Cramped urban sites are nothing new in the construction business, but solving problems afloat is an innovative idea.

The tight site at Two River Place, an 18-story, loft-style condominium project on the banks of the Chicago River, is flanked by a building, street, parking-structure access ramp and the river.

Josh Stark, project manager for the project's Chicago-based general contractor, Bovis Lend Lease, said there was precious little staging and storage space for the $39 million project that includes a significant amount of architectural and structural concrete.

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The storage solution for the 20-month project, scheduled for completion in July, was found flowing right beside the site.

"We called a barge company to see if they would deliver a barge," said Martin Maxey, project manager for the West Chicago-based Concrete Structures of the Midwest. "We had the barge delivered at about 7 o'clock one evening and tied it up to the bank."

Maxey said the barge essentially came with the necessary permit, but Concrete Structures had to take some safety precautions and provide water safety training to its employees.

"Anytime anyone walked on the barge, we had to provide them with a life vest," he added. He said safety training focused on deploying life-safety devices in the event someone should topple into the water. Stored items were transported to and from the barge by a tower crane, while personnel used a gangplank for access.

For safety, a barrier of two-by-fours supported by vertical stanchions was erected around the perimeter of the barge. Over the course of the six months the barge was in use, no personnel or equipment went overboard.

The other safety requirement, navigational lights, alerted river traffic to the barge's presence.

"The barge was long and narrow, 300 ft. by 20 ft., so it didn't interfere with river traffic," Maxey said. "We saw other barges and tourist boats going by every day."

He said it was the first time Concrete Structures had used a barge on a project, but the firm would do it again, in part because it provided storage space that no one else could encroach upon.

A Concrete Project

The project's use of architectural concrete played a big part in creating a need for the floating storage space.

"The building is loft style, with exposed, round columns and exposed concrete ceilings," Stark said. "We had to make sure the finishes on those columns and ceilings were far above what they would regularly be." Reusable formwork had to be carefully stored to maintain that high finish quality.

The building will have 169 units in one-, two- and three-bedroom arrangements and a fitness center. Unit costs range between the high $200,000 area and $800,000.

Brian Kidd, senior associate for project architect Pappageorge & Haymes Ltd. of Chicago, said the extensive use of concrete in Two River Place stemmed from economic and aesthetic concerns.

"Probably first and foremost was the economy of using concrete," he added. "It's a structural material but also a wall finish and exterior finish."

But aesthetic concerns, which he said included reflecting the look of the One River Place structure, which is also a concrete building, played a part on the decision.

"We were picking up on some of the vocabulary of One River Place," Kidd said. "Also, this is a high-rise loft building, and exposed concrete finishes are a part of that style."

Kidd added that two six-story buildings flank the 18-story tower and serve a dual purpose. Calling them "saddlebags," he said they add a different type of unit to the development, one in which residents can effectively pull into a parking space right outside the door to their individual units.

He also said they "enliven the ground floor where the 185-space parking garage is located and provide a base for the building."

Concrete caissons and spread footings support the three linked structures.

"The tower portion of the building is all on caissons, and the two six-story sections are on spread footings," Stark said. "They are connected by expansion joints that run the length of the building."

He said the building is set back from the river about 30 ft.

With concrete in abundance from the foundations to the finishes and nestled inside the structure by way of 46 transfer beams, each about 36-in. deep, delivery of concrete became another concern. Stark said careful coordination was required to maintain the steady stream of concrete trucks, which had only one staging area on Larrabee Street because of environmental concerns over diesel fumes in the residential neighborhood.

Tolerances were also an issue throughout the building.

"When you are doing a concrete building like this, the tolerances for concrete floors and for pre-engineered concrete floors are different," Stark said. "We have to keep an eye on floor flatness and on the window openings. The tolerances on the exterior columns had to be tight or the windows, which had been preordered, wouldn't fit."

Mechanicals Present Concerns

"Any time you have two separate uses, a parking garage and residential units, mixed up and combined, it becomes a challenge to find out how you are going to run all your mechanical work," Kidd said.

Part of the solution was found in creating greater floor heights at the top of the tower building and at the point where the tower meets the shorter buildings. That allowed room to thread necessary MEP and HVAC systems through the three buildings.

Stark said installation of those systems required constant communication between the trades.

"In floors seven through 17 there are 130 openings in each floor, because you have a plumbing riser for every bathroom and kitchen and duct opening for HVAC," he said. A mechanical penthouse on the tower's 18th floor houses chillers and boilers for all three buildings.

Stark said that all the electrical wiring has to run up into the walls, which means crews have to know where the walls will be before they pour the floors in order to line up the openings in the floor slab with the 3.5-in. depth of the walls.

Other Site Issues

Not all of the project's issues stemmed from a tight site and intricate concrete work.
Previous uses of the site also presented some headaches in the project's earliest days.

"The site originally had a surface parking lot on it and a small, one-story building that we demoed," Stark said. Prior to that it was a Montgomery Wards warehouse.

"When we excavated, we found a lot of foundation materials, wood piles, foundation walls and a bunch of rubble including pegboards and water heaters," he added. "It looked like they had just demoed the old building into the hole and built over it."

John Shipka, principal with the Enterprise Cos., developer of the project, said the underground obstructions cost nearly three weeks on the project schedule as crews worked to clear the site. He said the time has been made up by Bovis and Concrete Structures working extra hours and tweaking schedules.