Preparations are underway to make the Independence Day celebration at Seattle's Gas Works Park a blast.

“There is a grand opening that’s never been seen before. We want to keep it as a surprise, but you want to be here on time for what Seattle Cancer care has put together. The entire evening is put to a Pacific Northwest themed, very patriotic music track that will be simulcast all the way around Lake Union,” said Richard Anderson, president and CEO of Seafair.

For three days, crews have been setting up fireworks that will launch from a barge in Lake Union.

"Thousands of individual rounds, including 10-inch shells," said Heather Gobet, Western Display Fireworks owner. "They will travel 1,000 feet into the air and burst 1,000 feet across."

She says this year's show will include "more intricate single shot items" that can be better timed to the musical program.

Equipment has been brought in to shoot the fireworks in a variety of patterns, including effects that will appear directly on the surface of the lake.

The show is expected to last 20 minutes, but Gobet says planning began almost immediately after last year's Independence Day, because the pyrotechnics need to be ordered nearly a year in advance.

"From there we work with Seafair to develop the musical program, show choreography, and endless logistical details," she said.

Lead pyrotechnician Tom Bates says planning for the fireworks show began in April.

“It’s loud, especially with these walls. It reverberates in here. I’ve never been in the military, but probably like being struck with a mortar or something. I mean it really echoes in here,” Bates said about being the only person on the barge during the show.

This year, the Seattle Cancer Care Alliance Seafair Summer 4th fireworks show will be preceded by a display in appreciation of the Alliance for sponsoring this year's main show.

Seafair recommends walking, biking or using a ride-share company to get to Lake Union. Organizers have created a bike valet for riders and partnered with Uber for discounted rides.