Montessori de Terra Linda
DAC was the civil engineer for the project. The overall scope of project consisted of various site improvements, renovations of the permanent building, and construction of a new prefabricated classroom building. Our scope of work included preparation of grading, drainage, and utility plans as well as design of new AC and PCC pavements, evaluation of existing sanitary system, design update. In addition, we provided stormwater pollution prevention and dust control plans for the construction phase. Additional services included plan review, bid review, evaluation of construction bids received from contractors, construction observation, including subgrade preparation, pavement construction, and related items to check for conformance with approved project plans and specifications.
Mason Street Hotel Building
DAC was the geotechnical engineer for the project. The project consisted of adding 4 additional stories to an existing 8-story hotel structure in down town San Francisco. The structure also had a one level basement with maximum headroom clearance of about 10 feet. Due to limited access, a drill rig could not be used to perform our exploratory work. Our subsurface exploration was, therefore, limited to hand dug test pits within the crawl space area. Several test pits were excavated to determine the subgrade conditions and depth of the existing footings. Based on our observation of soil profile in the relatively shallow test pits, we prepared the required recommendations for the major addition as well as structural improvement of the hotel building as planned.
As the project manager, Darius directed the geotechnical investigation and foundation recommendation for a two and three story hotel building complex underlain by soft, compressible clay (Bay Mud). Due to the cost and environmental restraints, we recommended the use of light weight fill, below the mat foundation for the purpose of minimizing total and differential settlements. Up to 5 feet of fill was excavated and replaced with foam concrete (commercially known as Elastizell) to reduce the overburden pressure and subsequently reduce the soil bearing pressure in order to limit the consolidation settlements of the Bay Mud and the fill. A finite-element-analysis using the program ANSYS was performed to model the interaction between the soil and foundation, and to evaluate the impact of liquefaction induced settlements on the Elastizell and mat foundation system. It is noteworthy to mention that, this was the first application of foam concrete as light weight fill below a major structural foundation.