8-Story Mosteller Parking Structure,
West Chester, Pennsylvania

Overview: The Mosteller parking structure is an 8-story garage located on the corner of Chestnut and Walnut Streets in West Chester, Pennsylvania. GeoStructures conducted a geotechnical investigation to characterize the subsurface and determine the soil properties needed for settlement analysis.

Even though the previous parking structure at this site was supported on a deep foundation, GeoStructures determined that a cost-effective ($250,000 savings) shallow foundation system could be used for the new garage (provided innovative but simple settlement mitigation techniques were implemented). A detailed site characterization was developed from 12 core borings, 5 confirmatory cone penetrometer soundings, and numerous lab tests to nail down the soil properties needed for a thorough settlement analysis.

The settlement mitigation measures included sizing the footings according to a zone-specific bearing capacity (two design values) and ballast trenches below designated footings. The design was developed in close cooperation with The Harman Group, the structural engineer on the project. GeoStructures was present during construction to verify the footing subgrade and to monitor the ballast measures.