The USS Arizona Memorial visitors center, sinking in the gravel it was built on, is getting propped up with some sizable financial contributions from Hawai'i and the Mainland to build a replacement center.

TriWest Healthcare Alliance, a Phoenix-based corporation that partners with the Defense Department to provide healthcare access to military families, has pledged up to $1 million toward a new $34 million visitors center.

The contribution is being made as part of the Arizona Memorial's "ships and states" fund-raising drive that started in Hawai'i, shifted to Arizona, and next will focus on Nevada and Texas.

"Hawai'i started in June of 2005 and Arizona started a little after, and they've already done spectacularly," said Mathew Sgan, senior vice president of the Arizona Memorial Museum Association and Pearl Harbor Memorial Fund.

Private donations in Hawai'i have nearly reached the $1.5 million goal. First Hawaiian Bank Foundation is contributing a $100,000 grant.

Contributors in Arizona, the namesake state for the battleship that was sunk on Dec. 7, 1941, have put up $1.57 million and are now at the halfway point to the Arizona coordinating committee's fund-raising goal, Sgan said.

Moored along Battleship Row next to Ford Island, the USS Arizona went down with a crew of 1,177 when it was hit in the Japanese surprise attack that launched the United States into World War II.

"The USS Arizona Memorial reminds thousands of people every day of the sacrifices our men and women in uniform make defending our freedom, not only at Pearl Harbor, but also today in Iraq and Afghanistan," said David McIntyre Jr., president of TriWest, which provides access to Tricare — the military's healthcare program — in 21 states including Hawai'i.

The 24,000-square-foot visitors center, built in 1980, is sinking, and basement jacks cannot be raised further. The center was designed to accommodate 750,000 people a year, but draws double that.

Sgan said the award for design plans of a new center is expected to be made in March or April. It will take about 18 months for design and planning. Construction will take another 18 months.

About $15 million in private donations have been made so far. Another $3 million is expected from the state and $7 million from federal funding.

"All of our programs have fulfilled our expectations and we expect we will meet all of our milestones," Sgan said.

Reach William Cole at wcole@honoluluadvertiser.com.