Valley Forge Laboratories, Inc.

Location:   Near Collegeville, Montgomery County, PA

Client:   Rhone-Poulenc-Rorer Pharmaceuticals Inc.

Description:
The corporate headquarters of this pharmaceutical company occupy 1.1 million square feet of office space within an arc of three-story structures. The entire facility is supported on shallow foundations.

VFL served as the geotechnical engineer throughout design and construction. the project’s most noteworthy challenge was minimizing differential settlements between the adjacent structures while avoiding a costly deep foundation. Complications for a shallow foundation included a ground floor elevation difference of 30 feet and column loads between 20 and 700 kips.

To meet the above geotechnical challenges, VFL executed a thorough site investigation involving 106 test borings. Also, the soil strata of the 25-ft. overburden were characterized in considerable detail. A typical profile consisted of medium dense sandy silt/silty sand underlain by moderately to highly weathered, very broken red shale bedrock.

Due to the weak rock, caissons or piles were found not to be cost-effective. Using the detailed information from the site investigation, VFL was able to optimize a shallow foundation system for the building and satisfy an angular distortion limit of 1/300 for the precast facing. To accomplish this, VFL proportioned the footings for “equal settlement.” Five different allowable bearing pressures were established depending on specific conditions. At one extreme, footings were founded on rock, while others nearby were supported on 25 feet of soil.