Helical Anchor Install to Allow for Excavation
In 2010 on a project in Jacksonville, FL a client required excavation of a 35FT x 75FT space to allow for a new movie theatre. The excavation was within an existing building and would undermine several existing column pad foundations to a depth of 5FT that supported the structure and roof. The Owner through his own efforts pursued a process of supporting the columns while excavation would be competed. His means and methods would create challenges and multiple starts and stops in the work. He anticipated cost to exceed $100,000 to complete the work.
After a quick site review and load analysis, we determined installation of helical anchors would properly support the existing columns. We installed a total of 6 helical anchors, 2 at each column pad and 2 along an linear footing. This work was completed within one day and allowed excavation to proceed without any disruption in the following days. Total cost of the helical anchor installation was $7500 and the excavation cost $1000. Total savings to the Owner was over $90,000 and resulted in a significant time savings.
In 2019 on a project in Jacksonville, FL a client was required to create to retention ponds on their site, but due to limited space on the site the ponds would be in close proximity (5FT) to an existing building, new building, and the property lines. The ponds were excavated to a depth of 13FT and thus undermining the foundation systems for each building. The general contractor exhausted efforts with different systems to develop the ponds. This included cast-in-place concrete walls which are very expensive. They also explored steel sheet piles which was a costly solution, but ultimately landed on a stack stone concept that involved shrinking the ponds and providing underground water retention that would create additional cost for the Owner to resolve the challenge. This effort was estimated to cost $200,000.
Our team evaluated the site, met with material vendors, reviewed geotechnical data, and coordinated the engineering of a system that involved, helical anchors underpinning the existing and new foundations to a depth of 21FT. We then used a vinyl sheet pile to a depth of 12FT with an earth anchor tie back that did not interfere with the helical piles. These two systems allowed for a quick and efficient installation, allowing the excavation of the ponds to proceed. This was an important effort since this work directly impacted the critical path of construction of the new building which directly impacted the completion date. Total savings to the Owner was $70,000.
