Two Harbors, MN – Wastewater Treatment Facility Upgrade

Project(s): Wastewater Treatment Facility Upgrade

Owner: City of Two Harbors, MN

Value: $29.2 million |  3-year schedule

Scope of Work: Lakehead Constructors was hired as general contractor to overhaul this 64-year old municipal wastewater treatment facility, which discharges an average flow of 1.2 million gallons of treated water daily into Lake Superior. The project also included replacement of processing technology (some of it 50+ years old) that was beyond its life expectancy. Lakehead self-performed all concrete work, crane support and heavy rigging for the project.

Facility construction posed special challenges, thanks to strong winds off nearby Lake Superior and below-zero temperatures in winter months. Accommodations included building the facility’s two 75′ diameter clarifier domes on the ground, then using cranes to set them on top of the clarifiers. This not only increased worker safety, but ultimately reduced the number of work days lost to weather, increasing productivity as well.

Sitework started with rock blasting, removing 451 cubic yards of rock from the site. Workers installed underground piping and encasements and constructed a 91’ diameter x 37’ tall biosolids storage tank. Construction of two clarifiers and four aeration basins, along with supporting infrastructure, required 7,000 yards of concrete and 630,000 pounds of rebar. Lakehead workers also installed new chlorine contact tank with temporary sulfur dioxide feed and temporary effluent sampler setups, and re-purposed filter feed and filter backwash pumps in the existing filter building. Other work included installing new equipment, lighting, pumps, and piping in existing buildings, and installing a sulfur dioxide feed system and an automated effluent sampler.