In New Zealand's Otaga region, Lake Hayes receives the wastewater from a sewer system serving about 560 homes. The wastewater is pumped over a distance of about 2.4 km to the Shotover treatment station, along pipes averaging 150mm in diameter. The system's duty point is 28 l/s at 75 m.
The site is in the Queenstown Lakes district and the system is maintained by Fulton Hogan. At the time of installation the system consisted of a pair of pumps, operating in alternation. On average, the pumps tended to foul every 2 days. Every time, the system's operator had to drive them 15 km to the workshop for cleaning.
The new electric pump was chosen with the aid of Pump Selector, the Zenit selection and configuration tool (zenonavigator.com). In view of the duty point (28 l/s at 75 m), Pump Selector recommended installation of a pair of Zenit Uniqa ZUG OC 100F 45kW 2 pole units.
One key criterion in the choice of Uniqa pumps with open channel impeller (for submerged installation) was the Anti-Clogging System (ACS), which keeps the impeller turning even with heavily soiled liquids. The ideal solution to give the operating authority welcome savings on running and stoppage costs. Apart from the ACS, the modular design of the Uniqa pump body and impeller allows fast action, on the spot, in the event of a breakdown, with no need to disconnect the pump and transport it to the workshop.
The Zenit Group is represented in New Zealand by White International NZ Ltd.. Working in close contact with Hall Machinery, White's distributor, the two Uniqa pumps, together with a set of DAC 100/100V couplers and guide pipes, were supplied early in 2015. Fulton Hogan installed the electric pump set in July 2015.
The Uniqa electric pumps have operated without a break since installation. System operator Fulton Hogan has not had to deal with a single fouled pump - no more tiresome trips to the workshop or system shutdowns.
The annual saving for the system's operator is estimated at over 30,000 New Zealand dollars.