Designing Duluth’s “Grand Finale” lift station

Lift Station No. 8 is the final lift station on Duluth’s popular Park Point, a popular tourist destination. The Point’s single access is across the iconic, 180-foot-tall Lift Bridge. The lift station pumps all wastewater from the Point in a force main overtop the Lift Bridge.

Typically, sewer pipes are buried. But because of the city’s geography and geology, that wasn’t possible. The lift station pumps wastewater in a force main overtop the Lift Bridge. The Lift Station’s design addressed several unique challenges and goals set by the City. One of the largest challenges was to provide a constructible design while minimizing the risk of failure or overflow. The site was very small and not conducive to construction of a new structure. MSA’s design had to be rebuilt in the same location, while keeping the station operational at all times.

High levels of safety and reliability

Safety related to fall protection and electrical arc flash were primary objectives. A unique and innovative motor control center connects two electrical sources to the station. The system applied an isolated/separated source transfer control. In conjunction with the manufacturer, MSA designed the dual-feed electrical system that isolated a transfer device. This increases the system’s reliability and safety for operational staff since the lift station can be operated by either power source. It also allows both portions of the station to be completely isolated and de-energized, providing access for maintenance to the electrical power device while the station continues to operate in automatic mode.

The upgraded lift station was built with the latest energy-efficient LED lighting, Clean Power Variable Frequency Drives, energy recovery HVAC system and process equipment to minimize operational costs. The project qualified for multiple energy rebates in almost every category of construction.

Award-winning results

The new lift station structure blends into the neighborhood and features grass and plantings. In addition to increased energy efficiency, it also protects Lake Superior, which is a critical concern for the City of Duluth. When the power goes out, the lift station has backup power so sewage can be pumped from Park Point into the gravity system that feeds to the City’s wastewater collection system. Without this backup power, the sewage could be backed up into people’s homes, city streets and the nearby lake.

Now with the reconstructed lift station, the City has the capacity to support additional community development on Park Point, part of the community’s long-term vision of enhancing its close connection with Lake Superior. This project is the recipient of an ACEC-Minnesota Engineering Excellence Honor Award (Waste and Storm Water Category).