Xylem’s Flygt N3312 Electric Pump Provides Bypass Solution

By Bill Beasley

Forty-five miles south of Nashville is Columbia, Tenn., the county seat of Maury County. As part of its wastewater system, the city maintains 317 miles of gravity-enforced main sewer lines, 25 pump stations and a 14 million gallons per day wastewater treatment plant. In recent years, Columbia has engaged in sewer rehabilitation projects to help reduce or eliminate system overflows, including renovating and replacing several existing pump stations.

Among the pump stations slated to undergo scheduled upgrades in 2020 was the Santa Fe Pike pump station. But before those repairs could begin, the station experienced a major pump failure during the spring of 2020 that led to sewage overflows, spurring the city to engage Xylem Rental Solutions for emergency pump rental. The Nashville branch quickly dispatched a Godwin HL250 diesel pump for an emergency sewer bypass system.

Once the initial crisis was under control, the city of Columbia decided to move ahead with the $1.2 million planned upgrades for the Santa Fe Pike facility. City officials hired W&O Construction as the contractor for the project.

To maintain treatment operations while the upgrades were completed, W&O needed to set up a temporary sewer bypass system. Because rehabbing the pump station would take several months to complete, the Columbia Wastewater Department decided to switch to electric-drive pumps to improve pumping efficiency and reduce operating costs. For temporary bypass projects that last longer than three months, electric bypass pumps are cost effective because they do not rely on expensive diesel fuel.

However, Xylem Rental Solutions had a problem in that the only Godwin electric option in the local fleet – a Godwin HL250 pump with a 450-hp motor – was too powerful for the site’s 400-amp service.

“The local station didn’t have the correct electrical setup for the 450-hp pump,” said Bill Beasley, regional sales manager, Xylem. “The pump our competitor recommended to W&O Construction as an alternative isn’t made to pump solids. We knew clogging would be an issue.”

Finding the best rental solution

Seeking to ensure the Columbia Wastewater Department had the right electric pump and equipment for its temporary bypass system, Xylem’s Nashville branch tapped the experience and expertise of its national Xylem Rental Solutions base to identify the best solution within its rental fleet.

Ken Albaugh, director of sales, rental and equipment sales for Xylem, the Nashville team looked to Xylem’s Flygt pump line.

“It took Ken about 90 seconds to go through the Flygt options and identify a 3000 series Flygt pump with priming,” said Beasley.

For municipalities like the city of Columbia that needed to engage in lift station repairs or plant upgrades, Flygt 3000 Series submersible pumps are a cost-effective and environmentally friendly rental alternative that provides a quiet, efficient and easy-to-install bypass solution for many applications.

Xylem offers a wide horsepower for its Flygt 3000 electric submersible pumps – from 2 to 470 hp -- that can handle flow rates up to 16,000 GPM with heads up to 400 feet. The broad parameters of the Flygt 3000 series enabled Xylem to select the proper pump for this application. In particular, the Flygt 3000 Series pumps feature patented N-technology with self-cleaning impellers, designed to prevent clogs and build-ups. Made with robust, hard-iron impellers that are corrosion and abrasion-resistant, they also offer a long life span.

The Xylem team identified the Flygt N3312 submersible pump as the best model for the job.  But while it met the flow and head characteristics, it was too large to fit down the sewer manhole. To address this challenge, Xylem used a horizontal, dry pump installation. The Flygt N3312 pump was delivered to Xylem’s dewatering fabrication center in Carterville, Ill., where a crew built stands for both the pump and priming system within one working day. By the end of the weekend, the custom-engineered pump and priming system were delivered to the temporary bypass site in Columbia, Tenn., where the rental solution operated continuously for the duration of the bypass.

“We took the technology off the Godwin priming system and married it to the Flygt pump performance,” Beasley explained.

Running strong

With the Flygt N3312 electric pump serving as the primary pump and the HL250 diesel pump still onsite as the backup pump, the temporary bypass ran continuously for eight months with no issues and no clogging. The use of an electric bypass pump instead of a conventional diesel-powered pump improved pump efficiency and reduced costs, resulting in savings of nearly $125,000.

Bill Beasley is regional sales manager, Xylem.