Pier 1 heat exchanger a microcosm of team integration
Making the redevelopment of Pier 1 a success required a true collaborative effort. In fact, many of the mechanical design solutions, such as radiant heating and bay water cooling, grew out of the restrictions of the architectural scheme and the physical restrictions of the building itself.
'At first, we thought about a cooling tower, but there was no place to put it with the historic restrictions. So that became our baseline,' says Clark Bisel, a senior vice president with Flack + Kurtz, Pier 1's mechanical engineer.
According to Allan Montpellier, F+K's project manager, the radiant floor system helped meet the historical and architectural design goals 'because it's practically invisible.'
And because a new floor slab had to be poured, radiant tubing was a logical and fairly cost-effective option.
Similarly, submerging the heat exchanger in the bay provided another good example of adapting to conditions. 'The entire pier sits on piles over the water so use of the bay water for heat rejection became the logical alternative,' says Montpellier.
Similar to a ground loop or geothermal loops used in lakes, the relatively simple system is constituted of a number of polyethylene tubes bundled together in parallel closed loops.
Project architect Cathy Simon of SMWM, first heard of the technology on a project F+K had done in Massachusetts. 'With the bay being a cold heat sink, I think the thought hit us simultaneously.'
Constructing and installing the pods was another matter. 'The heat exchanger was very unusual. Nobody's ever done anything like that,' says Ken Lindberg, president of Power Engineering and Contracting, the marine specialty contractor on the job.
Bisel concurs. 'Constructablity was definitely the biggest issue with this product. Clearly the answers weren't automatic. You couldn't just do a design, give it to the contractor and say it's going to work. We needed construction expertise in this case.'
'The team did a lot of research,' adds Joe Mazzetti of general contractor Nibbi Brothers. The idea, he says, was that of F+K's director of advanced technology Dan Nall, who had experience on a similar, but much smaller system in a lake in Georgia. But nothing like this had ever been done in a marine environment with its related set of problems. To help build the construct, the team also consulted with some contractors from Vancouver, who were involved in some lake applications. In the end Mazzetti says it was really a lot of on-the-job learning.
Ultimately, five pods were conceived and premanufactured in Kentucky. When they arrived in San Francisco, Power transported the pods via barge to the pier where they were craned into the water. 'They had a 60-ft pile attached for ballast and support, but they still floated. So we literally pushed them into position,' says Mazzetti.
Sinking the pods was another matter. According to Lindberg, workers had to tip the oblong pod on an angle in order to achieve the necessary velocity to displace the air out of the 6-in. pipe.
The pods were then attached to a support structure anchored to the piles located under the pier. The steel cross bracing was installed to serve as a rack on the soft bay bottom to prevent pinching in any of the plastic lines. From the pods, 10 risers punch up to the mechanical room where they tie into the system via a header.