City of Columbus Southerly Wastewater Treatment Plant

New Headworks CIP 650352, Contract S-65 & S-67

The new Headworks facility at the Southerly Wastewater Treatment Plant, the largest treatment facility in the city of Columbus, will serve as a gateway for 330 million gallons per day (peak flow). The project was constructed in two phases and consists of two separate contracts: one for the Raw Sewage Pump Building, and one for the Screen and Grit Facility.

The $51-million Raw Sewage Pump Building includes four raw sewage pumps, which feature an innovative self-cleaning wet well designed to minimize the accumulation of solids, thereby reducing odors and maintenance, and eliminating the need for personnel entry. The building also features four mechanically cleaned bar racks, sluice gates, four 54-inch-diameter magnetic flow meters, instrumentation and control systems, plumbing, HVAC and electrical systems. The building is served by a new 102-inch-diameter inter-connector sewer, new outfall diversion structures, a new 14-by-18-foot plant influent sewer and a new influent junction chamber.

The $45.8-million Screen and Grit Facility will serve as a preliminary treatment facility, passing up to 330 million gallons per day through four 6-millimeter perforated panel screens in order to keep trash and other debris from entering the Scioto River. The facility also houses four 25-foot-diameter grit tanks with propeller/impeller and drive units, eight recessed centrifugal grit pumps, instrumentation and control systems, plumbing, HVAC and electrical systems. A system of 10 biological trickling filter towers will treat all of the air within the facility for odors without the use of chemicals.

The size and complexity of these two structures required separate contracts and H.R. Gray was selected to develop the schedule and manage both construction projects. Scheduling was critical to permit the contractors to coordinate their construction efforts at the jobsite. Adding to these challenges, a historic 100 year flood covered the construction site with three feet of water, which postponed the project for three months. However, H.R. Gray worked with the contractors on a recovery schedule and the project was completed on time and within the original budget.

More than 50,000 cubic yards of concrete were poured for the two buildings over a two-year period, including continuous monolithic pours of 1,500 cubic yards. Contractors used a special concrete mix that included ground granular blast furnace slag recycled from steel mills, and employed the facility's mass dewatering system to pump groundwater through cooling tubes to control the heat of hydration on the large pours.

The new Headworks facility will reduce backups and overflows caused by inclement weather and streamline the number of plant bypasses in the water treatment system.

 

Please contact H.R. Gray for additional information pertaining to any of our services.