Construction of two residential high-rise towers at the new Christina Landings waterfront is a landmark project for both the metropolitan area of Wilmington, Delaware, and concrete professionals Healy Long & Jevin, Inc. located there.
As the first major residential high-rise project being developed on the Christina River's southern bank, Christina Landings is at the crux of the transformation from a run-down industrial area into a premier neighborhood. Two luxurious towers — the completed 22-story Residence at Christina Landings Tower I apartments and the 27-story River Tower II condominiums now under construction next to it — are drawing new residents, new businesses and renewed vitality.
Architect on the project is Kling of Philadelphia, Pa. The general contractor is Gilbane Building Co. of Providence, R.I. The Buccini/Pollin Group, Inc. of Wilmington is the developer of both the Residence at Christina Landings Tower I apartments and the elite River Tower II condominiums, which are expected to be ready for occupancy in summer 2007.
Claimed to be the first cast-in-place concrete frame structures developed in Delaware in over 25 years, the high-profile towers drew attention from the local construction community to the special concrete placement techniques employed by Healy Long & Jevin. This Mid-Atlantic union concrete specialty contractor received two construction awards for their efforts on the project.
Recognition for Healy Long & Jevin came in the form of the 2006 American Concrete Institute — Mid-Atlantic grand prize award for Cast-In-Place Structures and the Delaware Contractors Association's Construction Excellence Award for Craftsmanship. Both honors were presented for the Residence at Christina Landings Tower I apartment project, which was completed in summer 2006.
"There is no question in my mind that the second condo tower at Christina Landings will also receive recognition when the building is fully completed and ready for occupancy," says Secretary/Treasurer Sean Healy of Healy Long & Jevin. "That's because it utilized even more extraordinary time- and labor-saving concrete placing methods in its construction.
"Major credit goes to our detachable Putzmeister concrete boom pump and placing tower," says Healy. "Owning the equipment almost instantly changed our company." While the firm has been in business since 1978, it waited until January 2006 to purchase its first concrete boom pump and placing tower. "We finished the second tower 45 days ahead of schedule."
Cole and Lambert, Inc., of Aberdeen, Md., helped specify the best concrete placing system to accommodate work typically performed by the contractor.
Even though market conditions and traditions within the Delaware region typically favor steel construction, concrete was chosen instead. While the first landmark tower was designed with concrete, the second one was not. The design changed, however, when a long 18-month delivery lead time for steel had the developer seeking alternatives.
To avoid the delay, Mike Jevin, president and chief estimator of Healy Long & Jevin, redesigned the building to employ 15,000 cubic yards of concrete. Once the developer and project's engineer approved it, the project commenced full speed ahead. Even though the River Tower II condominiums would use a construction approach similar to the first apartment high rise, it was a more complex structure under an even more demanding schedule.
To help expedite erection of the tower's cast-in-place concrete frame, Healy Long & Jevin utilized a truss-type flying form system for the structural decks. Instead of traditional handset frame and cross brace systems, various truss components and Aluma beams are assembled together.
The form resembles a big long table that is constructed only once and re-used from floor to floor. As a result, the entire table gets pulled out by a crane and flown for insertion on the next floor. This procedure avoids dismantling and re-assembling forms, realizing reduced labor yet improved productivity on buildings with repetitive floor plans.
In addition, a ganged wall system was utilized for the shear walls. Custom lightweight hand-set column forms which could be quickly put up and taken down without a crane were also employed.Bring on the concrete
Concrete producer Pioneer Concrete, Inc. of Wilmington developed a quick-setting 5,000-psi mix design that would achieve 75-percent strength in three days or less. The ready mix supplier was then relied upon to dispatch the concrete without delay.
For concrete placement, a Putzmeister 40Z-Meter was used. The boom could be quickly removed from the truck, installed on the tower and ready to place concrete within 20 minutes. Featuring 115 feet of horizontal reach, the longer boom accessed all areas of the pour from one location without dragging hose.
With its detached boom on the tower above, the .16H pump cell on the truck-mounted pump delivered concrete from ground level to the tower's highest point at 301 feet. The pump is rated at a maximum 210 cubic yards an hour output and pressures up to 1,233 psi on the rod side. However, it can be switched over to the piston side to achieve even higher pressures up to 1,885 psi.
"The pump had plenty of power all the way to the top 27th floor," notes Healy.
In just three hours, an 8-inch elevated floor slab was placed with 230 cubic yards of concrete, averaging about 80 cubic yards an hour output. At the completion of a pour, the boom was reattached to the truck. The pump would be back on the high rise the next day to pour all of the columns and walls. By the end of the following day, the walls and columns were in place and the flying form moved to the next level. With the pump handling the bulk of the work, the crew kept the project moving forward — resulting in a floor finished every six days.Towering above
To erect and raise their 60-foot system, the setup crew connected and secured the tower sections with four heavy-duty pins, which eliminated the time-consuming chore of torquing bolts. Plus, as all tower sides have a smooth surface, the crew could slide it through floor openings without interruption.
"The pin tower was extremely easy to jack up," says Healy, "so it kept the entire process moving along at an even faster pace than we ever experienced in any high-rise project before."
Recognized by Concrete Construction magazine as one of the top 100 Concrete Construction firms in the United States, Healy Long & Jevin has performed some of the heaviest and most difficult concrete construction in the region, including some of the tallest high rises in Philadelphia. However, even with almost three decades of field proven experience, the organization had never owned a concrete pump. In the past, logistical concerns on how a pump would be deployed to the major projects the company is involved with simultaneously across four different states — Delaware, Pennsylvania, New Jersey, and Maryland — prevented the purchase of a pump.
This all changed in 2005 when Healy Long & Jevin was awarded several projects of varying size, totaling $18 million, requiring 45,000 cubic yards of concrete within 30 miles of the company's headquarters.
"Although I had been pushing the issue of purchasing a pump for years, what finally sold my father on buying one was the $375,000 we spent renting pumps over a two-year period," says Healy. "The new projects would basically pay for a pump."