Transformer Vault Installation Relies on Multiple Protective Systems Coble Trench Safety shoring specialist, Bob Jellison plays a key role in assisting contractor in a project to install transformer vault for hospital additions. The Specifics The contractor was installing a transformer vault which was to power new additions to a hospital. The customer was excavating a trench that was approximately thirty-eight in length, twenty feet in depth. The project was planned to be twelve feet in width. A portion of the trench needed to go under an existing duct bank. The duct bank was approximately four feet from the top of the excavation and ran perpendicular to the trench. If you're facing a particularly challenging trench job, give Coble Trench Safety a call to learn how we can help you get it right the first time. Atlanta, GA 1.877.312.1776 Baltimore, MD 1.866.951.0809 Birmingham, AL 1.877.312.1782 Charleston, SC 1.866.957.3624 Charlotte 1.877.587.3624 D.C. / Northern VA 1.866.887.3624 Greensboro (Corporate) 1.866.587.3624 Greenville, SC 1.877.312.1780 Jacksonville, FL 1.877.312.1783 Knoxville, TN 1.877.312.1781 Myrtle Beach, SC 1.866.586.9404 Norfolk, VA 1.866.975.3490 Raleigh 1.888.587.3624 Richmond, VA 1.866.887.3630 Click links in red above for more detailed information. CTS also offers Competent Person for Trench & Excavation training, as well as Confined Space Entry training. To see available dates and sign-up CLICK HERE The Scenario The challenges of the project would be rather demanding. The duct bank presented an initial obstacle as the contractor would need to be able to traverse it, while digging below it. Further complicating matters were two fourteen inch I-Beams that had been installed for future construction that would have to be straddled during the excavation. The contractor was also dealing with limited space within the construction site that would limit the possibilities of shoring further. The final problem that would be encountered with the project was that concrete would have to be poured over a new duct bank that was being installed before the excavation was backfilled. These four problems combined to form a challenging jobsite environment that would have to be addressed intelligently through the shoring system chosen. The Solution The solution to this problem was quite challenging and required each issue to be addressed individually, with the exception of the limited space which affected the overall jobsite and all other issues. Two steel trench boxes were chosen to straddle the I-Beams. The trench boxes were stacked on one another, then pulled under the duct bank to provide the necessary shoring. Hydraulic vertical shoring was utilized as the system of choice to shore the remaining four feet of excavation, since it would allow for the duct bank issue to be addressed. In order to cap the ends of the excavation to provide the necessary protection, trench box panels were stacked and end-loaded against the existing stacked trench boxes. The panels were then back filled against, providing a stable form of enclosure for the excavation. The remainder of the excavation was a slightly easier alternative. Two steel eight feet by twenty four feet trench boxes were used to provide the additional length and depth to shore the excavation. Finally, an eight feet by ten feet aluminum shield was used to shore the last portion due to the inclined slope after clearing the duct bank. While the project required a complex analysis of the shoring restrictions and options available, it was ultimately a problem that was easily solved by the knowledge and experience of Bob Jellison in assisting the customer in assessing the options. The project was completely safely and efficiently without incident.