Adventist Healthcare White Oak Medical Center Retaining Wall

Serving its community for more than 112 years, Adventist HealthCare relocated its Takoma Park facility to a gleaming new 474,000 sf state-of-the-art facility in White Oak. The seven-story replacement hospital was one element of the 48-acre campus master plan. The organization engaged Schnabel Engineering DC (SEDC)* to design the retaining wall required along the site’s south side to achieve the grading necessary for the hospital’s layout.

We first conducted a detailed subsurface exploration program. This study characterized the site soils and provided recommendations for the design of the wall and its components. The process involved weighing various alternatives for suitability, including reinforced concrete, mechanically stabilized earth (MSE), mortared stone, and gabion walls. The client selected a gravity, mortared Class 1 riprap wall that is designed to resist lateral earth and vehicular surcharge pressures.

Constructed in a series of 21 sections ranging in length from 5–157 feet and in height from 5–30 feet, the prominent structure spans nearly 1,100 feet. Wall components include a six-foot-wide curb, a 42-inch high “traffic rail” parapet designed for vehicle impact loading per AASHTO specifications, and a drainage system of perimeter subdrains connected to weep holes.

During design, we used software programs PLAXIS 2D, for numerical analyses, and SLOPE/W, for limiting equilibrium analyses to estimate potential wall settlements, investigate the potential wall-induced stresses on underground utilities, and estimate global stability at specific wall sections. We were also present during construction to verify that field practices and materials met design intent.

^{*SEDC is an affiliate of Schnabel Engineering, Inc.}