Self-priming sewage pumps installed at power station

The asset owner at the Mount Piper Power Station, Rainer Scheurer, was looking for a solution to the maintenance issues associated with his submersible sewage pump stations on the site. The problems were many and varied, including lifting chains breaking, pumps becoming stuck on their guide rails and general reliability issues. Even with everything going well, operators would be exposed to a 7 m fall into the pit while hoisting submersible pumps to the surface for maintenance.

Scheurer came to Hydro Innovations for some ideas on how he could get away from these issues. Hydro Innovations suggested the use of Gorman-Rupp self-priming sewage pumps, which would mean that only one operator would be needed for most of the maintenance issues and any work could be done without opening wet well covers. Scheurer liked the idea, but the pit was so deep that self-priming pumps could not be located at ground level.

Hydro Innovations suggested putting the pumps into the existing valve vault in order to get pumps closer to water level, re-using the path the old discharge lines took and connecting directly into the existing rising main in the valve vault. Gorman-Rupp’s V3B60-B pumps were chosen for the job, as they were capable of not only delivering the 15 L/s flow rate but also repriming the required 7.6 m suction lift — a tough ask for most self-priming pumps.

Hydro Innovations explained that most self-priming pumps with a full casing of liquid are capable of priming to this level, but repriming automatically, with only a partially filled casing (as casing siphoning can occur between pump cycles), is a totally different proposition. As Gorman-Rupp publishes guaranteed reprime lifts on its sewage pump curves, Hydro Innovations had no hesitation applying the pump on this suction lift.

Hydro Innovations was given the go-ahead on the project and set to work designing a piping and valve system that could comfortably fit in the valve vault. A compact but practical design was approved and the project was delivered. Mount Piper Power Station now has a sewage pump station that is undercover (inside the valve vault), is easily accessed without the need for lifting apparatus and can be safely maintained by one operator.