Babbitt Wastewater Treatment Facility

Challenge

Since 2012, SEH has worked with the City of Babbitt, Minnesota, to navigate evolving regulatory requirements while maintaining reliable wastewater service for the community. As part of these ongoing efforts, the city needed to meet the state's effluent mercury discharge limits due to its location within the Lake Superior watershed. With an aging wastewater treatment facility dating back to the 1950s, the City faced the challenge of upgrading its system to comply with these evolving regulatory requirements while also improving efficiency and reducing operational costs.

Solution

SEH began with a condition assessment for the existing facility to review plant capacity as well as building and tank conditions. This was followed by a facility plan that explored treatment alternatives and provided documentation necessary for funding eligibility through the Public Facilities Authority (PFA). These efforts led to two major improvements:

• The addition of fine screening at the main lift station
• The construction of a new advanced membrane bioreactor (MBR) treatment facility to replace the aging infrastructure

These upgrades not only ensured compliance but also streamlined operations, reduced maintenance demands, and enhanced overall system reliability.

Main Lift Station Upgrade
The first major improvement was the upgrade to the main lift station, completed in 2018. This project involved retrofitting a new 6mm vertical fine screen within the existing wet well and constructing a new screening room above it. By protecting downstream equipment from debris and optimizing flow, the new fine screen has reduced maintenance needs and extended the lifespan of critical infrastructure. Additionally, the climate-controlled screening room provides extra benefits by creating a safer and more efficient workspace for City staff.

Building an Advanced Membrane Bioreactor (MBR) Treatment Facility
In 2019, SEH updated the facility plan and initiated the design of a new MBR facility. A crucial early step was the preselection of MBR equipment, ensuring the membrane bioreactor system would serve as the foundation for the design. After a pause in 2020 to secure funding, the project moved forward with design and bidding in 2021.

SEH was able to help the City obtain funding that was crucial to the success of the project, moving forward to completion. Overall, the City secured over $12 million in grant funding to pay for the $18 million project.

The Mercury Removal Improvement project introduced a new pretreatment building, aeration tanks, MBR treatment building, aerated sludge tanks, sludge storage tank, sludge loadout building, and plant recycle lift station. The project included the following:

• Parshall flume for influent flow measurement
• Vortex grit equipment and grit classifier/washer
• Rotary drum fine screens with 1mm openings to protect membranes downstream
• Fine bubble diffusers in aeration tanks
• Membrane Bioreactor (MBR) system
• Blowers for aeration tanks and MBR tanks
• Permeate (treated effluent) pumping
• Chemical storage and pumping for MBR cleaning
• A laboratory and office space
• New SCADA system and controls
• In-line UV disinfection
• Return activated sludge (RAS) and waste activated sludge (WAS) pumping
• Sludge storage pumping and loadout pumping
• Sufficient sludge storage with means of lime stabilization
• Plant recycle lift station to pump drains to head of plant
• Backup diesel powered generator to provide backup power to entire facility

Additionally, the existing aeration tanks from the original plant were repurposed as aerated sludge holding tanks to reuse as much existing infrastructure as possible. Throughout the two-year construction project, the existing treatment system remained in operation to ensure uninterrupted service to the community.

A Smarter, More Sustainable Future for Babbitt
Through a collaborative and phased approach, Babbitt now has a modernized wastewater treatment system that not only meets strict mercury discharge limits but also improves operational efficiency, reduces long-term costs, and provides more reliable service to residents. The advanced MBR system produces high-quality effluent that requires less operator intervention compared to older technologies.

With a future-ready facility, Babbitt is well-positioned to meet evolving environmental regulations while minimizing operational challenges. City staff now have a more efficient and user-friendly system, allowing them to focus on proactive maintenance and long-term sustainability. SEH’s partnership with Babbitt ensured that these improvements were not just about compliance, but also about creating a smarter, more resilient wastewater treatment system for the community – ultimately Building a Better World for All of Us^®.