City of Mankato, Minnesota
The City of Mankato was experiencing problems with aging infrastructure and the need for improvements to support a growing community at an affordable cost. The city retained Bolton & Menk to design their clarifier improvements project. A facility plan was expedited to qualify for State Revolving Fund low-interest loans. Working within the existing site and integrating the improvements into the current wastewater treatment facility were key considerations. Design included the demolition of two, 90-foot diameter secondary clarifiers and pump building. The project added a new 100-foot diameter final clarifier and pump room including tunnel access; replaced two, 80-foot primary clarifier mechanisms; added primary clarifier flow monitoring, sludge pumping, and phosphorus analyzers; and added ferric chloride feed systems, tunnel upgrades, and electrical and HVAC improvements to support the modifications. The project was completed on time and within budget. A video was produced explaining the need for the improvements and the impact the improvements had on the city.