Interchange improvements within an urban environment required the deepening of a hillside cut. Design restraints required as deep a cut as possible without disturbing a water tower located at the crest of the slope or interfering with a shopping center at the toe. The water tower, constructed in 1933 with a steel tank encased in a concrete and brick structure, was founded on shallow spread footings. Foundation soils were silts and silty sands with seams of silty clay. The design investigation involved hydrogeologic studies, SPT borings, undisturbed sampling, laboratory testing, and stability analyses. Laboratory studies involved routine and unusual testing procedures to evaluate deformation potential upon drying. Results of the investigation allowed the deepening of the cut some 20 feet using conventional construction techniques. This paper details the geotechnical investigation, laboratory testing, analysis procedure, construction monitoring, and project results
