Kennecott Humboldt Mill – Structural Strengthening
When Kennecott Eagle Minerals purchased a dormant mill in the Upper Peninsula of Michigan, numerous repairs were required to return the mill back to working condition. Known as the Humboldt Mill, the mill had served the region’s mining community from the 1950s until the 1990s.
Under its current ownership, the mill is utilized for production processes of copper and nickel mined from deposits nearby. The owner wanted to install bins on a mezzanine level in the mill to hold the ore after it was extracted from the mine, but the structure required upgrades to accommodate the loads.
Required improvements included enlarging 24 columns supporting the mezzanine level and strengthening the concrete floor. This had to be completed on a tight schedule in extreme weather conditions. PULLMAN was selected for the task because of the firm’s expertise and ability to meet the demands of similar challenging projects while maintaining high standards for safety and quality.
Project Design & Execution
Columns were designed to hold the required loads. To enlarge the columns, crews had to construct the specially designed formwork on site. The concrete needed to be pumped in one placement to minimize failures or voids. As such, self-consolidating concrete mix was specified by STRUCTURAL TECHNOLOGIES for the mix design. STRUCTURAL TECHNOLOGIES calculated the formwork requirements and generated the submittal drawings. Guidance from PULLMAN proved essential to coordinating with local ready mix suppliers who were new to working with this particular mix design.
To strengthen the columns, concrete scabblers prepared the surface for achieving the required bond. Rebar was added throughout the columns surface area for the enlargement of the 24 columns. The new concrete slab sections were heavily reinforced and placed over the enlarged column footings that PULLMAN formed, reinforced, and placed.
Michigan’s Upper Peninsula offered numerous challenges throughout this project. With limited resources available in this remote area, materials had to be shipped in from locations across the country. Coordination and scheduling were critical to completing the project within the owner’s timeframe. With the added obstacles of an early winter and tight working spaces, crews still were able to work efficiently and safely meeting all scheduled milestones.
In total, PULLMAN worked more than 11,000 hours on the job with no safety incidents and completed work on the Kennecott Humboldt Mill. The team met the owner’s schedule in the midst of a challenging work environment.