Existing Hill 57 pump station pumps were inadequate to meet peak hour demand in the pressure zone while maintaining adequate system pressure. Additionally, Pump 1 was 35 years old and neither was equipped with a variable frequency drive (VFD). The pump station limitations were exacerbated when the City scheduled a storage coating replacement project within the Hill 57 pressure zone.
In order to address immediate and future demands, a new 2,500-gpm vertical turbine pump with VFD replaced Pump 1 in the booster station. Increasing the capacity of one duty pump also allows the booster station to supply current peak hour demands in the Hill 57 pressure zone while the Skyline tank is off-line. An additional benefit of the VFD is reduction of pump starts/stops and associated hydraulic impacts to the distribution system through flow pacing based on system demands. Improvements included a new pump with piping, motor, VFD, valves, control devices and fittings to the suction and discharge headers.
Pump removal and replacement had to be scheduled during the low demand season to limit impacts to the distribution system. Although all available contractual and technical controls were employed a defective pump was originally supplied. Following a 15-week manufacturing and delivery period and two-week installation, defects were immediately obvious during equipment startup. Through correspondence with the manufacturer, it was discovered that although the vertical turbine pump was manufactured for a submerged applications rather than exposed conditions. The manufacturer failure was in spite of clearly identified operating conditions in the Construction Drawings and technical specifications that were reiterated in the shop drawing review. The pump was field repaired to the extent possible and commissioned for temporary operation during the peak demand season while the correct pump configuration was manufactured. Ultimately, a new pump fabricated for open air conditions was delivered and replaced the temporary pump.
Client Name
City of Great Falls
Job Site Location
Great Falls, MT
