Lauren Stanton | March 8, 2011
After breaking ground on February 15, construction continues on the new Center for Student Services slated to open in the fall of 2012. During the spring recess the process of preparing the site for excavation began. In order to excavate and eventually lay the foundation, contractors must first install a system to support the perimeter of the area that will be excavated.
Last week contractors began mobilizing equipment to install the retention wall that will be the perimeter of the excavation area from collapsing while digging 20 feet into ground. Traditionally, this would involve driving sheets of metal into the ground to form the wall. Instead of using the conventional method, the university opted to use an alternative that causes less vibration and noise, thus has less of an impact on those who live and work in the surrounding area.
Instead of creating a wall out of steel sheets, the contractors are installing a soil mix wall that is composed of soil from the site mixed with concrete. According to the Schnabel Foundation Company, “a Soil Mixed structural cutoff wall system provides a very economical solution to the problem of retaining the earth while excluding groundwater from the excavation”.
First, they dug a pre-trench around the entire perimeter to mark the placement of the retention wall. Next, a small auger—a machine that drills into the soil and deposits a mixture of cement and soil that is left to harden— was used to create two small sections of the wall that will have an opening. This window in the wall needs to be left in order to accommodate a telecommunication data bank that crosses into the area being excavated.
Starting next week, a larger auger with four drill heads will begin dig out the rest of the perimeter. Once the soil mix wall is in place it will be internally reinforced with steel braces for extra support. Excavation is expected to begin in about three weeks once the wall is completed.