measurements, to being able to monitor exactly what's going on in just about every aspect of the treatment," Doubikin said. "We can also control a large percentage of the equipment and processes from this system."

Expansion Details

Figure 1Two of the five primary sludge pumps at the City of Delaware wastewater treatment plant.

In the community of 30,000 people, located just north of Columbus, recent growth required more advanced treatment systems and increased capacity. The original facility was a two-stage activated sludge plant with no primary treatment. Wastewater treatment included influent pumping, flow equalization, screening, grit removal, carbonaceous biochemical oxygen demand removal in first stage aeration, intermediate settling, ammonia nitrogen removal in second stage aeration, final settling, tertiary filtration, chlorination and post aeration.

The $25 million upgrade to the plant included the details in Table 1.






•·  Septage Receiver

•·  Emergency Generator and Switchgear

•·  Belt filter press (BFP) and modification to a second BFP to provide thickening of waste solids


•·  Influent Pump Station

•·  Pretreatment building with mechanical screening and grit removal that could process the peak wet weather flows

•·  Primary tanks and raw sludge pumping of facilities

•·  Aeration tanks with enhancements for biological nitrogen and phosphorus treatment

•·  Odor control systems for the pretreatment area and the sludge solids dewatering and covered storage tanks


•·  Two intermediate settling tanks and replacement of collectors to improve the capture of solids

•·  Existing aeration tanks to include biological treatment for nitrogen and phosphorus; chemical additions also were provided to ensure permit compliance

•·  Two final settling tanks and construction of a new 70-ft diameter final settling tank to assist with solids capture

•·  Tertiary filters to improve operations and maintenance

•·  Sludge solids storage tanks

Chlorine disinfection system with ultraviolet disinfection, followed by improved post-aeration of the treated wastewater

Administration building to house a large training room and the new SCADA control center


Table 1

The expansion was executed as a design/build project with Fredericktown, Ohio-based Kokosing Construction and Lexington, Ky-based Quest Engineers, Inc., selected as the design/build team. Kokosing/Quest organized a project team to address the critical issues of the project, such as design, construction, environmental protection, site development and landscape architecture/restoration.