United Civil was the Civil Contractor hired to complete the large sitework package for the new Tobin Montessori & Vassal Lane Upper School. Included in the sitework package was the construction of a 1.5-million-gallon cast-in-place underground stormwater storage tank.

The excavation for the tank was completed within a sheeted cofferdam and featured an extensive dewatering system during the excavation, cast-in-place concrete and backfill activities due to the excavation’s proximity to an adjacent waterbody. The tank was supported by (114) 36”-diameter drilled shafts installed below the tank’s 3’-6” thick floor slab. A concrete placement sequence was developed and established for the 3,785 cubic yards of concrete needed to complete the stormwater storage tank, with all placements requiring the use of a concrete pump truck.

The sequence of the placement plan was also integral to with the cadence of SOE bracing removals. A total of 425 tons of rebar was installed and tied for reinforcement within the structures 2’-3’ thick walls, and the 16-18’ tall 2-4” square support columns.