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Case Study Pump Replacement By The Numbers Making the case for pump upgrades through cost-benefit analysis. by Steve London ndy Myracle knows how to make a strong case for facility upgrades to his senior management. As plant maintenance superintendent for Jackson Energy Authority, Myracle had watched aging — and high-maintenance — pumps in one of the utility's lift stations demand ever increasing man-hours for outages even after stepped up proactive maintenance inspections. The electric meter at the duplex station also implied recurring drag on the impellers and clogging resulting in high power consumption. These combined factors steadily sapped more and more of his budget, and the frequency of failures raised the risk of sanitary sewer overflows (SSOs). Given these recurring problems at the facility, Myracle felt replacing the pumps was the logical solution and began compiling the incremen- tal costs in electricity, man-hours, and truck use to make a document- ed case for replacing the pumps at the 321-gpm facility. This type of evaluation can help support future capital upgrade proposals for other projects to senior management. A "My reasoning was to show on paper our rising operating and maintenance costs that management could easily relate to in justifying the replacement cost for new pumps," Myracle said. "This particular station offered a good opportunity to show the before and after results of an upgrade. The electri- cally metered station also allowed a test of a new type of submersible pump whose energy efficiency and clog resistant impeller could also reduce our risk of SSOs." The before-and-after results strongly reinforced Myracle's credibility when proposing the recent capital improvements and future projects. A Utility Authority With Multiple Services Jackson Energy Authority evolved from its 19th century ori- gins into the present status as an autonomous public utility created by action of the state legislature in 2001. The util- ity supplies electric, gas, propane, water, wastewater, and 32 Water Online The Magazine, Wastewater Edition ■ wateronline.com broadband services to about 40,000 residences, businesses, and industry in Jackson, TN, and parts of Madison County. It remains one of the few utilities in the nation with this broad diversity of operations. The sanitary sewer system consists of approximately 33,200 connections, 2.8 million feet of collection lines ranging from 2-inch force mains up to 54-inch gravity lines, 120 lift stations, and two wastewater treatment plants. The treatment plants consist of a 6 mgd (million gallons per day) SBR facility and a 25-year-old, 17.4 mgd extended aeration plant. The Jackson Energy Authority sewer plant recently underwent an upgrade that replaced the original counter-current aeration system with a fine bubble diffuser system. The Authority's larger plant recently underwent a $2.6 mil- lion upgrade that included an improved process in the plant's two aeration basins. The proj- ect replaced the original counter- current aeration system in the two, nearly 9-mg basins with a Sanitaire fine bubble diffuser sys- tem. Also replaced were 10 cen- trifugal blowers previously serv- ing the two aeration basins. This involved the installation of six, 4500-cfm Neuros high-efficiency turbo blowers. Instead of the mechanical counter-current aeration, each of the basins, which have individual deni- trification cells, now are aerated by 9,000 Sanitaire mem- brane discs serving the eight zones in each tank. By eliminating the moving parts of the older mechani- cal aerators, Myracle expects an end to the excessively high maintenance imposed by the aging apparatus that had struggled and sometimes failed to deliver the plant's original design capacity. Bringing Man-Hour Expense Under Control Similar high maintenance has plagued the Rolling Acres Lift Station equipped with two, 7.5-hp/3-phase pumps. The facil- ity serves a mature residential area whose wastewater flows to the 6-mgd SBR wastewater treatment plant. "The Rolling Acres station presented ongoing problems for us due to age and clogging typically associated with older