Eugene/Springfield Water Pollution Control Facility 1984-1991

New Search

Section F: EQitIPMBNT MAINTSNANCB pretreatment comminutor, staff redesigned the internal cam follower and machined and replaced it with a solid aluminum/bronze rectangular slide block. No further breakdowns have occurred, sav- ing aconsiderable amount in repair costs and equipment downtime. GRIT COLLECTOR MECHANISMS In the first few months of operation, the grit collector mechanism broke several times and re- quired special modifications. The original system was designed without the guides that keep the grit collector flights in place, which allowed the drive chains to slip off the sprockets. By designing and installing guides, maintenance staff was able to correct the problem. The original wear shoes for the grit collector drive mechanisms were made of steel, which wore out within a short time. They were replacedwith shoes of polyethylene - a material that has a much longer life. The new shoes will save a considerable amount of money in replacement and repairs costs and in equipment downtime. COMBUSTIBLE GAS MONITORS Staff installed a continuous combustible gas moni- tor and an alarm system at pretreatment to wam employees if an industrial spill occurs. PLANT RECYCLE PUMP STATION The pretreatment recycle pump was modified by installing an oil system to lubricate lowerbearings. RETURN ACTIVATED SLUDGE PUMPS Within the first year of operation, the clutches on two of the return activated sludge pumps failed because of an inadequate anti-reverse clutch de- sign. Whenexamined, the manufacturerfound the clutches needed a modification that would allow properlubrication.Maintenance staffdisassembled the pumps, shipped them to the manufacturer, then reinstalled the modified parts; the manufac- turerpaid all modification expenses. Near the end of the first year of operation, mainte- nance staff found defective anti-reverse couplings Page 49 in the return sludge pumps. They were replaced with the help of the manufacturer. During the first year of operation, a pump shaft on a return activated sludge pump broke from the excessive torque resulting when the pumps started at full speed. Instrument technicians redesigned the lead/lag controls for the pumps, and a ramp star was installed to allow the pumps to reach full speed more gradually. DISSOLVED AIR FLOTATION (DAF) THICKENER During the process of thickening waste activated sludge, the drive chain for the flotation thickener broke down several times. Each breakdown took approximately nine hours to repair. The break- downs occurred after a new timed on/off control had been installed in the flights. Once staff mem- bers discontinued use of the timer control, they experienced no further problems. The collector flights now run continuously under variable speed control. DISINFECTION~DECHLORINATION EQUIPMENT During maintenance of the chlorinators, sulfonators, and evaporators at final treatment over the last five years, staff has replaced all regu- lators, gauges, diaphragms, and pressure vessels. TURBIDITY METER Staff installed a meter that continuously monitors final treatment turbidity. WZ SYSTEM In the second year of operation, several major failures of W2 pumps occurred. The lowerbearings of the magnetic clutch failed, creating enough heat to melt the slip-ring assembly. The problem oc- curred because the manufacturer's lubricant was unable to withstand the heat of the magnetic clutch. Staff switched to ahigh-temperature lubri- cant, but the clutch coil failed in one pump, and the electronic drive bearingfailed in anotherpump only one month after service. Less than a year later, the same pump bearing failed again. The plant purchased a new, larger end bell with two new