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Part II 

Construction:

The Hoffman One Building is currently under construction and in Phase 1 of the renovation project.  Similar to any building in the early stages of construction, there are always a variety of opportunities and threats that will arise as usual. The unique factor in regards to the Hoffman One is that there has been a great deal of focus to avoid any delays or potential threats.

With that focus, there have been multiple constructability concerns or challenges on the project. The most crucial constructability concern in terms of scheduling and coordination was the defective glass that was delivered and installed. Progressing through the schedule was a great success with crews working effectively and performing quality work on a daily basis. It wasn’t until after installing level 2 through 10 when a variety of window glass panels were noticed to have pink streaks appearing through the glazing fill.

After evaluating the situation, the number of glass panels began to increase throughout the building. With the building only about 4 floors away from being enclosed, there was an unforeseen error in the glass.

Coordination was key at this point, which is why the Owner, General Contractor, Subcontractor, and Manufacturer held a project solution meeting. The idea of developing a recovery plan was immediate; the project manager took the lead with the help of the subcontractors’ commitments and flowed a 4-week recovery plan.

As mentioned the building was now in the stages of being enclosed, which meant that the floors were no longer open for crane access and pick deliveries per floor. This created a minor issue, which threatened a delay on the project.

In order for the installation of the glass to occur the glass panels were delivered to each floor by the elevator. This was a major time delay for production; accessing the elevator with a 6’ x 3.5’ window panel was not very effective. The glass was removed from each floor due to the fabrication error on the glass. To ensure that the glass could be uninstalled at a reasonable pace, the Northwest corner on the 1st floor storefront was left open to increase production and removal. Unfortunately, the glass was not qualified for recycling.

One concern is in regards to the recent MEP coordination for the installation of the men and women’s bathroom located on the second floor level. The issue is that the existing structure specifically in the women’s bathroom is affecting the current design for the project. The owner desires 9-foot ceilings within the building, which is an issue when the existing beam is currently penetrating through the women’s handicap stall at precisely 7’-10” to the bottom of the beam. Through multiple efforts to ensure a timely delivery and the quality of the project, the MEP coordination pursued the resolution of constructing a bulkhead in that specific stall area. The reason this is not a significant issue is because the stall is a handicap accessible stall, therefore there are not height requirements or contingences.

In addition to the MEP coordination issue, there was a day where activity production was lost due to a permit misunderstanding. The problem was in regards to the design in the asphalt roofing system, which required a specific permit for installation. The permit pertains to the use of a kettle, which is a high risk and safety issue. The general contractor Balfour Beatty, did indeed acquire a kettle permit for this activity, but was shut down by the Fire Company instead. Originally, only a permit was required, but newly developed township codes demand the inspection of a fire company representative for approval. Moreover the activity was in fact delayed for approximately 2 weeks.

Although there have been a few issues in terms of construction sequencing and phasing, the opportunities for the schedule acceleration and improvement will be executed. 

Electrical:

The main building switchboard is rated for 4000A, 480/277V at 3 phases. The ground floor electrical system will be limited to the parameters with the design and installation of phase 1. The entrance vestibule heater will be wired to temporary service for future use and rough in details. Main lobby lighting will be installed to panel R-1A, which is through the distribution of transformer #2 rated at 2500kVA. There are four main transformers being installed in Phase 1, which are the known as transformer #1A, transformer #2A, utility transformer, and the penthouse transformer. Lastly, the building contains an emergency power system, which is supplied by one generator at 230kW.

Mechanical:

The Hoffman One Building renovation project’s mechanical system contains one 1000-ton rooftop-cooling tower, which will have an equalizer connection, as well as vibration isolation rail and vibration switch. Additionally, two 5 ton split system heat pump that will serve the main lobby on a temporary basis. Condensing units will sit in the unoccupied second floor tenant spaces, until a tenant is secured. Exterior vertical perimeter chilled water and outside air will be installed with capped connections at the mechanical exterior risers. The system consists of four 5kW unit heaters at the 14th floor level.

The penthouse/roof level will contain exterior vertical perimeter of outside air duct and distribution ductwork on the roof. These will be installed with the capped connections as mentioned previously, in the penthouse, which will be for future extension in later phases of the project.

For Phase 1 there will be (5) total Air Handling Units which will serve the lobby-east and west zones, the 2nd floor-east and west zones, and two our interior areas for the east and west zones for a typical floor. The air handling units for the interior and lobby area will range from 1200CFM-1700CFM, as for the 2nd floor AHU, it will total approximately 8100CFM. For future tenant equipment, there will be a chilled beam system, equating to four beams that will be passive at a nominal capacity of 200BTUH/LF. Lastly there will be (7) 2-pipe fan coil units installed for future tenant use, (2) of which will be utilized in Phase 1, whereas the remaining (5) will be for later Phases.

Structural:

The Hoffman One Building is a concrete structure supported by foundation walls (12”-24” in thickness) and spread footings on resourceful existing soil. In regards to the actual renovation project, the Hoffman One Building is not acquiring additional structural systems or supports to a great extend. With that being said, the renovation project will include an additional grade beam at the south elevation of the building below grade, as well as structural steel framing at the penthouse/roof level, and at the front entrance of the building. The grade beam within the soil is a A-36 at approximately 35’.

The structural steel framing at the penthouse can be seen in the figure 1 below, which was taken shortly after the erection of the system. There will be a new wind post column pier 20”x20” w/ 4-#7 vertical and 4-#3 at 4” o.c ties at the penthouse roof level. The structural system will be supported by (16) base plates with the majority of them being 16”x16”x1/2” base plates. The vertical and horizontal steel supports will consist of newly added HSS 8”8”x5/16” at differing lengths and heights. 

(Figure 1: Courtesy of John McCoach)

As for the structural steel located at the front entrance, it consists of a curtain wall system; a diagram displaying the structural steel for the building’s vestibule can be viewed in the figure 2.  The system consists of (2) base plates at the front entrance, which contain a 10”x10”x3/8” w/ (4)-1/2” o.c, for a 2” recessed finish below new grade. Additionally the structure will contain (2) base plates at 20”x20”x3/4” w/ (4)-3/4” o.c at level grade slab. The (2) main supports consist of HSS 2”x12”x3/8” columns that extend to the underside of the third floor, since the lobby area will be exposed. The vestibule framing mostly consists of HSS 3”x8”x3/8” structural steel. 

(Figure 1: Courtesy of Superior Steel)

Fire Protection:

The Hoffman One Building will contain a sprinkler system throughout the entire building, which will allow for one hundred percent coverage to provide adequate fire protection. The existing structure contains a fully automatic standpipe system, class 1, which will aid in the overall fire protection system. Elevator shafts will encase sprinklers within the shafts to ensure safety. The current fire company in jurisdiction of The Hoffman One Building is the Alexandria Fire Department Station/Engine #204.  Lastly, pertaining to the elevator shafts and lobby location there is an authorized Knox box rapid entry system for life safety-fire & rescue operations.