Six years ago, at an event marking the 50th anniversary of what remains the worst submarine disaster in U.S. history, the timing seemed right to galvanize support for a national monument to honor the 129 men lost in the tragedy.

The 50th anniversary captured the public's attention, Kevin Galeaz, who was spearheading the effort, told The Day at the time, so "if we're going to do it, it has got to be now."

The Thresher sank on April 10, 1963, east of Cape Cod after leaving the Portsmouth Naval Shipyard for deep-diving tests.

Now, Galeaz is making plans to unveil the memorial for the crew of the USS Thresher (SSN-593) to be built on the grounds of Arlington National Cemetery in Virginia and have a dedication ceremony this fall. The Secretary of the Army signed off on the project at the start of this year, giving the project the final approval it needed.

“I think of it as a means to perpetuate the memory of the boat and the crew and how it was a springboard for the SUBSAFE program,” said Bruce Harvey, 64, of Wethersfield, whose father, Lt. Cmdr. John W. Harvey, was the commanding officer of the Thresher.

The Thresher was the first nuclear submarine to be lost at sea, and shortly afterward the Navy created a program that developed new submarine safety standards, known as SUBSAFE, that’s still in existence today. No submarine certified under the program has been lost.

Galeaz has proposed that the Thresher memorial be placed on a non-active burial area next to the Space Shuttle Columbia Memorial. Many visitors pass through this area and NASA worked with SUBSAFE to improve safety standards in the space program after Columbia was lost. But the exact site has not yet been determined.

Lori Arsenault, 64, who was just 8 years old when her father, Chief Engineman Tilmon Arsenault, died in the tragedy, said the memorial is less for the families and “more for everybody else.”

“I feel we have an obligation to our nation to remember things like this, to learn from things like this. We can’t just keep it a private tragedy,” Arsenault, who lives in Maine, said by phone Tuesday.

j.bergman@theday.com