Municipal pump station rebuild

The challenge

A small water district was running three pumps installed in stages over twenty years. Two were oversized for the demand the town actually has now and were throttled at the valve; the third had been rebuilt twice. There was no flow metering worth the name, so nobody could say what any of it cost to run.

The district had assumed replacement meant a rate rise. It had not looked at the state revolving fund because a previous adviser told them the paperwork was only worth it above a threshold their project did not reach.

What we did

We metered the system for six weeks first, because an application that guesses at the baseline is an application that gets questioned. The data showed the demand curve had shifted enough to justify smaller pumps with drives rather than like-for-like replacement.

We specified the replacements to the efficiency tier the fund required, assembled the application with the metering data as evidence, and stayed on the file through two rounds of questions from the administrator.

The outcome

The work was completed in a single shutdown window. Energy use for pumping fell substantially against the metered baseline, and for the first time the district has flow and pressure data it can act on.

More usefully for them, the funded share meant the project was delivered without the rate rise they had been preparing residents for.

Equipment supplied

• Three variable-speed pump sets, sized to measured demand
• Variable frequency drives and new motor starters
• Magnetic flow metering on each line
• Pressure transducers and telemetry into the existing SCADA
• Control panel rebuild and sequencing

Figures are from the project file and the award documentation. The customer is not named at their request. Results depend on the site and are not a prediction for any other project.