Built in 1955, Cole Field House long served as the University of Maryland’s primary sports arena. Its $155 million renovation features a performance center, a 160,000 sf practice facility with an indoor, regulation-size football field, two outdoor turf fields, and training facilities, as well as a 40,000 sf research and clinical space. Schnabel provided geotechnical engineering services during its construction.

Converting a former basketball arena with concrete stadium seating surrounding a court to a level playing field presented numerous challenges. After the seating was removed, the soil had to be excavated back to the building perimeter, precipitating the need for 30-foot-high retaining walls. The foundation subcontractor proposed a soil nail wall as a practical solution and engaged us to design it and the foundation underpinning.

Although soil nail walls are typically passive systems where the nails develop resistance through ground movement, this one was different due to the proximity of existing footings. In response, we designed the soil nails with partial post-stressing to minimize ground and foundation movements, and then designed a temporary support of excavation so that the contractor could reach and underpin them with micropiles. Nearly 900 51 mm hollow bars were drilled at depths from 15–45 feet. Shotcrete solidified the wall and provided a permanent facing.

We provided the geotechnical engineering aspects of the construction phase services including observation of the soil nail and micropile load test program, observation and logging of the production soil nail and micropile installation, consultation on soil nail and underpinning installation, and shotcrete installation issues that arise during construction. We also provided construction inspection and material testing services for earthwork and foundation, micropile support foundations, concrete, paving and structural steel.