Constructed on the west campus of the former St. Elizabeth’s hospital site in Washington, D.C., the US Coast Guard Headquarters project includes an 11-story office building for 3,860 workers, a nine story 800,000 square foot parking garage, a central utility plant, and a National Operations Center. Clark Concrete Contractors poured 220,000 cubic yards of concrete and placed 15,000 tons of reinforcing steel on this $435 million dollar project.  Clark placed an average of 3,500 cubic yards of concrete every week for 42 consecutive weeks.  The largest single pour required 2,800 cubic yards of concrete over a fourteen-hour period for an eight-foot thick mat foundation.  Clark placed nearly 12 miles of foundation walls and 523,000 square feet of mat foundations.

The use of slag cement eliminated 50 million pounds of green house gases in the construction of this facility and contributes toward the goal of achieving LEED Gold certification for this building.  Some other green design features include a 400,000 square foot green roof, a vegetative wall panel system, and an orientation that minimizes solar heat gain and maximizes the opportunity for daylight harvesting. This project had to meet stringent blast resistance requirements.  Designs required high strength three-foot tall hanging perimeter turndown walls off most elevated slabs. Slag cement was also used to mitigate potential expansion due to a reactive aggregate.

Project credits: General Services Administration, Owner; WDG Architecture, Architect; Cagley and Associates, Engineer; Clark Concrete Contractors, Contractor; Concrete Mixes Inc., Concrete Supplier; Lafarge NewCemNorth America, Slag Cement Supplier