Glenview Hotel, Co. Wicklow

This was one of the most challenging pumping stations we have undertaken due to the complexity of the rising main route and variations in flow. The client had detailed weekly water consumption figures. Thus, we knew the amount that had to be pumped on average. The difficulty was determining the total dynamic head and designing a suitable pumping arrangement.

A route for the rising was chosen by the client and subsequently surveyed. On a preliminary basis, it was assumed that the rising main would be 700mm below ground level. The survey showed that there were 9 high points on the rising main and it was 3,200m long. Due to the topography of the route, the rising main is almost entirely empty when the pumps are off. When pumping for the normal duration of 3-5 minutes, steady state would not be achieved. A HDPE rising main with an internal diameter of 100mm was chosen. This diameter reduced the possibility of septicity. After detailed design and a hydrodynamic analysis, we selected the pump, designed sump, and selected method of control. The hydrodynamic analysis indicated that double acting air release valves should be located on each high point. To prevent any gross solids depositing in the rising main, a coarse bar screen was installed. 24 hour storage was provided in an overflow sump. To prevent the accumulation of solids, rags etc, in the sump, a submersible mixer was installed in the sump. This operates for a short period prior to a pump starting. An interlock prevents the mixer and a pump running simultaneously in either manual or automatic mode.

As steady state is not achieved during pump operation, an extended soft start/stop was selected. This was achieved using an inverter. A conventional soft/stop starter does not achieve the extended ramp-up time required for this project. The ramp-up time is 5min and ramp down time is 30seconds. A conventional soft start was provided as back-up in the event of inverter failure. The method of starting can be changed by a switch on the panel door. The rising main was then laid. It was re-surveyed to confirm pump selection.

Two ABS Pump Model AFP1045 M140-4 were installed in the sump. These pumps have a 14kW motor. The solids passage is 100mm. All sump pipework is ductile iron. The valves and flowmeter are located in a separate valve chamber. A drain down line is also provided.

The pumping station has performed well and has now operated successfully since 2004. The only operational problems to date have been a damaged float switch and a problem with incoming power supply to the panel for a short period (the voltage at the control panel was outside normal tolerance, preventing inverter and soft start from working). The float switch was easily replaced.

We carry out a complete maintenance check every 6 months.

Commissioning date: July 2004

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