WLSSD Secondary Clarifier Critical Failure Update
If you live in or visit Duluth, it is likely you’ve seen our large signature “domes” that glimmer in the sunlight from every angle. The domes are WLSSD’s mascot in a way, an iconic feature of the wastewater treatment process. The pot of gold to our wastewater treatment rainbow.
The largest domes that are the beacons of our wastewater treatment facility, known as secondary clarifiers, are just the tip of the iceberg. Each of the 4 secondary clarifiers can hold 2 million gallons of wastewater. Picture this—the dome-shaped top sits on a funnel-shaped bottom—and you end up with a giant ice cream cone structure. The shape informs its function. Let’s take a look.
When wastewater first gets to WLSSD, we screen out trash and grit, and provide the right environment for beneficial bacteria to breakdown and slurp up pollutants—cleaning up the wastewater in our “concrete river”. Then the wastewater flows into the clarifiers to quite literally, settle down. Wastewater solids like sticky, clumpy microbes; tiny tree bits; and itsy, bitsy Cheerio chunks settle to the bottom of the clarifier funnel, while cleaned wastewater “sits” on top. The clarifiers do just as their name implies – as the solids settle to the bottom and are then separated from wastewater, the wastewater becomes more clear – clarified! This step in wastewater treatment is crucial. We need the clarifiers to remove the majority of the suspended solids in order to send clean wastewater into the St. Louis River.
It just so happens that our clarifiers are in need of renovations. In October of 2022, one of our clarifiers incurred damage in its central operating mechanism that required us to shut it down. We are still dealing with the aftermath. This clarifier remains inoperable pending a mid to late summer delivery of replacement of the new center well pipe. In the interim, WLSSD completed an inspection of the remaining three clarifiers and found similar structural corrosion. To prevent immediate failure, WLSSD completed temporary repairs on these sections.
“It was sobering to see the degraded condition of the clarifiers during our inspections. We are pleased with the temporary repairs that have been made, but permanent structural and mechanical repairs are critical. WLSSD is seeking $17.5 million in state bonding funds to facilitate the completion of this project in a timely manner. The support we have received from our local legislators in this process is greatly appreciated.” – Marianne Bohren, Executive Director, WLSSD.
Want to see for yourself? We took a closer look at the damage recently, check it out!
This is a good reminder that WE CANNOT SETTLE FOR LESS! WLSSD will be making an increased request in the 2023 legislative session to cover half of the funding necessary to renovate all four clarifiers. We need your support now to ensure the continuation of clean water for environmental protection and public health. Talk to your state legislators today and remind them of the importance of WLSSD’s clarifiers for wastewater treatment—and a clean St. Louis River and Lake Superior. Thank you!