San Francisco Flower Mart

The future home of the San Francisco Flower Mart in Potrero Hill.  The project consists of constructing a new parking garage and an extensive seismic retrofit of the existing warehouse that was built in 1898 for Pacific Rolling Mill Co.  The project site was originally the historic shoreline in Mission Bay pre-1895 thus creating many geologic challenges from heterogeneous fill to soft clay (Young Bay Mud), sand, stiff clay, and bedrock all within 50 feet from grade.  The seismic retrofit of the warehouse consisted of enlarging the existing spread foundations and adding micropiles.  After Malcolm performed a pile load test program confirming the pile design, 54 micropiles were installed to depths reaching 65 feet below grade.  The new parking garage structure required the improvement of the existing ground as the heterogeneous fill and Bay Mud are not suitable to support the building loads.  Malcolm designed a ground improvement system to meet the required foundation bearing pressures by utilizing rigid inclusions to transfer building loads to a deeper bearing stratum.  After an extensive load test program, Malcolm installed over 500 rigid inclusions at varying depths up to 35 feet below grade.