Letters

I'm writing in response to your August 2, 2006, news story about the lawsuit settlement for the Boston Convention and Exhibition Center (BCEC) between the Massachusetts Convention Center Authority (MCCA) and the project's design and engineering team. (“Boston convention center gets $24 million for design errors,” BDC eNews, www.bdcnetwork.com/article/CA6362243.html)

In the story, mention is made of the roof drainage system as being one subject of the settlement. Unfortunately, those who read about the settlement who also happen to know that a siphonic roof drainage system was used for the first time in the U.S. in this building might reach the wrong conclusion about the siphonic drainage system.

The story about the settlement does not point out one important fact—The BCEC has three different roof levels: the center exhibit hall roof, the outer meeting hall roofs, and a mechanical roof. The first two roof levels are drained to the lower mechanical roof by means of conventional drains and downspouts. The siphonic roof drainage system starts at the mechanical roof level and drains from the back of the building and out the front. By all accounts, the siphonic roof drainage system has worked as intended even after several challenging rainfall events in Boston.

The problem that was the subject of the MCCA suit involved the gutter and drain design of the upper exhibit hall roof.

While the details of the situation are not important, a solution has been proposed to remedy the situation. While there was some speculation as to whether the nature of the drainage gutter problem adversely affected the siphonic roof drains below, there were no observations to this effect.

The BCEC was a challenging design project that spurred innovation among the design team. What is not generally known is that the employment of siphonic roof drainage on this project eliminated the need for a large stormwater pumping station estimated to be upwards of $20 million.

John M. Rattenbury, PE, CIPE, LEED AP

President

RMS Engineering LLC

Salem, Va.

Your article on wind-resistant roof design was very interesting (“Worry-free Wind Design,” September 2006, p. 51).

As a mechanical engineer, I agreed with your conclusion that the appropriate fixation needs to be specified for rooftop equipment. The problem, though, is that it requires more then just specifying the need.

How to design the right fixation and who is responsible for each installation becomes the big problem. No one wants to become liable by association.

The Federal Emergency Management Agency provides some guidelines on proper fixation methods, and many mechanical engineers have ideas on how to do it. But structural engineers say it's not their responsibility, and manufacturers don't want to assume the liability by getting involved.

Designing proper fixation methods and determining who is responsible for the application would be a great topic for an article in your magazine.

Dennis DeHaven, PE

Chief mechanical engineer

Giovanetti Shulman Associates

Broomall, Pa.

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Building Design+Construction

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