In 2015, one of the largest retailers in the US, faced a unique and multi-faceted issue at one of their local NC locations, and URETEK MA was consulted as a sub-contractor. The retaining wall behind this local retailer, due to issues with original placement, was rotating away from the store. This retaining wall, which totaled approximately 450 feet in length, was situated between the store, and protected North Carolina Wetlands. Beyond the immediate priority of complying with NC regulations, and working to preserve these wetlands, space was also a major consideration. With both the wetlands, and limited work space to consider, traditional installation methods were immediately ruled out.
Access to the site was limited to the area between the store and the front of the retaining wall, and a small 10 foot area between the back of the retaining wall, and the start of the wetlands. Situating a crane in front of the retailer, to reach over the store, and hold the drill for the duration of the project was considered. This option was ruled out due to cost, and more importantly, leaving this NC location with no choice but to close during repairs, was not an option- a minimally disruptive plan was critical.
Successfully completing this project called for a creative, in-house solution, and a custom drill was fabricated. A pneumatic-powered drill was chosen due to its lighter weight design, and was mounted on the front of an extended-reach fork lift, using a custom winching system. This winching system used a hydraulic swing break to lower and raise the drill. The drill could be moved both up and down, but could also reach over the wall to work on the wetlands facing side of the retaining wall. This allowed the crew access to the retaining wall, without infringing on the wetlands with the necessary equipment.
Further precautions were taken to prevent water used during the project, from draining into the wetlands. A sump pit was constructed to collect the water used for drilling. The water was pumped back over the wall, away from the wetlands, and contained to a sediment tank. A berm was also used as an additional barrier between the work site and the wetlands.
For the completion of this project, 306 tieback anchors were installed at a depth of 35 feet. These anchors were installed using a Contech TITAN 40/20 hollow bar. Due to the sensitive environmental limitations, the anchors were drilled with water, and then grouted. This approach was chosen to eliminate any excess grout. The URETEK MA team worked for four months to complete this project, and was able to successfully repair the retaining wall. By working to remain non-invasive to the national retailer, and the vital wetlands, URETEK was able to craft a custom, creative solution to fit the needs of both the client, and the environment.