Wyeth Worldwide Headquarters, Collegeville, Pennsylvania

Overview: Sitting on a 320-acre campus along U.S. Route 422, Wyeth’s Worldwide Headquarters was designed and constructed in two phases; one from 1988-1991 and the second from 2000-2003. At the time, the Wyeth facility housed 4,000 workers and 1.85 million SF of office and laboratory space. GeoStructures was responsible for the geotechnical design and quality assurance during the construction of both phases. 

GeoStructures was in charge of the geotechnical design and quality assurance during construction of both phases. Major aspects of the project included:

• Ten 4- to 5-story buildings and one 5-level parking garage
• Miles of loop roads and numerous parking lots
• Two bridges across Perkiomen Creek
• Four stormwater detention basins
• Widening S.R. 29 near the main entrance drive

To characterize the site, more than 300 test borings were completed, as were extensive laboratory index and shear strength tests. Brunswick Formation geology comprises reddish brown shale, mudstone, and siltstone, with a few fine-grained sandstone beds. Depth to rock varied from 2 to 40 ft. The soils transitioned with depth from clays, silts, and silty sands, to silty gravels. Perched water was also present in certain sublayers.

A unique design aspect was the extreme variation in ground floor elevation across the building footprint. Certain adjacent wings had floor levels differing by nearly 25 ft. To mitigate potential differential settlements and to facilitate the use of shallow foundations, 6 different bearing capacities (ranging from 4 ksf on structural fill to 15 ksf on weathered siltstone) were specified. The column loads ranged from 200 kips to nearly 1600 kips.

Specialized work on the bridges involved optimizing 25-ft high approach embankments by designing 1H:1V, geogrid-reinforced slopes. Sections of the geogrid layers and internal drainage were furnished together with details for slope erosion control measures. Other services included bentonite liner design for detention basins, stabilization of weak existing fill by the use of ballast trenches, pavement design, and subsurface drainage design.