WASHINGTON -- Arlington National Cemetery dedicated a new addition Thursday, extending available burial space in the the cemetery, with a ceremony that included the interment of two Union Civil War Soldiers.

The Millennium Project adds 27 acres to Arlington National Cemetery, or ANC, providing 27,282 interment spaces located either above or below ground, said David Fedroff, ANC's deputy chief of engineering, during a media tour of the new area before the 3 p.m. ceremony that also included the naming of two new streets.

MILLENNIUM ADDITION

Of the cemetery's 27,282 new spaces, 16,400 niche spaces are available in five columbaria. Two overlook a steep, wooded ravine with a meandering stream. Two more columbaria are located in a downhill portion of the addition with a view of the Arlington and Washington, D.C. skylines, including the Washington Monument. The final columbarium is in what Fedroff called a "niche wall."

The niche wall's uphill location has an expansive view of the Millennium addition and an old growth forest separating the addition from the rest of ANC.

These are much-needed spaces, Fedroff said. With an average of four to five funerals per hour, ANC would run out of plots by around 2030 without this extra space, which includes Sections 77 to 85 in the northwest area of the cemetery. The extra spaces should extend active burial operations into the early 2040s, he said.

Construction of the Millennium addition began in 2014 with a projected cost of $81.7 million, he said. Of the addition's 27 acres, 12 were transferred from the National Park Service, 9.9 from Joint Base Myer-Henderson Hall, and the remainder was existing ANC land.

CONSTRUCTION CHALLENGE

Greg Hegge, Norfolk District, U.S. Army Corps of Engineers ANC program manager, said that from an engineering perspective, one of the big challenges of the project was the steep terrain, which made roadwork, columbaria construction and landscaping a challenge.

As a result of the steep terrain, periodic storm runoff caused erosion of much of the area and silt buildup in the stream, which bisects the Millennium addition, he said. Extensive work went into restoring the stream and surrounding land.

For example, the stream channel had to be moved in spots, ripple pools were created in others and a manmade but natural-appearing floodplain was created so that silt could be deposited along the banks instead of into the Potomac River, he said.

Landscapers also had their work cut out for them, Hegge noted. Many invasive plant species, like English ivy, were removed from the area around the stream and forest. Thousands of shrubs, trees, flowers and grasses were planted in the unforested areas.

The result of that work is an appearance that is both beautiful as well as tranquil, he offered. And, the beauty will increase as the trees mature. "We want this to be a space where people can come and reflect," he said.

CIVIL WAR SOLDIERS INTERRED

The Millennium addition is on a historic part of the Arlington Estate, said Karen Durham-Aguilera, Army National Military Cemeteries executive director. In 1864, ANC buried its first Civil War Soldier, she said. Now 154 years later, two more are being laid to rest.

"The true cost of the Civil War is a debt that can never be repaid," she added. The two unknown Civil War Soldiers "join a special group and now rest among many others who gave their last full measure of devotion."

The Soldiers were discovered in June at Manassas National Battlefield Park. Historians determined they fought during the Second Battle of Manassas and were killed by Confederate forces in 1862, said P. Daniel Smith, National Park Service deputy director.

Although their identities are unknown, forensic investigators from the Smithsonian Institute determined them to be Union Soldiers, Smith said.

The Soldiers were wrapped in Civil War replica blankets and their handmade, historically accurate Civil War coffins were constructed out of a 90-year-old oak tree from the Manassas battlefield that toppled during a storm.

STREETS HONOR TWO HEROES

Lighthouse keeper Ida Lewis never met Gunnery Sgt. Jonathan W. Gifford. But their names now intersect at two roads in the Millennium addition.

Secretary of the Army Dr. Mark T. Esper and Kathryn Condon, former Army National Military Cemeteries executive director, participated in the unveiling of two street names -- Lewis Drive and Gifford Drive -- in the Millennium addition.

Durham-Aguilera noted that in 1854 Lewis saved the lives of four men whose boat had capsized. "At the time, she was only 12 years old."

Over the course of her lifetime, she rescued many more, becoming "a living legend, at the time, called the bravest woman in America," she said.

This is the first time a street in ANC has been named for a woman, Durham-Aguilera said. Also, as Lewis represented the U.S. Coast Guard in her capacity as a lighthouse keeper, she also is the first of her branch to have a street named at ANC.

Gifford gave his life when he led a counterattack in 2012 that routed the enemy in Afghanistan, saving many lives. He received the Navy Cross posthumously.

This is the first street at ANC named after a Marine, Condon said. Many members of the Gifford family were in attendance at the ceremony.