From the initial groundbreaking through the completion of the David H. Koch Center for Cancer Care ambulatory outpatient facility project, the construction means and methods had to be implemented with flood mitigation in mind. A key component of the flood mitigation strategy was the construction of a waterproof bathtub foundation.
The construction of the foundation system was closely coordinated among the project’s construction manager, geotechnical consultant, mechanical-electrical-plumbing consultant, foundation contractor and owner to confirm that the work in place aligned with the project’s design criteria.
Physically implementing the construction posed numerous challenges. As the site was within the 100-year flood elevation, the water table was high. To excavate the site and remove the required soil and rock to achieve two below-grade levels to support the parking requirements for the site, a construction dewatering system was used during excavation and needed to remain in place during excavation, foundation construction and steel erection.
The system remained in place until steel was erected above the 15th floor of the building and the associated floor slabs were poured to balance the weight of the site soil and rock that was excavated compared to the weight of new building construction material placed within the same footprint.
Another construction logistics challenge was ascertaining how to pour a 6-foot-thick foundation mat slab based on the quantity of concrete trucks required to execute the slab pour.
To minimize traffic impacts within the area associated with concrete trucks, there were a series of overnight concrete pours coordinated with the local community. This allowed larger sections of the foundation slab to be poured at a given time and helped reduce disruptions to the community and construction traffic during the day.