A commercial development at 50 Calle included construction of a four-level underground parking garage. Malcolm designed and constructed the diaphragm wall, optimizing the design to enable the wall to perform the dual function of being a temporary retaining wall for the excavation and a permanent wall for the basement. This resulted in substantially reducing the schedule and large savings in the overall project costs.

The permanent basement walls of the residential building were constructed by means of diaphragm wall construction using reinforced concrete panels. Two levels of tiebacks were installed as excavation of the basement progressed, which provided temporary support of the basement walls. The diaphragm wall was socketed into rock to cut off potential groundwater flow, and temporary tiebacks were installed to support the basement excavation. Malcolm utilized state-of-the-art equipment to excavate the slurry diaphragm wall panels and diaphragm wall end stops equipped with embedded water stops at the construction joints. Approximately 28,000 square feet of slurry diaphragm walls were installed, all keyed into the underlying bedrock.