Construction at the KA Block progresses in downtown Minneapolis. Project Manager Chad Rempe provided these details on May 27 as preparations were underway for erection of the first of two tower cranes to be installed at the site, serving the KA headquarters office and upcoming work on the mixed-use site, which is under development by Kraus-Anderson Development Company.
Q: At this writing, the foundation for the tower crane has been set. What did that process entail?
REMPE: Tower crane foundation was poured in two stages. A mud slab approximately 1’-0” thick was placed first to provide a stable surface for the tower crane base section (approx. 21,000#) to set on. Once the mud slab was cured the tower crane foundation was formed and reinforced, tower crane base section was set, and then foundation was poured; all of which took place over the course of two days. Tower crane foundation including mud slab is 200 cubic yards of concrete or approximately 405 tons of concrete.
Q: How was the tower crane placement location determined?
REMPE: Tower crane placement is a function of maximizing site coverage and minimizing openings in the structure requiring infill after the tower crane is demobilized. Other items taken into consideration when developing the hoisting plan for the block were:
-Tower Crane Air Rights Easement Approvals from affected neighboring property owners
-Tower Crane size, capacity, hook height, and jib length
-Layout of neighboring structures and cranes
To name a few.
Q: When will erection of the crane tower be done? How long will it take? How high will the completed crane be?
REMPE: The first of two tower cranes will be erected beginning June 1 and be complete and operational on Friday June 3, weather permitting (and it did). Initially this tower crane will be installed with a hook height of 150’-0” to support the parking garage construction. Later this summer, the tower crane will be jacked up to its final hook height of 243’ to service the 17-story residential tower. At the same time we’ll be erecting the second tower crane to a hook height of 161’ to support construction of the 8-story hotel.
Q: Will it be left in place when construction of our building is done? (for further construction on the block)?
REMPE: KA’s office building will be built using mobile cranes to erect structural steel and set architectural precast wall panels; this allows the two tower cranes to focus solely on construction of the hotel and apartment buildings. The two tower cranes will be in use through 2016 and into 2017. Demobilization of the tower crane servicing the hotel will be in June 2017 followed by the tower crane servicing the apartments in October 2017.
Q: What will be the deepest point of excavation of the site? When is that point being reached?
REMPE: The hotel elevator pit foundation is the deepest excavation at – 34’ below grade. Currently mass excavation of the North half is substantially complete. North half foundation excavation is scheduled to begin week of June 6. Hotel elevator pit foundations will begin in the next 30 days.
Q: How will excavating equipment be removed from the site?
REMPE: Large excavating equipment will be removed via a temporary access ramp. Excavators will remove the ramp as they back out of the excavation. However, not all of the ramp will be able to be removed while maintaining safe operating slopes, therefore smaller excavating equipment will be left in the excavation to remove balance of temporary access road and will be either craned out of the hole or drive out once the permanent entry/exit ramp is in place.