Xylem's non-clog sewer by-pass solution

Flygt 3000 Series electric submersible pumps are a cost-effective and environmentally friendly rental alternative to diesel-driven pumps.
Flygt 3000 Series electric submersible pumps are a cost-effective and environmentally friendly rental alternative to diesel-driven pumps.
Using the Flygt N 3312 pump improved pumping efficiency and reduced operating costs.
Using the Flygt N 3312 pump improved pumping efficiency and reduced operating costs.

When a US pump station experienced a pump failure, a temporary sewer by-pass system had to be installed. Xylem Rental Solutions quickly identified the Flygt N 3312 electric pump as the best model to provide ­non-clog sewer by-pass solution.

Located 45 miles south of Nashville, the city of Columbia, Tennessee, has a population of approximately 36,000 people and is 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 (MGD) 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 sometime 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 of Columbia to engage Xylem Rental Solutions for emergency pump rental. The local Nashville branch quickly dispatched a Godwin HL250 diesel pump for an emergency sewer by-pass system. 

The challenge  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 on the project. 

To maintain treatment operations while the upgrades were completed, W&O Construction needed to set up a temporary sewer by-pass system, and because rehabbing the pump station would take several months to complete, the Columbia Wastewater Department made the decision to switch to electric- drive pumps to improve pumping efficiency and reduce operating costs.

For temporary by-pass projects that last longer than three months, electric by-pass pumps are a cost-effective option as they do not rely on expensive diesel fuel. However, Xylem Rental Solutions hit a snag in the process; the only Godwin electric option in the local fleet (Godwin HL250 pump with a 450 hp motor) was too powerful for the site’s 400 A service. 

Clogging issue “The local station didn’t have the correct electrical setup for the 450 hp pump,” explained 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.” 

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

The Xylem solution  Working with Ken Albaugh, director of sales, rental and equipment sales, 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 need 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 by-pass solution for many applications. 

Xylem offers a wide horsepower range of its versatile 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 ft. 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 innovative self-cleaning impellers, which are 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 quickly identified the Flygt N 3312 submersible pump as the best model for the Santa Fe Pike pump station by-pass. But while the Flygt N 3312 met the flow and head ­characteristics, it was too largeto fit down the sewer manhole. To address this new challenge, the Xylem team used a ­horizontal, dry pump installation. The Flygt N 3312 pump was delivered to Xylem’s dewatering fabrication center in Carterville, Illinois, 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 by-pass site in Columbia, Tennessee, where the rental solution operated continuously for the duration of the by-pass. “We took the technology off the Godwin priming system and married it to the Flygt pump ­performance,” Beasley explained. 

Results  With the Flygt N 3312 electric pump serving as the primary pump and the HL250 diesel pump still onsite as the backup pump, the temporary by-pass system has been running continuously with no issues and no clogging. ­Additionally, the use of an electric by-pass pump over a conventional diesel- powered pump has improved pump efficiency and reduced costs, resulting in savings of nearly $124,000 to-date.