The alarm in your pump station sounds when the level reaches the high level alarm float. This could be caused by a number of issues, mains failure, pump failure, rush in water ingress, etc.
If the alarm sounding is connected to a foul water pump station, please refrain from using any of the facilities connected to the pump station (toilet, hand basin, washing machine, etc.).
In the event of a high level alarm, please contact PPS on 0330 9000 999 as soon as possible.