Gunderson Lutheran Clinic - Cogenration System
Challenge
Gunderson Lutheran Clinic owned land near a tributary of the Mississippi River in La Crosse, WI where they planned to build a Cogeneration System. After three separate soil boring samples were conducted by Braun Intertech geotechnical engineers on site, the results proved that soil settlement could be an issue. Each boring sample was drilled to a depth of 31 feet below surface. The results showed that the water level was found at around 18 feet below surface, and the soil consisted of poorly compacted existing fill, as well as alluvial sands that were considered very loose. Due to the risk of potential damaging differential settlements, helical pier installation was recommended.
Solution
American Waterworks solved the problem by installing eighteen helical piles, designed to support the weight of the generator, despite the possibility of soil settlement in the specified area. The piles used were designed to have 10-12 inch double helix lead sections. The installation process of the helical piles took a total of two days to complete. Of the eighteen helical piles installed, four reached depths of 50-60 feet, while the other fourteen helical piles were installed at depths of 22-27 feet before reaching the correct (PSI) of 1750, which allowed for a safety factor of two, for the ultimate load capacity of 25 kip. The installation of the eighteen new construction, helical piles went smoothly. Combined; the helical piles stabilized the weight of the generator, sped up the entire construction process, and the project was completed ahead of schedule.
