The Pros and Cons of Below-Grade Wastewater Pumps

July 23, 2021

One of the most important technological advances in the past couple hundred years has been wastewater treatment. Whether on a small or large scale, the ability to transport wastewater safely away has increased sanitation and minimized the risk of airborne and waterborne diseases.

A key cog of wastewater treatment is the wastewater pump. There are three main types of below-grade wastewater pumps used in water treatment facilities. They are dry-pit pumps, dry-pit submersible pumps and wet-pit submersible pumps. This article will cover the pros and cons of each type of wastewater pump.

Dry-pit pump

A dry-pit pump is typically located below ground next to a wet well. It’s housed in a dry pit (hence the name) and consists of a series of pipes, motors and drive shafts. The dry-pit pump is accessible via a superstructure mounted over the top of the well:

  • Pros: Because dry-pit pumps aren’t immersed in wastewater, their parts are easily accessible to personnel for monitoring, inspection and maintenance. This kind of pump is also safer and quicker for technicians to work on because the pump is not covered in sewage.
  • Cons: Dry-pit pumps are usually installed below grade, which makes them vulnerable to flooding. They also cost more than the other type of pumps and require more space to build.

Dry-pit submersible pump

A dry-pit submersible pump is a cross between a dry-pit pump and a wet-pit pump, which is also called a submersible pump. Its motor is affixed to the pump which, in turn, nullifies the need for the intermediate shaft. Glycol or sewage cools the motor as it runs.

  • Pros: This type of pump excels in tight spaces and isn’t susceptible to flooding like a dry-pit pump. (Speaking of dry-pit pumps, most of them can be altered to work as dry-pit submersible pumps.)
  • Cons: Problems can arise, like the motor overheating due to improper flushing of surrounding sewage. Additionally, retrofitting dry pumps can be tricky, as some of the pipes might not match up exactly, making the process costly and time-consuming.

Wet-pit submersible pump

This pump is sometimes just called a submersible pump or a wet pump. These wastewater pumps are designed to function within the wet well and use a tightly-sealed motor to perform their function.

  • Pros: Cost-effective and requiring relatively little construction, wet-pit submersible pumps don’t require a fully-built control center—just a cabinet over the well.
  • Cons: Submersible pumps are difficult to access due to their location amidst the surrounding wastewater and sewage. This makes monitoring, inspection and fixing problems extremely difficult if not virtually impossible—it also poses a safety hazard. Unfortunately, the pump usually breaks down before any problems are identified, and there’s not much that can be done about that.

Call for wastewater pump maintenance today

Now that you know some of the advantages and disadvantages of using dry-pit pumps, dry-pit submersible pumps and wet-pit submersible pumps, give us a call at Enviro-Line Co., Inc. We’re the leading authority on wastewater treatment and maintenance, and we’d love nothing more than to use our 50 years of experience to demonstrate that.

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Enviro-Line Co, Inc.