City Council wrapped up 2008 yesterday with one piece of legislation sure to make the building-trades unions happy and another bill that's already raising concerns.

Council unanimously approved zoning changes needed to build the American Commerce Center, a 1,510-foot tower planned for 18th and Arch streets. The $1.1 billion skyscraper is expected to generate $15 million for the city in taxes on construction work.

Councilman Darrell Clarke also introduced legislation that would allow builders to use PVC pipe in all construction. The plastic pipe, which is cheaper in material and labor to install than metal pipe, can now only be used in new residential construction of buildings with three stories or less.

Peter Kelsen, an attorney for the American Commerce Center, yesterday acknowledged a "challenging" economy might make it difficult for the developers to build the skyscraper. The developer has already spent millions to plan the structure, he added.

"We feel cautiously optimistic that even with these economic times we can bring to bear this project and we have the resources to do so," Kelsen said.

The project calls for a 1,210-foot office tower topped with a 300-foot spire and a 477-foot hotel attached by a sky bridge.

Clarke said he is seeking to expand the use of PVC pipe in all residential and commercial construction because builders have repeatedly complained about the cost of using metal pipe. He has met with leaders of the Plumbers Union, Local 690, which has opposed the use of PVC pipe in city construction because it requires fewer workers.

"We know this is near and dear to their heart," said Clarke, who is working to tailor the legislation's language to ease concerns.

John Kane, Local 690's business manager, said his union opposes the legislation but will work on it with Clarke and others in the plumbing industry.

"I think there's a possibility that we might be able to amend it," Kane said. "We're hoping we can compromise."

Council members, now on a holiday break for more than a month, will deal with Clarke's bill when they return in January. *