Two Nine North is a four-story, wood-framed podium apartment building with 238 units and a single-level underground parking garage with a 14” thick post-tensioned concrete lid. The development includes a 100-kW solar photovoltaic rooftop array, two courtyards, a heated saltwater pool and hot tub, fourth-floor roof deck, fitness center, and cyber cafe. The building is certified by the Boulder Green (Green Points) Program.
The complete structural concrete scope includes more than 11,000 cubic yards of concrete. MW self-performed major components of the concrete work including drilled piers, 155 columns, and 2,650 lineal feet of walls and 341 caissons.
The 317-space, 3.5-acre underground parking structure required 15 feet of excavation, which was well below the existing water table (8 feet). A perimeter dewatering system was installed to allow for the excavation and construction of the cast-in-place structure.
Unexpected contaminated water was encountered during this dewatering operation. MW brought in filtration equipment that had to be operated 24 hours a day to eliminate the contaminants and allow construction to continue. Dewatering and filtration occurred for approximately 10 months with levels as high as 30 gallons per minute being pumped from the building’s foundation perimeter.