Eight crewmen.

Five hundred feet of flame-retardant plastic.

And, on wooden racks stretching half the length of a football field, there will be more than 1,400 shells weighing 3,000 pounds.

Welcome to "backstage" for Wednesday night's fireworks show to fill the sky of downtown San Antonio.

"Some of the shells will probably go 150 to 200 feet above the Tower of the Americas," said Michael Walden, vice president of operations for Pyro Shows, the LaFollette, Tenn., company in charge of the show.

The company, responsible for fireworks shows on the National Mall and some 200 other places this Independence Day, was selected by the Greater San Antonio Chamber of Commerce for what is believed to be downtown's first Fourth of July fireworks show in 20 years.

"In order to get them up high enough to where everybody can see the fireworks, you have to use a bigger firework," said Walden, noting that shells up to 8 inches in size will be used in the Stars & Stripes Over San Antonio show.

To prepare for the show, Walden said, he used satellite imagery to mark boundaries and make diagrams. He took into account the layout of the HemisFair Park area, the buildings and trees.

"The big challenge here is finding enough room and enough space that you can meet all the fire codes," he said.

The 9:30 p.m. show, which Walden described as resembling the Washington, D.C., show but about a quarter the size, is a new addition to the city's official Fourth of July celebration at Woodlawn Lake Park, where fireworks will begin at 9 p.m. The fireworks at last year's Woodlawn Lake event were canceled because severe drought left the landscape too dry.

The chamber of commerce is launching the inaugural downtown event as Joint Bases Randolph and Lackland are forgoing the tradition.

"We had some business leaders come to us and say now that the Department of Defense is not able to have the fireworks productions we used to have at the Air Force bases, that it's time for the business community to step up," said Becky Bridges, vice president for image and communications at the chamber. "It really should be this way and not the other way around."

All costs are being covered by corporate sponsors, she said, and the event is free to the public.

"It was time for San Antonio to begin to think in big, big terms," Bridges said. "We wanted to bring it back downtown because access is a little bit better downtown. We don't want it to be in competition with what's going on at Woodlawn. We want it to be complementary."

So as San Antonians load their cars with folding chairs and picnic blankets to stake out a spot to see the dazzling night sky, you can bet pyrotechnics workers are sweating on a slab of pavement near the Tower.

"When we're up in the D.C. area, we usually coordinate box lunches" for the workers, said Catherine Miller, whose job it will be to check on the crew and make sure coolers are kept full of water.

Here, she said, "they may take a longer lunch to get them out of the heat for a while."

mjaffee@express-news.net