Tips for Successfully Starting a Sewer Bypass

You’ve done all the necessary planning for your sewer bypass and checked and rechecked every component as you installed it — and now the system won’t start.

“In spite of best efforts, there are times when some issues can arise,” said Bart Ros, Senior Product Manager at United Rentals. Ros recommends looking at these four potential trouble spots to eliminate the most common culprits.

Open the volute drain valve and close the priming system valve

There’s a lot of sophisticated planning that goes into the automatic priming system on a low-medium head pump, but when something goes wrong, the culprit may be simple: Someone left the drain valve open or the priming system valve closed.

“This is the first question we ask when we get a call about priming issues. If there’s one thing I’ve noticed throughout my career, it’s that valves have a way of magically opening or closing themselves,” said Ros.

Suspected leak in gasket or suction pipe/hose

Look for the easy fixes first. The answer could be as simples as a €5 gasket that’s cut or missing inside the suction hose.

“Do a quick check to make sure all gaskets are present and in good condition,” Ros advised. “Also, look for any physical damage such as holes or creases. Everything might have been good on installation but something may have happened as it sat during the night before startup.”

Check valve malfunction causing issues

If the check valve is open just a little bit, there is potential for an air leak. The check valve is a hard rubber flapper or seated ball that has a lip seal around its circumference, and over time it can wear out. If check valves do not make a positive seal, you will have an air leak.

“If you get to this point in your troubleshooting, inspect the valve and if it appears good, apply a thick coat of a petroleum jelly around the lip seal of the flapper. Push it down firmly to seat it and try the startup again,” Ros suggested.

The suction lift is too high 

“The suction lift can be tricky and depends on several factors,” said Ros. If you are working out of a manhole or wetwell, vault or other structure that is deeper than 8 metres, make sure you measure the vertical distance between the level of the water and the centerline of the pump.

Water levels fluctuate in sewer systems, and if the depth is greater than 8 metres, the pump will not prime. It’s possible the water level increased just when you were trying to start up your system. 

Planning and execution of a sewer bypass can be a large and costly undertaking and you should always consult with an expert regarding the specific circumstances, applicable rules and regulations related to your site and to your situation.

Read also “Sewer Bypass Success: Essential Tips for Planning and Implementation”