Wastewater treatment key in environmental stewardship Published April 13, 2012 By Mike W. Ray Tinker Public Affairs TINKER AIR FORCE BASE, Okla. -- Tinker AFB has separate industrial and sanitary sewer systems, related Brandt Fleharty, Wastewater Program Manager for the Environmental Management Branch, Operations Section, 72nd ABW Civil Engineering Directorate. Approximately one-half to two-thirds of the wastewater produced daily in the 464 buildings at Tinker is discharged on the northwest side of the base directly into Oklahoma City's sanitary sewer system, to be processed by one of Oklahoma City's four sewage treatment plants. But wastewater from several facilities is tainted from industrial processes and therefore is handled differently. Those include Bldg. 3001, of course, as well as Bldgs. 2280, 2136, 3234, 3225, 3228, 3703 and 3705, Mr. Fleharty said. Wastewater contaminated with chemicals and/or heavy metals (chromium, cadmium, copper, zinc, lead, etc.) is sent directly to an industrial wastewater treatment plant for pre-treatment. After pre-treatment the industrial wastewater is mixed with wastewater from Tinker's sanitary sewer system and then discharged into Oklahoma City's sewer system, Mr. Flaherty related. According to Trudi Logan, Chief, Environmental Operations Engineering Section, Tinker's IWTP (located east of the intersection of East Drive and Industrial Road) processes 500,000 to 700,000 gallons of wastewater each day, which constitutes one-third to one-half of all the wastewater generated daily on the base. Sludge is a by-product of the wastewater treatment process. Since sludge from the IWTP is deemed to be a hazardous waste, it is shipped to the Lone Mountain landfill near Waynoka for burial. The Propulsion Maintenance Group plating shop recently installed a chrome meter for its wastewater pre-treatment process. "Instead of sending its wastewater directly to the IWTP for pre-treatment, the meter will recycle/reprocess any wastewater that has high concentrations of chrome," said Van Nguyen, a pollution prevention engineer in the Civil Engineering Directorate. By sending only low-chrome wastewater to the IWTP, "We hope to eventually bypass the IWTP and go straight into Oklahoma City's sewer system," Ms. Nguyen said. That would "greatly reduce costs and chemical usage at the IWTP," she said. A similar "green" measure introduced in the PMXG plating shop was a "5-tank alternative" to perchlorethylene degreaser that's used to remove wax residuals in the plating process, Ms. Nguyen said. The 5-tank alternative, a combination of non-toxic cleaners and water rinse tanks, is "better for employees and for the environment," she said. In yet another related matter, storm water runoff from the plating shop rooftop receives extra attention, Tinker Storm water Program Manager John Truong reported. Media filters have been installed on seven downspouts at Bldg. 3001 because zinc in the runoff rainwater exceeds permissible limits, he said. The zinc is from a galvanized steel air scrubber support structure on the plating shop rooftop. Galvanized steel is zinc-coated steel, Mr. Truong explained. The zinc coating reacts with the rainwater, instead of the iron in the steel, to prevent the steel from rusting as quickly. Over time, though, the zinc gradually leaches off into the water. The adsorptive media filters are designed to remove the zinc. The runoff rainwater from those seven downspouts is routed through a vegetated filter strip that Tinker's Environmental Management Branch constructed to aid in removal of the zinc. "Through the two treatment medias we are removing 40 percent of the zinc from the storm water," Mr. Truong said.